Effects of overexpression of atpA, purHD and ndh on the growth of Escherichia coli DH5a

Abstract:

[Objective] To study the mechanism of the differences in cell growth and acetate production between Escherichia coli DH5a and its acetate-tolerant mutant DA19. [Methods] Based on our previous analysis of the proteome and mass and energy balances for both strains, we first amplified the genes of atpIBEFHAGDC, purHD, and ndh, their regulation regions, as well as the regulation region of nuoA-N in both strains by PCR, and compared the sequences. Then, we constructed the recombinant strains DH5a (pTrc99a-atpA), DH5a (pTrc99a-purHD)?and DH5α (pTrc99a-ndh) to study the effect of overexpression of atpA, purHD and ndh in DH5a on growth. [Results] The sequences of the structural genes and the regulation regions in the two strains were completely identical with those of E. coli K-12. Overexpression of atpA, purHD and ndh separately in DH5a improved cell growth to some extent. [Conclusion] Overexpression of ndh, purHD and atpA resulted in improved growth of DH5a, but the growth of these recombinant strains was still lower than that of DA19, indicating the importance of global regulation to the cellular metabolism.

Key words:Escherichia coli; Expression; atpA; purH; ndh