title: Streptococcus mitis and S. oralis Lack a Requirement for CdsA, the Enzyme Required for Synthesis of Major Membrane Phospholipids in Bacteria.
abstract: Synthesis and integrity of the cytoplasmic membrane are fundamental to cellular life. Experimental evolution studies have hinted at unique physiology in the Gram-positive bacteriaStreptococcus mitisandS. oralisThese organisms commonly cause bacteremia and infectious endocarditis (IE) but are rarely investigated in mechanistic studies of physiology and evolution. Unlike in other Gram-positive pathogens, high-level (MIC ≥ 256 μg/ml) daptomycin resistance rapidly emerges inS. mitisandS. oralisafter a single drug exposure. In this study, we found that inactivating mutations incdsAare associated with high-level daptomycin resistance inS. mitisandS. oralisIE isolates. This is surprising given thatcdsAis an essential gene for life in commonly studied model organisms. CdsA is the enzyme responsible for the synthesis of CDP-diacylglycerol, a key intermediate for the biosynthesis of all major phospholipids in prokaryotes and most anionic phospholipids in eukaryotes. Lipidomic analysis by liquid chromatography-mass spectrometry (LC-MS) showed that daptomycin-resistant strains have an accumulation of phosphatidic acid and completely lack phosphatidylglycerol and cardiolipin, two major anionic phospholipids in wild-type strains, confirming the loss of function of CdsA in the daptomycin-resistant strains. To our knowledge, these daptomycin-resistant streptococci represent the first model organisms whose viability is CdsA independent. The distinct membrane compositions resulting from the inactivation ofcdsAnot only provide novel insights into the mechanisms of daptomycin resistance but also offer unique opportunities to study the physiological functions of major anionic phospholipids in bacteria.
authors.affiliation: Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA.
authors.forename: Hannah M
authors.initials: HM
authors.lastname: Adams
authors.affiliation: Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA.
authors.forename: Luke R
authors.initials: LR
authors.lastname: Joyce
authors.affiliation: Department of Biochemistry, Duke University Medical Center, Durham, North Carolina, USA.
authors.forename: Ziqiang
authors.initials: Z
authors.lastname: Guan
authors.affiliation: Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA.|Methodist Charlton Medical Center, Dallas, Texas, USA.
authors.forename: Ronda L
authors.initials: RL
authors.lastname: Akins
authors.affiliation: Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA kelli.palmer@utdallas.edu.
authors.forename: Kelli L
authors.identifier: 0000-0002-7343-9271
authors.initials: KL
authors.lastname: Palmer
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002308:Cardiolipins / Q000378:metabolism; D003567:Cytidine Diphosphate Diglycerides / Q000096:biosynthesis; D017576:Daptomycin / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial / Q000235:genetics; D006801:Humans; D008563:Membrane Lipids / Q000096:biosynthesis; D008826:Microbial Sensitivity Tests; D009713:Nucleotidyltransferases / Q000235:genetics*; D010712:Phosphatidic Acids / Q000378:metabolism; D010715:Phosphatidylglycerols / Q000378:metabolism; D010743:Phospholipids / Q000096:biosynthesis; D013290:Streptococcal Infections / Q000382:microbiology / Q000473:pathology; D034361:Streptococcus mitis / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D019533:Streptococcus oralis / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D002308:Cardiolipins; D003567:Cytidine Diphosphate Diglycerides; D008563:Membrane Lipids; D010712:Phosphatidic Acids; D010715:Phosphatidylglycerols; D010743:Phospholipids; D009713:Nucleotidyltransferases; C022348:phosphatidate cytidylyltransferase; D017576:Daptomycin
keywords: Streptococcus; daptomycin; lipidomics