La unión y formación de poros de las actinoporinas están determinadas por las propiedades fisicoquímicas de la membrana
Fecha
2022
Autores
Alvarez Valcárcel, Carlos M
Pedrera, Lohans
Soto Febles, Carmen
Alvarado Mesén, Javier
Ros, Uris
Lanio Ruíz, María E.
Valle Garay, Aisel
Fanani, Maria Laura
Pazos Santos, Fabiola
Valiente Flores, Pedro Alberto
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Editor
Academia de Ciencias de Cuba (Cuba)
Resumen
Introducción. Las actinoporinas (AP) son proteínas formadoras de poro (PFP) que se asocian
a membranas conduciendo a la muerte celular. Sticholysinas I y II (St, StI/II) se encuentran
entre las AP más potentes descritas en la naturaleza. El objetivo del presente trabajo
fue estudiar la influencia de la composición lipídica y dinámica de la membrana en la unión
y formación de poros por StI/II y nigrelysina (Ngr), una nueva AP aquí descrita. Métodos. La
unión y formación de poros se estudiaron mediante membranas modelo combinadas con
espectroscopía de fluorescencia y microscopía. Resultados y discusión. St y Ngr se unen y
permeabilizan preferencialmente membranas que contienen esfingomielina (SM) cuando se
compara con fosfatidilcolina (PC), debido a la presencia, en SM, de la unidad de fosfocolina
de PC más la unidad ceramida (Cer). StI reconoce a Cer y a gangliósidos, aunque en menor
extensión. En términos de propiedades dinámicas, StI penetra preferencialmente membranas
con elevada movilidad lateral y adecuado nivel de SM. StI permeabiliza más eficientemente
membranas con esteroles además de SM. Los bordes de la coexistencia de dominios
lipídicos no constituyen un factor determinante para su unión y actividad. La heterogeneidad
molecular de las membranas, más allá de la presencia de dominios, favorece la actividad de
AP. Conclusiones. Estos estudios explican la relevancia de SM, otros lípidos de base Cer y
esteroles a la actividad de St, Ngr, y por extensión, a las AP. Desde una perspectiva dinámica,
una fase altamente fluida y moderadamente enriquecida en SM y esteroles constituye una
plataforma ideal para la formación de poros por AP.
Introduction. Actinoporins (AP) are pore-forming proteins (PFPs) that readily bind to membranes leading to cell death. Sticholysins I and II (St, StI/II) are among the most potent AP described in nature. This proposal aimed to characterize the influence of lipid composition and dynamic properties of membranes on binding and pore-formation by StI/II and nigrelysin (Ngr), a novel AP here described. Methods. Binding and pore-formation were studied using model membranes such as liposomes and lipidic monolayers combined with fluorescence spectroscopy and microscopic techniques. Results and Discussion. St and Ngr bind and preferentially permeabilize membranes containing sphingomyelin (SM) over phosphatidylcholine (PC). This is explained by the presence of the PC phosphocholine unit plus a ceramide moiety (Cer) in SM. StI also recognizes Cer and gangliosides although to a lesser extent. In terms of dynamic properties, StI penetrates preferentially membranes with high lateral mobility and moderately enriched in SM. Also, StI permeabilizes more efficiently membranes containing sterols, in addition to SM. The appearance of borders resulting from lipidic domains coexistence is not a determining factor for binding or activity in membranes. Indeed, the activity is enhanced by membrane molecular heterogeneity beyond the presence of lipidic domains. As a conclusion these studies explain the relevance of SM and sterols for St, Ngr, and by extension, to APs binding to membrane and explain the contribution of other Cer-based lipids to their activity. In dynamic terms, a highly fluid phase, and moderately enriched in SM and sterols, is an ideal platform for the formation of pores in the membrane for AP.
Introduction. Actinoporins (AP) are pore-forming proteins (PFPs) that readily bind to membranes leading to cell death. Sticholysins I and II (St, StI/II) are among the most potent AP described in nature. This proposal aimed to characterize the influence of lipid composition and dynamic properties of membranes on binding and pore-formation by StI/II and nigrelysin (Ngr), a novel AP here described. Methods. Binding and pore-formation were studied using model membranes such as liposomes and lipidic monolayers combined with fluorescence spectroscopy and microscopic techniques. Results and Discussion. St and Ngr bind and preferentially permeabilize membranes containing sphingomyelin (SM) over phosphatidylcholine (PC). This is explained by the presence of the PC phosphocholine unit plus a ceramide moiety (Cer) in SM. StI also recognizes Cer and gangliosides although to a lesser extent. In terms of dynamic properties, StI penetrates preferentially membranes with high lateral mobility and moderately enriched in SM. Also, StI permeabilizes more efficiently membranes containing sterols, in addition to SM. The appearance of borders resulting from lipidic domains coexistence is not a determining factor for binding or activity in membranes. Indeed, the activity is enhanced by membrane molecular heterogeneity beyond the presence of lipidic domains. As a conclusion these studies explain the relevance of SM and sterols for St, Ngr, and by extension, to APs binding to membrane and explain the contribution of other Cer-based lipids to their activity. In dynamic terms, a highly fluid phase, and moderately enriched in SM and sterols, is an ideal platform for the formation of pores in the membrane for AP.
Descripción
Palabras clave
ACTINOPORINAS, PROTEÍNAS FORMADORAS DE PORO, FLUIDEZ, MODEL MEMBRANES, LIPID PHASES