title: Characterization of new DsbB-like thiol-oxidoreductases of Campylobacter jejuni and Helicobacter pylori and classification of the DsbB family based on phylogenomic, structural and functional criteria.
abstract: In Gram-negative bacterial cells, disulfide bond formation occurs in the oxidative environment of the periplasm and is catalysed by Dsb (disulfide bond) proteins found in the periplasm and in the inner membrane. In this report the identification of a new subfamily of disulfide oxidoreductases encoded by a gene denoted dsbI, and functional characterization of DsbI proteins from Campylobacter jejuni and Helicobacter pylori, as well as DsbB from C. jejuni, are described. The N-terminal domain of DsbI is related to DsbB proteins and comprises five predicted transmembrane segments, while the C-terminal domain is predicted to locate to the periplasm and to fold into a beta-propeller structure. The dsbI gene is co-transcribed with a small ORF designated dba (dsbI-accessory). Based on a series of deletion and complementation experiments it is proposed that DsbB can complement the lack of DsbI but not the converse. In the presence of DsbB, the activity of DsbI was undetectable, hence it probably acts only on a subset of possible substrates of DsbB. To reconstruct the principal events in the evolution of DsbB and DsbI proteins, sequences of all their homologues identifiable in databases were analysed. In the course of this study, previously undetected variations on the common thiol-oxidoreductase theme were identified, such as development of an additional transmembrane helix and loss or migration of the second pair of Cys residues between two distinct periplasmic loops. In conjunction with the experimental characterization of two members of the DsbI lineage, this analysis has resulted in the first comprehensive classification of the DsbB/DsbI family based on structural, functional and evolutionary criteria.
authors.affiliation: Department of Bacterial Genetics, Institute of Microbiology, Warsaw University, Miecznikowa 1, 02-096 Warsaw, Poland.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Raczko
authors.affiliation: Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology, Trojdena 4, 02-109 Warsaw, Poland.
authors.forename: Janusz M
authors.initials: JM
authors.lastname: Bujnicki
authors.affiliation: Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology, Trojdena 4, 02-109 Warsaw, Poland.|Department of Bacterial Genetics, Institute of Microbiology, Warsaw University, Miecznikowa 1, 02-096 Warsaw, Poland.
authors.forename: Marcin
authors.initials: M
authors.lastname: Pawłowski
authors.affiliation: Department of Bacterial Genetics, Institute of Microbiology, Warsaw University, Miecznikowa 1, 02-096 Warsaw, Poland.
authors.forename: Renata
authors.initials: R
authors.lastname: Godlewska
authors.affiliation: Department of Bacterial Genetics, Institute of Microbiology, Warsaw University, Miecznikowa 1, 02-096 Warsaw, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Lewandowska
authors.affiliation: Department of Bacterial Genetics, Institute of Microbiology, Warsaw University, Miecznikowa 1, 02-096 Warsaw, Poland.
authors.forename: Elżbieta K
authors.initials: EK
authors.lastname: Jagusztyn-Krynicka
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000145:classification* / Q000235:genetics / Q000378:metabolism; D016123:Campylobacter jejuni / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D019295:Computational Biology / Q000379:methods; D016480:Helicobacter pylori / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D008565:Membrane Proteins / Q000737:chemistry / Q000145:classification* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry / Q000145:classification* / Q000235:genetics / Q000378:metabolism; D010802:Phylogeny; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013438:Sulfhydryl Compounds / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; C079503:DsbB protein, Bacteria; D008565:Membrane Proteins; D013438:Sulfhydryl Compounds; D010088:Oxidoreductases