title: A novel methyltransferase methylates Cucumber mosaic virus 1a protein and promotes systemic spread.
abstract: In mammalian and yeast systems, methyltransferases have been implicated in the regulation of diverse processes, such as protein-protein interactions, protein localization, signal transduction, RNA processing, and transcription. The Cucumber mosaic virus (CMV) 1a protein is essential not only for virus replication but also for movement. Using a yeast two-hybrid system with tobacco plants, we have identified a novel gene encoding a methyltransferase that interacts with the CMV 1a protein and have designated this gene Tcoi1 (tobacco CMV 1a-interacting protein 1). Tcoi1 specifically interacted with the methyltransferase domain of CMV 1a, and the expression of Tcoi1 was increased by CMV inoculation. Biochemical studies revealed that the interaction of Tcoi1 with CMV 1a protein was direct and that Tcoi1 methylated CMV 1a protein both in vitro and in vivo. The CMV 1a binding activity of Tcoi1 is in the C-terminal domain, which shows the methyltransferase activity. The overexpression of Tcoi1 enhanced the CMV infection, while the reduced expression of Tcoi1 decreased virus infectivity. These results suggest that Tcoi1 controls the propagation of CMV through an interaction with the CMV 1a protein.
authors.affiliation: School of Life Sciences and Biotechnology, Korea University, 1, 5-ga, Anam-dong, Sungbuk-gu, Seoul 136-701, Republic of South Korea.
authors.forename: Min Jung
authors.initials: MJ
authors.lastname: Kim
authors.forename: Sung Un
authors.initials: SU
authors.lastname: Huh
authors.forename: Byung-Kook
authors.initials: BK
authors.lastname: Ham
authors.forename: Kyung-Hee
authors.initials: KH
authors.lastname: Paek
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D017799:Cucumovirus / Q000502:physiology*; D020869:Gene Expression Profiling; D008745:Methylation; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana / Q000821:virology*; D020798:Two-Hybrid System Techniques; D014764:Viral Proteins / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D014764:Viral Proteins; C508104:1a protein, cucumber mosaic virus; D008780:Methyltransferases