A research team from the Universidad Autonoma de Madrid directed by Professor Luis Carrasco has published new discoveries concerning the membrane permeabilizing proteins of the polio virus.
Mechanisms that create non selective pores in cellular membranes have been a defence and attack tool used by a wide range organisms form time immemorial. Cytotoxic proteins with this capacity are produced by bacteria, amoebas, fungi, anemone, and vertebrates (as part of their immune system) as well as in the poison of some arthropods and snakes. Although, the proteins that are capable of producing such destabilising pores in the cellular membrane of organisms can be very different in terms of the sequence of amino acids that forms them, they all create permeabilizing structures that increase the overall permeability of the semi-permeable cellular membrane allowing for a passive flow of ions and other small substances. Up to now there was no evidence of such properties from viral origin.
The research group led by Professor Luis Carrasco from the Centro de Biología Molecular Severo Ochoa (UAM-CSIC) in Madrid has been studying the mechanism of late permeabilization caused by different viruses and among them the poliomyelitis virus. In the late stages of the infection produced by most animal viruses, a permeabilization phenomenon takes place in the cellular membranes that is very important to ensure an easier release of the new viral particles to the exterior of the cell.
In the last few years, different studies have demonstrated that the individual expression of certain viral genes could reproduce this process in several cellular systems. It was then that the name “viroporin” was established for the viral proteins that shared some structural properties in addition to the permeabilizing effect on the membranes.
The poliovirus protein 2B, known as the causal agent of poliomyelitis, as well as its precursor (2BC), are viroporins that increase the permeability of bacterial and mammalian cell membranes. In previous studies, with the application of biophysical techniques, it was proven that the addition of the purified protein 2B induces permeabilization in artificial membranes (liposomes) to substances of a low molecular weight, fitting in with this phenomenon in cells.