title: Expression and regulation of a silent operon, hyf, coding for hydrogenase 4 isoenzyme in Escherichia coli.
abstract: On the basis of hyf-lacZ fusion studies, the hyf operon of Escherichia coli, noted for encoding the fourth hydrogenase isoenzyme (HYD4), is not expressed at a significant level in a wild-type strain. However, mutant FhlA proteins (constitutive activators of the hyc-encoded hydrogenase 3 isoenzyme) activated hyf-lacZ. HyfR, an FhlA homolog encoded by the hyfR gene present at the end of the hyf operon, also activated transcription of hyf-lacZ but did so only when hyfR was expressed from a heterologous promoter. The HYD4 isoenzyme did not substitute for HYD3 in H(2) production. Optimum expression of hyf-lacZ required the presence of cyclic AMP receptor protein-cyclic AMP complex and anaerobic conditions when HyfR was the activator.
authors.affiliation: Department of Molecular Biology and Microbiology, University of Central Florida, Orlando, Florida 32816, USA.
authors.forename: William T
authors.initials: WT
authors.lastname: Self
authors.forename: Adnan
authors.initials: A
authors.lastname: Hasona
authors.forename: K T
authors.initials: KT
authors.lastname: Shanmugam
mesh_terms: D000332:Aerobiosis; D001483:Base Sequence; D000242:Cyclic AMP / Q000502:physiology; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D029968:Escherichia coli Proteins; D005561:Formates / Q000494:pharmacology; D015964:Gene Expression Regulation, Bacterial; D006864:Hydrogenase / Q000235:genetics*; D008969:Molecular Sequence Data; D008982:Molybdenum / Q000494:pharmacology; D009876:Operon; D014158:Transcription, Genetic
chemical_list: D029968:Escherichia coli Proteins; D005561:Formates; C030544:formic acid; C044659:molybdate; D008982:Molybdenum; D000242:Cyclic AMP; D006864:Hydrogenase; C455599:hydrogenase 4, E coli