title: Phosphorylation of TGB1 by protein kinase CK2 promotes barley stripe mosaic virus movement in monocots and dicots.
abstract: The barley stripe mosaic virus (BSMV) triple gene block 1 (TGB1) protein is required for virus cell-to-cell movement. However, little information is available about how these activities are regulated by post-translational modifications. In this study, we showed that the BSMV Xinjiang strain TGB1 (XJTGB1) is phosphorylated in vivo and in vitro by protein kinase CK2 from barley and Nicotiana benthamiana. Liquid chromatography tandem mass spectrometry analysis and in vitro phosphorylation assays demonstrated that Thr-401 is the major phosphorylation site of the XJTGB1 protein, and suggested that a Thr-395 kinase docking site supports Thr-401 phosphorylation. Substitution of Thr-395 with alanine (T395A) only moderately impaired virus cell-to-cell movement and systemic infection. In contrast, the Thr-401 alanine (T401A) virus mutant was unable to systemically infect N. benthamiana but had only minor effects in monocot hosts. Substitution of Thr-395 or Thr-401 with aspartic acid interfered with monocot and dicot cell-to-cell movement and the plants failed to develop systemic infections. However, virus derivatives with single glutamic acid substitutions at Thr-395 and Thr-401 developed nearly normal systemic infections in the monocot hosts but were unable to infect N. benthamiana systemically, and none of the double mutants was able to infect dicot and monocot hosts. The mutant XJTGB1T395A/T401A weakened in vitro interactions between XJTGB1 and XJTGB3 proteins but had little effect on XJTGB1 RNA-binding ability. Taken together, our results support a critical role of CK2 phosphorylation in the movement of BSMV in monocots and dicots, and provide new insights into the roles of phosphorylation in TGB protein functions.
authors.affiliation: State Key laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Hu
authors.affiliation: State Key laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China.
authors.forename: Zhenggang
authors.initials: Z
authors.lastname: Li
authors.affiliation: State Key laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Yuan
authors.affiliation: State Key laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China.
authors.forename: Xuejiao
authors.initials: X
authors.lastname: Jin
authors.affiliation: State Key laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China.
authors.forename: Lijie
authors.initials: L
authors.lastname: Yan
authors.affiliation: State Key laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China.
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Zhao
authors.affiliation: State Key laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China.
authors.forename: Yongliang
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Plant and Microbial Biology, University of California-Berkeley, Berkeley, CA 94720, USA.
authors.forename: Andrew O
authors.initials: AO
authors.lastname: Jackson
authors.affiliation: State Key laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China.
authors.forename: Xianbing
authors.initials: X
authors.lastname: Wang
authors.affiliation: State Key laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China.
authors.forename: Chenggui
authors.initials: C
authors.lastname: Han
authors.affiliation: State Key laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China.
authors.forename: Jialin
authors.initials: J
authors.lastname: Yu
authors.affiliation: State Key laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China dawei.li@cau.edu.cn.
authors.forename: Dawei
authors.initials: D
authors.lastname: Li
mesh_terms: D047390:Casein Kinase II / Q000378:metabolism*; D001467:Hordeum / Q000378:metabolism* / Q000821:virology; D010766:Phosphorylation; D010940:Plant Proteins / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D012328:RNA Viruses / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism*; D014026:Nicotiana / Q000378:metabolism* / Q000821:virology; D017361:Viral Nonstructural Proteins / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D016601:RNA-Binding Proteins; D017361:Viral Nonstructural Proteins; C103801:betab protein, barley stripe mosaic virus; D047390:Casein Kinase II
keywords: Barley stripe mosaic virus; phosphorylation; promotion; protein kinase CK2; triple gene block 1 (TGB1) protein; viral movement.