title: Phosphorylation of SPT5 by CDKD;2 Is Required for VIP5 Recruitment and Normal Flowering inArabidopsis thaliana.
abstract: The elongation factor suppressor of Ty 5 homolog (Spt5) is a regulator of transcription and histone methylation. In humans, phosphorylation of SPT5 by P-TEFb, a protein kinase composed of Cyclin-dependent kinase 9 (CDK9) and cyclin T, interacts with the RNA polymerase II-associated factor1 (PAF1) complex. However, the mechanism of SPT5 phosphorylation is not well understood in plants. Here, we examine the function of SPT5 inArabidopsis thalianaand find thatspt5mutant flowers early under long-day and short-day conditions. SPT5 interacts with the CDK-activating kinase 4 (CAK4; CDKD;2) and is specifically phosphorylated by CDKD;2 at threonines. The phosphorylated SPT5 binds VERNALIZATION INDEPENDENCE5 (VIP5), a subunit of the PAF1 complex. Genetic analysis showed thatVIP5acts downstream ofSPT5andCDKD;2Loss ofSPT5orCDKD;2function results in early flowering because of decreased amounts ofFLOWERING LOCUS C(FLC) transcript. Importantly,CDKD;2andSPT5are required for the deposition of VIP5 and the enhancement of trimethylation of histone 3 lysine 4 in the chromatin of theFLClocus. Together, our results provide insight into the mechanism by which the Arabidopsis elongation factor SPT5 recruits the PAF1 complex via the posttranslational modification of proteins and suggest that the phosphorylation of SPT5 by CDKD;2 enables it to recruit VIP5 to regulate chromatin and transcription in Arabidopsis.
authors.affiliation: CAS Center for Excellence in Molecular Plant Sciences, School of Life Sciences, University of Science and Technology of China, Anhui, China 230027.
authors.forename: Chengyuan
authors.initials: C
authors.lastname: Lu
authors.affiliation: CAS Center for Excellence in Molecular Plant Sciences, School of Life Sciences, University of Science and Technology of China, Anhui, China 230027.
authors.forename: Yongke
authors.initials: Y
authors.lastname: Tian
authors.affiliation: CAS Center for Excellence in Molecular Plant Sciences, School of Life Sciences, University of Science and Technology of China, Anhui, China 230027.
authors.forename: Shiliang
authors.initials: S
authors.lastname: Wang
authors.affiliation: CAS Center for Excellence in Molecular Plant Sciences, School of Life Sciences, University of Science and Technology of China, Anhui, China 230027.
authors.forename: Yanhua
authors.initials: Y
authors.lastname: Su
authors.affiliation: CAS Center for Excellence in Molecular Plant Sciences, School of Life Sciences, University of Science and Technology of China, Anhui, China 230027.
authors.forename: Ting
authors.initials: T
authors.lastname: Mao
authors.affiliation: CAS Center for Excellence in Molecular Plant Sciences, School of Life Sciences, University of Science and Technology of China, Anhui, China 230027.
authors.forename: Tongtong
authors.identifier: 0000-0002-6615-1149
authors.initials: T
authors.lastname: Huang
authors.affiliation: CAS Center for Excellence in Molecular Plant Sciences, School of Life Sciences, University of Science and Technology of China, Anhui, China 230027.
authors.forename: Qingqing
authors.initials: Q
authors.lastname: Chen
authors.affiliation: CAS Center for Excellence in Molecular Plant Sciences, School of Life Sciences, University of Science and Technology of China, Anhui, China 230027.
authors.forename: Zuntao
authors.initials: Z
authors.lastname: Xu
authors.affiliation: CAS Center for Excellence in Molecular Plant Sciences, School of Life Sciences, University of Science and Technology of China, Anhui, China 230027 dingyong@ustc.edu.cn.
authors.forename: Yong
authors.identifier: 0000-0003-1901-7729
authors.initials: Y
authors.lastname: Ding
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D018844:Cyclin-Dependent Kinases / Q000378:metabolism* / Q000502:physiology; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017874:Immediate-Early Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D010766:Phosphorylation; D035602:Transcriptional Elongation Factors
chemical_list: D029681:Arabidopsis Proteins; D017874:Immediate-Early Proteins; C000625899:Spt5 protein, Arabidopsis; D035602:Transcriptional Elongation Factors; C000625900:VIP5 protein, Arabidopsis; C514673:CDKD;2 protein, Arabidopsis; D018844:Cyclin-Dependent Kinases