title: Cys184 and Cys187 of NifL protein of Klebsiella pneumoniae are not absolutely required for inhibition of NifA activity.
abstract: The sequence Cys184-Ala-Asp-Cys187 in the NifL protein of Klebsiella pneumoniae, for which a role in oxygen sensing and/or metal binding has been proposed, was altered by introducing two mutations, Cys184----Ala and Cys187----Ala, using oligodeoxyribonucleotide-directed mutagenesis. Neither mutation abolished ammonium or oxygen control of nif transcription, although some impairment of function was apparent. The two Cys residues are therefore unlikely to have a direct role in oxygen sensing or metal binding, but probably make some contribution to protein folding or stability.
authors.affiliation: AFRC Institute of Plant Sciences Research, Nitrogen Fixation Laboratory, Uiversity of Sussex, Brighton, U.K.
authors.forename: A
authors.initials: A
authors.lastname: Contreras
authors.forename: M
authors.initials: M
authors.lastname: Drummond
mesh_terms: D000595:Amino Acid Sequence; D000641:Ammonia / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D003545:Cysteine / Q000502:physiology; D004252:DNA Mutational Analysis; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005798:Genes, Bacterial; D007700:Kinetics; D007711:Klebsiella pneumoniae / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009586:Nitrogen Fixation / Q000235:genetics*; D010100:Oxygen / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; C061338:NifA protein, Bacteria; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D000641:Ammonia; D003545:Cysteine; D010100:Oxygen