In vivo and in vitro mutants of FNR the anaerobic transcriptional regulator of E. coli

FEBS Lett. 1990 Sep 17;270(1-2):119-22. doi: 10.1016/0014-5793(90)81248-m.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Anaerobiosis / genetics
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics*
  • Base Sequence
  • Chromosome Deletion
  • Cysteine
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / physiology
  • Escherichia coli / genetics*
  • Models, Molecular
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Mutation
  • Protein Conformation
  • Structure-Activity Relationship
  • Transcription Factors / chemistry
  • Transcription Factors / genetics
  • Transcription Factors / physiology*

Substances

  • Bacterial Proteins
  • DNA-Binding Proteins
  • Transcription Factors
  • Cysteine