[en] Dynamic regulation of membrane shape by lipid-protein interactions is imperative for many intra and intercellular processes. Matrix proteins of many enveloped viruses have been suggested as the main responsible of the shape transformation of the cellular membrane into the viral vesicle. In order to investigate the molecular mechanism behind the matrix protein driven budding this process has been reconstituted with M protein purified from the NDV and different model lipid systems (planar lipid membranes, large and giant unilamellar vesicles and lipid monolayer). M protein budding activity has been characterized by different experimental approaches, including electric admittance measurements, fluorescence microscopy, spectroscopic approaches, electron microscopy and surface pressure measurements. The experimental data had shown that the interaction of the matrix protein from NDV with model lipid system results in membrane budding and production of membrane vesicles with a size distribution similar to that of the NDV. Thus, NDV matrix protein does not need the presence of any cellular component in order to activate its budding activity. NDV matrix protein binding and budding activities were dependent on the membrane lipid composition, being enhanced in the presence of molecules such as cholesterol in the membrane. Moreover, it was observed that the M protein of NDV organizes fluid-like domains on the lipid membrane prior to the membrane budding. The unidirectionality of budding produced by M protein indicated that the self-assembly of the protein on the membrane surface induced creation of a negative curvature. Fluid-like proteolipid domain creation had been proposed as the mechanism behind the cellular membrane budding induced by the matrix protein of the Newcastle Disease Virus.

[es] La regulaci?n din?mica de la forma de la membrana celular mediante interacciones proteolip?dicas es importante para procesos intra- e inter-celulares. Se sabe que la gemaci?n de muchos virus con envoltura se basa en la acci?n excusiva de una ?nica prote?na: la prote?na matriz ? M. En el presente trabajo la gemaci?n viral ha sido reconstituida usando la prote?na M del virus de la enfermedad de Newcastle (NDV) y diferentes sistemas lip?dicos modelo (membranas planas, ves?culas unilamelares gigantes y grandes, y monocapas lip?dicas). As?, la gemaci?n por parte de la prote?na M de NDV ha sido caracterizada mediante diferentes t?cnicas experimentales, tales como medidas de admitancia el?ctrica, microscop?a de fluorescencia, t?cnicas espectrosc?picas, microscop?a electr?nica y medidas de presi?n superficial. Los datos experimentales obtenidos se?alan que la interacci?n de la prote?na matriz del NDV con los sistemas lip?dicos modelo lleva a la gemaci?n de membrana y producci?n de ves?culas cuya distribuci?n de tama?os es similar a la del NDV. De ?sta forma, la prote?na matriz del NDV es capaz de inducir la gemaci?n de la membrana lip?dica en ausencia de otros componentes de la maquinaria celular o viral. La adsorci?n y gemaci?n por parte de la prote?na matriz del NDV depende de la composici?n lip?dica de la membrana, viendose ?mbas favorecidas por la presencia de moleculas como el colesterol. Adem?s, se observa que la prote?na M del NDV organiza dominios fuidos sobre la membrana lip?dica antes de que ocurra la gemaci?n de la membrana. La unidireccionalidad de la gemaci?n producida por la prote?na M indica que el autoensamblaje de la prote?na sobre la superficie de la membrana lip?dica induce una curvatura negativa en la membrana. La formaci?n de dominios proteolip?dicos l?quidos sobre la superf?cie de la membrana se propone como el mecanismo para la gemaci?n de membrana celular por parte de la prote?na M del NDV.