Mechanistic Analysis of AKT1 Regulation by the CBL–CIPK–PP2CA Interactions

Lan, Wenzhi; Lee, Sung-Chul; Che, Yufen; Jiang, Yuan‐Qing; Luan, Sheng

doi:10.1093/mp/ssr031

Cited by 143 publications

(149 citation statements)

References 36 publications

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“…It was also shown that PP2CA inactivates CIPK (CBL-interacting protein kinases)-dependent AKT1 (Arabidopsis K + transporter 1) [27]. Sequence comparison of the Clade A PP2Cs from Arabidopsis suggested that PP2CA is closely related to HAI1/2/3 ( Figure 4C and Supplementary information, Figures S1 and S2).…”

Section: Discussionmentioning

confidence: 95%

Molecular basis for the selective and ABA-independent inhibition of PP2CA by PYL13

Wang

Sheng

et al. 2013

Cell Res

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PYR1/PYL/RCAR family proteins (PYLs) are well-characterized abscisic acid (ABA) receptors. Among the 14 PYL members in Arabidopsis thaliana, PYL13 is ABA irresponsive and its function has remained elusive. Here, we show that PYL13 selectively inhibits the phosphatase activity of PP2CA independent of ABA. The crystal structure of PYL13-PP2CA complex, which was determined at 2.4 Å resolution, elucidates the molecular basis for the specific recognition between PP2CA and PYL13. In addition to the canonical interactions between PYLs and PP2Cs, an extra interface is identified involving an element in the vicinity of a previously uncharacterized CCCH zinc-finger (ZF) motif in PP2CA. Sequence blast identified another 56 ZF-containing PP2Cs, all of which are from plants. The structure also reveals the molecular determinants for the ABA irresponsiveness of PYL13. Finally, biochemical analysis suggests that PYL13 may hetero-oligomerize with PYL10. These two PYLs antagonize each other in their respective ABA-independent inhibitions of PP2Cs. The biochemical and structural studies provide important insights into the function of PYL13 in the stress response of plant and set up a foundation for future biotechnological applications of PYL13.

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Section: Discussionmentioning

confidence: 95%

Molecular basis for the selective and ABA-independent inhibition of PP2CA by PYL13

Wang

Sheng

et al. 2013

Cell Res

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“…A mechanism of OST1 inhibition by physical interaction with phosphatase has been described for AtPP2CA (34), and the inhibition of CIPKs by PP2Cs is also thought to involve both physical interaction and dephosphorylation of the kinases (35). The most studied example of a PP2C/substrate interaction is between HAB1 and OST1.…”

Section: Discussionmentioning

confidence: 99%

“…Mutations that inactivate PP2Cs have been used to address their mechanism of action (16,18,35,52,59). The mutants we designed reproduce amino acid substitutions in critical residues characterized in AtPP2CA or homologous PP2Cs.…”

Section: Discussionmentioning

confidence: 99%

“…The G139D (G174D in ABI1) mutation of AtPP2CA, close to the DG (aspartate-glycine) metal-coordinating residues (DGHG motif), is commonly used (6,18,35). The G139D mutation inactivates AtPP2CA, but it does not interfere with its expression in yeast (18,35) or its interaction abilities with kinase partners (6,18,35).…”

Section: Atpp2ca Mutants Display a Decreased Transpiration Phenotype mentioning

confidence: 99%

“…Another closely related phosphatase, AIP1/ HAI2, binds and regulates AKT1 (34,35). The AKT1 model predicts that different calcineurin B-like interacting protein kinases (CIPKs) interact with the ankyrin domain to phosphorylate the channel (34,35), whereas PP2C phosphatases (including AtPP2CA) inactivate AKT1 by interacting specifically with some of these CIPKs. The direct effect of AIP1 on AKT1 activity was not addressed.…”

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confidence: 99%

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The Arabidopsis AtPP2CA Protein Phosphatase Inhibits the GORK K+ Efflux Channel and Exerts a Dominant Suppressive Effect on Phosphomimetic-activating Mutations

Lefoulon

Boeglin

Moreau

et al. 2016

Journal of Biological Chemistry

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The regulation of the GORK (Guard Cell Outward Rectifying) Shaker channel mediating a massive K ؉ efflux in Arabidopsis guard cells by the phosphatase AtPP2CA was investigated. Unlike the gork mutant, the atpp2ca mutants displayed a phenotype of reduced transpiration. We found that AtPP2CA interacts physically with GORK and inhibits GORK activity in Xenopus oocytes. Several amino acid substitutions in the AtPP2CA active site, including the dominant interfering G145D mutation, disrupted the GORK-AtPP2CA interaction, meaning that the native conformation of the AtPP2CA active site is required for the GORKAtPP2CA interaction. Furthermore, two serines in the GORK ankyrin domain that mimic phosphorylation (Ser to Glu) or dephosphorylation (Ser to Ala) were mutated. Mutations mimicking phosphorylation led to a significant increase in GORK activity, whereas mutations mimicking dephosphorylation had no effect on GORK. In Xenopus oocytes, the interaction of AtPP2CA with "phosphorylated" or "dephosphorylated" GORK systematically led to inhibition of the channel to the same baseline level. Single-channel recordings indicated that the GORK S722E mutation increases the open probability of the channel in the absence, but not in the presence, of AtPP2CA. The dephosphorylation-independent inactivation mechanism of GORK by AtPP2CA is discussed in relation with well known conformational changes in animal Shaker-like channels that lead to channel opening and closing. In plants, PP2C activity would control the stomatal aperture by regulating both GORK and SLAC1, the two main channels required for stomatal closure.The plant clade A protein phosphatases 2C (PP2Cs) 5 are Mg 2ϩ -and Mn 2ϩ -dependent serine/threonine phosphatases that were first identified as components of the abscisic acid (ABA) signal transduction pathway (1, 2). The clade A APP2C members in Arabidopsis are mostly known as negative regulators of ABA signaling (3). Among this clade, ABI1, ABI2 (4), HAB1 (5), and AtPP2CA (6 -8) are well characterized. These proteins are involved in ABA-regulated germination (7-10). Of these, the ABI1, ABI2, and AtPP2CA genes are highly induced by ABA in guard cells (5). The abi1, abi2, atpp2ca, and hab1 mutants exhibit stomatal phenotypes (1, 4, 5). In particular, the atpp2ca-1 mutant displays impaired control of the stomatal aperture in epidermal strips in response to ABA (7). The role of clade A PP2Cs in stomatal closure in response to ABA has been discovered recently (reviewed in Refs. 11,12). Briefly, the Pyrabactin resistance (PYR)/PYR1-like (PYL)/regulatory component of the ABA receptor (RCAR)-soluble ABA receptors undergo a conformational change upon binding ABA, allowing them to bind and inactivate PP2Cs (13-15) and release the SnRK2.6/OST1 kinase. Without ABA, PP2Cs can bind to OST1 and inactivate it (16, 17). Active OST1 mediates anion efflux through the activation of SLAC1 (18,19). This signaling pathway is important for guard cell plasma membrane depolarization, which drives K ϩ efflux and causes stomatal closure. Besides OST...

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Modulation of ABA responses by the protein kinase WNK8

et al. 2018

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Abscisic acid (ABA) regulates growth and developmental processes in response to limiting water conditions. ABA functions through a core signaling pathway consisting of PYR1/PYL/RCAR ABA receptors, type 2C protein phosphatases (PP2Cs), and SnRK2‐type protein kinases. Other signaling modules might converge with ABA signals through the modulation of core ABA signaling components. We have investigated the role of the protein kinase WNK8 in ABA signaling. WNK8 interacted with PP2CA and PYR1, phosphorylated PYR1 in vitro, and was dephosphorylated by PP2CA. A hypermorphic wnk8‐ct Arabidopsis mutant allele suppressed ABA and glucose hypersensitivities of pp2ca‐1 mutants during young seedling development, and WNK8 expression in protoplasts suppressed ABA‐induced reporter gene expression. We conclude that WNK8 functions as a negative modulator of ABA signaling.

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Mechanistic Analysis of AKT1 Regulation by the CBL–CIPK–PP2CA Interactions

Cited by 143 publications

References 36 publications

Molecular basis for the selective and ABA-independent inhibition of PP2CA by PYL13

Molecular basis for the selective and ABA-independent inhibition of PP2CA by PYL13

The Arabidopsis AtPP2CA Protein Phosphatase Inhibits the GORK K+ Efflux Channel and Exerts a Dominant Suppressive Effect on Phosphomimetic-activating Mutations

Modulation of ABA responses by the protein kinase WNK8

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