Affiliation:
1. Departments of Microbiology1 and
2. Pediatrics,2 University of Texas Southwestern Medical Center, Dallas, Texas 75235-9048
Abstract
ABSTRACT
The UspA1 and UspA2 proteins of
Moraxella catarrhalis
are structurally related, are exposed on the bacterial cell surface, and migrate as very high-molecular-weight complexes in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Previous analysis of
uspA1
and
uspA2
mutants of
M. catarrhalis
strain 035E indicated that UspA1 was involved in adherence of this organism to Chang conjunctival epithelial cells in vitro and that expression of UspA2 was essential for resistance of this strain to killing by normal human serum (C. Aebi, E. R. Lafontaine, L. D. Cope, J. L. Latimer, S. R. Lumbley, G. H. McCracken, Jr., and E. J. Hansen, Infect. Immun. 66:3113–3119, 1998). In the present study, isogenic
uspA1
,
uspA2
, and
uspA1 uspA2
mutations were constructed in three additional
M. catarrhalis
strains: 012E, TTA37, and 046E. The
uspA1
mutant of strain 012E had a decreased ability to attach to Chang cells. However, inactivation of the
uspA1
gene in both strain TTA37 and strain 046E did not cause a significant decrease in attachment ability. Inactivation of the
uspA2
gene of strain TTA37 did result in a loss of attachment ability. Nucleotide sequence analysis revealed that the predicted protein encoded by the
uspA2
genes of both strains TTA37 and 046E had a N-terminal half that resembled the N-terminal half of UspA1 proteins, whereas the C-terminal half of this protein was nearly identical to those of previously characterized UspA2 proteins. The gene encoding this “hybrid” protein was designated
uspA2H
. PCR-based analysis revealed that approximately 20% of
M. catarrhalis
strains apparently possess a
uspA2H
gene instead of a
uspA2
gene. The
M. catarrhalis uspA1
,
uspA2
, and
uspA2H
genes were cloned and expressed in
Haemophilus influenzae
cells, which were used to prove that both the UspA1 and UspA2H proteins can function as adhesins in vitro.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
153 articles.
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