Engineering of Escherichia coli Glyceraldehyde-3-Phosphate Dehydrogenase with Dual NAD⁺/NADP⁺ Cofactor Specificity for Improving Amino Acid Production.

ABSTRACT: Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a key enzyme in the central metabolism of microbial cells. GAPDHs differ in cofactor specificity and use NAD⁺, NADP⁺, or both cofactors, reducing them to NADH and NADPH, respectively. Sufficient NADPH supply is one of the critical factors required for synthesis of the amino acids l-lysine, l-threonine, and l-proline in industrially important Escherichia coli-based producer strains. E. coli cells have NAD⁺-dependent glycolytic GAPDH. One reasonable approach to increase NADPH formation in cells is to change the specificity of the GAPDH from NAD⁺ to NADP⁺. In this study, we modified the cofactor specificity of E. coli GAPDH by amino acid substitutions at positions 34, 188 and 189. Several mutant enzymes with dual NAD⁺/NADP⁺ cofactor specificity were obtained, and their kinetic parameters were determined. Overexpression of the genes encoding the resulting mutant GAPDHs with dual cofactor specificity in cells of l-lysine-, l-threonine-, and l-proline-producing E. coli strains led to a marked increase in the accumulation of the corresponding amino acid in the culture medium. This effect was more pronounced when cultivating on xylose as a carbon source. Other possible applications of the mutant enzymes are discussed.

SUBMITTER: Slivinskaya EA 

PROVIDER: S-EPMC9145139 | biostudies-literature | 2022 May

REPOSITORIES: biostudies-literature