Viral Membrane Channels: Role and Function in the Virus Life Cycle

Sze, Ching Wooen; Tan, Yee-Joo

In the family of Coronaviridae, viroporin appears to be encoded by the small envelope membrane (E) proteins [124] [125] [126] . Conflicting results have been obtained for the structural determination of E protein in different coronaviruses, due to their tendency to aggregate and the various conditions used to express the protein that affect the palmitoylation of the protein [127] [128] [129] [130] . The E protein is important for the assembly and morphogenesis of the virus [29,30]. In the murine coronavirus, co-expression of the E protein and another membrane glycoprotein, M, were sufficient for the assembly and release of viral envelope particle, independent of the nucleopcapsid, an assembly process that is unlike many other enveloped viruses [28] . When mutations were made in the E gene, the overall fitness of the mutant viruses were significantly reduced as compared to the wild type [131] . Future studies are needed in order to fully decipher the mechanism of viroporin E in the assembly and egress of the virus.