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 b-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.

Critical role of a thiolate-quinone charge transfer complex and its adduct form in de novo disulfide bond generation by DsbB

“…We have already discussed that Cys-44 and Arg-48 should be placed on an ␣-helix and separated by three residues in between. This feature is conserved among the DsbB͞DsbI family of proteins (25). Arg-48 is immediately followed by the second transmembrane sequence and is likely to be ''snorkeling'' from the lipid phase (26).…”

Characterization of Two Homologous Disulfide Bond Systems Involved in Virulence Factor Biogenesis in Uropathogenic Escherichia coli CFT073

“…The protein forming the P-ring of E. coli flagella, FlgI, was one of the first DsbA substrates identified (10) and flagellum-mediated motility was subsequently demonstrated to require the presence of functional DsbA in several gram-negative pathogens, including Salmonella enterica (1), Proteus mirabilis (8), Erwinia carotovora subsp. atroseptica (9), Burkholderia cepacia (17), and Campylobacter jejuni (42). In Yersinia pestis, S. enterica, Shigella flexneri, and enteropathogenic E. coli, deletion of dsbA results in defective type III secretion, a major virulence mechanism employed by these enteric pathogens to manipulate the host during infection.…”

Comparative proteome analysis of Helicobacter pylori clinical strains by two-dimensional gel electrophoresis

“…However, none of the seven identified proteins showed similarities with virulence factors reported in previous studies (Govorun et al, 2003;Zhang et al, 2009). For example, (1) it has been established that Dsb family (DsbA, DsbB, DsbC, DsbD, and DsbG) of redox proteins is involved in correct formation of disulfide bond into proteins in the periplasm or assembly of many pathogenic virulence factors (Raczko et al, 2005). Many bacteria use an oxidative protein-folding machinery to assemble proteins that are necessary for cell integrity and to produce virulence factors.…”