Beschreibung:
<jats:title>ABSTRACT</jats:title>
<jats:p>
The gene
<jats:italic>lrrA</jats:italic>
, encoding a leucine-rich repeat protein, LrrA, that contains eight consensus tandem repeats of 23 amino acid residues, has been identified in
<jats:italic>Treponema denticola</jats:italic>
ATCC 35405. A leucine-rich repeat is a generally useful protein-binding motif, and proteins containing this repeat are typically involved in protein-protein interactions. Southern blot analysis demonstrated that
<jats:italic>T. denticola</jats:italic>
ATCC 35405 expresses the
<jats:italic>lrrA</jats:italic>
gene, but the gene was not identified in
<jats:italic>T. denticola</jats:italic>
ATCC 33520. In order to analyze the functions of LrrA in
<jats:italic>T. denticola</jats:italic>
, an
<jats:italic>lrrA</jats:italic>
-inactivated mutant of strain ATCC 35405 and an
<jats:italic>lrrA</jats:italic>
gene expression transformant of strain ATCC 33520 were constructed. Characterization of the mutant and transformant demonstrated that LrrA is associated with the extracytoplasmic fraction of
<jats:italic>T. denticola</jats:italic>
and expresses multifunctional properties. It was demonstrated that the attachment of strain ATCC 35405 to HEp-2 cell cultures and coaggregation with
<jats:italic>Tannerella forsythensis</jats:italic>
were attenuated by the
<jats:italic>lrrA</jats:italic>
mutation. In addition, an in vitro binding assay demonstrated specific binding of LrrA to a portion of the
<jats:italic>Tannerella forsythensis</jats:italic>
leucine-rich repeat protein, BspA, which is mediated by the N-terminal region of LrrA. It was also observed that the
<jats:italic>lrrA</jats:italic>
mutation caused a reduction of swarming in
<jats:italic>T. denticola</jats:italic>
ATCC 35405 and consequently attenuated tissue penetration. These results suggest that the leucine-rich repeat protein LrrA plays a role in the attachment and penetration of human epithelial cells and coaggregation with
<jats:italic>Tannerella forsythensis</jats:italic>
. These properties may play important roles in the virulence of
<jats:italic>T. denticola</jats:italic>
.
</jats:p>