Expression of the pfl Gene and Resulting Metabolite Flux Distribution in nuo and ackA-pta E. coli Mutant Strains

• Published in: Biotechnology progress 2006-05, Vol.22 (3), p.898-902
• Main Authors: Singh, Randeep, Yang, Yea-Tyng, Lu, Biqing, Bennett, George N., San, Ka-Yiu
• Format: Article
• Language: English
• Subjects: Acetates - metabolism; Acetyltransferases - genetics; Acetyltransferases - metabolism; Anaerobiosis; Bacterial Proteins - genetics; Biological and medical sciences; Biotechnology; Cells, Cultured; Escherichia coli; Escherichia coli - enzymology; Escherichia coli - genetics; Escherichia coli - metabolism; Ethanol - metabolism; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Bacterial; Gene Expression Regulation, Enzymologic; Multigene Family; Mutation; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - genetics; RNA, Messenger - metabolism
• ISSN: 8756-7938; 1520-6033
• DOI: 10.1021/bp050326h

Our laboratory previously studied the interaction between nuo and the acetate‐producing pathway encoded by ackA‐ptain Escherichia coli.We examined metabolic patterns, particularly the ethanol and acetate production rates, of several mutant strains grown under anaerobic growth conditions. Since the pyruvate formate‐lyase (PFL) pathway is the major route for acetyl‐CoA and formate production under anaerobic conditions, we examined the effects of nuo and ackA/pta mutations on the expression of pyruvate formate‐lyase (pfl) under anaerobic conditions. The ackA‐pta mutant has a pfl::lacZ expression level much higher than that of the wild‐type strain, and cultures also exhibit the highest ethanol production. Real‐time PCR demonstrated that the adhE gene expression in the ack‐pta mutant strain was approximately 100 fold that of the same gene in theackA‐pta nuo mutant strain. This result correlates with the observed ethanol production rates in cultures of the strain. However, the lack of exact correlation between the ethanol production rates and the RT‐PCR data suggests additional regulation actions at the posttranslation level. In addition, the activity of the pflgene as indicated by mRNA levels was also considerably greater in the ack‐pta mutant. We can conclude that deletions of nuo and ack/ptacan partially affect the expression of the genes encoding adhE and pflunder anaerobic conditions.