Streptococcus mitis and S. oralis Lack a Requirement for CdsA, the Enzyme Required for Synthesis of Major Membrane Phospholipids in Bacteria

Synthesis and integrity of the cytoplasmic membrane are fundamental to cellular life. Experimental evolution studies have hinted at unique physiology in the Gram-positive bacteria and These organisms commonly cause bacteremia and infectious endocarditis (IE) but are rarely investigated in mechanisti...

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Bibliographic Details
Published in:Antimicrobial agents and chemotherapy 2017-05, Vol.61 (5)
Main Authors: Adams, Hannah M, Joyce, Luke R, Guan, Ziqiang, Akins, Ronda L, Palmer, Kelli L
Format: Article
Language:English
Subjects:
Anti-Bacterial Agents
Anti-Bacterial Agents - pharmacology
Bacteria
Cardiolipins - metabolism
Cytidine Diphosphate Diglycerides - biosynthesis
Daptomycin
Daptomycin - pharmacology
Drug Resistance, Bacterial - genetics
Humans
Mechanisms of Resistance
Membrane Lipids - biosynthesis
Microbial Sensitivity Tests
Nucleotidyltransferases
Nucleotidyltransferases - genetics
Phosphatidic Acids - metabolism
Phosphatidylglycerols - metabolism
Phospholipids - biosynthesis
Streptococcal Infections - microbiology
Streptococcal Infections - pathology
Streptococcus mitis
Streptococcus mitis - drug effects
Streptococcus mitis - genetics
Streptococcus mitis - isolation & purification
Streptococcus oralis
Streptococcus oralis - drug effects
Streptococcus oralis - genetics
Streptococcus oralis - isolation & purification
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Summary:Synthesis and integrity of the cytoplasmic membrane are fundamental to cellular life. Experimental evolution studies have hinted at unique physiology in the Gram-positive bacteria and These 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 in and after a single drug exposure. In this study, we found that inactivating mutations in are associated with high-level daptomycin resistance in and IE isolates. This is surprising given that is 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 of not 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.
ISSN:0066-4804
1098-6596
DOI:10.1128/AAC.02552-16