title: In vitro susceptibility of Staphylococcus aureus to thrombin-induced platelet microbicidal protein-1 (tPMP-1) is influenced by cell membrane phospholipid composition and asymmetry.
abstract: Thrombin-induced platelet microbicidal proteins (e.g. tPMP-1) are small cationic peptides released from mammalian platelets. As the cytoplasmic membrane (CM) is a primary target of tPMPs, distinct CM characteristics are likely to affect the cells' susceptibility profiles. In Staphylococcus aureus, CM surface charge and hydrophobicity are principally determined by the content and distribution of its three major phospholipid (PL) constituents: negatively charged phosphatidylglycerol (PG) and cardiolipin (CL) and positively charged lysyl-PG (LPG). PL composition profiles, and inner vs outer CM leaflet PL distributions, were compared in an isogenic tPMP-susceptible (tPMP(S)) and -resistant (tPMP(R)) S. aureus strain pair (ISP479C vs ISP479R respectively). All PLs were asymmetrically distributed between the outer and inner CM leaflets in both strains. However, in ISP479R, the outer CM leaflet content of LPG was significantly increased vs ISP479C (27.3+/-11.0 % vs 18.6+/-7.0 % respectively; P=0.05). This observation correlated with reduced binding of the cationic proteins cytochrome c, poly-L-lysine, tPMP-1 and the tPMP-1-mimetic peptide, RP1, to tPMP-1(R) whole cells and to model liposomal CMs with LPG content and distribution similar to that of tPMP-1(R) strains. Collectively, selected CM parameters correlated with reduced staphylocidal capacities of tPMP-1 against certain S. aureus strains, including relative increases in outer CM leaflet positive charge and reduced surface binding of cationic molecules. These findings offer new insights into mechanisms of antimicrobial peptide susceptibility and resistance in S. aureus.
authors: The LA Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA.
authors: Kasturi
authors: K
authors: Mukhopadhyay
authors: The LA Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA.
authors: William
authors: W
authors: Whitmire
authors: The David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.|The Department of Medicine, Harbour-UCLA Medical Center, Torrance, CA, USA.|The LA Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA.
authors: Yan Q
authors: YQ
authors: Xiong
authors: The Department of Medicine, Harbour-UCLA Medical Center, Torrance, CA, USA.
authors: Jaime
authors: J
authors: Molden
authors: The LA Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA.
authors: Tiffanny
authors: T
authors: Jones
authors: Cellular and Molecular Microbiology, Medical Microbiology and Hygiene, University of Tübingen, Tübingen, Germany.
authors: Andreas
authors: A
authors: Peschel
authors: Cellular and Molecular Microbiology, Medical Microbiology and Hygiene, University of Tübingen, Tübingen, Germany.
authors: Petra
authors: P
authors: Staubitz
authors: Department of Microbiology, California State Polytechnical State University-Pomona, Pomona, CA, USA.
authors: Jill
authors: J
authors: Adler-Moore
authors: Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, WI, USA.
authors: Peter J
authors: PJ
authors: McNamara
authors: Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, WI, USA.
authors: Richard A
authors: RA
authors: Proctor
authors: The David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.|The Department of Medicine, Harbour-UCLA Medical Center, Torrance, CA, USA.|The LA Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA.
authors: Michael R
authors: MR
authors: Yeaman
authors: The David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.|The Department of Medicine, Harbour-UCLA Medical Center, Torrance, CA, USA.|The LA Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA.
authors: Arnold S
authors: AS
authors: Bayer
mesh_terms: D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000378:metabolism; D001798:Blood Proteins / Q000378:metabolism*; D002308:Cardiolipins / Q000032:analysis; D002462:Cell Membrane / Q000737:chemistry; D002845:Chromatography / Q000379:methods; D045304:Cytochromes c / Q000378:metabolism; D005434:Flow Cytometry / Q000379:methods; D010715:Phosphatidylglycerols / Q000032:analysis; D010743:Phospholipids / Q000032:analysis*; D011107:Polylysine / Q000378:metabolism; D011817:Rabbits; D013211:Staphylococcus aureus / Q000166:cytology / Q000378:metabolism*
chemical_list: D023181:Antimicrobial Cationic Peptides; D001798:Blood Proteins; D002308:Cardiolipins; D010715:Phosphatidylglycerols; D010743:Phospholipids; C077150:platelet microbicidal protein, Oryctolagus cuniculus; D011107:Polylysine; D045304:Cytochromes c