title: Viroporin activity and membrane topology of classic swine fever virus p7 protein.
abstract: Viroporins are a group of viral proteins that participate in viral replication cycles, including modification of membrane permeability and promotion of viral release. Although biological data have been accumulated on viroporion-like proteins of other viruses belonging to family Flaviviridae, the viroporin activity and membrane topology of p7 protein from classical swine fever virus (CSFV), a member of the genus Pestivirus of the family Flaviviridae, are largely unknown. In this study, sequence analysis of the primary structure of p7 polypeptide demonstrates that p7 contains two putative transmembrane regions connected by a short hydrophilic segment. Expression of p7 protein in Escherichia coli leads to the permeabilization of bacterial cells to small molecules. The p7 protein also enhances the permeability of mammalian cells, increasing the intracellular Ca(2+) concentration and the permeability of cells to the translation inhibitor Hygromycin B. This protein is an integral membrane protein and can form homo-oligomers. It mainly localizes to the ER at the early stage of the expression and can be transferred to the plasma membrane at the late stage of the expression. Detergent permeabilization assays confirmed that the p7 protein is a 2-pass transmembrane protein and its N and C termini are exposed to the ER lumen. Deletion analysis showed that amino acid residues 41-63 may be essential for the viroporin activity of the protein. Our studies demonstrate that CSFV p7 possesses properties commonly associated with viroporins, which could be a potential target for the development of a therapeutic intervention for classic swine fever virus infection.
authors.affiliation: State Key Laboratory of Veterinary Etiological Biology and Key Laboratory of Animal Virology of Ministry of Agriculture, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping 1, Lanzhou, Gansu 730046, People's Republic of China.
authors.forename: Hui-Chen
authors.initials: HC
authors.lastname: Guo
authors.forename: Shi-Qi
authors.initials: SQ
authors.lastname: Sun
authors.forename: De-Hui
authors.initials: DH
authors.lastname: Sun
authors.forename: Yan-Quan
authors.initials: YQ
authors.lastname: Wei
authors.forename: Jin
authors.initials: J
authors.lastname: Xu
authors.forename: Mei
authors.initials: M
authors.lastname: Huang
authors.forename: Xiang-Tao
authors.initials: XT
authors.lastname: Liu
authors.forename: Zai-Xin
authors.initials: ZX
authors.lastname: Liu
authors.forename: Jian-Xiong
authors.initials: JX
authors.lastname: Luo
authors.forename: Hong
authors.initials: H
authors.lastname: Yin
authors.forename: Ding Xiang
authors.initials: DX
authors.lastname: Liu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002463:Cell Membrane Permeability; D006692:Classical Swine Fever Virus / Q000378:metabolism*; D006921:Hygromycin B; D008565:Membrane Proteins / Q000378:metabolism; D019590:Nucleocapsid Proteins / Q000378:metabolism*; D020539:Sequence Analysis, Protein; D013552:Swine; D054334:Viral Regulatory and Accessory Proteins / Q000378:metabolism*; D057074:Virus Release; D014779:Virus Replication
chemical_list: D000900:Anti-Bacterial Agents; D008565:Membrane Proteins; D019590:Nucleocapsid Proteins; D054334:Viral Regulatory and Accessory Proteins; D006921:Hygromycin B