Role of surface electrostatic potential on the association of dehydrogenases to model membranes

AVILA, C L DE ARCURI, B GONZALEZ, D CHEHIN, R MORERO, R

Rosario, Argentina

Congreso; XXXV Reunion Anual de la Sociedad Argentina de Biofisica; 2006

Membrane fusion is an ubiquitous cell event present in process such asmembrane trafficking, exocitosis, virus infection and gamete formation.Lipids membranes do not spontaneously fuse and energy must be invested toovercome hydration repulsion between membranes that approach each other andto disrupt normal bilayer structure of the fusing membranes. Understandingthe molecular events that occur in cell membranes upon binding and insertionof fusogenic proteins represents an intriguing challenge. For severalproteins it has been demonstrated that non-specific electrostatic andhydrophobic interactions play a major role in their association to lipidbilayers and the segments involved have been identified. In vitro studiesdemonstrated the ability of some dehydrogenases to induce fusion ofliposomes. Glyceraldehide-3-phosphate dehydrogenase has also been involvedin fusion events in vivo and its ability to bind to phospholipids monolayershas been studied. In the present communication a comparative study on theability of several dehydrogenases to associate to liposomes was carried outusing fluorescent probes. We also report calculations of the nonspecificelectrostatic contribution to the binding of the proteins to membranes. Thecalculations were carried out with the finite-difference Poisson-Boltzmannmethod, which has proved accurate in its ability to account forelectrostatic of protein-membrane systems. The results provide evidence onthe importance of nonspecific electrostatic interactions for the membraneassociation properties of this group of proteins.