Transcriptional regulation of Corynebacterium glutamicum methionine biosynthesis genes in response to methionine supplementation under oxygen deprivation.

Expression at the mRNA level of six methionine biosynthesis genes in Corynebacterium glutamicum cells under oxygen-deprived conditions was repressed by supplementation of medium with methionine. The repression was not observed in a mutant deficient in the TetR-type transcriptional repressor McbR. Analysis of transcriptional start sites of the methionine biosynthesis genes confirmed that McbR binding motifs exist in the promoter regions of all genes repressed by methionine supplementation. Furthermore, electrophoretic mobility shift assays revealed that not only S-adenosylhomocysteine but also S-adenosylmethionine affects binding of McbR to the promoter region of metY, suggesting that both of these methionine metabolites are involved in the regulation of methionine biosynthesis genes.