title: Inactivation of a fibronectin-binding TonB-dependent protein increases adhesion properties of Bacteroides fragilis.
abstract: Bacteroides fragilis is the Gram-negative strictly anaerobic bacterium most frequently isolated from clinical infections, including intra-abdominal abscess and bacteraemia. A number of factors can contribute to its virulence, including the expression of adhesins. Some of them are already characterized and can recognize and bind to extracellular matrix components, such as fibronectin. One of the molecules responsible for fibronectin-binding is an outer-membrane protein previously described by our group, which belongs to the TonB-dependent family. The aim of the present work was to characterize this protein. Initially, it was confirmed by fluorescence and electron microscopy that the fibronectin-binding molecules were located in the bacterial surface, but the distribution of these molecules on the surface was not uniform. To further evaluate the role of this protein, the gene bf1991, responsible for encoding this protein, was inactivated by a suicide vector and the mutant strains generated were used in several experiments to verify possible phenotypical alterations. In adherence assays with fibronectin immobilized on latex beads an increased adhesion was observed with the mutant strains compared with the wild-type strain. Western blot analysis in the mutant strain revealed the absence of the 120 kDa TonB-dependent outer-membrane protein and an alteration in the expression of an unknown 30 kDa protein. Killing assays using peritoneal macrophages were performed to evaluate the role of this protein as a virulence attribute and it was observed that the mutant strains were more efficiently internalized than the wild-type strains, with more internalization in the samples covered with fibronectin than in the samples not covered with it.
authors.affiliation: Laboratório de Biologia de Anaeróbios, Departamento de Microbiologia Médica, Instituto de Microbiologia Paulo de Góes/Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Heidi
authors.initials: H
authors.lastname: Pauer
authors.affiliation: Laboratório de Biologia de Anaeróbios, Departamento de Microbiologia Médica, Instituto de Microbiologia Paulo de Góes/Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Soraia N V
authors.initials: SNV
authors.lastname: Cavalcanti
authors.affiliation: Laboratório de Biologia de Anaeróbios, Departamento de Microbiologia Médica, Instituto de Microbiologia Paulo de Góes/Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Felipe L
authors.initials: FL
authors.lastname: Teixeira
authors.affiliation: Laboratório de Biologia de Anaeróbios, Departamento de Microbiologia Médica, Instituto de Microbiologia Paulo de Góes/Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Joaquim
authors.initials: J
authors.lastname: Santos-Filho
authors.affiliation: Laboratório de Ultraestrutura Celular Herth, Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Rossiane C
authors.initials: RC
authors.lastname: Vommaro
authors.affiliation: Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Ana Carolina S C
authors.initials: ACSC
authors.lastname: Oliveira
authors.affiliation: Universidade Federal do Rio de Janeiro, Polo Xerém, Rio de Janeiro, RJ, Brazil.
authors.forename: Eliane O
authors.initials: EO
authors.lastname: Ferreira
authors.affiliation: Laboratório de Biologia de Anaeróbios, Departamento de Microbiologia Médica, Instituto de Microbiologia Paulo de Góes/Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Regina R M C P
authors.initials: RRMCP
authors.lastname: Domingues
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001422:Bacterial Adhesion; D001441:Bacteroides fragilis / Q000472:pathogenicity / Q000502:physiology*; D015153:Blotting, Western; D055786:Gene Knockout Techniques; D017737:Macrophages, Peritoneal / Q000276:immunology / Q000382:microbiology; D008565:Membrane Proteins / Q000032:analysis / Q000235:genetics; D051379:Mice; D050296:Microbial Viability; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D018829:Adhesins, Bacterial; D008565:Membrane Proteins; D037521:Virulence Factors; C078635:fibronectin-binding proteins, bacterial