Čeština
EnglishSPINDLY inhibits class I TCP proteolysis to promote sensitivity to cytokinin
Steiner E., Livne S., Kobinson-Katz T., Tal L., Pri-Tal O., Mosquna A., Tarkowská D., Mueller B., Tarkowski P., Weiss D.
PLANT PHYSIOLOGY http://dx.doi.org/10.1104/pp.16.00343: , 2016
Keywords:
Abstract: The Arabidopsis thaliana SPINDLY (SPY) is a putative Ser and Thr O-linked N-acetylglucosamine (O-GlcNAc) transferase (OGT). While SPY has been shown to suppress gibberellin (GA) signaling and promote cytokinin (CK) responses its catalytic OGT activity was never demonstrated and its effect on protein fate is not known. We previously showed that SPY interacts physically and functionally with TCP14 and TCP15 to promote CK responses. Here, we aimed to identify how SPY regulates TCP14/15 activities and how these TCPs promote CK responses. We show that SPY activity is required for TCP14 stability. Mutation in the putative OGT domain of SPY (spy-3) stimulated TCP14 proteolysis by the 26S proteasome, which was reversed by mutation in CULLIN 1 (CUL1), suggesting a role for SKP, Cul1, F-box (SCF) E3 ubiquitine ligase in TCP14 proteolysis. TCP14 proteolysis in spy-3 suppressed all TCP14-missexpression phenotypes, including the enhanced CK responses. The increased CK activity in TCP14/15-overexpress ing flowers resulted from increased sensitivity to the hormone and not from higher CK levels. TCP15 overexpression enhanced the response of the K-induced synthetic promoter pTCS to CK, suggesting that TCP14/15 affect early steps in CK signaling. We propose that post-translational modification of TCP14/15 by SPY, inhibits their proteolysis and the accumulated proteins promote the activity of the CK phosphorelay cascade in developing Arabidopsis leaves and flowers. IEB authors: Danuše Tarkowská
PLANT PHYSIOLOGY http://dx.doi.org/10.1104/pp.16.00343: , 2016
Keywords:
Abstract: The Arabidopsis thaliana SPINDLY (SPY) is a putative Ser and Thr O-linked N-acetylglucosamine (O-GlcNAc) transferase (OGT). While SPY has been shown to suppress gibberellin (GA) signaling and promote cytokinin (CK) responses its catalytic OGT activity was never demonstrated and its effect on protein fate is not known. We previously showed that SPY interacts physically and functionally with TCP14 and TCP15 to promote CK responses. Here, we aimed to identify how SPY regulates TCP14/15 activities and how these TCPs promote CK responses. We show that SPY activity is required for TCP14 stability. Mutation in the putative OGT domain of SPY (spy-3) stimulated TCP14 proteolysis by the 26S proteasome, which was reversed by mutation in CULLIN 1 (CUL1), suggesting a role for SKP, Cul1, F-box (SCF) E3 ubiquitine ligase in TCP14 proteolysis. TCP14 proteolysis in spy-3 suppressed all TCP14-missexpression phenotypes, including the enhanced CK responses. The increased CK activity in TCP14/15-overexpress ing flowers resulted from increased sensitivity to the hormone and not from higher CK levels. TCP15 overexpression enhanced the response of the K-induced synthetic promoter pTCS to CK, suggesting that TCP14/15 affect early steps in CK signaling. We propose that post-translational modification of TCP14/15 by SPY, inhibits their proteolysis and the accumulated proteins promote the activity of the CK phosphorelay cascade in developing Arabidopsis leaves and flowers. IEB authors: Danuše Tarkowská