In situ characterization of lipid A interaction with antimicrobial peptides using surface X-ray scattering.
Lipid A structure at the air-aqueous interface has been studied using pressure-area isotherm methods coupled with the surface X-ray scattering techniques of X-ray reflectivity (XR) and grazing incidence X-ray diffraction (GIXD). Lipid A monolayers were formed at the air-aqueous interface to represent the lipid moiety of the outer membrane of Gram-negative bacteria. Lipid A structure was characterized at surface pressures between 10 and 35 mN/m. Interactions of alpha-helical antimicrobial peptides LL-37, SMAP-29 and D2A22 with lipid A monolayers were subsequently studied. Although insertion into the lipid A monolayers was observed with the alpha-helical peptides, little change was seen from the X-ray data, suggesting that the lipid A hydrocarbon chains are involved in reorientation during insertion and that the hydrocarbon chains have a relatively rigid structure.
Neville
Frances
F
School of Process, Environmental and Materials Engineering, University of Leeds, Leeds LS2 9JT, UK.
Hodges
Chris S
CS
Liu
Chao
C
Konovalov
Oleg
O
Gidalevitz
David
D
D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry*; D001798:Blood Proteins / Q000737:chemistry; D054804:Cathelicidins; D006801:Humans; D066298:In Vitro Techniques; D008050:Lipid A / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry; D008969:Molecular Sequence Data; D015394:Molecular Structure; D011312:Pressure; D012542:Scattering, Radiation; D013499:Surface Properties; D013816:Thermodynamics; D014965:X-Rays
D023181:Antimicrobial Cationic Peptides; D001798:Blood Proteins; D054804:Cathelicidins; D008050:Lipid A; D008051:Lipid Bilayers; C403305:SMAP29 protein, Ovis aries