Overexpression of NAD kinases improves the L-isoleucine biosynthesis in Corynebacterium glutamicum ssp. lactofermentum.

Abstract:

:NADPH is the key cofactor in L-isoleucine (Ile) biosynthetic pathway. To increase the Ile biosynthesis in Corynebacterium glutamicum ssp. lactofermentum JHI3-156, NADPH supply needs to be enhanced. Here NAD kinase, the key enzyme for the de novo biosynthesis of NADP(+) and NADPH, were cloned and expressed in JHI3-156, and their influences on Ile production were analysed. Meanwhile, enzyme properties of NAD kinase from JHI3-156 (CljPpnK) were compared with that from C. glutamicum ssp. lactofermentum ATCC 13869 (ClPpnK). Four variations existed between CljPpnK and ClPpnK. Both PpnKs were poly(P)/ATP-dependent NAD kinases that used ATP as the preferred phosphoryl donor and NAD(+) as the preferred acceptor. CljPpnK exhibited a higher activity and stability than ClPpnK and less sensitivity towards the effectors NADPH, NADP(+), and NADH, partly due to the variations between them. The S57P variation decreased their activity. Expression of CljppnK and ClppnK in JHI3-156 increased the ATP-NAD(+) kinase activity by 69- and 47-fold, respectively, the intracellular NADP(+) concentration by 36% and 101%, respectively, the NADPH concentration by 95% and 42%, respectively, and Ile production by 37% and 24%, respectively. These results suggest that overexpressing NAD kinase is a useful metabolic engineering strategy to improve NADPH supply and isoleucine biosynthesis.

journal_name

Enzyme Microb Technol

authors

Shi F,Huan X,Wang X,Ning J

doi

10.1016/j.enzmictec.2012.04.003

subject

Has Abstract

pub_date

2012-07-15 00:00:00

pages

73-80

issue

2

eissn

0141-0229

issn

1879-0909

pii

S0141-0229(12)00053-1

journal_volume

51

pub_type

杂志文章