title: Functional analysis of the N-terminal basic motif of a eukaryotic satellite RNA virus capsid protein in replication and packaging.
abstract: Efficient replication and assembly of virus particles are integral to the establishment of infection. In addition to the primary role of the capsid protein (CP) in encapsidating the RNA progeny, experimental evidence on positive sense single-stranded RNA viruses suggests that the CP also regulates RNA synthesis. Here, we demonstrate that replication of Satellite tobacco mosaic virus (STMV) is controlled by the cooperative interaction between STMV CP and the helper virus (HV) Tobacco mosaic virus (TMV) replicase. We identified that the STMV CP-HV replicase interaction requires a positively charged residue at the third position (3R) in the N-terminal 13 amino acid (aa) motif. Far-Northwestern blotting showed that STMV CP promotes binding between HV-replicase and STMV RNA. An STMV CP variant having an arginine to alanine substitution at position 3 in the N-terminal 13aa motif abolished replicase-CP binding. The N-terminal 13aa motif of the CP bearing alanine substitutions for positively charged residues located at positions 5, 7, 10 and 11 are defective in packaging full-length STMV, but can package a truncated STMV RNA lacking the 3' terminal 150 nt region. These findings provide insights into the mechanism underlying the regulation of STMV replication and packaging.
authors.affiliation: Department of Plant Pathology &Microbiology, University of California, Riverside, CA 92521, USA.
authors.forename: Venkatesh
authors.initials: V
authors.lastname: Sivanandam
authors.affiliation: Department of Plant Pathology &Microbiology, University of California, Riverside, CA 92521, USA.
authors.forename: Deborah
authors.initials: D
authors.lastname: Mathews
authors.affiliation: Department of Chemistry &Biochemistry, University of California, Los Angeles, CA, 90095, USA.
authors.forename: Rees
authors.initials: R
authors.lastname: Garmann
authors.affiliation: Department of Physics &Astronomy, University of California, Riverside, CA 92521, USA.
authors.forename: Gonca
authors.initials: G
authors.lastname: Erdemci-Tandogan
authors.affiliation: Department of Physics &Astronomy, University of California, Riverside, CA 92521, USA.
authors.forename: Roya
authors.initials: R
authors.lastname: Zandi
authors.affiliation: Department of Plant Pathology &Microbiology, University of California, Riverside, CA 92521, USA.
authors.forename: A L N
authors.initials: AL
authors.lastname: Rao
mesh_terms: D060054:Agrobacterium / Q000821:virology; D020816:Amino Acid Motifs; D036022:Capsid Proteins / Q000378:metabolism*; D006378:Helper Viruses / Q000502:physiology; D012367:RNA, Viral / Q000096:biosynthesis; D012324:RNA-Dependent RNA Polymerase / Q000378:metabolism; D014026:Nicotiana / Q000821:virology; D014027:Tobacco Mosaic Virus / Q000201:enzymology; D019400:Tobacco mosaic satellite virus / Q000502:physiology*; D014771:Virion; D019065:Virus Assembly; D014779:Virus Replication
chemical_list: D036022:Capsid Proteins; D012367:RNA, Viral; C085103:tobacco mosaic virus replicase; D012324:RNA-Dependent RNA Polymerase