title: In vivo and in vitro mutants of FNR the anaerobic transcriptional regulator of E. coli.
abstract: FNR regulates the expression of target genes in response to anaerobiosis. It resembles the catabolite gene activator or cAMP-receptor protein (CRP) except for the presence of an N-terminal cysteine cluster, which may form a redox-sensing iron-binding site. Site-directed mutagenesis has shown that 3 of the 4 cysteine residues in the N-terminal cluster (Cys-20, -23 and -29, but not Cys-16) and the only other cysteine residue (Cys-122), are essential for the normal activation and repression of FNR-dependent promoters. Deletion of residues Pro-3-Arg-9 (inclusive) had no effect, but FNR was inactivated by a frameshift extending through the C-terminal DNA-binding domain. Four independent in vivo mutants contained identical Gly-96----Asp substitutions, which may inactivate FNR by distorting a sharp turn between beta-strands in the predicted structure.
authors.affiliation: Krebs Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, UK.
authors.forename: A D
authors.initials: AD
authors.lastname: Sharrocks
authors.forename: J
authors.initials: J
authors.lastname: Green
authors.forename: J R
authors.initials: JR
authors.lastname: Guest
mesh_terms: D000595:Amino Acid Sequence; D000693:Anaerobiosis / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D002872:Chromosome Deletion; D003545:Cysteine; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology; D004926:Escherichia coli / Q000235:genetics*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D011487:Protein Conformation; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D014157:Transcription Factors; D003545:Cysteine