Enhancing the activity of aspartate kinase for an overproduction of L-lysine by corynebacterium glutamicum

Abstract

Background: As in all the bacteria investigated, lysine biosynthesis in Corynebacterium glutamicum starts from aspartate and aspartate kinase is the principal enzyme involved in the lysine biosynthesis metabolic pathway. In C. glutamicum, this enzyme was regarded as potential target for improved production of lysine. Here the increased production of lysine by deregulating aspartate kinase gene in wild type C. glutamicum ATCC 13032 was described. Materials and Methods: Key regulatory enzyme aspartate kinase of C. glutamicum was manipulated by performing site-directed mutagenesis. The region coding for regulatory β-subunit in the aspartate kinase (lys C) gene was mutated by replacing the codon TCC-GTC to deregulate it from feedback inhibition, which resulted in improved lysine production. Results: About 4.2 g L-1 of more lysine yield was observed in the recombinant mutant compared to the wild type and the studies proved recombinants of C. glutamicum with feedback resistant aspartate kinase would be a potential option to increase the L-lysine production by biotechnological process. The mutant lysine producing strain reported in this investigation can be economical for industrial application. Conclusion: It was concluded that the metabolic engineering strategy reported here could serve as good concept for the development of microorganisms as capable cellular factories for the production of industrially important metabolites.