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Infect. Immun. doi:10.1128/IAI.00258-07
Copyright (c) 2007, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

The Chymotrypsin-Like Protease (CTLP) Complex of Treponema denticola ATCC 35405 Mediates Fibrinogen Adherence and Degradation

Oral Microbiology Unit, Department of Oral and Dental Science, University of Bristol, Lower Maudlin Street, Bristol BS1 2LY, United Kingdom, and Department of Biologic and Materials Sciences, School of Dentistry, University of Ann Arbor, Michigan

^* To whom correspondence should be addressed. Email: howard.jenkinson{at}bristol.ac.uk.

	Abstract

Treponema denticola is an anaerobic spirochete strongly associated with human periodontal disease. The bacteria interact with a range of host tissue proteins including fibronectin, laminin and fibrinogen. The latter localizes in the extracellular matrix where tissue damage has occurred, and interactions with fibrinogen may play a key role in T. denticola colonization of those sites. T. denticola ATCC 35405 showed saturable binding of fluid phase fibrinogen to the cell surface and saturable adherence to immobilized fibrinogen. Levels of fibrinogen binding were enhanced in the presence of serine protease inhibitor PMSF. The A and B chains of fibrinogen, but not the chains, were specifically recognized by T. denticola. Following fibrinogen affinity chromatography of cell surface extracts, a major fibrinogen-binding component (polypeptide mol. mass 100 kDa) was purified, which also degraded fibrinogen. Upon heating at 100 °C the polypeptide was dissociated into three components (apparent molecular masses 80 kDa, 48 kDa and 45 kDa) that did not individually bind or degrade fibrinogen. The native 100-kDa polypeptide complex was identified as chymotrypsin-like protease (CTLP) or dentilisin. An isogenic CTLP^- mutant strain CKE was >90% reduced in chymotryptic-like activity and was abrogated in fibrinogen binding and hydrolysis. An isogenic mutant strain MHE, deficient in production of Msp (major surface protein) showed 40% reduced levels of CTLP and correspondingly reduced levels of fibrinogen binding and proteolysis. Thrombin clotting times were extended in the presence of wild-type T. denticola cells but not with strain CKE (CTLP^-) cells. The results suggest that interactions of T. denticola with fibrinogen, which may promote colonization and modulate hemostasis, are mediated principally by CTLP.