INIBIOLP   05426
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE LA PLATA "PROF. DR. RODOLFO R. BRENNER"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Sterol carrier protein of Yarrowia lipolytica transfers fatty acids to acceptor membranes through a collision-mediated mechanism
Autor/es:
FALOMIR, L.; NOELIA I. BURGARDT; FERREYRA R; CEOLIN M; MARIO R. ERMÁCORA; CÓRSICO, B
Lugar:
Vancouver, Canada.
Reunión:
Congreso; 6th Lipid Binding Protein Meeting.; 2007
Resumen:
Sterol carrier protein-2 (SCP2) is an intracellular, small, basic protein domain widely expressed in all living organisms. SCP2 was originally described as a sterol binding protein, but more recently it has been shown to also bind phospholipids, fatty acids, and fatty acyl-coenzyme A. The biological function of SCP2 remains obscure, although it has been extensively studied in mammalian cells. It is hypothesized that SCP2 targets its ligand molecules into compartmentalized intracellular pools. A novel SCP2 from Yarrowia lipolítica (YLSCP2) has been recently cloned and characterized for its optical, hydrodynamic and thermodynamic properties as well as its fatty acid binding capacity. In this work, employing a fluorescence energy transfer assay, we have analyzed the rates and mechanisms of anthroyloxy-fatty acid (AOFA) transfer from YLSCP2 to phospholipids membranes containing NBD-PC (N-(7-nitro-2,1,3-benzoxadiazol-4-yl) egg phosphatidylcholine) as an energy transfer acceptor of the anthroyloxy group donor. Binding of AOFA and relative partition coefficient for AOFA between YLSCP2 and vesicles were determined in order to establish the transfer experiment’s conditions. The effect of acceptor membrane phospholipid concentration on rates of ligand transfer has been used to distinguish between aqueous diffusion and collision-mediated mechanisms. AOFA transfer from YLSCP2 to model zwitterionic membranes was examined as a function of increasing SUV concentration, showing a proportional increase in transfer rates as a function of vesicle concentration, thus suggesting a collision mechanism of FA transfer. Changes in the surface charge properties of the acceptor vesicles can also influence ligand transfer rates if electrostatic interactions between donor protein and acceptor membranes are involved.  AOFA transfer from YLSCP2 was increased from 4-fold to over 30-fold to acceptor membranes which contained an additional 25 mol % negatively charged phosphatidylserine or cardiolipin, respectively. Our results suggest that YLSCP2 is a membrane‑interactive protein which is able to transfer fatty acids to acceptor membranes through a collision-mediated mechanism which involves electrostatic interactions between protein and membrane.