title: Attenuation of Histone Methyltransferase KRYPTONITE-mediated transcriptional gene silencing by Geminivirus.
abstract: Although histone H3K9 methylation has been intensively studied in animals and a model plant Arabidopsis thaliana, little is known about the evolution of the histone methyltransferase and its roles in plant biotic stress response. Here we identified a Nicotiana benthamiana homolog of H3K9 histone methyltransferase KRYPTONITE (NbKYP) and demonstrated its fundamental roles on methylation of plant and virus, beside of leading to the suppression of endogenous gene expression and virus replication. NbKYP and another gene encoding DNA methyltransferase CHROMOMETHYLTRANSFERASE 3 (NbCMT3-1) were further identified as the key components of maintenance of transcriptional gene silencing, a DNA methylation involved anti-virus machinery. All three types of DNA methylations (asymmetric CHH and symmetric CHG/CG) were severely affected in NbKYP-silenced plants, but only severe reduction of CHG methylation found in NbCMT3-1-silenced plants. Attesting to the importance of plant histone H3K9 methylation immunity to virus, the virulence of geminiviruses requires virus-encoded trans-activator AC2 which inhibits the expression of KYP via activation of an EAR-motif-containing transcription repressor RAV2 (RELATED TO ABI3 and VP1). The reduction of KYP was correlated with virulence of various similar geminiviruses. These findings provide a novel mechanism of how virus trans-activates a plant endogenous anti-silencing machinery to gain high virulence.
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Yan-Wei
authors.initials: YW
authors.lastname: Sun
authors.affiliation: Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Singapore.
authors.forename: Chuan-Sia
authors.initials: CS
authors.lastname: Tee
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Yong-Huan
authors.initials: YH
authors.lastname: Ma
authors.affiliation: Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Singapore.
authors.forename: Gang
authors.initials: G
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Xiang-Mei
authors.initials: XM
authors.lastname: Yao
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.|Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Singapore.
authors.forename: Jian
authors.initials: J
authors.lastname: Ye
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics; D029681:Arabidopsis Proteins; D020134:Catalytic Domain; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D044127:Epigenesis, Genetic; D017791:Geminiviridae / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D017930:Genes, Reporter; D000076983:Histone Methyltransferases; D011495:Histone-Lysine N-Methyltransferase / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D014026:Nicotiana / Q000201:enzymology / Q000235:genetics* / Q000821:virology*; D015533:Transcriptional Activation; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; D006657:Histones; D010940:Plant Proteins; D014764:Viral Proteins; D000076983:Histone Methyltransferases; D011495:Histone-Lysine N-Methyltransferase