The pertussis agent Bordetella pertussis produces a number of virulence factors, of which the filamentous hemagglutinin (FhaB) plays a role in B. pertussis adhesion to epithelial and phagocytic cells. Moreover, FhaB was recently found to play a crucial role in nasal cavity infection and B. pertussis transmission to new hosts. The 367 kDa FhaB protein translocates through an FhaC pore to the outer bacterial surface and is eventually processed to a ~220 kDa N-terminal FHA fragment by the SphB1 protease. A fraction of the mature FHA then remains associated with bacterial cell surface, while most of FHA is shed into the bacterial environment. Previously reported indirect evidence suggested that FHA, or its precursor FhaB, may bind the β2 integrin CD11b/CD18 of human macrophages. Therefore, we assessed FHA binding to various cells producing or lacking the integrin and show that purified mature FHA does not bind CD11b/CD18. Further results then revealed that the adhesion of B. pertussis to cells does not involve an interaction between the bacterial surface-associated FhaB and/or mature FHA and the β2 integrin CD11b/CD18. In contrast, FHA binding was strongly inhibited at micromolar concentrations of heparin, corroborating that the cell binding of FHA is ruled by the interaction of its heparin-binding domain with sulfated glycosaminoglycans on the cell surface.

• Klíčová slova
• Bordetella pertussis, CD11b/CD18, adenylate cyclase toxin, filamentous hemagglutinin, heparin, integrin,
• MeSH
• antigeny CD18 MeSH
• bakteriální adheze MeSH
• bakteriální adheziny metabolismus   MeSH
• Bordetella pertussis * metabolismus   MeSH
• faktory virulence rodu Bordetella MeSH
• glykosaminoglykany MeSH
• hemaglutininy metabolismus   MeSH
• heparin MeSH
• integriny MeSH
• lidé MeSH
• makrofágový antigen 1 MeSH
• pertuse * MeSH
• proteasy MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antigeny CD18 MeSH
• bakteriální adheziny MeSH
• faktory virulence rodu Bordetella MeSH
• glykosaminoglykany MeSH
• hemaglutininy MeSH
• heparin MeSH
• integriny MeSH
• makrofágový antigen 1 MeSH
• proteasy MeSH

Filamentous hemagglutinin (FHA) mediates adherence and plays an important role in lower respiratory tract infections by pathogenic Bordetellae. The mature FHA proteins of B. pertussis (Bp-FHA) and the B. bronchiseptica (Bb-FHA) are generated by processing of the respective FhaB precursors by the autotransporter subtilisin-type protease SphB1. We have used bottom-up proteomics with differential 16O/18O labeling and show that despite high-sequence conservation of the corresponding FhaB segments, the mature Bp-FHA (~ 230 kDa) and Bb-FHA (~ 243 kDa) proteins are processed at different sites of FhaB, after the Ala-2348 and Lys-2479 residues, respectively. Moreover, protease surface accessibility probing by on-column (on-line) digestion of the Bp-FHA and Bb-FHA proteins yielded different peptide patterns, revealing structural differences in the N-terminal and C-terminal domains of the Bp-FHA and Bb-FHA proteins. These data indicate specific structural variations between the highly homologous FHA proteins.

• Klíčová slova
• Bordetella bronchiseptica, Bordetella pertussis, bacterial pathogenesis, mass spectrometry (MS), protein processing, serine protease,
• Publikační typ
• časopisecké články MeSH