Miscibility of oncoproteins with phospholipids

Buenos Aires

Congreso; XL Reunión anual de SAB; 2011

Sociedad Argentina de Biofísica

Oncoproteins are well known for their interaction with DNA and with other proteins whereas, although some of their functions are unquestionably linked to membranes, their interaction with membranes is much less understood [1]. Miscibility of oncoproteins with phospholipids may be important for their effect on membrane metabolism and restructuring. We have addressed the issue with three different approaches: deviation from ideal mixing behavior [2], phase diagrams [3] and topography [4]. Complete miscibility and immiscibility between proteins and lipids are extreme situations. Partial miscibility is often the case, and its occurrence at different levels can be discerned and integrated with these three techniques. Our analysis focuses on mixtures of the oncoproteins c-Fos, Fra-1 and c-Jun with dilauroyl phosphatidyl choline (DLPC) and sphingomyelin. We have found that the three oncoproteins have different miscibilities with these phospholipids, and c-Fos is the most miscible with both at a wider range of hyerarchical levels. Oncoproteins are also appreciably more miscible with sphingomyelin than bovine serum albumin. 1. Borioli, G.A. Immediate Early proto-Oncoproteins and membranes: not just an innocent liaison. Minireview. Current Protein & Peptide Science. 2011. In press. 2. R.E. Pagano, N.L. Gershfeld, Physical chemistry of lipid films at the air-water interface. II. Binary lipid mixtures. The principles governing miscibility of lipids in surfaces, J Phys Chem 76 (1972) 1238-1243. 3. R. Maget-Dana, M. Ptak, Penetration of the insect defensin A into phospholipid monolayers and formation of defensin A-lipid complexes, Biophys J 73 (1997) 2527-2533. 4. S. Keller, Coexisting liquid phases in lipid monolayers and bilayers, J Phys: Condens Matter 14 (2002) 4763?4766. .Acknowledgements: This work was funded by FONCyT, CONICET and SECyT-UNC