title: A calmodulin-like protein suppresses RNA silencing and promotes geminivirus infection by degrading SGS3 via the autophagy pathway in Nicotiana benthamiana.
abstract: A recently characterized calmodulin-like protein is an endogenous RNA silencing suppressor that suppresses sense-RNA induced post-transcriptional gene silencing (S-PTGS) and enhances virus infection, but the mechanism underlying calmodulin-like protein-mediated S-PTGS suppression is obscure. Here, we show that a calmodulin-like protein from Nicotiana benthamiana (NbCaM) interacts with Suppressor of Gene Silencing 3 (NbSGS3). Deletion analyses showed that domains essential for the interaction between NbSGS3 and NbCaM are also required for the subcellular localization of NbSGS3 and NbCaM suppressor activity. Overexpression of NbCaM reduced the number of NbSGS3-associated granules by degrading NbSGS3 protein accumulation in the cytoplasm. This NbCaM-mediated NbSGS3 degradation was sensitive to the autophagy inhibitors 3-methyladenine and E64d, and was compromised when key autophagy genes of the phosphatidylinositol 3-kinase (PI3K) complex were knocked down. Meanwhile, silencing of key autophagy genes within the PI3K complex inhibited geminivirus infection. Taken together these data suggest that NbCaM acts as a suppressor of RNA silencing by degrading NbSGS3 through the autophagy pathway.
authors.affiliation: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.|State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: Fangfang
authors.initials: F
authors.lastname: Li
authors.affiliation: State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: Zhenghe
authors.identifier: 0000-0001-5497-2575
authors.initials: Z
authors.lastname: Li
authors.affiliation: State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: Xiongbiao
authors.initials: X
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: Yaqin
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Xiuling
authors.initials: X
authors.lastname: Yang
authors.affiliation: Ministry of Agriculture Key Laboratory of Agricultural Entomology, Institute of Insect Sciences, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: Shu-Sheng
authors.initials: SS
authors.lastname: Liu
authors.affiliation: Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada.
authors.forename: Aiming
authors.initials: A
authors.lastname: Wang
authors.affiliation: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.|State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: Xueping
authors.initials: X
authors.lastname: Zhou
mesh_terms: D001343:Autophagy; D002147:Calmodulin / Q000378:metabolism*; D017791:Geminiviridae; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D015151:Immunoblotting; D010935:Plant Diseases / Q000235:genetics / Q000821:virology*; D010940:Plant Proteins / Q000378:metabolism; D016133:Polymerase Chain Reaction; D034622:RNA Interference / Q000502:physiology; D014026:Nicotiana / Q000821:virology*
chemical_list: D002147:Calmodulin; D010940:Plant Proteins