title: Conserved amino acids within the N-terminus of the West Nile virus NS4A protein contribute to virus replication, protein stability and membrane proliferation.
abstract: The West Nile virus strain Kunjin virus (WNVKUN) NS4A protein is a multifunctional protein involved in many aspects of the virus life-cycle and is a major component of the WNVKUN replication complex (RC). Previously we identified a conserved region in the C-terminus of NS4A regulating proteolytic processing and RC assembly, and now investigate key conserved residues in the N-terminus of NS4A and their contribution to WNVKUN replication. Mutation of P13 completely ablated replication, whereas, mutation of P48 and D49, near the first transmembrane helix, and G66 within the helix, showed variable defects in replication, virion secretion and membrane proliferation. Intriguingly, the P48 and G66 NS4A mutants resulted in specific proteasome depletion of NS4A that could in part be rescued with a proteasome inhibitor. Our results suggest that the N-terminus of NS4A contributes to correct folding and stability, essential for facilitating the essential roles of NS4A during replication.
authors.affiliation: Department of Microbiology and Immunology, University of Melbourne, Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia.
authors.forename: R L
authors.initials: RL
authors.lastname: Ambrose
authors.affiliation: Department of Microbiology and Immunology, University of Melbourne, Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia. Electronic address: jason.mackenzie@unimelb.edu.au.
authors.forename: J M
authors.initials: JM
authors.lastname: Mackenzie
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D002460:Cell Line; D002462:Cell Membrane / Q000821:virology*; D017124:Conserved Sequence; D006801:Humans; D008969:Molecular Sequence Data; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017361:Viral Nonstructural Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication; D014901:West Nile Fever / Q000821:virology*; D014902:West Nile virus / Q000737:chemistry / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
chemical_list: C080106:NS4A protein, flavivirus; D017361:Viral Nonstructural Proteins
keywords: Intracellular membrane proliferation; Replication complex; Virus replication; West Nile virus