title: YeiL, the third member of the CRP-FNR family in Escherichia coli.
abstract: The yeiL open reading frame located at 48.5 min (2254 kb) in the nfo-fruA region of the Escherichia coli chromosome was predicted to encode a CRP and FNR paralogue capable of forming inter- or intra-molecular disulphide bonds and incorporating one iron-sulphur centre per 25 kDa subunit. Purified MBP-YeiL (a maltose-binding-protein-YeiL fusion protein) was a high-molecular-mass oligomer or aggregate which released unstable monomers (68 kDa) under reducing conditions. The MBP-YeiL protein contained substoichiometric amounts of iron and acid-labile sulphide, and an average of one disulphide bond per monomer. The iron and sulphide contents increased consistent with the acquisition of one [4Fe-4S] cluster per monomer after anaerobic NifS-catalysed reconstitution. By analogy with FNR and FLP (the FNR-like protein of Lactobacillus casei) it was suggested that the transcription-regulatory activity of YeiL might be modulated by a sensory iron-sulphur cluster and/or by reversible disulphide bond formation. A yeiL-lacZ transcriptional fusion showed that aerobic yeiL expression increases at least sixfold during stationary phase, requires RpoS, and is positively autoregulated by YeiL, positively activated by Lrp (and IHF in the absence of FNR) and negatively regulated by FNR. A regulatory link between the synthesis of YeiK (a potential nucleoside hydrolase) and YeiL was inferred by showing that the yeiK and yeiL genes are divergently transcribed from overlapping promoters. A 10-15% deficiency in aerobic growth yield and an enhanced loss of viability under nitrogen starvation conditions were detected with a yeiL::kan(R) mutant, suggesting that YeiL might function as a post-exponential-phase nitrogen-starvation regulator.
authors: The Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK1.
authors: Muna F
authors: MF
authors: Anjum
authors: The Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK1.
authors: Jeffrey
authors: J
authors: Green
authors: The Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK1.
authors: John R
authors: JR
authors: Guest
mesh_terms: D018528:ATP-Binding Cassette Transporters; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002373:Cyclic AMP Receptor Protein / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D007506:Iron-Sulfur Proteins / Q000235:genetics* / Q000378:metabolism; D058619:Maltose-Binding Proteins; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins; D009154:Mutation; D009584:Nitrogen / Q000378:metabolism; D016366:Open Reading Frames; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D002352:Carrier Proteins; D002373:Cyclic AMP Receptor Protein; D029968:Escherichia coli Proteins; C060704:FNR protein, E coli; D007506:Iron-Sulfur Proteins; D058619:Maltose-Binding Proteins; D009004:Monosaccharide Transport Proteins; D011993:Recombinant Fusion Proteins; C461599:maltose transport system, E coli; D009584:Nitrogen