Genetically modifying aspartate aminotransferase and aspartate ammonia-lyase affects metabolite accumulation in L-lysine producing strain derived from Corynebacterium glutamicum ATCC13032

摘要

The aspartate aminotransferase (AAT) and aspartate ammonia-lyase (AAL) catalyzes respectively the reversible reaction of oxaloacetate (OAA) and fumarate to form L-aspartate. However, the effects of AAT and AAL on metabolite variations have not been clearly elucidated as yet. Now, the effects of AAT and AAL on metabolite variations in genetically defined L-lysine producing strains were studied by genetically modifying AAT gene aspB and AAL gene aspA. AAL was not detected in Corynebacterium glutamicum Lys1 but increased in aspB-deleted strain. Inversely, AAT exhibited high activity in Lysl, but it was not detected in aspB-deleted strains. Moreover, the deletion of aspB was bad for cell growth and metabolites production. The expression of Escherichia coli aspA in aspB-deleted strain not only restored cell growth and L-lysine production, but also accumulated some metabolites. However, the over-expression of aspB or aspA in aspB-natural strain did not affect cell growth and metabolites production except L-aspartate production. Although E. coli AAL could used to restore cell growth and metabolites accumulation in aspB-deleted strain, the effect on L-lysine production was significantly worse than that of AAT. Results indicates that native AAT is both necessary and sufficient for cell growth and L-lysine production, and deepens our understanding of the role of native aspB and E. coli aspA on cell growth and metabolites productions. (C) 2015 Elsevier B.V. All rights reserved.