Defining the role of post-translational regulation by extracellular proteases in the pathogenesis of Staphylococcus aureus osteomyelitis

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SUMMARY ABSTRACT We have demonstrated that mutation of the staphylococcal accessory regulatory (sarA) in Staphylococcus aureus results in an increase in the production of extracellular proteases to a degree that limits biofilm formation, limits cytotoxicity for mammalian cells including osteoblasts and osteoclasts, and limits the accumulation of both surface-associated and extracellular virulence factors. We have also demonstrated that this can be correlated with decreased virulence in animal models of sepsis and osteomyelitis. Moreover, we have confirmed that all of these phenotypes are evident in diverse clinical isolates of S. aureus and that they can be reversed by eliminating the ability of sarA mutants to produce extracellular proteases. In this proposal, we will expand on these observations to identify the specific extracellular proteases that are most relevant in the context of our underlying scientific hypothesis in diverse clinical isolates of S. aureus (Aim 1) and use the information gained to interrogate the impact of these proteases on the virulence factor repertoire on these clinical isolates, define the impact sarA and these proteases on bone remodeling and the host response in bone infection, and ultimately identify and evaluate the contribution of specific S. aureus virulence factors alone and in combination with each other on these phenotypes (Aim 2).