title: A critical domain of the Cucumber mosaic virus 2b protein for RNA silencing suppressor activity.
abstract: Alignment of Cucumber mosaic virus (CMV) 2b protein sequences from two CMV subgroups revealed two highly variable regions. To examine contributions of variable sequence domains to the suppressor activity, we performed a comparative study between 2b proteins of a subgroup I strain (SD-CMV) and a subgroup II strain (Q-CMV). Here we show that the suppressor activity of SD2b is stronger than that of Q2b and that a domain existent in SD2b but absent in Q2b is a major determinant of the suppressor activity of SD2b. We further show that the same domain is responsible for inhibition of Nicotiana benthamiana AGO4-1 transcription. Our results implicate AGO4 as a mediator for CMV 2b to suppress systemic silencing and DNA methylation.
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Chaoyang District, Beijing, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Ye
authors.forename: Jing
authors.initials: J
authors.lastname: Qu
authors.forename: Jian-Feng
authors.initials: JF
authors.lastname: Zhang
authors.forename: Yun-Feng
authors.initials: YF
authors.lastname: Geng
authors.forename: Rong-Xiang
authors.initials: RX
authors.lastname: Fang
mesh_terms: D000595:Amino Acid Sequence; D017799:Cucumovirus / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000235:genetics / Q000821:virology; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D014026:Nicotiana / Q000235:genetics / Q000821:virology; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: C404227:2b protein, cucumber mosaic virus; D014764:Viral Proteins