Binding and degradation of fibrinogen by Bacteroides fragilis and characterization of a 54 kDa fibrinogen-binding protein

作者：Houston Simon; Blakely Garry W; McDowell Andrew; Martin Lorraine; Patrick Sheila^*

来源：Microbiology-SGM, 2010, 156: 2516-2526.

DOI：10.1099/mic.0.038588-0

Bacteroides fragilis is a bacterium that resides in the normal human gastro-intestinal tract, however, it is also the most commonly isolated Gram-negative obligate anaerobe from human clinical infections, such as intra-abdominal abscesses, and the most common cause of anaerobic bacteraemia Abscess formation is important in bacterial containment, limiting dissemination of infection and bacteraemia In this study, we investigated B fragilis binding and degradation of human fibrinogen, the major structural component involved in fibrin abscess formation We have shown that B fragilis NCTC9343 binds human fibrinogen. A putative Bacteroides fragilis fibrinogen-binding protein, designated BF-FBP, identified in the genome sequence of NCTC9343, was cloned and expressed in Escherichia coli. The purified recombinant BF-FBP bound primarily to the human fibrinogen B beta-chain In addition, we have identified fibrinogenolytic activity in B fragilis exponential phase culture supernatants, associated with fibrinogenolytic metalloproteases in NCTC9343 and 638R, and cysteine protease activity in YCH46 All nine clinical isolates of B fragilis examined degraded human fibrinogen, with eight isolates, initial A alpha-chain degradation was observed, with varying B beta-chain and gamma-chain degradation. With one blood culture isolate,B beta-chain and gamma-chain degradation occurred first, followed by subsequent As-chain degradation Our data raise the possibility that the fibrinogen-binding protein of B fragilis, along with a variety of fibrinogenolytic proteases, may be an important virulence factor that facilitates dissemination of infection via reduction or inhibition of abscess formation

• 出版日期2010-8