title: Porin from the halophilic species Ectothiorhodospira vacuolata: cloning, structure of the gene and comparison with other porins.
abstract: The gene coding for the anion-specific porin of the halophilic eubacterium Ectothiorhodospira (Ect.) vacuolata was cloned and sequenced, the first such gene so analyzed from a purple sulfur bacterium. It encodes a precursor protein consisting of 374 amino acid (aa)-residues including a signal peptide of 22-aa residues. Comparison with aa sequences of porins from several other members of the Proteobacteria revealed little homology. Only two regions showed local homology with the previously sequenced porins of Neisseria species, Comamonas acidovorans, Bordetella pertussis, Alcaligenes eutrophus, and Burkholderia cepacia. Genomic Southern blot hybridization studies were carried out with a probe derived from the 5' end of the gene coding for the porin of Ect. vacuolata. Two related species, Ect. haloalkaliphila and Ect. shaposhnikovii, exhibited a clear signal, while the extremely halophilic bacterium Halorhodospira (Hlr.) halophila (formerly Ect. halophila) did not show any cross-hybridization even at low stringency. This result is in good accordance with a recently proposed reassignment within the family Ectothiorhodospiraceae, which included the separation of the extremely halophilic species into the new genus Halorhodospira.
authors.affiliation: Institut für Biologie II-Mikrobiologie, Albert-Ludwigs-Universitat, Freiburg, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Wölf
authors.forename: G
authors.initials: G
authors.lastname: Achatz
authors.forename: J F
authors.initials: JF
authors.lastname: Imhoff
authors.forename: E
authors.initials: E
authors.lastname: Schiltz
authors.forename: J
authors.initials: J
authors.lastname: Weckesser
authors.forename: M C
authors.initials: MC
authors.lastname: Lamers
mesh_terms: D000595:Amino Acid Sequence; D001419:Bacteria / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D015139:Blotting, Southern; D003001:Cloning, Molecular; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism; D004926:Escherichia coli / Q000737:chemistry; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D016133:Polymerase Chain Reaction; D018272:Porins / Q000737:chemistry* / Q000235:genetics*; D011498:Protein Precursors / Q000737:chemistry / Q000235:genetics; D021382:Protein Sorting Signals / Q000737:chemistry / Q000235:genetics; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D018272:Porins; D011498:Protein Precursors; D021382:Protein Sorting Signals; C024388:CTGCAG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific