title: Escherichia coli rpoS gene has an internal secondary translation initiation region.
abstract: Sigma S (sigma(s)) encoded by rpoS in Escherichia coli is a stationary phase specific sigma subunit of the RNA polymerase holoenzyme. Widespread among the E. coli K12 strains is an amber mutation that prematurely terminates sigma(s). These rpoSAm mutants would be expected to show no sigma(s) activity. However, suppressor free rpoSAm mutants retain an intermediate catalase activity, a sigma S controlled function. By analyzing the sequence of the rpoS gene we hypothesize that a 277 amino acids long delta1-53 sigma(s) of about 30 kDa can be translated from an internal secondary translation initiation region (STIR, AGGGAGN11GUG) that is located downstream of the amber codon. By cloning this rpoSAm gene, following the expression, function, and N-terminal sequence of this mutant protein, we report the presence of a functional internal STIR in E. coli rpoS, from where a truncated but nevertheless functional form of sigma(s) can be synthesized.
authors.affiliation: Department of Molecular Genetics, National Institute of Genetics, Mishima--411-8540, Shizuoka-ken, Japan. spochi@med.miami.edu
authors.forename: Pochi Ramalingam
authors.initials: PR
authors.lastname: Subbarayan
authors.forename: Malancha
authors.initials: M
authors.lastname: Sarkar
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002374:Catalase / Q000378:metabolism; D018387:Codon, Initiator / Q000235:genetics; D018388:Codon, Terminator / Q000235:genetics; D016384:Consensus Sequence; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D015151:Immunoblotting; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis / Q000235:genetics*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012808:Sigma Factor / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D018387:Codon, Initiator; D018388:Codon, Terminator; D029968:Escherichia coli Proteins; D012336:RNA, Ribosomal, 16S; D011994:Recombinant Proteins; D012808:Sigma Factor; C069567:sigma factor KatF protein, Bacteria; D002374:Catalase