Comparative proteome analysis of global effect of POS5 and zwf-ppnK overexpression in L-isoleucine producing Corynebacterium glutamicum ssp. lactofermentum.

Corynebacterium glutamicum ssp. lactofermentum strain JHI3-156 produces L-isoleucine (Ile). Overexpression of the Saccharomyces cerevisiae-derived NADH kinase gene (POS5) and the endogenous glucose-6-phosphate dehydrogenase and NAD kinase genes (zwf-ppnK) in JHI3-156 increased Ile production by 26 and 31 %, respectively. To decipher the global effect of POS5 and zwf-ppnK overexpression on Ile biosynthesis, proteomic analysis was conducted. Twenty-four differentially expressed proteins were identified in the POS5-overexpressing strain, most of which are related to inositol catabolism, central carbon metabolism, anaplerotic pathway, protein biosynthesis and the stress response. In the zwf-ppnK-overexpressing strain, seven differentially-expressed proteins, including PpnK and anaplerotic enzymes, were identified. This result indicates the involvement of a novel inositol catabolism step and the importance of the anaplerotic pathway in Ile biosynthesis. This finding will be helpful in the systematic metabolic engineering of C. glutamicum for Ile biosynthesis.