Infection and Immunity, October 2001, p. 6193-6200, Vol. 69, No. 10
0019-9567/01/$04.00+0 DOI: 10.1128/IAI.69.10.6193-6200.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, Michigan 48109-1078,1 and Department of Oral Microbiology, College of Dentistry, Kangnung National University, Kangnung, Korea2
Received 9 May 2001/Returned for modification 14 June 2001/Accepted 22 June 2001
High levels of Treponema denticola in subgingival
dental plaque are associated with severe periodontal disease.
T. denticola, along with Porphyromonas
gingivalis and Bacteroides forsythus, are the
only cultivatable oral microorganisms that produce significant amounts
of "trypsin-like" peptidase activity. The ability of subgingival plaque to hydrolyze
N-
-benzoyl-DL-arginine-2-naphthylamide
(BANA) is associated with high levels of one or more of these
organisms. The purpose of this study was to identify the gene encoding
trypsin-like activity in T. denticola and thus
facilitate molecular-level studies of its potential role in disease.
Using published peptide sequences of a T. denticola
surface-associated oligopeptidase with BANA-hydrolyzing activity, we
identified the gene, designated opdB, in an apparently noncoding region of the T. denticola genome unannotated
contigs (11/2000; http://www.tigr.org). The opdB gene
begins with a TTG start codon and encodes a 685-residue peptide with
high homology to the oligopeptidase B family in prokaryotes and
eukaryotes. An isogenic T. denticola opdB mutant was
constructed by allelic replacement mutagenesis using an
ermF/AM gene cassette. The mutant lacked
BANA-hydrolyzing activity and had a slightly slower growth rate than
the parent strain. This mutant will be used in future studies of
interactions of T. denticola with host cells and tissue.
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