Investigating the role of two-component regulatory systems in regulating FnBP-A of Staphylococcus aureus
Abstract
Staphylococcus aureus infection relies on a large array of virulence factors, such as fibronectin-binding protein A (FnBP-A). Previously shown by our lab, inactivation of the purine biosynthesis repressor (PurR) aberrantly upregulates FnBP-A, which underpins hyper-clumping in serum. Furthermore, preliminary data generated by our lab revealed that deletion of either SaeRS or ArlRS abolishes PurR-dependent hyper-clumping. Thus, I hypothesize that PurR, SaeRS and ArlRS coordinately regulate FnBP-A. I performed clumping assays to show that complementation of saeRS and arlRS restored the hyper-clumping phenotype in the aforementioned double mutants. Furthermore, inactivation of saeRS or arlRS in a purR mutant, reduced fnbA transcript level and FnBP-A expression. I overexpressed and purified SaeS, SaeR and PurR proteins, and subsequently performed electrophoretic mobility shift assays to show that PurR and SaeR directly bind to the fnbA promoter/operator region, suggesting that SaeR and PurR regulate FnBP-A expression by modulating fnbA transcription.