title: A tobacco CBL-interacting protein kinase homolog is involved in phosphorylation of the N-terminal domain of the cucumber mosaic virus polymerase 2a protein.
abstract: The replication and transcription of cucumber mosaic virus (CMV) are catalyzed by multi-protein complex RNA-dependent RNA polymerase (RdRp), which is composed of the viral-encoded 1a and 2a proteins with host factors. We have reported that the N-terminal region of the polymerase 2a protein, composed of 126 amino acids, is required for interaction with the helicase 1a protein, and that the phosphorylation of the region abrogated interaction with the 1a protein, suggesting a mechanism of resistance in host plants against viral infection. Here, we found that three protein 2a kinases, of 60, 55, and 38 kDa, co-purified with the tobacco membrane fraction in an in-gel kinase assay. By yeast two-hybrid library screening using the N-terminal 126 amino acids of 2a as a bait, we identified CBL-interacting protein kinase 12 (NtCIPK12) corresponding to 55 kDa protein 2a kinase. The bacterially expressed protein kinase showed protein 2a kinase (t2aK) activity in vitro. We found that NtCIPK12 stabilized upon CMV infection at the post-translational level, and accumulated more heavily to the membrane than in the cytosol.
authors.affiliation: College of Life Sciences and Biotechnology, Korea University, Anam-dong, Seoul 136-701, Korea.
authors.forename: Hyun Ku
authors.initials: HK
authors.lastname: Kang
authors.forename: Seung Hwan
authors.initials: SH
authors.lastname: Yang
authors.forename: Young Pyo
authors.initials: YP
authors.lastname: Lee
authors.forename: Young In
authors.initials: YI
authors.lastname: Park
authors.forename: Sang Hyon
authors.initials: SH
authors.lastname: Kim
mesh_terms: D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000201:enzymology / Q000821:virology; D003001:Cloning, Molecular; D017799:Cucumovirus / Q000201:enzymology*; D004795:Enzyme Stability; D008969:Molecular Sequence Data; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D012324:RNA-Dependent RNA Polymerase / Q000737:chemistry* / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana / Q000166:cytology / Q000201:enzymology* / Q000821:virology
chemical_list: D017346:Protein Serine-Threonine Kinases; D012324:RNA-Dependent RNA Polymerase