Details

Autor(en) / Beteiligte

• Dong, Xunyan
• Zhao, Yue
• Zhao, Jianxun
• Wang, Xiaoyuan

Titel

Characterization of aspartate kinase and homoserine dehydrogenase from Corynebacterium glutamicum IWJ001 and systematic investigation of l-isoleucine biosynthesis

Ist Teil von

• Journal of industrial microbiology & biotechnology, 2016-06, Vol.43 (6), p.873-885

Ort / Verlag

Berlin/Heidelberg: Springer Berlin Heidelberg

Erscheinungsjahr

2016

Link zum Volltext

Quelle

SpringerLink (Online service)

Beschreibungen/Notizen

• Previously we have characterized a threonine dehydratase mutant TD F383V (encoded by ilvA 1) and an acetohydroxy acid synthase mutant AHAS P176S, D426E, L575W (encoded by ilvBN 1) in Corynebacterium glutamicum IWJ001, one of the best l -isoleucine producing strains. Here, we further characterized an aspartate kinase mutant AK A279T (encoded by lysC 1) and a homoserine dehydrogenase mutant HD G378S (encoded by hom 1) in IWJ001, and analyzed the consequences of all these mutant enzymes on amino acids production in the wild type background. In vitro enzyme tests confirmed that AK A279T is completely resistant to feed-back inhibition by l -threonine and l -lysine, and that HD G378S is partially resistant to l -threonine with the half maximal inhibitory concentration between 12 and 14 mM. In C. glutamicum ATCC13869, expressing lysC 1 alone led to exclusive l -lysine accumulation, co-expressing hom 1 and thrB 1 with lysC 1 shifted partial carbon flux from l -lysine (decreased by 50.1 %) to l -threonine (4.85 g/L) with minor l -isoleucine and no l -homoserine accumulation, further co-expressing ilvA 1 completely depleted l -threonine and strongly shifted carbon flux from l -lysine (decreased by 83.0 %) to l -isoleucine (3.53 g/L). The results demonstrated the strongly feed-back resistant TD F383V might be the main driving force for l -isoleucine over-synthesis in this case, and the partially feed-back resistant HD G378S might prevent the accumulation of toxic intermediates. Information exploited from such mutation-bred production strain would be useful for metabolic engineering.