Author ORCID Identifier
0000-0003-3814-6884
Date of Graduation
5-2024
Document Type
Dissertation (PhD)
Program Affiliation
Microbiology and Infectious Diseases
Degree Name
Doctor of Philosophy (PhD)
Advisor/Committee Chair
Cesar Arias
Committee Member
Danielle Garsin
Committee Member
Anna Konovalova
Committee Member
Samuel Shelburne
Committee Member
Dianna Milewicz
Abstract
Daptomycin is a last-resort lipopeptide antibiotic that disrupts cell membrane (CM) and peptidoglycan homeostasis (Grein et al., 2020a; Müller et al., 2016a). Enterococcus faecalis has developed a sophisticated mechanism to avoid daptomycin killing by redistributing CM anionic phospholipids away from the septum. The CM changes are orchestrated by a three-component regulatory system, designated LiaFSR, with a possible contribution of cardiolipin synthase (Cls) (Cesar A Arias et al., 2011a; Khan et al., 2019b; Palmer et al., 2011a; Panesso et al., 2015a; Reyes et al., 2015a). However, the mechanism by which LiaFSR controls the cell membrane response and the role of Cls are unknown. Here, we show that cardiolipin synthase activity is essential for anionic phospholipid redistribution and daptomycin resistance since deletion of the two genes (cls1 and cls2) encoding Cls abolished CM remodeling. We identified LiaY, a transmembrane protein regulated by LiaFSR, as an important mediator of cell membrane remodeling required for re-distribution of anionic phospholipid microdomains via interactions with Cls1. Together, our insights provide a mechanistic framework on the enterococcal response to cell envelope antibiotics that could be exploited therapeutically.
Keywords
enterococci, daptomycin