Affiliation:
1. Department of Microbiology, Molecular Biology and Biochemistry, University of Idaho, Moscow, Idaho 83844,1 and
2. Inhibitex Inc., Norcross, Georgia 300922
Abstract
ABSTRACT
Staphylococcus aureus
expresses several surface proteins that promote adherence to host cell extracellular matrix proteins, including fibronectin (Fn). Since this organism has recently been shown to be internalized by nonprofessional phagocytes, a process that typically requires high-affinity binding to host cell receptors, we investigated the role of its Fn binding proteins (FnBPs) and other surface proteins in internalization by the bovine mammary gland epithelial cell line (MAC-T). Efficient internalization of
S. aureus
8325-4 required expression of FnBPs; an isogenic mutant (DU5883), not expressing FnBPs, was reduced by more than 95% in its ability to invade MAC-T cells. Moreover, D3, a synthetic peptide derived from the ligand binding domain of FnBP, inhibited the internalization of the 8325-4 strain in a dose-dependent fashion and the efficiency of staphylococcal internalization was partially correlated with Fn binding ability. Interestingly, Fn also inhibited the internalization and adherence of
S. aureus
8325-4 in a dose-dependent manner. In contrast to internalization, adherence of DU5883 to MAC-T was reduced by only approximately 40%, suggesting that surface binding proteins, other than FnBPs, can mediate bacterial adherence to cells. Adherence via these proteins, however, does not necessarily result in internalization of the staphylococci. An inhibitor of protein tyrosine kinase, genistein, reduced MAC-T internalization of
S. aureus
by 95%, indicating a requirement for a host signal transduction system in this process. Taken together, these results indicate that
S. aureus
invades nonprofessional phagocytes by a mechanism requiring interaction between FnBP and the host cell, leading to signal transduction and subsequent rearrangement of the host cell cytoskeleton.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
241 articles.
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