Periodic bilayer organization in the complexes of Beta-2 Glycoprotein I with anionic lipid membranes

OLIVEIRA, RAFAEL G.; PAOLOROSSI, MARIANA; CAVALCANTI, LEIDE PASSOS; MALFATTI-GASPERINI, ANTONIO; MONTICH, GUILLERMO G.

COLLOIDS AND SURFACES B-BIOINTERFACES

ELSEVIER SCIENCE BV

Año: 2021 vol. 208

0927-7765

#946;2 glycoprotein I (β2GPI) is a soluble protein that participates in blood coagulation, clearance of apoptotic bodies and generation of antigens in antiphospholipid syndrome among many other functions. We studied the aggregates formed by β2GPI with the anionic phospholipids palmitoyloleoylphosphatidyl glycerol, dimyristoylphosphatidyl glycerol, dipalmitoylphosphatidyl glycerol and cardiolipin using small angle X-ray scattering. The complexes obtained in a medium containing 0.01 M NaCl showed Bragg peaks up to the sixth order in a well-defined integer sequence indicating the presence of a lamellar stacking with a periodicity of 17.8 nm and with largely reduced membrane fluctuations. Modeling the complex signal allowed us to conclude that the coherence length was only two bilayers and that about 15% of the total surface was actually stacked. The space between bilayers allows accommodating an extended β2GPI molecule making a bridge between the interacting bilayers. The