title: Phylogeny and functional conservation of sigma(E) in endospore-forming bacteria.
abstract: Conservation of the sporulation processes between Bacillus spp. and Clostridium spp. was investigated through evolutionary and complementation analyses of sigma(E). Alignment of partial predicted sigma(E) amino acid sequences from three Bacillus spp., Paenibacillus polymyxa and five Clostridium spp. revealed that amino acid residues previously reported to be involved in promoter utilization (M124, E119 and N120) and strand opening (C117) are conserved among all these species. Phylogenetic analyses of various sigma factor sequences from endospore-forming bacteria revealed that homologues of sigma(E), sigma(K) and sigma(G) clustered together regardless of genus, suggesting a common origin of sporulation sigma factors. The functional equivalence between Clostridium acetobutylicum sigma(E) and Bacillus subtilis sigma(E) was investigated by complementing a non-polar B. subtilis sigma(E) null mutant with the spoIIG operon from either B. subtilis (spoIIG(Bs)) or C. acetobutylicum (spoIIG(Ca)). Single-copy integration of spoIIG(Bs) into the amyE locus of the sigma(E) null mutant completely restored the wild-type sporulation phenotype, while spoIIG(Ca) only partially restored sporulation. Maximal expression of spoIIG(Ca)-lacZ occurred approximately 12 h later than maximal expression of spoIIG(Bs)-lacZ. Differences in temporal expression patterns for spoIIG(Ca) and spoIIG(Bs) in the B. subtilis background may at least partially explain the observed sporulation complementation phenotypes. This study suggests a common phylogenetic ancestor for sigma(E) in Bacillus spp. and Clostridium spp., although regulation of sigma(E) expression may differ in these two genera.
authors.affiliation: Food Science Department, Cornell University, Ithaca, NY 14853, USA1.
authors.forename: Edna F
authors.initials: EF
authors.lastname: Arcuri
authors.affiliation: Food Science Department, Cornell University, Ithaca, NY 14853, USA1.
authors.forename: Martin
authors.initials: M
authors.lastname: Wiedmann
authors.affiliation: Food Science Department, Cornell University, Ithaca, NY 14853, USA1.
authors.forename: Kathryn J
authors.initials: KJ
authors.lastname: Boor
mesh_terms: D000595:Amino Acid Sequence; D001407:Bacillus / Q000737:chemistry / Q000235:genetics* / Q000254:growth & development; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics*; D002725:Chloroform; D003013:Clostridium / Q000737:chemistry / Q000235:genetics* / Q000254:growth & development; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D016415:Sequence Alignment; D012808:Sigma Factor / Q000737:chemistry / Q000235:genetics*; D013045:Species Specificity; D013997:Time Factors; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics*; D014158:Transcription, Genetic; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D012808:Sigma Factor; D014157:Transcription Factors; C063202:sporulation-specific sigma factors; D002725:Chloroform; D001616:beta-Galactosidase