title: Helicase ATPase activity of the Tobacco mosaic virus 126-kDa protein modulates replicase complex assembly.
abstract: Mutations disrupting helicase domain motifs of the Tobacco mosaic virus 126/183-kDa proteins were investigated for their effect on replicase function and assembly. These mutations inhibited virus replication but did not affect 126-kDa induced N gene resistance or RNAi suppression. However, in vivo expressed 126-kDa motif mutants yielded two distinct cytoplasmic phenotypes that correlated with ATPase activity. Specifically, ATPase active 126-kDa proteins produced small cytoplasmic bodies that resembled the ovoid granular-like bodies found early in virus infection while 126-kDa proteins defective in ATPase activity produced large tubule containing cytoplasmic bodies similar to those observed late in infection. Additional studies indicate that the helicase ATPase activity resides predominantly within monomer and dimer helicase forms and that motifs affecting ATPase activity induce alterations in helicase assembly. Combined these findings indicate that helicase ATPase activity modulates the progression of replicase complex assembly and maturation.
authors.affiliation: Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA.
authors.forename: Xiao
authors.initials: X
authors.lastname: Wang
authors.forename: Zvi
authors.initials: Z
authors.lastname: Kelman
authors.forename: James N
authors.initials: JN
authors.lastname: Culver
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D055503:Protein Multimerization; D012324:RNA-Dependent RNA Polymerase / Q000378:metabolism*; D014026:Nicotiana / Q000821:virology; D014027:Tobacco Mosaic Virus / Q000502:physiology*; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication
chemical_list: C071899:130k protein, Tobacco mosaic virus; D014764:Viral Proteins; D012324:RNA-Dependent RNA Polymerase; D000251:Adenosine Triphosphatases