title: Impact of the β-Lactam Resistance Modifier (-)-Epicatechin Gallate on the Non-Random Distribution of Phospholipids across the Cytoplasmic Membrane of Staphylococcus aureus.
abstract: The polyphenol (-)-epicatechin gallate (ECg) inserts into the cytoplasmic membrane (CM) of methicillin-resistant Staphylococcus aureus (MRSA) and reversibly abrogates resistance to β-lactam antibiotics. ECg elicits an increase in MRSA cell size and induces thickened cell walls. As ECg partially delocalizes penicillin-binding protein PBP2 from the septal division site, reduces PBP2 and PBP2a complexation and induces CM remodelling, we examined the impact of ECg membrane intercalation on phospholipid distribution across the CM and determined if ECg affects the equatorial, orthogonal mode of division. The major phospholipids of the staphylococcal CM, lysylphosphatidylglycerol (LPG), phosphatidylglycerol (PG), and cardiolipin (CL), were distributed in highly asymmetric fashion; 95%-97% of LPG was associated with the inner leaflet whereas PG (~90%) and CL (~80%) were found predominantly in the outer leaflet. ECg elicited small, significant changes in LPG distribution. Atomic force microscopy established that ECg-exposed cells divided in similar fashion to control bacteria, with a thickened band of encircling peptidoglycan representing the most recent plane of cell division, less distinct ribs indicative of previous sites of orthogonal division and concentric rings and "knobbles" representing stages of peptidoglycan remodelling during the cell cycle. Preservation of staphylococcal membrane lipid asymmetry and mode of division in sequential orthogonal planes appear key features of ECg-induced stress.
authors.affiliation: School of Pharmacy, University College London, London WC1N 1AX, UK. h.rosado@ucl.ac.uk.
authors.forename: Helena
authors.initials: H
authors.lastname: Rosado
authors.affiliation: Krebs Institute, University of Sheffield, Western Bank, Sheffield S10 2TN, UK. r.d.turner@sheffield.ac.uk.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Turner
authors.affiliation: Krebs Institute, University of Sheffield, Western Bank, Sheffield S10 2TN, UK. s.foster@sheffield.ac.uk.
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Foster
authors.affiliation: School of Pharmacy, University College London, London WC1N 1AX, UK. peter.taylor@ucl.ac.uk.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Taylor
mesh_terms: D002308:Cardiolipins / Q000737:chemistry; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002462:Cell Membrane / Q000737:chemistry* / Q000187:drug effects; D008239:Lysine / Q000737:chemistry; D008563:Membrane Lipids / Q000737:chemistry; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects* / Q000254:growth & development; D018625:Microscopy, Atomic Force; D010457:Peptidoglycan / Q000737:chemistry; D010641:Phenotype; D010715:Phosphatidylglycerols / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry*; D047090:beta-Lactams / Q000378:metabolism*
chemical_list: D002308:Cardiolipins; D008563:Membrane Lipids; D010457:Peptidoglycan; D010715:Phosphatidylglycerols; D010743:Phospholipids; D047090:beta-Lactams; C002285:lysylphosphatidylglycerol; D002392:Catechin; C062669:epicatechin gallate; D008239:Lysine
keywords: Staphylococcus aureus; bacterial cell division; beta-lactam susceptibility; epicatechin gallate; membrane asymmetry; membrane phospholipids