title: DNA-binding and enzymatic domains of the bifunctional biotin operon repressor (BirA) of Escherichia coli.
abstract: The negative regulation of the biotin biosynthetic (bio) operon in Escherichia coli is mediated by the bifunctional birA gene product, which serves as the bio repressor and biotin-activating enzyme. Nucleotide sequence analysis of 18 mutations in the birA gene was employed to study the DNA-binding and enzymatic functions of the BirA protein. The results indicate that a predicted helix-turn-helix structure, from amino acid (aa) positions 18 to 39 within the 321-aa BirA protein, may be responsible for sequence-specific DNA binding, whereas the temperature-sensitive mutations affecting biotin activation are found in two regions from aa positions 83-119 and 189-235.
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001710:Biotin / Q000494:pharmacology; D004269:DNA, Bacterial / Q000378:metabolism*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D005796:Genes; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D009154:Mutation; D009876:Operon; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D012097:Repressor Proteins; D014157:Transcription Factors; C036824:biotin repressor; D001710:Biotin