De izquierda a derecha: Dr. Eduardo
Lissi (Chile), Dr. Bruno Maggio (Argentina), Dr. Pietro
Ciancaglini (Brasil), Dra. Rosana Chein (Organizadora, Argentina), Dra. María
E. Lanio (Cuba), Dr. Carlos Alvarez (Cuba), Dra. Rosangela
Itri (Brasil), Dr. Leandro Barboza (Brasil), Dra. Maria Laura Fanani (Argentina), Dr. Rodrigo
Montecinos (Chile) Reunion CYTED-BIOTOX (Toxinas de Interes Biomédico) en San Javier Tucumán Simposio CYTED-BIOTOX Disertacion: The action and regulation of Sphingomyelinasein lipid membranes |
Sphingomyelinase (SMase) is a phospholipase that hydrolyzessphingomyelin producing ceramide, which remains in the membrane, andthe water-soluble phosphocholine. It is present in bacterial hemolyticcocktails, spider venoms and has an important role in mammalian cell signaltransduction. The production of ceramide induces important changes in thephysical organization of the membrane, which is proposed as its mainbiological function. In cholesterol-poor membranes the enzymaticallyproduced ceramide laterally segregates forming condensed ceramideenricheddomains (1) whose composition and morphology depends on thekinetics of ceramida production (2). On the other hand, in cholesterol-richmembranes the produced ceramide partitions preferentially in cholesterolrichliquid-ordered domains, freeing the more expanded (SMase-rich) activephase from product and allowing the liquid-ordered domains to act assubstrate reservoir. As a consequence SMase shows an enhanced activitywhen acting in a membrane that exhibit the coexistence of liquid-expanded/liquid-ordered phases (3) compared to fully liquid-expanded or fully liquidorderedphases. Therefore, lipid diffusion and preferential partitioning in thedifferent phases determine the membrane reactivity, dynamics and bidimensionalstructure that are relevant for the enzymatic function.References:1) Fanani, M. L., Hartel, S., Maggio, B., De, T. L., Jara, J., Olmos, F., and Oliveira, R. G.(2010) Biochim. Biophys Acta 1798, 1309-1323.2) Fanani, M. L., De, T. L., Hartel, S., Jara, J., and Maggio, B. (2009) Biophys. J. 96, 67-763) Ale, E. C., Maggio, B., and Fanani, M. L. (2012) Biochim Biophys Acta 1818, 2767-2776Acknoledgments: This work was supported by CONICET, FONCyT; SECyT-UNC. MLF andBM are career researchers of CONICET.