Objective Corynebacterium crenatum MT, a mutant from C. crenatum AS 1.542 with a lethal argR gene, exhibits high arginine production. To confirm the effect of ArgR on arginine biosynthesis in C. crenatum, an intact ar...Objective Corynebacterium crenatum MT, a mutant from C. crenatum AS 1.542 with a lethal argR gene, exhibits high arginine production. To confirm the effect of ArgR on arginine biosynthesis in C. crenatum, an intact argR gene from wild-type AS 1.542 was introduced into C. crenatum MT, resulting in C. crenatum MT. sp, and the changes of transcriptional levels of the arginine biosynthetic genes and arginine production were compared between the mutant strain and the recombinant strain. Methods Quantitative real-time polymerase chain reaction was employed to analyze the changes of the related genes at the transcriptional level, electrophoretic mobility shift assays were used to determine ArgR binding with the argCJBDF, argGH, and carAB promoter regions, and arginine production was determined with an automated amino acid analyzer. Results Arginine production assays showed a 69.9% reduction in arginine from 9.01±0.22 mg/mL in C. crenatum MT to 2.71±0.13 mg/mL （P〈0.05） in C. crenatum MT. sp. The argC, argB, argD, argF, argJ, argG, and carA genes were down-regulated significantly in C. crenatum MT. sp compared with those in its parental C. crenatum MT strain. The electrophoretic mobility shift assays showed that the promoter regions were directly bound to the ArgR protein. Conclusion The arginine biosynthetic genes in C crenatum are clearly controlled by the regulator ArgR, and intact ArgR in C. crenatum MT results in a significant descrease in production. negative arginine production.展开更多
Objective: Corynebacterium crenatum AS1.542, a Gram-positive bacterium and indigenous nonpatho-genic corynebacteria, is widely exploited for the in-dustrial production of amino acids. The objective of this paper is to...Objective: Corynebacterium crenatum AS1.542, a Gram-positive bacterium and indigenous nonpatho-genic corynebacteria, is widely exploited for the in-dustrial production of amino acids. The objective of this paper is to clarify the genetic information of the arginine biosynthetic pathway, and further more contribute to the improvement of arginine produc-tion. Methods: Polymerase chain reaction (PCR) technology was employed for obtaining the arginine biosynthetic gene sequence, and softwares eg. Laser-gene, BPROM, RNAshapes were used for the analysis of obtained sequences. Results: Arginine biosynethetic gene cluster of C. crenatum, comprising argJ, argB, argD, argF, argR and part of argC, has been ampli-fied and sequenced. The gene order has been estab-lished as argCJBDFR, with a entire length of 6.08kb. Conclusion: An internal promoter was found in the upstream of argB gene, four argBDFR ORFs are lo-cated in a same transcription unit, and the tran-scripiton termination of argC gene is irrelevant with the rho-factor. Comparison with ornithine acetyl-transferase (coded by argJ gene) from C. glutamate, ornithine acetyltransferase from C. crenatum also belongs to the monofunctional enzymes.展开更多
基金supported by Natural Science Foundation of China,No.1360219 and No.30960012
文摘Objective Corynebacterium crenatum MT, a mutant from C. crenatum AS 1.542 with a lethal argR gene, exhibits high arginine production. To confirm the effect of ArgR on arginine biosynthesis in C. crenatum, an intact argR gene from wild-type AS 1.542 was introduced into C. crenatum MT, resulting in C. crenatum MT. sp, and the changes of transcriptional levels of the arginine biosynthetic genes and arginine production were compared between the mutant strain and the recombinant strain. Methods Quantitative real-time polymerase chain reaction was employed to analyze the changes of the related genes at the transcriptional level, electrophoretic mobility shift assays were used to determine ArgR binding with the argCJBDF, argGH, and carAB promoter regions, and arginine production was determined with an automated amino acid analyzer. Results Arginine production assays showed a 69.9% reduction in arginine from 9.01±0.22 mg/mL in C. crenatum MT to 2.71±0.13 mg/mL （P〈0.05） in C. crenatum MT. sp. The argC, argB, argD, argF, argJ, argG, and carA genes were down-regulated significantly in C. crenatum MT. sp compared with those in its parental C. crenatum MT strain. The electrophoretic mobility shift assays showed that the promoter regions were directly bound to the ArgR protein. Conclusion The arginine biosynthetic genes in C crenatum are clearly controlled by the regulator ArgR, and intact ArgR in C. crenatum MT results in a significant descrease in production. negative arginine production.
文摘Objective: Corynebacterium crenatum AS1.542, a Gram-positive bacterium and indigenous nonpatho-genic corynebacteria, is widely exploited for the in-dustrial production of amino acids. The objective of this paper is to clarify the genetic information of the arginine biosynthetic pathway, and further more contribute to the improvement of arginine produc-tion. Methods: Polymerase chain reaction (PCR) technology was employed for obtaining the arginine biosynthetic gene sequence, and softwares eg. Laser-gene, BPROM, RNAshapes were used for the analysis of obtained sequences. Results: Arginine biosynethetic gene cluster of C. crenatum, comprising argJ, argB, argD, argF, argR and part of argC, has been ampli-fied and sequenced. The gene order has been estab-lished as argCJBDFR, with a entire length of 6.08kb. Conclusion: An internal promoter was found in the upstream of argB gene, four argBDFR ORFs are lo-cated in a same transcription unit, and the tran-scripiton termination of argC gene is irrelevant with the rho-factor. Comparison with ornithine acetyl-transferase (coded by argJ gene) from C. glutamate, ornithine acetyltransferase from C. crenatum also belongs to the monofunctional enzymes.
