RRC ID 53784
Author Haverkorn van Rijsewijk BR, Kochanowski K, Heinemann M, Sauer U.
Title Distinct transcriptional regulation of the two Escherichia coli transhydrogenases PntAB and UdhA.
Journal Microbiology (Reading, Engl.)
Abstract Transhydrogenases catalyse interconversion of the redox cofactors NADH and NADPH, thereby conveying metabolic flexibility to balance catabolic NADPH formation with anabolic or stress-based consumption of NADPH. Escherichia coli is one of the very few microbes that possesses two isoforms: the membrane-bound, proton-translocating transhydrogenase PntAB and the cytosolic, energy-independent transhydrogenase UdhA. Despite their physiological relevance, we have only fragmented information on their regulation and the signals coordinating their counteracting activities. Here we investigated PntAB and UdhA regulation by studying transcriptional responses to environmental and genetic perturbations. By testing pntAB and udhA GFP reporter constructs in the background of WT E. coli and 62 transcription factor mutants during growth on different carbon sources, we show distinct transcriptional regulation of the two transhydrogenase promoters. Surprisingly, transhydrogenase regulation was independent of the actual catabolic overproduction or underproduction of NADPH but responded to nutrient levels and growth rate in a fashion that matches the cellular need for the redox cofactors NADPH and/or NADH. Specifically, the identified transcription factors Lrp, ArgP and Crp link transhydrogenase expression to particular amino acids and intracellular concentrations of cAMP. The overall identified set of regulators establishes a primarily biosynthetic role for PntAB and link UdhA to respiration.
Volume 162(9)
Pages 1672-1679
Published 2016-9
DOI 10.1099/mic.0.000346
PMID 27488847
MeSH Escherichia coli / enzymology* Escherichia coli / genetics Escherichia coli Proteins / genetics* Escherichia coli Proteins / metabolism Gene Expression Regulation, Bacterial Gene Expression Regulation, Enzymologic* NADP Transhydrogenases / genetics* NADP Transhydrogenases / metabolism Transcription Factors / genetics Transcription Factors / metabolism Transcription, Genetic
IF 1.922
Prokaryotes E. coli