title: Effect of acyl chain structure and bilayer phase state on binding and penetration of a supported lipid bilayer by HPA3.
abstract: The effect of acyl chain structure and bilayer phase state on binding and penetration by the peptide HPA3 was studied using dual polarisation interferometry. This peptide is an analogue of Hp(2-20) derived from the N-terminus of Helicobacter pylori ribosomal protein L1 (RpL1) which has been shown to have antimicrobial and cell-penetrating properties. The binding of HPA3 to zwitterionic 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) or 1-palmitolyl-2-oleyl-sn-glycero-3-phosphocholine (POPC) and negatively charged membranes composed of DMPC and 1,2-dimyristoyl-sn-glycero-3-(phosphor-rac-(1-glycerol)) (DMPG) or POPC and 1-palmitolyl-2-oleyl-sn-glycero-3-(phosphor-rac-(1-glycerol)) (POPG) was determined using dual polarisation interferometry (DPI). Mass and birefringence were measured in real time, enabling the creation of birefringence-mass plots for detailed analysis of the changes in lipid bilayer order during the peptide-binding process. HPA3 bound to all four lipids and the binding progressed as a single phase for the saturated gel phase bilayers DMPC and DMPC-DMPG. However, the binding process involved two or more phases, with penetration of the unsaturated fluid phase POPC and POPC-POPG bilayers. Structural changes in the saturated bilayer were partially reversible whereas binding to the unsaturated bilayer resulted in irreversible changes in membrane structure. These results demonstrate that more disordered unsaturated bilayers are more susceptible to further disorganisation and have a lower capacity to recover from peptide-induced structural changes than saturated ordered bilayers. In addition, this study further establishes DPI as powerful tool for analysis of multiphase peptide-insertion processes associated with complex structural changes in the liquid-crystalline membrane.
authors.affiliation: Department of Biochemistry & Molecular Biology, Monash University, Clayton, VIC 3800, Australia.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Hirst
authors.forename: Tzong-Hsien
authors.initials: TH
authors.lastname: Lee
authors.forename: Marcus J
authors.initials: MJ
authors.lastname: Swann
authors.forename: Sharon
authors.initials: S
authors.lastname: Unabia
authors.forename: Yoonkyung
authors.initials: Y
authors.lastname: Park
authors.forename: Kyung-Soo
authors.initials: KS
authors.lastname: Hahm
authors.forename: Marie Isabel
authors.initials: MI
authors.lastname: Aguilar
mesh_terms: D000213:Acyl Carrier Protein / Q000737:chemistry / Q000494:pharmacology*; D000890:Anti-Infective Agents / Q000737:chemistry / Q000494:pharmacology*; D001665:Binding Sites / Q000187:drug effects; D002942:Circular Dichroism / Q000379:methods; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry / Q000378:metabolism; D007368:Interferometry / Q000379:methods; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology*; D010713:Phosphatidylcholines / Q000737:chemistry / Q000378:metabolism; D010715:Phosphatidylglycerols / Q000737:chemistry / Q000378:metabolism; D012269:Ribosomal Proteins / Q000737:chemistry / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D000213:Acyl Carrier Protein; D000890:Anti-Infective Agents; C530859:HPA3 peptide; D008051:Lipid Bilayers; D010446:Peptide Fragments; D010713:Phosphatidylcholines; D010715:Phosphatidylglycerols; D012269:Ribosomal Proteins; C002773:dimyristoylphosphatidylglycerol; D004134:Dimyristoylphosphatidylcholine