Sterol carrier protein from Yarrowia lipolytica transfers fatty acids to acceptor membranes through a collision-mediated mechanism

FALOMIR LOCKHART LJ; BURGARDT NI; FERREYRA RG; CEOLIN M; ERMÁCORA, ME; CÓRSICO B

Maastricht

Congreso; 49th International Conference on the Bioscience of Lipids (ICBL); 2008

ICBL

A novel SCP2 from Yarrowia lipolytica yeast (YLSCP2) has been recently cloned and characterized. Y. lipolytica is an important model for studying lipid metabolism because of its remarkable capacity for surviving with palmitate as carbon and energy only source. Employing an energy transfer assay, we analyzed the rates and mechanisms of anthroyloxy-fatty acid (AOFA) transfer from YLSCP2 to phospholipids membranes (SUV) containing an energy transfer acceptor. The effect of increasing acceptor SUV concentration on rates of ligand transfer was used to distinguish a collision-mediated mechanisms of AOFA transfer from YLSCP2, showing a proportional increase. Changes in the surface charges of the SUV can also influence ligand transfer rates if electrostatic interactions between donor protein and acceptor membranes are involved. AOFA transfer was increased from 4-fold to over 40-fold to SUV which contained a 25 mol% negatively charged phosphatidylserine or cardiolipin, respectively. As expected for collisional mechanisms, no significant effect was observed for an increase in the ionic strength of the media. The transfer rates were also analyzed as a function of temperature to calculate the thermodynamic parameters of the process. 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. This may be suggesting a specialized function in lipid targeting and metabolism in specialized intracellular compartments.