Viroporins

Abstract

Viroporins are a group of proteins that participate in several viral functions, including the promotion of release of viral particles from cells. These proteins also a¡ect cellular functions, including the cell vesicle system, glycoprotein tra⁄ck-ing and membrane permeability. Viroporins are not essential for the replication of viruses, but their presence enhances virus growth. Comprising some 60^120 amino acids, viroporins have a hydrophobic transmembrane domain that interacts with and expands the lipid bilayer. Some viroporins also contain other motifs, such as basic amino acid residues or a domain rich in aromatic amino acids that confers on the protein the ability to interact with the interfacial lipid bilayer. Viroporin oligomerization gives rise to hydrophilic pores at the membranes of virusinfected cells. As the list of known viroporins steadily grows, recent research e¡orts focus on deciphering the actions of the viroporins poliovirus 2B, alphavirus 6K, HIV-1 Vpu and in£u-enza virus M2. All these proteins can enhance the passage of ions and small molecules through membranes depending on their concentration gradient. Future work will lengthen the list of viroporins and will provide a deeper understanding of their mechanisms of action.

Oligomerization state and supramolecular structure of the HIV‐1 Vpu protein transmembrane segment in phospholipid bilayers

“…Moreover, oligomerization and ion channel formation by Vpu is of inherent interest and is relevant to the more general issues of viroporin structure and function. [44][45][46][47] …”

Effects of human T‐cell leukemia virus type 1 (HTLV‐1) p13 on mitochondrial K+ permeability: A new member of the viroporin family?

“…A growing number of animal viruses have been shown to encode ''viroporins", a class of small hydrophobic integral membrane proteins characterized by at least one amphipathic a-helix [16].…”

“…Upon membrane insertion, viroporins oligomerize and assemble into pores that control membrane permeability (reviewed in [16]). The properties of viroporins suggest that they might represent ancestors of more complex cellular channels in which the pore is formed by a bundle of transmembrane helixes contained in a single protein rather than by a multimeric bundle of separate proteins.…”

Mumps virus small hydrophobic protein targets ataxin-1 ubiquitin-like interacting protein (ubiquilin 4)

“…In addition, the SH protein of HRSV has been predicted to act as a viroporin (Perez et al, 1997;Kochva et al, 2003). Viroporins are a group of highly hydrophobic small viral proteins that are able to homo-oligomerize and induce membrane permeability (Gonzalez & Carrasco, 2003).…”