A regulatory factor for expression of nitrilase gene and a gene thereof
8 claims: 8 independent, 0 dependent
- 1A two component regulatory factor which activates a nitrilase gene promoter, comprising a polypeptide having the amino acid sequence of SEQ ID No:1 and a polypeptide having the amino acid sequence of SEQ ID No: 2. Facteur régulateur à deux composants qui active un promoteur de gène de nitrilase, comprenant un polypeptide ayant la séquence d'acides aminés de SEQ ID No :1 et un polypeptide ayant la séquence d'acides aminés de SEQ ID No : 2. Zwei Komponenten-Regulationsfaktor, der einen Nitrilasegen-Promotor aktiviert, umfassend ein Polypeptid mit der Aminosäuresequenz von SEQ ID No. 1 und ein Polypeptid mit der Aminosäuresequenz von SEQ ID No. 2.
- 2A regulatory factor according to claim 1 whose activation of the nitrilase gene promoter is enhanced in the presence of a nitrile. Facteur régulateur selon la revendication 1, dont l'activation du promoteur de gène de nitrilase est augmentée en présence d'un nitrile. Regulationsfaktor nach Anspruch 1, dessen Aktivierung des Nitrilasegen-Promotors in Gegenwart eines Nitrils verstärkt ist.
- 4A DNA molecule according to claim 3 which possesses the nucleotide sequences of SEQ ID Nos:3 and 4. DNA-Molekül nach Anspruch 3, das die Nucleotidsequenzen von SEQ ID No. 3 und 4 besitzt. Molécule d'ADN selon la revendication 3, qui possède les séquences nucléotidiques de SEQ ID No : 3 et 4.
- 5A recombinant plasmid containing DNA coding for a regulatory factor of claim 1 or 2, a nitrilase gene containing a promoter region and a DNA region capable of replicating in cells of a microorganism belonging to the genus Rhodococcus. Plasmide recombiné contenant un ADN codant un facteur régulateur selon la revendication 1 ou 2, un gène de nitrilase contenant une région promotrice et une région d'ADN capable de se répliquer dans les cellules d'un micro-organisme appartenant au genre Rhodococcus. Rekombinantes Plasmid, enthaltend DNA, die einen Regulationsfaktor nach Anspruch 1 oder 2 codiert, ein Nitrilasegen, das eine Promotorregion enthält, und eine DNA-Region, die fähig ist zur Replikation in Zellen eines Mikroorganismus der Gattung Rhodococcus.
- 6A recombinant plasmid according to claim 5 wherein the DNA region capable of replicating in cells of a microorganism belonging to the genus Rhodococcus is from plasmid pRCOO1 (ATCC 4276), pRC002 (ATCC 14349), pRC003 (ATCC 14348) or pRC004 (IFO 3338). Plasmide recombiné selon la revendication 5 où la région d'ADN capable de se répliquer dans les cellules d'un micro-organisme appartenant au genre Rhodococcus provient du plasmide pRC001 (ATCC 4276), pRC002 (ATCC 14349), pRC003 (ATCC 14348) ou pRC004 (IFO 3338). Rekombinantes Plasmid nach Anspruch 5, wobei die DNA-Region, die in Zellen eines Mikroorganismus der Gattung Rhodococcus replizieren kann, vom Plasmid pRC001 (ATCC 4276), pRC002 (ATCC 14349), pRC003 (ATCC 14348) oder pRC004 (IFO 3338) stammt.
- 7A microorganism belonging to the genus Rhodococcus transformed with a recombinant plasmid of claim 5 or 6. Micro-organisme appartenant au genre Rhodococcus transformé avec un plasmide recombiné selon la revendication 5 ou 6. Mikroorganismus der Gattung Rhodococcus, transformiert mit einem rekombinanten Plasmid nach Anspruch 5 oder 6.
- 8A process for producing nitrilase, which process comprises:(i) culturing a microorganism of the genus Rhodococcus containing a recombinant DNA molecule encoding the regulatory factor of claim 1 or 2 and a nitrilase gene including its promoter under conditions such that the regulatory factor activates expression of the nitrilase gene;and(ii) recovering nitrilase from the culture. Procédé de production de nitrilase, lequel procédé comprend: (i) la culture d'un micro-organisme du genre Rhodococcus contenant une molécule d'ADN recombiné codant le facteur régulateur selon la revendication 1 ou 2 et un gène de nitrilase incluant son promoteur dans des conditions telles que le facteur régulateur active l'expression du gène de nitrilase;et(ii) la récupération de nitrilase à partir de la culture. Verfahren zur Produktion von Nitrilase, umfassend (i) Züchten eines Mikroorganismus der Gattung Rhodococcus, der ein rekombinantes DNA-Molekül enthält, das den Regulationsfaktor nach Anspruch 1 oder 2 codiert, und ein Nitrilasegen einschließlich seines Promotors, unter Bedingungen, unter denen der Regulationsfaktor die Expression des Nitrilasegens aktiviert;und(ii) Gewinnung der Nitrilase aus der Kultur.
Independent claims8
89 paragraphs in 11 sections, as filed
FIELD OF THE INVENTION
The present invention relates to a regulatory factor involved in expression of a nitrilase gene and a DNA coding for the same and particularly to a regulatory factor derived from the strain <u>Rhodococcus erythropolis</u> SK92 and activating a nitrilase gene promoter, as well as to DNAs coding for the same, a recombinant plasmid containing the DNAs and a transformant transformed with said recombinant plasmid.
BACKGROUND OF THE INVENTION
As known processes of producing organic acids by conversion from their corresponding nitriles, mention may be made of chemical synthetic means and biological means. The latter involves the use of a microorganism or a microorganism-derived enzyme as a catalyst to hydrolyze nitriles, so this means is advantageous in that organic acids can be produced under mild conditions. Microorganisms belonging to the genus <u>Rhodococcus</u> are known as such catalysts for use in production of amides or organic acids by hydration or hydrolysis of their corresponding nitriles (see Japanese Laid-Open Patent Publication Nos. 251,192/1991, 91,189/1987, 470/1990, and 84,198/1990).
As compared with the above-mentioned conventional processes, the use of a nitrilase gene cloned for hydrolysis of nitriles by genetic recombination is expected to drastically improve the catalytic ability of the microorganism to hydrate nitriles because the microorganism can be engineered to contain multiple copies of the same gene. To obtain such a catalyst organism with higher catalytic activity, the present inventors successfully cloned a nitrilase gene from the strain <u>Rhodococcus</u><u>erythropolis</u> SK92 and constructed a plasmid by inserting said gene into a region downstream of an <u>E</u>. <u>coli</u> lactose promoter. By introducing this plasmid into <u>E</u>. <u>coli</u>, the organism came to exhibit higher nitrilase activity during incubation in the presence of IPTG (isopropyl-β -D-thiogalactoside). The present inventors further attempted to obtain a transformant of the genus <u>Rhodococcus</u> to attain higher performance as a catalyst organism. In this attempt, the nitrilase gene was inserted into a <u>Rhodococcus</u>-<u>E.</u><u>coli</u> hybrid plasmid vector (see Japanese Laid-Open Patent Publication Nos. 64,589/1993 and 68,566/1993), and the vector thus constructed was introduced into a microorganism of the genus <u>Rhodococcus.</u> However, no nitrilase activity was expressed, and there is demand for a method of permitting the expression of nitrilase activity in a transformant of the genus <u>Rhodococcus.</u>
SUMMARY OF THE INVENTION
The present inventors speculated that the gene derived from the genus <u>Rhodococcus</u> is not expressed because the promoter for the nitrilase gene fails to function, and that a gene coding for a regulatory factor that allows the promoter to function might be present somewhere on the chromosomal DNA derived from SK92. Through screening, the present inventors found it in a region upstream of the nitrilase structural gene and succeeded thereby in expression of nitrilase activity in a transformant of the genus <u>Rhodococcus</u>.
That is, the present invention relates to a regulatory factor consisting of 2 components i.e. a polypeptide having the amino acid sequence of SEQ ID No: 1 and a polypeptide having the amino acid sequence of SEQ ID No: 2 to activate the nitrilase gene promoter, as well as to DNAs coding for them.
Introduction of the gene coding for the regulatory factor of the invention along with the nitrilase gene containing its promoter permits a microorganism of the genus <u>Rhodococcus</u> to produce nitrilase. More specifically, according to the present invention there is provided a two component regulatory factor which activates a nitrilase gene promoter, comprising a polypeptide having the amino acid sequence of SEQ ID No: 1 and a polypeptide having the amino acid sequence of SEQ ID No: 2.
The invention also provides: <ul id="ul0001" list-style="dash" compact="compact"><li>a DNA molecule encoding a regulatory factor of the invention;</li><li>a recombinant plasmid containing DNA coding for a regulatory factor of the invention, a nitrilase gene containing a promoter region and a DNA region capable of replicating in cells of a microorganism belonging to the genus <u>Rhodococcus;</u></li><li>a microorganism of the genus <u>Rhodococcus</u> transformed with a recombinant plasmid of the invention; and</li><li>a process for producing nitrilase, which process comprises: <ul id="ul0002" list-style="none" compact="compact"><li>(i) culturing a microorganism of the genus <u>Rhodococcus</u> containing a DNA molecule encoding the regulatory factor of the invention and a nitrilase gene including its promoter under conditions such that the regulatory factor activates expression of the nitrilase gene; and</li><li>(ii) recovering nitrilase from the culture.</li></ul></li></ul>
A regulatory factor of the invention may show enhanced activation of the nitrilase gene promoter in the presence of a nitrile. A DNA molecule of the invention may possess the nucleotide sequence of SEQ ID Nos: 3 and 4.
The DNA region capable of replicating in cells of a microorganism belong to the genus <u>Rhodococcus</u> in a recombinant plasmid of the invention may be from plasmid pRC001 (ATCC 4276), pRC002 (ATCC 14349), pRC003 (ATCC 14348) or pRC004 (IFO 3338).
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 shows a schematic drawing of deletion plasmids, where the arrows on the DNA fragment from SK92 indicate the location and direction of the gene coding for the regulatory factor of the invention and the gene coding for nitrilase, respectively.
Fig. 2 shows a restriction enzyme map of recombinant plasmid pSK108.
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention is described in detail. The present invention is practiced in the following steps.
(1) Preparation of chromosomal DNA from the strain SK92:
Chromosomal DNA is isolated from <u>Rhodococcus</u><u>erythropolis</u> SK92.
(2) Construction of a DNA Library:
The chromosomal DNA is cleaved with restriction enzymes, and a DNA fragment containing the target gene is detected by Southern hybridization using the nitrilase gene of SK92 as probe. This fragment is inserted into a hybrid plasmid vector capable of replicating in cells of <u>E.</u><u>coli</u> and the genus <u>Rhodococcus</u> to prepare a library.
(3) Transformation of
E
.
coli
and selection of recombinant DNA:
The recombinant library constructed in step (2) is used to prepare transformants. They are subjected to colony hybridization using the probe obtained in step (2) to select a colony carrying the target recombinant DNA.
(4) Preparation of recombinant plasmid:
A plasmid is prepared from the recombinant obtained in step (3).
(5) Transformation of a microorganism of the genus
Rhodococcus
and the nitrilase activity of the transformant:
The resulting plasmid is introduced into a microorganism of the genus <u>Rhodococcus,</u> and its nitrilase activity is determined.
(6) Deletion plasmids and nitrilase activity:
Deletion plasmids are prepared by deleting various regions from the plasmid obtained in step (4) to identify the region essential for expression of the nitrilase structural gene. The plasmids prepared are not necessary to be capable of replicating in <u>E</u>. <u>coli</u> and are sufficient if they include a DNA region capable of replicating in cells of the genus <u>Rhodococcus.</u>
(7) Nucleotide sequencing:
The nucleotide sequence of the region identified in step (6) is determined.
As the above hybrid plasmid vector, mention may be made of pKl, pK2, pK3 and pK4. These plasmids were introduced into <u>R</u>. <u>rhodochrous</u> ATCC 12674 and have been deposited respectively as <u>R</u>. <u>rhodochrous</u> ATCC 12674/pK1 (FERM BP-3728), <u>R</u>. <u>rhodochrous</u> ATCC 12674/pK2 (FERM BP-3729), <u>R</u>. <u>rhodochrous</u> ATCC 12674/pK3 (FERM BP-3730) and <u>R</u>. <u>rhodochrous</u> ATCC 12674/pK4 (FERM BP-3731) with the National Institute of Bioscience and Human-Technology, Agency of Industrial Science and Technology, Japan (see Japanese Laid-Open Patent Publication No. 68,556/1993).
As the above DNA region capable of replicating in cells of the genus <u>Rhodococcus,</u> mention may be made of those derived from plasmids pRC001, pRC002, pRC003 and pRC004, and these may be the whole of the plasmid or a partial fragment thereof. The above plasmids are derived respectively from the strains <u>R</u>. <u>rhodochrous</u> ATCC 4276, ATCC 14349, ATCC 14348 and IFO 3338 (see Japanese Laid-Open Patent Publication No. 68,556/1993).
<u>Rhodococcus</u><u>erythropolis</u> SK92 has been deposited as FERM BP-3324 with the Fermentation Research Institute, Agency of Industrial Science and Technology. Plasmid pSK108 containing the nitrilase gene and the regulatory gene has been deposited as transformant JM109/pSK108 (FERM BP-5322) carrying said plasmid pSK108, with the National Institute of Bioscience and Human-Technology, Agency of Industrial Science and Technology. The strain SK92 was previously identified as belonging to the genus <u>Rhodococcus</u> on the basis of its bacterial properties (see Japanese Laid-Open Patent Publication No. 280,889/1991). This organism is further identified as <u>Rhodococcus</u><u>erythropolis</u> on the basis of the following detailed properties: <tables id="tabl0001" num="0001"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col1" align="left">ITEMS EXAMINED</entry><entry namest="col2" nameend="col2" align="center">RESULTS</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">decomposition of adenine</entry><entry namest="col2" nameend="col2" align="center">+</entry></row><row><entry namest="col1" nameend="col1" align="left">decomposition of tyrosine</entry><entry namest="col2" nameend="col2" align="center">+</entry></row><row><entry namest="col1" nameend="col1" align="left">decomposition of urea</entry><entry namest="col2" nameend="col2" align="center">+</entry></row><row><entry namest="col1" nameend="col1" align="left">utilization</entry><entry namest="col2" nameend="col2" /></row><row><entry namest="col1" nameend="col1" align="left"> inositol</entry><entry namest="col2" nameend="col2" align="center">+</entry></row><row><entry namest="col1" nameend="col1" align="left"> maltose .</entry><entry namest="col2" nameend="col2" align="center">-</entry></row><row><entry namest="col1" nameend="col1" align="left"> mannitol</entry><entry namest="col2" nameend="col2" align="center">+</entry></row><row><entry namest="col1" nameend="col1" align="left"> rhamnose</entry><entry namest="col2" nameend="col2" align="center">-</entry></row><row><entry namest="col1" nameend="col1" align="left"> sorbitol</entry><entry namest="col2" nameend="col2" align="center">+</entry></row><row><entry namest="col1" nameend="col1" align="left"> sodium m-hydroxy-benzoate</entry><entry namest="col2" nameend="col2" align="center">-</entry></row><row><entry namest="col1" nameend="col1" align="left"> sodium benzoate</entry><entry namest="col2" nameend="col2" align="center">+</entry></row><row><entry namest="col1" nameend="col1" align="left"> sodium citrate</entry><entry namest="col2" nameend="col2" align="center">+</entry></row><row><entry namest="col1" nameend="col1" align="left"> sodium lactate</entry><entry namest="col2" nameend="col2" align="center">+</entry></row><row><entry namest="col1" nameend="col1" align="left"> testosterone</entry><entry namest="col2" nameend="col2" align="center">+</entry></row><row><entry namest="col1" nameend="col1" align="left"> acetamide</entry><entry namest="col2" nameend="col2" align="center">+</entry></row><row><entry namest="col1" nameend="col1" align="left"> sodium pyruvate</entry><entry namest="col2" nameend="col2" align="center">+</entry></row><row><entry namest="col1" nameend="col1" align="left">growth in the presence of 0.02 % sodium azide</entry><entry namest="col2" nameend="col2" align="center">+</entry></row><row><entry namest="col1" nameend="col1" align="left">growth at 10 °C</entry><entry namest="col2" nameend="col2" align="center">+</entry></row><row><entry namest="col1" nameend="col1" align="left">growth at 40 °C</entry><entry namest="col2" nameend="col2" align="center">-</entry></row><row><entry namest="col1" nameend="col1" align="left">growth in the presence of 0.001 % crystal violet</entry><entry namest="col2" nameend="col2" align="center">-</entry></row><row><entry namest="col1" nameend="col1" align="left">growth in the presence of 0.3 % phenyl ethanol</entry><entry namest="col2" nameend="col2" align="center">-</entry></row><row><entry namest="col1" nameend="col1" align="left">growth in the presence of 5 % NaCl</entry><entry namest="col2" nameend="col2" align="center">+</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">growth in the presence of 7 % NaCl</entry><entry namest="col2" nameend="col2" align="center">+</entry></row></tbody></tgroup></table></tables>
EXAMPLES
Hereinafter, the present invention will be illustrated in detail by reference to the following examples which however are not intended to limit the scope of the invention.
Cloning of the nitrilase gene from SK92 and the expression thereof in <u>E</u>. <u>coli</u> and <u>Rhodococcus</u> will be further illustrated in Reference Example.
(1) Preparation of chromosomal DNA from SK92
The strain SK92 was incubated at 30 °C for 72 hours under shaking in 100 ml MY medium (0.5 % polypeptone, 0.3 % Bacto-yeast extract, 0.3 % Bacto-molt extract). The cells were harvested and the pellet was suspended in 4 ml Saline-EDTA solution (0.1 M EDTA, 0.15 M NaCl, pH 8.0). 8 mg of lysozyme were added to the suspension. The suspension was incubated at 37 °C for 1 to 2 hours under shaking and then frozen. Then, 10 ml of Tris-SDS solution (1 % SDS, 0.1 M NaCl, 0.1 M Tris, pH 9.0) was added to it under gentle shaking, followed by addition of proteinase K (Merk) to a final concentration of 0.1 mg/ml. The mixture was incubated under shaking at 37 °C for 1 hour and then at 60 °C. An equal amount of phenol saturated with TE (TE: 10 mM Tris, 1 mM EDTA, pH 8.0) was added to the mixture, stirred, and centrifuged. A 2-fold excess amount of ethanol was added to the upper layer, and the DNA was recovered using a glass rod. The phenol was removed successively with 90 %, 80 % and 70 % ethanol. Then, the DNA was dissolved in 3 ml TE buffer, and a solution of ribonuclease A (previously treated by heating at 100 °C for 15 min.) was added to it in an amount of 10 <i>µ</i> g/ml. The mixture was incubated at 37 °C for 30 minutes under shaking, followed by addition of proteinase K. The mixture was incubated at 37 °C for 30 minutes under shaking. An equal amount of TE-saturated phenol was added to the mixture, and it was separated by centrifugation into upper and lower layers. The upper layer was subjected twice to the same procedure, followed by the same procedure of extraction with an equal amount of chloroform containing 4 % isoamyl alcohol (these procedures are referred to hereinafter as phenol treatment). Then, a 2-fold excess amount of ethanol was added to the upper layer and the DNA was recovered with a glass rod whereby the chromosomal DNA was obtained.
(2) Construction of a DNA library
10 <i>µ</i> l plasmid pSK002 prepared by inserting into vector pUC118 a DNA fragment containing the nitrilase gene from the strain SK92 (see Reference Example) was cleaved at 37 °C for 2 hours with a mixture of 2 <i>µ</i> l of restriction enzyme <u>Sac</u> I, 10 <i>µ</i> l of the reaction buffer (10-fold conc.), and 78 <i>µ</i> l of sterilized water, and the digest was electrophoresed on 0.7 % agarose gel to separate an <u>Sal</u> I fragment, 1.1 kb long.
Separately, the chromosomal DNA from SK92 obtained in step (1) was digested with <u>Eco</u> RI, electrophoresed on agarose gel and subjected to Southern hybridization where the above 1.1 kb <u>Sac</u> I fragment, labeled using a DIG DNA Labeling Kit (Boehringer Mannheim), was used as the probe (Southern E.M., Mol. Bionl. <u>98,</u> 503 (1975)) to detect an about 14 kb DNA fragment. A DNA fraction containing the 14 kb fragment hybridized with the probe was cut off from the agarose gel and then inserted into a separately prepared <u>Eco</u> RI-cleaved hybrid plasmid vector pK4 (FERM BP-3731 containing plasmid pRC004 from the genus <u>Rhodococcus</u> and vector pHSG299 from <u>E</u>. <u>coli</u> (see Japanese Laid-Open Patent Publication Nos. 64,589/1993 and 68,566/1993)).
The above pK4 fragment used as vector was prepared as follows: 10 <i>µ</i> l of the reaction buffer (10-fold conc.), 77 <i>µ</i> l of sterilized water and 2 <i>µ</i> l of restriction enzyme <u>Eco</u> RI were added to 10 <i>µ</i> l of vector pK4. The mixture was allowed to react at 37 °C for 2 hours, then treated with phenol, precipitated with ethanol, dried, and dissolved in 50 <i>µ</i> l sterilized water. 1 <i>µ</i> l of alkaline phosphatase (Takara Shuzo Co., Ltd.), 10 <i>µ</i> l of the reaction buffer (10-fold conc.) and 39 <i>µ</i> l of sterilized water were added to it. The mixture was allowed to react at 65 °C, treated with phenol, precipitated with ethanol, dried, and dissolved in sterilized water.
As described above, 1 <i>µ</i> l of the above DNA fraction containing the 14 kb fragment was inserted into the above <u>Eco</u> RI-cleaved pK4 by overnight reaction at 4°C using a ligation kit (Takara Shuzo Co., Ltd.) to prepare a DNA library.
(3) Transformation of
E
.
coli
and selection of recombinant DNA
<u>E</u>. <u>coli</u> JM109 (available from Takara Shuzo Co., Ltd.) was inoculated into 1 ml of LB medium (1 % Bacto-trypton extract, 0.5 % Bacto-yeast extract, 0.5 % NaCl) and pre-incubated at 37 °C for 5 hours. 100 <i>µ</i> l of the culture was inoculated into 50 ml of SOB medium (2 % Bacto-trypton, 0.5 % Bacto-yeast extract, 10 mM NaCl, 2.5 mM KCl, 1 mM MgSO4, 1 mM MgCl2) and incubated at 18 °C for 20 hours. The cells were recovered by centrifugation, and the pellet was suspended in 13 ml cold TF solution (20 mM PIPES-KOH, pH 6.0, 200 mM KCl, 10 mM CaCl<sub>2</sub>, 40 mM MnCl<sub>2</sub>), allowed to stand at 0 °C for 10 minutes and centrifuged again. After the supernatant was removed, the <u>E</u>. <u>coli</u> pellet was suspended in 3.2 ml of cold TF solution, followed by addition of 0.22 ml dimethyl sulfoxide. The suspension was allowed to stand at 0 °C for 10 minutes. 10 <i>µ</i> l of the recombinant plasmid (DNA library) prepared in step (2) was added to 200 <i>µ</i> l of the competent cells thus prepared. The mixture was incubated at 0 °C for 30 minutes, then heat-shocked at 42 °C for 30 seconds and cooled at 0 °C for 2 minutes, followed by addition of 0.8 ml of SOC medium (2 % Bacto-trypton, 0-5 % Bacto-yeast extract, 20 mM glucose, 10 mM NaCl, 2.5 mM KCl, 1 mM MgSO<sub>4</sub>, 1 mM MgCl<sub>2</sub>). The mixture was incubated at 37 °C for 60 minutes under shaking. The culture was plated in an amount of 200 <i>µ</i> l per plate on LB agar medium containing 100 <i>µ</i> g/ml ampicillin. The plate was incubated at 37 °C. Selection of transformants carrying the nitrilase gene from the colonies grown on the plate was carried out by colony hybridization in the following manner. The colonies grown on the plate were transferred to a nylon membrane [Biodyne A (trademark) produced by Nippon Paul] and the microorganisms were lysed. The DNA was fixed on the membrane and then hybridized with the probe (1.1 kb fragment) constructed in step (2), and the colony containing the target recombinant DNA was selected using a DIG Luminescent Detection Kit (trademark) (Boehringer Mannheim).
(4) Preparation of recombinant plasmid
The transformant selected in step (3) was incubated at 37 °C overnight in 100 ml of LB medium, and the cells were harvested and washed with sterilized water. 5 ml of solution I (2 mM glucose, 10 mM EDTA, 25mM Tris-HCl buffer, pH 8.0) and 25 mg lysozyme were added to the cells. It was allowed to stand at 0 °C for 30 minutes. 10 ml of solution II (1 N NaOH, 5 % SDS) was added thereto, and the mixture was allowed to stand at 0 °C for 5 minutes. 7.5 ml of solution III (3 M sodium acetate, pH 4.8) was added thereto, and the mixture was allowed to stand at 0 °C for 30 minutes and centrifuged. 50 ml ethanol was added to the supernatant. It was centrifuged again to remove the supernatant. 5 ml of solution IV (10 mM sodium acetate, 50 mM Tris-HCl buffer, pH 8.0) and 2.5 <i>µ</i> l of 10 mg/ml ribonuclease A were added thereto. The mixture was allowed to stand at room temperature for 20 minutes, followed by addition of 12 ml ethanol. It was centrifuged, dried, and dissolved in sterilized water.
(5) Transformation of a microorganism of the genus
Rhodococcus
, and the nitrilase activity of the transformant
<u>Rhodococcus</u><u>rhodochrous</u> ATCC 12674 at the logarithmic growth phase was harvested by centrifugation, washed 3 times with ice-cold sterilized water and suspended in sterilized water. 1 <i>µ</i> g of plasmid pSK104 obtained in step (4) was mixed with 10 <i>µ</i> l of the cell suspension, and the mixture was cooled on ice. This mixture of the DNA and the microorganism was introduced into the chamber in a electroporation apparatus CET-200 (Japan Spectroscopic Co., Ltd.), and the sample was pulsed 20 times with a density of electric field of 3.8 kV/cm and a pulse width of 1 ms. The cell suspension thus treated was placed on ice for 10 minutes and heat-shocked at 37 °C for 10 minutes. 500 <i>µ</i> l of MYK medium (0.5 % polypeptone, 0.3 % Bacto-moit extract, 0.3 % Bacto-yeast extract, 0.2 % KH<sub>2</sub> PO<sub>4</sub>, 0.2 % K<sub>2</sub> HPO<sub>4</sub> (pH 7.0)) was added thereto. The cell suspension was then incubated at 26 °C for 3 hours under shaking. The suspension was plated on an MYK agar plate containing 75 <i>µ</i> g/ml kanamycin and incubated at 26 °C for 3 days.
The resultant transformant of the genus <u>Rhodococcus</u> was inoculated into 10 ml MYK medium containing 50 <i>µ</i> g/ml kanamycin and pre-incubated at 30 °C for 24 hours. 1 ml of the culture was added to 100 ml of GGP medium (1.5 % glucose, 0.1 % Bacto-yeast extract, 1.0 % sodium glutamate, 0.05 % KH<sub>2</sub> PO<sub>4</sub>, 0.05 % K<sub>2</sub> HPO<sub>4</sub>, 0.05 % MgSO<sub>4</sub> 7H<sub>2</sub>O (pH 7.2)) containing 1.5 % ethylene cyanohydrin (ECH) as inducer and 75 <i>µ</i> g/ml kanamycin. The microorganism was incubated at 30 °C for 48 hours and harvested, and the pellet was suspended in 50 mM phosphate buffer, pH 7.7, and a part of the suspension was allowed to react at 30 °C for 20 minutes in 50 mM phosphate buffer, pH 7.7, containing 100 mM acrylonitrile. The reaction was stopped by addition of 1 N HCl, and the. amount of acrylic acid formed in the reaction solution was determined by high performance liquid chromatography (HPLC). The result indicated the formation of 8 mM acrylic acid in the transformant ATCC 12674/pSK104. It was revealed that the gene coding for the regulatory factor necessary for expression of nitrilase is present upstream or downstream of the structural gene of nitrilase.
(6) Deletion plasmids and nitrilase activity
Because pSK104 was estimated to still contain a number of regions not required for expressing nitrilase, various deletion plasmids were prepared therefrom. Microorganisms transformed with the deletion plasmids were examined for their nitrilase activity (Table 1, Fig. 1). <tables id="tabl0002" num="0002"><table frame="all"><title>Table 1.</title><tgroup cols="3" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="52.50mm" /><colspec colnum="2" colname="col2" colwidth="52.50mm" /><colspec colnum="3" colname="col3" colwidth="52.50mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col3" align="center">Deletion plasmids and formation of acrylic acid</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" rowsep="0" /><entry namest="col2" nameend="col3" align="center">amount of formed acrylic acid (mM)</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" rowsep="0" /><entry namest="col2" nameend="col3" align="center">inducer (ECH)</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" /><entry namest="col2" nameend="col2" align="center">absent</entry><entry namest="col3" nameend="col3" align="center">present</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="right">1) pSK102</entry><entry namest="col2" nameend="col2" align="char" char=".">0</entry><entry namest="col3" nameend="col3" align="char" char=".">0</entry></row><row><entry namest="col1" nameend="col1" align="right">2) pSK104</entry><entry namest="col2" nameend="col2" align="char" char=".">0.77</entry><entry namest="col3" nameend="col3" align="char" char=".">8.00</entry></row><row><entry namest="col1" nameend="col1" align="right">3) pSK105</entry><entry namest="col2" nameend="col2" align="char" char=".">0</entry><entry namest="col3" nameend="col3" align="char" char=".">1.71</entry></row><row><entry namest="col1" nameend="col1" align="right">4) pSK123</entry><entry namest="col2" nameend="col2" align="char" char=".">0</entry><entry namest="col3" nameend="col3" align="char" char=".">0</entry></row><row><entry namest="col1" nameend="col1" align="right">5) pSK124</entry><entry namest="col2" nameend="col2" align="char" char=".">0</entry><entry namest="col3" nameend="col3" align="char" char=".">0</entry></row><row><entry namest="col1" nameend="col1" align="right">6) pSK106</entry><entry namest="col2" nameend="col2" align="char" char=".">1.14</entry><entry namest="col3" nameend="col3" align="char" char=".">6.38</entry></row><row><entry namest="col1" nameend="col1" align="right">7) pSK107</entry><entry namest="col2" nameend="col2" align="char" char=".">0</entry><entry namest="col3" nameend="col3" align="char" char=".">3.40</entry></row><row><entry namest="col1" nameend="col1" align="right">8) pSK125</entry><entry namest="col2" nameend="col2" align="char" char=".">0</entry><entry namest="col3" nameend="col3" align="char" char=".">0</entry></row><row><entry namest="col1" nameend="col1" align="right">9) pSK126</entry><entry namest="col2" nameend="col2" align="char" char=".">0</entry><entry namest="col3" nameend="col3" align="char" char=".">0</entry></row><row><entry namest="col1" nameend="col1" align="right">10) pSK127</entry><entry namest="col2" nameend="col2" align="char" char=".">0</entry><entry namest="col3" nameend="col3" align="char" char=".">0</entry></row><row><entry namest="col1" nameend="col1" align="right">11) pSK109</entry><entry namest="col2" nameend="col2" align="char" char=".">0</entry><entry namest="col3" nameend="col3" align="char" char=".">0</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="right">12) pSK108</entry><entry namest="col2" nameend="col2" align="char" char=".">0</entry><entry namest="col3" nameend="col3" align="char" char=".">8.05</entry></row></tbody></tgroup></table></tables>
As is evident from the table, ATCC12674/pSK108 (6.2 kb <u>Hind</u>III-<u>Eco</u>RV fragment) (FIG. 2) is of high nitrilase activity.
Additional deletion plasmids were constructed and examined for the gene coding for the regulatory factor. The result revealed that the gene is located within a far upstream region (about 3 kb <u>Bam</u>HI-<u>Eco</u>RV fragment) from the structural gene of nitrilase.
(7) Nucleotide sequencing
The gene coding for the regulatory factor essential for expression of nitrilase, revealed in step (6), was sequenced using Fluorescence Sequencer ALFII (Pharmacia). The sequence analysis revealed the nucleotide sequence of SEQ ID No: 5, and the presence of 2 open reading frames coding respectively for the amino acid sequences of SEQ ID Nos: 1 and 2 was found. Comparison with Amino Acid Sequence Data Base NBRF (National Biomedical Research Foundation) suggested that the regulatory factor belongs to a family of two-component regulators. The nucleotide sequences of these open reading frames are shown in SEQ ID Nos: 3 and 4.
Reference Example
(1) Preparation of the chromosomal DNA from the strain SK92
The chromosomal DNA from SK92 was prepared in the same manner as in Example, step (1).
(2) Preparation of a probe and construction of a DNA library.
Polymerase chain reaction was carried out using 100 <i>µ</i> l solution containing 10 <i>µ</i> l of DNA as substrate (diluted 20-fold), 10 <i>µ</i>l of the reaction buffer (10-fold conc.), 4 <i>µ</i>l of 5 mM dNTP, 5 <i>µ</i>l (500 pmol) each of 5'-AACTGCTGGGA(AG)CACTTCCA-3' as primer #1 (20 nucleotides corresponding to the amino acid sequence NCWEHFQ) and 5'-GA(AG)TA(AG) TG(AG)CC(CG)AC(ACTG)GG(AG)TC-3'as primer #2 (20 nucleotides corresponding to the amino acid sequence DPVGHYS), and 1 <i>µ</i> l of Tth DNA polymerase (Toyo Boseki). The above 2 primers were prepared on the basis of amino acid sequences having high homologies with known various nitrilases. The reaction involved 50 cycles each consisting of the incubation of the sample at 93 °C for 30 seconds (denaturation step), 45 °C for 30 seconds (annealing step) and 72 °C for 2 minutes (elongation step). A 410 bp DNA fragment coding for the nitrilase from SK92 was obtained from the reaction solution. This DNA fragment was labeled as probe using a DIG DNA Labeling Kit (trademark) (Boehringer Mannheim).
10 <i>µ</i> l of the reaction buffer (10-fold conc.), 37 <i>µ</i> l of sterilized water and 3 <i>µ</i> l of restriction enzyme <u>Sal</u> I were added to 50 <i>µ</i> l of the chromosomal DNA from SK92. The mixture was allowed to react at 37 °C for 2 hours, then precipitated with ethanol and electrophoresed on agarose gel. A DNA fragment, about 1.1 kb, was recovered using DNA PREP (trademark) (DIA-IATRON). The DNA fragment was inserted into the <u>Sal</u> I site of <u>E</u>. <u>coli</u> vector pUC118 using a ligation kit (Takara Shuzo Co., Ltd.) whereby a recombinant DNA library was prepared.
The above pUC118 fragment was prepared in the following manner. 10 <i>µ</i> l of the reaction buffer (10-fold conc.), 77 <i>µ</i> l of sterilized water and 2 <i>µ</i> l of restriction enzyme <u>Sal</u> I were added to 10 <i>µ</i> l of pUC118. The mixture was allowed to react at 37 °C for 2 hours, then treated with phenol, precipitated with ethanol, dried, and dissolved in 50 <i>µ</i> l of sterilized water. 1 <i>µ</i> l of alkaline phosphatase (Takara Shuzo Co., Ltd.), 10 <i>µ</i> l of the reaction buffer (10-fold conc.) and 39 <i>µ</i> l of sterilized water were added thereto. The sample solution was allowed to react at 65 °C, treated with phenol, precipitated with ethanol, dried, and dissolved in sterilized water.
(3) Transformation of
E
.
coli
and selection of recombinant DNA
Competent cells of <u>E</u>. <u>coli</u> JM109 were prepared in the same manner as in Example, step (3). 10 <i>µ</i> l solution (DNA library) containing the recombinant plasmid prepared in step (2) was added to 200 <i>µ</i> l of the competent cells. The cells were allowed to stand at 0 °C for 30 minutes, then heat-shocked at 42 °C for 30 seconds and cooled at 0 °C for 2 minutes. 0.8 ml of SOC medium was added thereto, and the cells were incubated at 37 °C for 60 minutes under shaking. The culture was plated in an amount of 200 <i>µ</i> l per plate onto LB agar medium containing 100 <i>µ</i> g/ml ampicillin, followed by incubation at 37 °C. Selection of a transformant carrying the- nitrilase gene from the colonies grown on the agar medium was carried out by colony hybridization in the following manner. The transformants grown on the agar medium were transferred to a nylon membrane [Biodaine A (trademark) produced by Paul Co., Ltd.] and they were lysed to fix DNA. The DNA was treated with the probe (410 bp fragment) prepared in step (2), and the colony containing the target recombinant DNA was selected using a DIG Luminescent Detection Kit (trademark) (Boehringer Mannheim).
(4) Construction of recombinant plasmids and preparation of a restriction enzyme map
The transformant selected in step (3) was treated in the same manner as in Example, step (4). The recombinant plasmid pSK002 thus obtained was cleaved with several restriction enzymes to prepare a restriction enzyme map.
(5) Production of nitrilase by transformed
E
.
coli
and conversion of a nitrile into an acid
The JM109/pSK002 strain was inoculated into 1 ml of 2× YT medium (1.6 % Bacto-trypton, 1.0 Bacto-yeast extract, 0.5 % Nacl) containing 50 <i>µ</i> g/ml ampicillin and incubated at 37 °C for 8 hours. 1 ml of the culture was inoculated into 100 ml of 2 × YT medium containing 50 <i>µ</i> g/ml ampicillin and 1 mM IPTG, followed by incubation at 37 °C for 14 hours. After harvested, the microorganisms were suspended in 50 mM phosphate buffer, pH 7.7, and a part of the suspension was allowed to react at 30 °C for 20 minutes in 50 mM phosphate buffer, pH 7.7, containing 100 mM acrylonitrile. The reaction was stopped by addition of 1 N HCl, and the amount of acrylic acid formed in the reaction solution was determined by HPLC. In the control test, the strain JM109 before transformation was used. The result indicates that while no acrylic acid was detected in the host JM109, the formation of 18 mM acrylic acid was found in the transformant JM109/pSK002.
(6) Introduction of the DNA fragment containing the nitrilase gene into a hybrid plasmid vector
A DNA fragment (5.8 kb <u>Bg</u>III-<u>Hind</u>III fragment) containing the nitrilase structural a gene and a region speculated to contain its promoter were cloned into hybrid plasmid vector pK4 whereby plasmid pSK 120 was constructed.
(7) Transformation of a microorganism of the genus
Rhodococcus
and the nitrilase activity of the transformant
<u>Rhodococcus</u><u>rhodochrous</u> ATCC 12674 at the logarithmic growth phase was harvested by centrifugation, washed 3 times with ice-cold sterilized water, and suspended in sterilized water. 10 <i>µ</i> g cell suspension was mixed with 1 g g of plasmid pSK120 obtained in step (6), and the mixture was then cooled on ice. This mixture of the DNA and the microorganism was introduced into the chamber in a gene-introducing unit CET-200 (Nippon Bunko) where the sample was pulsed 20 times with a density of electric field of 3.8 kV/cm and a pulse width of 1ms.
The cell suspension thus treated was placed on ice for 10 minutes and heat-shocked at 37 °C for 10 minutes. 500 <i>µ</i> l of MYK medium was added to the suspension and the mixture was then incubated at 26 °C for 3 hours under shaking. The culture was plated onto MYK agar medium containing 75 <i>µ</i> g/ml kanamycin and incubated at 26 °C for 3 days.
The thus obtained transformant of the genus <u>Rhodococcus</u> was inoculated into 10 ml MYK medium containing 50 <i>µ</i> g/ml kanamycin and pre-incubated at 30 °C for 24 hours. 1 ml of the culture was added to 100 ml of GGP medium containing 75 <i>µ</i> g/ml kanamycin. 1.5 % ECH was added thereto as inducer. The transformant was incubated at 30 °C for 48 hours. After recovered, the cells were suspended in 50 mM phosphate buffer, pH 7.7, and their nitrilase activity was examined in the same manner as in step (5). No activity was found in it.
SEQUENCE LISTING
<ul id="ul0003" list-style="none" compact="compact"><li>SEQ ID No: 1</li><li>LENGTH: 244</li><li>TYPE: amino acid</li><li>TOPOLOGY: linear</li><li>MOLECULAR TYPE: protein</li><li>ORIGINAL SOURCE</li><li>ORGANISM: <u>Rhodococcus</u><u>erythropolis</u></li><li>STRAIN: SK92</li><li>SEQUENCE:<img file="EP0719862B1_D0001.tif" /><img file="EP0719862B1_D0002.tif" /></li></ul><ul id="ul0004" list-style="none" compact="compact"><li>SEQ ID No: 2</li><li>LENGTH: 534</li><li>TYPE: amino acid</li><li>TOPOLOGY: linear</li><li>MOLECULAR TYPE: protein</li><li>ORIGINAL SOURCE</li><li>ORGANISM: <u>Rhodococcus</u><u>erythropolis</u></li><li>STRAIN: SK92</li><li>SEQUENCE:<img file="EP0719862B1_D0003.tif" /><img file="EP0719862B1_D0004.tif" /><img file="EP0719862B1_D0005.tif" /><img file="EP0719862B1_D0006.tif" /></li></ul><ul id="ul0005" list-style="none" compact="compact"><li>SEQ ID No: 3</li><li>LENGTH: 735</li><li>TYPE: nucleic acid</li><li>STRANDEDNESS: double</li><li>TOPOLOGY: linear</li><li>ORIGINAL SOURCE</li><li>ORGANISM: <u>Rhodococcus</u><u>erythropolis</u></li><li>STRAIN: SK92</li><li>SEQUENCE:<img file="EP0719862B1_D0007.tif" /><img file="EP0719862B1_D0008.tif" /></li></ul><ul id="ul0006" list-style="none" compact="compact"><li>SEQ ID No: 4</li><li>LENGTH: 1605</li><li>TYPE: nucleic acid</li><li>STRANDEDNESS: double</li><li>TOPOLOGY: linear</li><li>ORIGINAL SOURCE</li><li>ORGANISM: <u>Rhodococcus</u><u>erythropolis</u></li><li>STRAIN: SK92</li><li>SEQUENCE:<img file="EP0719862B1_D0009.tif" /><img file="EP0719862B1_D0010.tif" /><img file="EP0719862B1_D0011.tif" /></li></ul><ul id="ul0007" list-style="none" compact="compact"><li>SEQ ID No: 5</li><li>LENGTH: 2336</li><li>TYPE: nucleic acid</li><li>STRANDEDNESS: double</li><li>TOPOLOGY: linear</li><li>ORIGINAL SOURCE</li><li>ORGANISM: <u>Rhodococcus</u><u>erythropolis</u></li><li>STRAIN: SK92</li><li>SEQUENCE:</li></ul><img file="EP0719862B1_D0012.tif" /><img file="EP0719862B1_D0013.tif" /><img file="EP0719862B1_D0014.tif" /><img file="EP0719862B1_D0015.tif" /><img file="EP0719862B1_D0016.tif" />
Contents11
18 sheets
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Every citation, both waysCites: the store holds 1 of 2
| Document | Relation | Office |
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| EP0502476A | Cites | European Patent Office (EPO) |
13 members in 7 offices
Priority claims5
| Document | Office | Kind | Date |
|---|---|---|---|
| 33765294 | Japan | A | |
| 33765294 | Japan | A | |
| 33765294 | Japan | – | |
| 33765294 | – | – | – |
| JP19940337652 | – | – | – |
Members13
| Document | Office | Kind | |
|---|---|---|---|
| EP0719862A2 | European Patent Office (EPO) | A2 | |
| JPH08173169A | Japan | A | |
| KR960023057A | Republic of Korea | A | |
| CN1133341A | China | A | |
| US5602014A | United States of America | A | |
| EP0719862A3 | European Patent Office (EPO) | A3 | |
| TW387895B | Taiwan Province of China | B | |
| JP3154633B2 | Japan | B2 | |
| EP0719862B1This record | European Patent Office (EPO) | B1 | |
| DE69522192D1 | Germany | D1 | |
| CN1080306C | China | C | |
| DE69522192T2 | Germany | T2 | |
| KR100358532B1 | Republic of Korea | B1 |
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Numbers
- Publication
- 0719862
- Publication, DOCDB
- 0719862
- Publication, EPODOC
- EP0719862
- Application
- 95309454
- Application, DOCDB
- 95309454
- Application, EPODOC
- EP19950309454
Titles3
- German
- Regulierende Faktor für die Expression des Nitrilasegens und ein entsprechendes Gen
- English
- A regulatory factor for expression of nitrilase gene and a gene thereof
- French
- Facteur régulateur de l'expression du gène de nitrilase et un gène le codant
Classification
- CPC, 5
- C12N9/78
- C12N15/11
- C07K14/195
- C12N15/74
- C12N15/63
- IPC, 7
- C12N15 09
- C07K14 195
- C12N1 21
- C12N9 78
- C12N15 31
- C12N15 74
- C12R1 01
Designated states5
- Contracting states, 5
- Switzerland
- Germany
- France
- United Kingdom
- Liechtenstein
