In vivo and in vitro mutants of FNR the anaerobic transcriptional regulator of E. coli.
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.
Sharrocks
A D
AD
Krebs Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, UK.
Green
J
J
Guest
J R
JR
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*
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D014157:Transcription Factors; D003545:Cysteine