A role of the transcriptional regulator LldR (NCgl2814) in glutamate metabolism under biotin-limited conditions in Corynebacterium glutamicum

The Journal of General and Applied Microbiology

Masaaki Wachi¹  Tanyanut Supkulsutra¹  Tomoya Maeda¹  Kosuke Kumagai¹ 

[1] Department of Bioengineering, Tokyo Institute of Technology

关键词: Corynebacterium glutamicum;    L-glutamate;    L-lactate;    lactate dehydrogenase;    LdhA;    LldD;    LldR;   

DOI  :  10.2323/jgam.59.207

学科分类：微生物学和免疫学

来源: Applied Microbiology, Molecular and Cellulrar Biosciences Research Foundation

【 摘 要 】

Corynebacterium glutamicum is a Gram-positive, rod-shaped, aerobic bacterium used for the fermentative production of L-glutamate. LldR (NCgl2814) is known as a repressor for ldhA and lldD encoding lactate dehydrogenases. LdhA is responsible for production of L-lactate, while LldD is for its assimilation. Since L-lactate production was observed as a by-product of glutamate production under biotin-limited conditions, LldR might play a regulatory role in the glutamate metabolism. Here for the first time, we investigated effects of overproduction or deletion of LldR on the glutamate metabolism under biotin-limited conditions in C. glutamicum. It was found that glutamate production under biotin-limited conditions was decreased by overproduction of LldR. In the wild-type cells, L-lactate was produced in the first 24 h and it was re-consumed thereafter. On the other hand, in the overproduced cells, L-lactate was produced like the wild type, but it was not re-consumed. This means that L-lactate assimilation, which is catalyzed by LldD, was suppressed by the overproduction of LldR, but L-lactate production, which is catalyzed by LdhA, was not affected, indicating that LldR mainly controls the expression of lldD but not of ldhA under biotin-limited conditions. This was confirmed by quantitative real-time RT-PCR. From these results, it is suggested that L-lactate metabolism, which is controlled by LldR, has a buffering function of the pyruvate pool for glutamate production.

【 授权许可】

Unknown