Characterization of a Novel Outer Membrane Hemin-Binding Protein of Porphyromonas gingivalis
AUTOR(ES)
Dashper, S. G.
FONTE
American Society for Microbiology
RESUMO
Porphyromonas gingivalis is a gram-negative, anaerobic coccobacillus that has been implicated as a major etiological agent in the development of chronic periodontitis. In this paper, we report the characterization of a protein, IhtB (iron heme transport; formerly designated Pga30), that is an outer membrane hemin-binding protein potentially involved in iron assimilation by P. gingivalis. IhtB was localized to the cell surface of P. gingivalis by Western blot analysis of a Sarkosyl-insoluble outer membrane preparation and by immunocytochemical staining of whole cells using IhtB peptide-specific antisera. The protein, released from the cell surface, was shown to bind to hemin using hemin-agarose. The growth of heme-limited, but not heme-replete, P. gingivalis cells was inhibited by preincubation with IhtB peptide-specific antisera. The ihtB gene was located between an open reading frame encoding a putative TonB-linked outer membrane receptor and three open reading frames that have sequence similarity to ATP binding cassette transport system operons in other bacteria. Analysis of the deduced amino acid sequence of IhtB showed significant similarity to the Salmonella typhimurium protein CbiK, a cobalt chelatase that is structurally related to the ATP-independent family of ferrochelatases. Molecular modeling indicated that the IhtB amino acid sequence could be threaded onto the CbiK fold with the IhtB structural model containing the active-site residues critical for chelatase activity. These results suggest that IhtB is a peripheral outer membrane chelatase that may remove iron from heme prior to uptake by P. gingivalis.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=94793Documentos Relacionados
- Hemin uptake in Porphyromonas gingivalis: Omp26 is a hemin-binding surface protein.
- Hemin-induced modifications of the antigenicity and hemin-binding capacity of Porphyromonas gingivalis lipopolysaccharide.
- Isolation of an outer membrane hemin-binding protein of Haemophilus influenzae type b.
- Identification of an Iron-Regulated, Hemin-Binding Outer Membrane Protein in Sinorhizobium meliloti
- Hemin-Binding Surface Protein from Bartonella quintana