Las actinoporinas son un grupo de toxinas producidas por anémonas marinas, entre las que se encuentran la esticolisina II (StnII). Estas toxinas se unen a membranas mediante el reconocimiento específico de esfingomielina. Tras ello, ejercen su toxicidad formando poros en la bicapa. En este artículo hemos estudiado la permeabilidad de dichos poros usando diferentes sondas fluorescentes. Nuestros resultados indican que, una vez formados, los poros permanecen abiertos. La carga de las moléculas y, sobre todo, su tamaño, son los factores que determinan la selectividad de los poros de StnII.
Resumen
Release of aqueous contents from model lipid vesicles has been a standard procedure to evaluate pore formation efficiency by actinoporins, such as sticholysin II (StnII), for the last few decades. However, regardless of the probe of choice, the results reported that StnII action was never able to empty the vesicles completely. This was hard to explain if StnII pores were to be stable and always leaky for the probes used. To address this question, we have used a variety of probes, including rhodamine 6G or Tb3+, to test the permeability of StnII's pores. Our results indicate that calcein was in fact too large to fit through StnII's pores, and that the standard method in the field is actually reporting StnII-induced transient permeation of the membrane rather than the passage of solutes through the stable assembled pores. In order to evaluate the permeability of these structures, we used a di- thionite-based assay, which showed that the final pores were in fact open. Thus, our results indicate that the stable actinoporins' pores are open in spite of plateaued classic release curves. Besides the proper pore, the first stages of pore formation would inflict serious damage to living cells as well.
Sobre el grupo investigador
En este grupo de investigación buscamos la comprensión a nivel molecular del mecanismo de acción de proteínas tóxicas, con el fin de poder utilizarlas como herramientas biotecnológicas. En los proyectos relacionados con las actinoporinas, hemos contado con la colaboración del profesor J. Peter Slotte y su grupo, de la universidad Åbo Akademi de Turku (Finlandia), expertos en el estudio del comportamiento de lípidos.
Referencia del artículo
Palacios-Ortega, J., Rivera-de-Torre, E., Gavilanes, J. G., Slotte, J. P., & Martínez-del-Pozo, Á. (2020). Evaluation of different approaches used to study membrane permeabilization by actinoporins on model lipid vesicles. Biochimica et Biophysica Acta (BBA)-Biomembranes, 183311
https://doi.org/10.1016/j.bbamem.2020.183311
