Selective association of acid and basic FABPs to cationic lipid membranes: evidencing the dipolarity of the interaction protein-membrane

GALASSI V; VILLARREAL MA; MONTICH GG

Tucuman

Congreso; XLI Reunión Anual de la Sociedad Argentina de Biofísica; 2012

P { margin-bottom: 0.08in; } We have already shown that two peripheral proteins that belong to the FABP superfamily interact selectively with anionic membranes regarding zwitterionic ones1-4, regardless their net charge: one is negatively charged (z=-1) while the other bears positive net charge (z=+2). This interaction is driven, at least in part, by the interaction of the protein macro-dipole with the membrane electric field. These proteins show a preferred orientation in the charged interface, which results from the alienation of the macro-dipole in the membrane electric field2,4. When bound to the interface, this proteins undergo a partial unfolding, losing some tertiary native contacts. The extent of this conformational change has been found to correlate with the membrane electric field intensity2,3. We found that both proteins exhibit interaction with cationic membranes. This further evidences the dipolar character of the interaction, as long as regardless the protein net charge, it interacts with charged membranes, either anionic or cationic, while it does not bind zwitterionic membranes. The orientation of the proteins in cationic membranes was evaluated by molecular dynamics, and was also found to be compatible with the macro-dipole most favorable orientation in the membrane electric field.