Defining the structural characteristics of annexin V binding to a mimetic apoptotic membrane.
Annexin V is of crucial importance for detection of the phosphatidylserine of apoptotic cell membranes. However, the manner in which different amounts of phosphatidylserine at the membrane surface at different stages of apoptosis contribute to binding of annexin V is unclear. We have used a quartz crystal microbalance combined with dissipative monitoring (QCM-D) and neutron reflectivity to characterize binding of human annexin V to supported bilayers of different phospholipid composition. We created model apoptotic bilayers of 1-palmitoyl-2-oleoyl-sn-glycerophosphocholine and 1-palmitoyl-2-oleoyl-sn-glycerophosphoserine (POPS) in the ratios 19:1, 9:1, 6.7:1, 4:1, 3:1, and 2:1 (w/w) in the presence of 2.5 mM CaCl2. QCM-D data revealed that annexin V bound less to supported fluid lipid bilayers with higher POPS content (>25 % POPS). Neutron reflectivity was used to further characterize the detailed composition of lipid bilayers with membrane-bound annexin V. Analysis confirmed less annexin V binding with higher POPS content, that bound annexin V formed a discrete layer above the lipid bilayer with little effect on the overall structure of the membrane, and that the thickness and volume fraction of the annexin V layer varied with POPS content. From these results we show that the POPS content of the outer surface of lipid bilayers affects the structure of membrane-bound annexin V.
School of Biomedical Sciences, Monash University, Melbourne, 3800, Australia.|Faculty of Engineering, Monash University, Melbourne, 3800, Australia.
Jingxiong
J
Lu
The Bragg Institute, Australian Nuclear Science and Technology Organization (ANSTO), New Illawarra Rd, Lucas Heights, NSW, 2234, Australia.
Anton P
AP
Le Brun
School of Biomedical Sciences, Monash University, Melbourne, 3800, Australia.
Seong Hoong
SH
Chow
School of Biomedical Sciences, Monash University, Melbourne, 3800, Australia.
Takuya
T
Shiota
School of Biomedical Sciences, Monash University, Melbourne, 3800, Australia.
Bo
B
Wang
Department of Chemistry, Tunghai University, No. 181, Sec. 3, Taichung Port Rd., Taichung, 40704, Taiwan.
Tsung-Wu
TW
Lin
Centre for Eye Research Australia, Department of Ophthalmology, University of Melbourne, East Melbourne, Australia.
Guei-Sheung
GS
Liu
School of Biomedical Sciences, Monash University, Melbourne, 3800, Australia. hsin-hui.shen@monash.edu.|Faculty of Engineering, Monash University, Melbourne, 3800, Australia. hsin-hui.shen@monash.edu.
Hsin-Hui
HH
Shen
D000595:Amino Acid Sequence; D017304:Annexin A5 / Q000737:chemistry* / Q000378:metabolism; D017209:Apoptosis; D001665:Binding Sites; D006801:Humans; D008051:Lipid Bilayers / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D011485:Protein Binding
D017304:Annexin A5; D008051:Lipid Bilayers
Annexin V; Apoptosis and lipid bilayer; Neutron reflectivity; Solid–liquid interface