AI Article Synopsis
- Gibberellins (GAs) in plants are regulated through a negative feedback mechanism involving the transcriptional activator RSG, which is impacted by GA levels.
- The 14-3-3 proteins play a crucial role by binding to RSG and keeping it in the cytoplasm, a process that requires phosphorylation at Ser-114, facilitated by the tobacco CDPK1 enzyme.
- The study highlights that CDPK1 helps decode calcium signals from GAs, affects RSG’s location within the cell, and influences feedback regulation on GA biosynthetic genes.
Article Abstract
The homeostasis of gibberellins (GAs) is maintained by negative feedback in plants. REPRESSION OF SHOOT GROWTH (RSG) is a tobacco (Nicotiana tabacum) transcriptional activator that has been suggested to play a role in GA feedback by the regulation of GA biosynthetic enzymes. The 14-3-3 signaling proteins negatively regulate RSG by sequestering it in the cytoplasm in response to GAs. The phosphorylation on Ser-114 of RSG is essential for 14-3-3 binding of RSG. Here, we identified tobacco Ca(2+)-dependent protein kinase (CDPK1) as an RSG kinase that promotes 14-3-3 binding to RSG by phosphorylation of Ser-114 of RSG. CDPK1 interacts with RSG in a Ca(2+)-dependent manner in vivo and in vitro and specifically phosphorylates Ser-114 of RSG. Inhibition of CDPK repressed the GA-induced phosphorylation of Ser-114 of RSG and the GA-induced nuclear export of RSG. Overexpression of CDPK1 inhibited the feedback regulation of a GA 20-oxidase gene and resulted in sensitization to the GA biosynthetic inhibitor. Our results suggest that CDPK1 decodes the Ca(2+) signal produced by GAs and regulates the intracellular localization of RSG.
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| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2630431 | PMC |
| http://dx.doi.org/10.1105/tpc.107.057489 | DOI Listing |
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- The 14-3-3 proteins play a crucial role by binding to RSG and keeping it in the cytoplasm, a process that requires phosphorylation at Ser-114, facilitated by the tobacco CDPK1 enzyme.
- The study highlights that CDPK1 helps decode calcium signals from GAs, affects RSG’s location within the cell, and influences feedback regulation on GA biosynthetic genes.
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