Browsing by Author "Rodriguez, Pedro L."
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- Abscisic acid inhibits type 2C protein phosphatases via the PYR/PYL family of START proteinsPublication . Park, Sang-Youl; Fung, Pauline; Nishimura, Noriyuki; Jensen, Davin R.; Fujii, Hiroaki; Zhao, Yang; Lumba, Shelley; Santiago, Julia; Rodrigues, Américo; Chow, Tsz-fung F.; Alfred, Simon E.; Bonetta, Dario; Finkelstein, Ruth; Provart, Nicholas J.; Desveaux, Darrell; Rodriguez, Pedro L.; McCourt, Peter; Zhu, Jian-Kang; Schroeder, Julian I.; Volkman, Brian F.; Cutler, Sean R.Type 2C protein phosphatases (PP2Cs) are vitally involved in abscisic acid (ABA) signaling. Here, we show that a synthetic growth inhibitor called pyrabactin functions as a selective ABA agonist. Pyrabactin acts through PYRABACTIN RESISTANCE 1 (PYR1), the founding member of a family of START proteins called PYR/PYLs, which are necessary for both pyrabactin and ABA signaling in vivo. We show that ABA binds to PYR1, which in turn binds to and inhibits PP2Cs. We conclude that PYR/PYLs are ABA receptors functioning at the apex of a negative regulatory pathway that controls ABA signaling by inhibiting PP2Cs. Our results illustrate the power of the chemical genetic approach for sidestepping genetic redundancy.
- A dual function of SnRK2 kinases in the regulation of SnRK1 and plant growthPublication . Belda-Palazón, Borja; Adamo, Mattia; Valerio, Concetta; Ferreira, Liliana J.; Confraria, Ana; Reis-Barata, Elena; Rodrigues, Américo; Meyer, Christian; Rodriguez, Pedro L.; Baena-González, ElenaAdverse environmental conditions trigger responses in plants that promote stress tolerance and survival at the expense of growth1. However, little is known of how stress signalling pathways interact with each other and with growth regulatory components to balance growth and stress responses. Here, we show that plant growth is largely regulated by the interplay between the evolutionarily conserved energy-sensing SNF1-related protein kinase 1 (SnRK1) protein kinase and the abscisic acid (ABA) phytohormone pathway. While SnRK2 kinases are main drivers of ABA-triggered stress responses, we uncover an unexpected growth-promoting function of these kinases in the absence of ABA as repressors of SnRK1. Sequestration of SnRK1 by SnRK2 containing complexes inhibits SnRK1 signalling, thereby allowing target of rapamycin (TOR) activity and growth under optimal conditions. On the other hand, these complexes are essential for releasing and activating SnRK1 in response to ABA, leading to the inhibition of TOR and growth under stress. This dual regulation of SnRK1 by SnRK2 kinases couples growth control with environmental factors typical for the terrestrial habitat and is likely to have been critical for the water-to-land transition of plants.
- HAB1–SWI3B interaction reveals a link between abscisic acid signaling and putative SWI/SNF chromatin-remodeling complexes in arabidopsisPublication . Saez, Angela; Rodrigues, Américo; Santiago, Julia; Rubio, Silvia; Rodriguez, Pedro L.Abscisic acid (ABA) has an important role for plant growth, development, and stress adaptation. HYPERSENSITIVE TO ABA1 (HAB1) is a protein phosphatase type 2C that plays a key role as a negative regulator of ABA signaling; however, the molecular details of HAB1 action in this process are not known. A two-hybrid screen revealed that SWI3B, an Arabidopsis thaliana homolog of the yeast SWI3 subunit of SWI/SNF chromatin-remodeling complexes, is a prevalent interacting partner of HAB1. The interaction mapped to the N-terminal half of SWI3B and required an intact protein phosphatase catalytic domain. Bimolecular fluorescence complementation and coimmunoprecipitation assays confirmed the interaction of HAB1 and SWI3B in the nucleus of plant cells. swi3b mutants showed a reduced sensitivity to ABA-mediated inhibition of seed germination and growth and reduced expression of the ABA-responsive genes RAB18 and RD29B. Chromatin immunoprecipitation experiments showed that the presence of HAB1 in the vicinity of RD29B and RAB18 promoters was abolished by ABA, which suggests a direct involvement of HAB1 in the regulation of ABA-induced transcription. Additionally, our results uncover SWI3B as a novel positive regulator of ABA signaling and suggest that HAB1 modulates ABA response through the regulation of a putative SWI/SNF chromatin-remodeling complex.