title: Manganese-dependent polioviruses caused by mutations within the viral polymerase.
abstract: Viral RNA-dependent RNA polymerases exhibit great sequence diversity. Only six core amino acids are conserved across all polymerases of positive-strand RNA viruses of eukaryotes. While exploring the function of one of these completely conserved residues, asparagine 297 in the prototypic poliovirus polymerase 3D(pol), we identified three viable mutants with noncanonical amino acids at this conserved position. Although asparagine 297 could be replaced by glycine or alanine in these mutants, the viruses exhibited Mn(2+)-dependent RNA replication and viral growth. All known RNA polymerases and replicative polymerases of bacterial, eukaryotic, and viral organisms are thought to be magnesium dependent in vivo, and therefore these mutant polioviruses may represent the first viruses with a requirement for an alternative polymerase cation. These results demonstrate the extreme functional flexibility of viral RNA-dependent RNA polymerases. Furthermore, the finding that strictly conserved residues in the nucleotide binding pocket of the polymerase can be altered in a manner that supports virus production suggests that drugs targeting this region of the enzyme will still be susceptible to the problem of drug-resistant escape mutants.
authors.affiliation: Department of Microbiology and Immunology, University of California, San Francisco 94143-0414, USA.
authors.forename: Shane
authors.initials: S
authors.lastname: Crotty
authors.forename: David
authors.initials: D
authors.lastname: Gohara
authors.forename: Devin K
authors.initials: DK
authors.lastname: Gilligan
authors.forename: Sveta
authors.initials: S
authors.lastname: Karelsky
authors.forename: Craig E
authors.initials: CE
authors.lastname: Cameron
authors.forename: Raul
authors.initials: R
authors.lastname: Andino
mesh_terms: D000595:Amino Acid Sequence; D006367:HeLa Cells; D006801:Humans; D008345:Manganese / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D017955:Poliovirus / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D012367:RNA, Viral / Q000096:biosynthesis* / Q000235:genetics; D012324:RNA-Dependent RNA Polymerase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014162:Transfection; D014779:Virus Replication
chemical_list: D012367:RNA, Viral; D008345:Manganese; D012324:RNA-Dependent RNA Polymerase