The influence of mild acidity on lysyl-phosphatidylglycerol biosynthesis and lipid membrane physico-chemical properties in methicillin-resistant Staphylococcus aureus

摘要: The increased biosynthesis of lysyl-phosphatidylglycerol in Staphylococcus aureus when cultured under conditions mild acidity and the resultant proportion this lipid plasma membrane bacterium, alters physico-chemical properties bilayers a manner which is itself dependent upon environmental pH. Clinically relevant strains S. aureus, both methicillin susceptible resistant, all exhibited response to acidity, albeit differing degrees, from ∼30% ∼55% total phospholipid. Polar extracts these bacteria were analysed by 31P NMR reconstituted into vesicles monolayers, characterised zeta potential measurements Langmuir isotherms respectively. A combination content found synergistically neutralise charge membranes, one instance altering -56mV +21mV, induce closer packing between lipids. Challenge model membranes antimicrobial peptide magainin 2 F5W was examined using monolayer subphase injection neutron diffraction, revealed that ionisation headgroup α-amine at pH 5.5, reduced magnitude peptide-lipid interaction 80%, more important for resisting partitioning than alone. significance results discussed relation how colonising mildly acidic environments such as human mucosa may be facilitated implications further biophysical analysis role bacterial membranes.