Regulation of ldh expression during biotin-limited growth of Corynebacterium glutamicum

Abstract

Corynebacterium glutamicum is a biotin-auxotrophic bacterium and some strains efficiently produce glutamic acid under biotin-limiting conditions. In an effort to understand C. glutamicum metabolism under biotin limitation, growth of the type strain ATCC 13032 was investigated in batch cultures and a time-course analysis was performed. A transient excretion of organic acids was observed and we focused our attention on lactate synthesis. Lactate synthesis was due to the ldh-encoded l-lactate dehydrogenase (Ldh). Features of Ldh activity and ldh transcription were analysed. The ldh gene was shown to be regulated at the transcriptional level by SugR, a pleiotropic transcriptional repressor also acting on most phosphotransferase system (PTS) genes. Electrophoretic mobility shift assays (EMSAs) and site-directed mutagenesis allowed the identification of the SugR-binding site. Effector studies using EMSAs and analysis of ldh expression in a ptsF mutant revealed fructose 1-phosphate as a highly efficient negative effector of SugR. Fructose 1,6-bisphosphate also affected SugR binding.

Involvement of Regulatory Interactions among Global Regulators GlxR, SugR, and RamA in Expression of ramA in Corynebacterium glutamicum

“…However, it is interesting to note that the effects of inactivation of these regulators in any combinations tested on the ramA promoter activity appeared to be unaffected by the carbon source used. Because SugR represses genes involved in sugar uptake and metabolism in the absence of sugar and its repressor activity is inhibited by sugar metabolites (32,35,36,55), the degree of derepression of most SugR target genes in the sugR mutant is higher in the absence of sugar than in its presence. However, the degree of derepression of ramA promoter activity in the sugR mutant in the presence of glucose was comparable to that in the presence of acetate.…”

Arabitol Metabolism of Corynebacterium glutamicum and Its Regulation by AtlR

“…The Cg0146 protein was isolated for the first time by DNA affinity chromatography with the promoter region of the lactate dehydrogenase (LDH) gene ldhA (22). However, the specific LDH activity of a Cg0146-deficient mutant was not different from that of the parental wild-type (WT) strain, and thus, the physiological role of Cg0146 in ldhA expression remained unclear (22).…”

“…However, the specific LDH activity of a Cg0146-deficient mutant was not different from that of the parental wild-type (WT) strain, and thus, the physiological role of Cg0146 in ldhA expression remained unclear (22). In 2010, Cg0146 was reported to be a novel regulator (designated SucR), which binds to the succinyl-CoA synthetase operon sucCD and slightly represses its expression when cells are grown on acetate (17).…”

Gene Expression Profiling of Corynebacterium glutamicum during Anaerobic Nitrate Respiration: Induction of the SOS Response for Cell Survival

“…It has recently been found that transcription of the C. glutamicum ldhA gene is directly regulated by a sugar-responsive regulator, SugR (11,14,60), and an L-lactate-responsive regulator, LldR (59). However, for gene regulation mechanisms in response to anaerobiosis, no oxygen and/or redox-sensing global regulators similar to ResDE, Fnr, ArfM, Rex, and ArcAB, which coordinately control anaerobic respiration and fermentation genes in E. coli and B. subtilis (9,20,27,33,52), have been identified in C. glutamicum.…”