Affiliation:
1. Department of Microbiology and Molecular Genetics, School of Medicine, Loma Linda University, Loma Linda, California 92350
Abstract
ABSTRACT
A 0.9-kb open reading frame encoding a unique 32-kDa protein was identified downstream of the
recA
gene of
Porphyromonas gingivalis
. Reverse transcription-PCR and Northern blot analysis showed that both the
recA
gene and this open reading frame are part of the same transcriptional unit. This cloned fragment was insertionally inactivated using the
ermF-ermAM
antibiotic resistance cassette to create a defective mutant by allelic exchange. When plated on
Brucella
blood agar, the mutant strain, designated
P. gingivalis
FLL92, was non-black pigmented and showed significant reduction in beta-hemolysis compared with the parent strain,
P. gingivalis
W83. Arginine- and lysine-specific cysteine protease activities, which were mostly soluble, were approximately 90% lower than that of the parent strain. Expression of the
rgpA
,
rgpB
, and
kgp
protease genes was the same in
P. gingivalis
FLL92 as in the wild-type strain. In contrast to the parent strain,
P. gingivalis
FLL92 showed increased autoaggregration in addition to a significant reduction in hemagglutinating and hemolysin activities. In in vivo experiments using a mouse model,
P. gingivalis
FLL92 was dramatically less virulent than the parent strain. A molecular survey of this mutant and the parent strain using all known
P. gingivalis
insertion sequence elements as probes suggested that no intragenomic changes due to the movement of these elements have occurred in
P. gingivalis
FLL92. Taken together, these results suggest that the
recA
downstream gene, designated
vimA
(virulence-modulating gene), plays an important role in virulence modulation in
P. gingivalis
W83, possibly representing a novel posttranscriptional or translational regulation of virulence factors in
P. gingivalis
.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
58 articles.
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