title: Crosstalk of Escherichia coli FadR with global regulators in expression of fatty acid transport genes.
abstract: Escherichia coli FadR plays two regulatory roles in fatty acid metabolism. FadR represses the fatty acid degradation (fad) system and activates the unsaturated fatty acid synthetic pathway. Cross-talk between E. coli FadR and the ArcA-ArcB oxygen-responsive two-component system was observed that resulted in diverse regulation of certain fad regulon β-oxidation genes. We have extended such analyses to the fadL and fadD genes, the protein products of which are required for long chain fatty acid transport and have also studied the role of a third global regulator, the CRP-cAMP complex. The promoters of both the fadL and fadD genes contain two experimentally validated FadR-binding sites plus binding sites for ArcA and CRP-cAMP. Despite the presence of dual binding sites FadR only modestly regulates expression of these genes, indicating that the number of binding sites does not determine regulatory strength. We report complementary in vitro and in vivo studies indicating that the CRP-cAMP complex directly activates expression of fadL and fadD as well as the β-oxidation gene, fadH. The physiological relevance of the fadL and fadD transcription data was validated by direct assays of long chain fatty acid transport.
authors.affiliation: Department of Microbiology, University of Illinois, Urbana, Illinois, United States of America.
authors.forename: Youjun
authors.initials: Y
authors.lastname: Feng
authors.forename: John E
authors.initials: JE
authors.lastname: Cronan
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001665:Binding Sites; D001692:Biological Transport; D003066:Coenzyme A Ligases / Q000235:genetics* / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism*; D002373:Cyclic AMP Receptor Protein / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D050612:Fatty Acid Transport Proteins / Q000235:genetics* / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D018085:Regulon; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D014158:Transcription, Genetic
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002373:Cyclic AMP Receptor Protein; D029968:Escherichia coli Proteins; C057119:FadR protein, Bacteria; D050612:Fatty Acid Transport Proteins; D005227:Fatty Acids; D008565:Membrane Proteins; D012097:Repressor Proteins; C041610:arcA protein, E coli; C481662:crp protein, E coli; C065691:fadL protein, E coli; D000242:Cyclic AMP; D011494:Protein Kinases; C065271:arcB protein, E coli; D003066:Coenzyme A Ligases; C085934:acyl-coenzyme A synthetase, E coli; D010100:Oxygen