Hospital- and community- acquired infections caused by Staphylococcus aureus are a significant threat to human morbidity and mortality. The emergence of S. aureus strains resistant to all known antimicrobials contributes to this threat by eliminating available treatment options. Identifying novel therapeutic targets against S. aureus is critical to our continued ability to successfully treat these infections. Promising antimicrobial targets are S. aureus systems involved in virulence gene regulation and heme transport as both of these processes are required for successful staphylococcal infection. In this application we describe a novel staphylococcal virulence regulator that recognizes host heme, resulting in a coordinated change in staphylococcal protein expression and heme transport. We have identified two integral components of the S. aureus machinery responsible for this adaptive response: the heme sensor system (Hss) and the heme regulated transporter (Hrt). Preliminary experiments suggest that Hss-mediated activation of Hrt is responsible for protecting S. aureus against the cytoplasmic accumulation of toxic levels of host heme. Animal infection experiments have demonstrated a critical role for Hrt and Hss in staphylococcal pathogenesis, underscoring the importance of heme recognition and transport to staphylococcal virulence. Based on these recent discoveries, new studies are proposed to understand the mechanism and function of Hrt/Hss in host molecule recognition, virulence gene regulation, and small molecule transport during staphylococcal pathogenesis. Preliminary experiments suggest that Hss is a molecular sensor that recognizes heme as a systemic marker of infection. In turn, Hss-mediated activation of HrtAB facilitates small molecule efflux from the cytoplasm protecting S. aureus from toxic metabolite accumulation. This proposal focuses on testing this model. We will utilize genetics, biochemistry and animal infection experiments to (i) determine the role of HssRS in staphylococcal gene regulation, (ii) define the functional consequence of heme-dependent HrtAB activation, and (iii) delineate the role of the Hrt and Hss systems in S. aureus pathogenesis.
Results from these studies will yield mechanistic insight into two newly identified systems involved in an adaptive bacterial response to a host marker of invasive infection. The conservation of these systems in the organisms that cause listeriosis, anthrax, and enterococcal infections enable our results to be extrapolated to multiple human pathogens.
|Pishchany, Gleb; Sheldon, Jessica R; Dickson, Claire F et al. (2014) IsdB-dependent hemoglobin binding is required for acquisition of heme by Staphylococcus aureus. J Infect Dis 209:1764-72|
|Wakeman, Catherine A; Stauff, Devin L; Zhang, Yaofang et al. (2014) Differential activation of Staphylococcus aureus heme detoxification machinery by heme analogues. J Bacteriol 196:1335-42|
|Mike, Laura A; Choby, Jacob E; Brinkman, Paul R et al. (2014) Two-component system cross-regulation integrates Bacillus anthracis response to heme and cell envelope stress. PLoS Pathog 10:e1004044|
|Becker, Kyle W; Skaar, Eric P (2014) Metal limitation and toxicity at the interface between host and pathogen. FEMS Microbiol Rev 38:1235-49|
|Hammer, Neal D; Cassat, James E; Noto, Michael J et al. (2014) Inter- and intraspecies metabolite exchange promotes virulence of antibiotic-resistant Staphylococcus aureus. Cell Host Microbe 16:531-7|
|Moore, Jessica L; Caprioli, Richard M; Skaar, Eric P (2014) Advanced mass spectrometry technologies for the study of microbial pathogenesis. Curr Opin Microbiol 19:45-51|
|Mayfield, Jeffrey A; Hammer, Neal D; Kurker, Richard C et al. (2013) The chlorite dismutase (HemQ) from Staphylococcus aureus has a redox-sensitive heme and is associated with the small colony variant phenotype. J Biol Chem 288:23488-504|
|Cassat, James E; Hammer, Neal D; Campbell, J Preston et al. (2013) A secreted bacterial protease tailors the Staphylococcus aureus virulence repertoire to modulate bone remodeling during osteomyelitis. Cell Host Microbe 13:759-72|
|Hammer, Neal D; Reniere, Michelle L; Cassat, James E et al. (2013) Two heme-dependent terminal oxidases power Staphylococcus aureus organ-specific colonization of the vertebrate host. MBio 4:|
|Pishchany, Gleb; Haley, Kathryn P; Skaar, Eric P (2013) Staphylococcus aureus growth using human hemoglobin as an iron source. J Vis Exp :|
Showing the most recent 10 out of 33 publications