Biophysical study of the perturbation of model membrane structure caused by seminal plasma protein PDC-109.
PDC-109, the major heparin-binding protein of bull seminal plasma, binds specifically to sperm choline lipids at ejaculation and mediates capacitation by stimulating cholesterol and phospholipid efflux. We carried out a biophysical study to investigate the membrane perturbation effect caused by PDC-109. Binding of PDC-109 to phosphatidylcholine model membranes was maximal at a 12:1 phosphatidylcholine to protein molar ratio. The process was independent of the membrane structure and involved a slight conformational change of the protein, compatible with an increased exposure to the solvent. PDC-109 binding to dimyristoylphosphatidylcholine prevented lipid molecules from participating in the gel-to-liquid phase transition, due to enhancement of both acyl chain disorder and interfacial hydration. Visualization of the lipid-protein complexes by electron microscopy showed surface irregularities and the presence of 10-nm particles. Permeability assays confirmed the PDC-109-induced disruption of the vesicles. This effect was not modified by heparin. However, presence of cholesterol inhibited the process in a concentration-dependent manner.
Gasset
M
M
Instituto de Química-Física "Rocasolano" C.S.I.C., Serrano 119, Madrid, 28006, Spain.
Magdaleno
L
L
Calvete
J J
JJ
D000818:Animals; D002151:Calorimetry; D002417:Cattle; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry*; D008297:Male; D010713:Phosphatidylcholines / Q000737:chemistry*; D029584:Prostatic Secretory Proteins; D011485:Protein Binding; D011489:Protein Denaturation; D011506:Proteins / Q000737:chemistry* / Q000302:isolation & purification; D012661:Semen / Q000737:chemistry; D029589:Seminal Plasma Proteins; D013050:Spectrometry, Fluorescence / Q000379:methods; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013816:Thermodynamics
D008081:Liposomes; D010713:Phosphatidylcholines; D029584:Prostatic Secretory Proteins; D011506:Proteins; D029589:Seminal Plasma Proteins; C043076:beta-microseminoprotein; D004134:Dimyristoylphosphatidylcholine