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:
LISANDRO J. FALOMIR-LOCKHART; GISELA R. FRANCHINI; NOELIA I. BURGARDT; RAÚL G. FERREYRA; MARCELO CEOLIN; MARIO R. ERMÁCORA; BETINA CÓRSICO
Lugar:
Rosario, Argentina
Reunión:
Congreso; XXXV Reunión anual de la Soc. Argentina de Biofísica; 2006
Institución organizadora:
Sociedad Argentina de Biofísica
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
experiments 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.