title: Novel surface layer protein genes in Bacillus sphaericus associated with unusual insertion elements.
abstract: The surface layer (S-layer) protein genes of the uranium mining waste pile isolate Bacillus sphaericus JG-A12 and of its relative B. sphaericus NCTC 9602 were analysed. The almost identical N-termini of the two S-layer proteins possess a unique structure, comprising three N-terminal S-layer homologous (SLH) domains. The central parts of the proteins share a high homology and are related to the S-layer proteins of B. sphaericus CCM 2177 and P-1. In contrast, the C-terminal parts of the S-layer proteins of JG-A12 and NCTC 9602 differ significantly between each other. Surprisingly, the C-terminal part of the S-layer protein of JG-A12 shares a high identity with that of the S-layer protein of B. sphaericus CCM 2177. In both JG-A12 and NCTC 9602 the chromosomal S-layer protein genes are followed by a newly identified putative insertion element comprising three ORFs, which encode a putative transposase, a putative integrase/recombinase and a putative protein containing a DNA binding helix-turn-helix motif, and the S-layer-protein-like gene copies sllA (9602) or sllB (JG-A12). Interestingly, both B. sphaericus strains studied were found to contain an additional, plasmid-located and silent S-layer protein gene with the same sequence as sllA and sllB. The primary structures of the corresponding putative proteins are almost identical in both strains. The N-terminal and central parts of these S-layer proteins share a high identity with those of the chromosomally encoded functional S-layer proteins. Their C-terminal parts, however, differ significantly. These results strongly suggest that the S-layer protein genes have evolved via horizontal transfer of genetic information followed by DNA rearrangements mediated by mobile elements.
authors.affiliation: Institute of Radiochemistry, Forschungszentrum Rossendorf, D-01314 Dresden, Germany.
authors.forename: Katrin
authors.initials: K
authors.lastname: Pollmann
authors.affiliation: Institute of Radiochemistry, Forschungszentrum Rossendorf, D-01314 Dresden, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Raff
authors.affiliation: Institute of Radiochemistry, Forschungszentrum Rossendorf, D-01314 Dresden, Germany.
authors.forename: Michaela
authors.initials: M
authors.lastname: Schnorpfeil
authors.affiliation: Institute of Radiochemistry, Forschungszentrum Rossendorf, D-01314 Dresden, Germany.
authors.forename: Galina
authors.initials: G
authors.lastname: Radeva
authors.affiliation: Institute of Radiochemistry, Forschungszentrum Rossendorf, D-01314 Dresden, Germany.
authors.forename: Sonja
authors.initials: S
authors.lastname: Selenska-Pobell
mesh_terms: D001407:Bacillus / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D004251:DNA Transposable Elements / Q000502:physiology*; D022761:Gene Transfer, Horizontal; D005798:Genes, Bacterial; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D019895:Transposases / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D008562:Membrane Glycoproteins; C055764:S-layer proteins; D019895:Transposases