title: The Arabidopsis O-linked N-acetylglucosamine transferase SPINDLY interacts with class I TCPs to facilitate cytokinin responses in leaves and flowers.
abstract: O-linked N-acetylglucosamine (O-GlcNAc) modifications regulate the posttranslational fate of target proteins. The Arabidopsis thaliana O-GlcNAc transferase (OGT) SPINDLY (SPY) suppresses gibberellin signaling and promotes cytokinin (CK) responses by unknown mechanisms. Here, we present evidence that two closely related class I TCP transcription factors, TCP14 and TCP15, act with SPY to promote CK responses. TCP14 and TCP15 interacted with SPY in yeast two-hybrid and in vitro pull-down assays and were O-GlcNAc modified in Escherichia coli by the Arabidopsis OGT, SECRET AGENT. Overexpression of TCP14 severely affected plant development in a SPY-dependent manner and stimulated typical CK morphological responses, as well as the expression of the CK-regulated gene RESPONSE REGULATOR5. TCP14 also promoted the transcriptional activity of the CK-induced mitotic factor CYCLIN B1;2. Whereas TCP14-overexpressing plants were hypersensitive to CK, spy and tcp14 tcp15 double mutant leaves and flowers were hyposensitive to the hormone. Reducing CK levels by overexpressing CK OXIDASE/DEHYDROGENASE3 suppressed the TCP14 overexpression phenotypes, and this suppression was reversed when the plants were treated with exogenous CK. Taken together, we suggest that responses of leaves and flowers to CK are mediated by SPY-dependent TCP14 and TCP15 activities.
authors.affiliation: Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
authors.forename: Evyatar
authors.initials: E
authors.lastname: Steiner
authors.forename: Idan
authors.initials: I
authors.lastname: Efroni
authors.forename: Manjula
authors.initials: M
authors.lastname: Gopalraj
authors.forename: Katie
authors.initials: K
authors.lastname: Saathoff
authors.forename: Tong-Seung
authors.initials: TS
authors.lastname: Tseng
authors.forename: Martin
authors.initials: M
authors.lastname: Kieffer
authors.forename: Yuval
authors.initials: Y
authors.lastname: Eshed
authors.forename: Neil
authors.initials: N
authors.lastname: Olszewski
authors.forename: David
authors.initials: D
authors.lastname: Weiss
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003583:Cytokinins / Q000378:metabolism*; D035264:Flowers / Q000235:genetics / Q000378:metabolism*; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D003583:Cytokinins; D012097:Repressor Proteins; C101465:SPY protein, Arabidopsis; C558187:TCP15 protein, Arabidopsis; D014157:Transcription Factors; D010088:Oxidoreductases; C019984:cytokinin oxidase