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Aminoacyl lipids, Catanionic monolayers, Antimicrobial resistance, Staphylococcus aureus, Membrane biophysics
Abstract:
Ion pairing between the major phospholipids oftheStaphylococcus aureusplasma membrane (phosphatidylglycerol –PG and lysyl-phosphatidylglycerol - LPG) confers resistance to antimicrobial peptides and other antibiotics. We developed 3adLPG, a stable synthetic analogue which can substitute for the highy-labile native LPG,in biophysical experiments examiningthe membrane-protecting role of lipid ion pairing,in S. aureusand other important bacteria. Here we examine the surface charge and lipid packing characteristics of synthetic biomimetic mixtures of DPPG and DP3adLPGin Langmuir monolayers, using a combinationof complementary surface-probingtechniques such asinfrared reflection-absorption spectroscopyand grazing-incidence x-ray diffraction.The resultantphase diagram for the ion paired lipids sheds light on the mixing behavior of lipids in monolayer models of resistant phenotype bacterial membranes, and provides a platform for future biophysical studies.
