Understanding the high L-valine production in Corynebacterium glutamicum VWB-1 using transcriptomics and proteomics

Toward the elucidation of the advanced mechanism of L-valine production by Corynebacterium glutamicum, a highly developed industrial strain VWB-1 was analyzed, employing the combination of transcriptomics and proteomics methods. The transcriptional level of 1155 genes and expression abundance of 96 proteins were changed significantly by the transcriptome and proteome comparison of VWB-1 and ATCC 13869. It was indicated that the key genes involved in the biosynthesis of L-valine, ilvBN, ilvC, ilvD, ilvE were up-regulated in VWB-1, which together made prominent contributions in improving the carbon flow towards L-valine. The L-leucine and L-isoleucine synthesis ability were weakened according to the down-regulation of leuB and ilvA. The up-regulation of the branched chain amino acid transporter genes brnFE promoted the L-valine secretion capability of VWB-1. The NADPH and ATP generation ability of VWB-1 were strengthened through the up-regulation of the genes involved in phosphate pentose pathway and TCA pathway. Pyruvate accumulation was achieved through the weakening of the L-lactate, acetate and L-alanine pathways. The up-regulation of the genes coding for elongation factors and ribosomal proteins were beneficial for L-valine synthesis in C. glutamicum. All information acquired were useful for the genome breeding of better industrial L-valine producing strains.