Graduation Year
2023
Document Type
Thesis
Degree
M.S.
Degree Name
Master of Science (M.S.)
Degree Granting Department
Biology (Cell Biology, Microbiology, Molecular Biology)
Major Professor
Lindsey N. Shaw, Ph.D.
Committee Member
Prahathees Eswara, Ph.D.
Committee Member
Zhiming Ouyang, Ph.D.
Keywords
M82, proteolysis, PrsS, regulated intramembrane proteolysis, DNA-damage
Abstract
Staphylococcus aureus is a major threat to human health, which is only exacerbated by its resistance to methicillin and other frontline antibiotics. Consequently, annual hospitalizations resulting from methicillin-resistant Staphylococcus aureus (MRSA) have been recorded in the hundreds of thousands for decades. However, the global impact of this opportunistic pathogen cannot solely be attributed to its antibiotic resistance, as S. aureus is also an expert at adapting to host conditions and responding to external stress. Here we attempt to gain a better understanding of a S. aureus factor that aids in circumventing such external insult - PrsS - a membrane protease that governs the response to DNA damage and cell-wall targeting antibiotics. We began by performing a structure-function analysis of PrsS, exploring its 8 transmembrane domains (TMD) and 4 conserved protease motifs. Here, we found seven residues within TMDs 4-7 that were necessary for PrsS function, all of which are in conserved protease motifs. We also investigated the function of the N-terminal extension of PrsS as well as its C-terminal tail (CTT), finding the first five amino acids in the CTT to be imperative for responding to DNA damage. Further to this, we evaluated the transcriptional regulation of prsS, identifying multiple factors modulating its expression. Interestingly, prsS expression is repressed by SigB, PurR, HrcA, SarZ, and GlcT, and activated by Rsp. Notably, SrrA was found to repress prsS expression, but only in the presence of MMS. Finally, we used N-terminomic methodologies to identify potential substrates of PrsS. A wealth of important proteins were found to be cleaved by PrsS, including ribosomal subunits, the cell division protein FtsZ, and a cryptic membrane protein of unknown function. In summary, we have generated important new knowledge, not only on PrsS’ role in S. aureus virulence, but more broadly on a protease family that is conserved across all kingdoms of life.
Scholar Commons Citation
Schott, Baylie M., "Regulated Intramembrane Proteolysis by M82 Peptidases: The Role of PrsS in the Staphylococcus aureus Stress Response" (2023). USF Tampa Graduate Theses and Dissertations.
https://digitalcommons.usf.edu/etd/10089
