title: Mutations in a gene encoding a new Hsp70 suppress rapid DNA inversion and bgl activation, but not proU derepression, in hns-1 mutant Escherichia coli.
abstract: Mutations in hns, the gene encoding the nucleoid-associated protein H-NS, affect both the expression of many specific unlinked genes and the inversion rate of the DNA segment containing the pilA promoter in Escherichia coli. A second-site mutation, termed hscA1, compensated for the effect of an hns-1 mutant allele on the pilA promoter inversion rate and on activation of the bgl operon. The proU operon, induced in an hns-1 background, remained derepressed in an hns-1 hscA1 strain and was induced at an intermediate level in an hns hscA1 strain. An insertion mutant allele, hscA2-cat, conferred the same partial hns-1 compensatory phenotype as the hscA1 allele. The hscA gene encoded a 66-kDa protein product that is a member of the Hsp70 protein class. The gene encoding this product is part of a bicistronic operon that is preceded by a possible sigma 32 promoter and also encodes a 21-kDa protein with significant homology to the DnaJ protein family. The mutation defining the hscA1 allele resulted in a phenylalanine substituting a conserved serine residue located in the ATP-binding region of other Hsp70 proteins.
authors.affiliation: Department of Microbiology and Immunology, University of North Carolina at Chapel Hill 27599-7290.
authors.forename: T H
authors.initials: TH
authors.lastname: Kawula
authors.forename: M J
authors.initials: MJ
authors.lastname: Lelivelt
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D016153:Genes, Suppressor; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics; D015183:Restriction Mapping
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C031908:H-NS protein, bacteria; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D009687:Nuclear Proteins; C085650:hscA protein, E coli