Open Stomata 1 (<scp>OST</scp>1) is limiting in abscisic acid responses of Arabidopsis guard cells

Acharya, Bibhudendra; Jeon, Byeong Wook; Zhang, Wei; Assmann, Sarah M.

doi:10.1111/nph.12469

Cited by 171 publications

(159 citation statements)

References 101 publications

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“…It is considered that activation, with some dependence on Ca 2+ , of anion channels is a key and early step of the cascade resulting in ABA-triggered stomatal closure (Scherzer et al, 2012). CPK4 may eventually combine its action with that of other guard cell-expressed kinases, like OPEN STOMATA1 (Acharya et al, 2013;Imes et al, 2013) and CPK3/CPK6/CPK21/CPK23 (Mori et al, 2006;Brandt et al, 2012), which have been reported as promoting stomatal closure through their action on anion channels.…”

Section: Resultsmentioning

confidence: 99%

CPK13, a Noncanonical Ca2+-Dependent Protein Kinase, Specifically Inhibits KAT2 and KAT1 Shaker K+ Channels and Reduces Stomatal Opening

et al. 2014

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Ca2+ -dependent protein kinases (CPKs) form a large family of 34 genes in Arabidopsis (Arabidopsis thaliana). Based on their dependence on Ca 2+ , CPKs can be sorted into three types: strictly Ca 2+ -dependent CPKs, Ca 2+ -stimulated CPKs (with a significant basal activity in the absence of Ca 2+ ), and essentially calcium-insensitive CPKs. Here, we report on the third type of CPK, CPK13, which is expressed in guard cells but whose role is still unknown. We confirm the expression of CPK13 in Arabidopsis guard cells, and we show that its overexpression inhibits light-induced stomatal opening. We combine several approaches to identify a guard cell-expressed target. We provide evidence that CPK13 (1) specifically phosphorylates peptide arrays featuring Arabidopsis K + Channel KAT2 and KAT1 polypeptides, (2) inhibits KAT2 and/or KAT1 when expressed in Xenopus laevis oocytes, and (3) closely interacts in plant cells with KAT2 channels (Förster resonance energy transfer-fluorescence lifetime imaging microscopy). We propose that CPK13 reduces stomatal aperture through its inhibition of the guard cellexpressed KAT2 and KAT1 channels.

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Section: Resultsmentioning

confidence: 99%

CPK13, a Noncanonical Ca2+-Dependent Protein Kinase, Specifically Inhibits KAT2 and KAT1 Shaker K+ Channels and Reduces Stomatal Opening

et al. 2014

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“…The SnRK2-type protein kinase OST1 is one of the major ABA signaling components in guard cells, but it also functions in roots and seeds Mustilli et al, 2002;Yoshida et al, 2002;Xie et al, 2006;Fujita et al, 2009;Acharya et al, 2013). Our goal was to identify OIPs using in planta protein complex isolations followed by LC-MS/MS analyses.…”

Section: Discussion Design and Aba Responses Of Ost1-hf Linesmentioning

confidence: 99%

Identification of Open Stomata1-Interacting Proteins Reveals Interactions with Sucrose Non-fermenting1-Related Protein Kinases2 and with Type 2A Protein Phosphatases That Function in Abscisic Acid Responses

et al. 2015

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The plant hormone abscisic acid (ABA) controls growth and development and regulates plant water status through an established signaling pathway. In the presence of ABA, pyrabactin resistance/regulatory component of ABA receptor proteins inhibit type 2C protein phosphatases (PP2Cs). This, in turn, enables the activation of Sucrose Nonfermenting1-Related Protein Kinases2 (SnRK2). Open Stomata1 (OST1)/SnRK2.6/SRK2E is a major SnRK2-type protein kinase responsible for mediating ABA responses. Arabidopsis (Arabidopsis thaliana) expressing an epitope-tagged OST1 in the recessive ost1-3 mutant background was used for the copurification and identification of OST1-interacting proteins after osmotic stress and ABA treatments. These analyses, which were confirmed using bimolecular fluorescence complementation and coimmunoprecipitation, unexpectedly revealed homo-and heteromerization of OST1 with SnRK2.2, SnRK2.3, OST1, and SnRK2.8. Furthermore, several OST1-complexed proteins were identified as type 2A protein phosphatase (PP2A) subunits and as proteins involved in lipid and galactolipid metabolism. More detailed analyses suggested an interaction network between ABA-activated SnRK2-type protein kinases and several PP2A-type protein phosphatase regulatory subunits. pp2a double mutants exhibited a reduced sensitivity to ABA during seed germination and stomatal closure and an enhanced ABA sensitivity in root growth regulation. These analyses add PP2A-type protein phosphatases as another class of protein phosphatases to the interaction network of SnRK2-type protein kinases.

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“…ABA needs to first trigger the production of reactive oxygen species to activate Ca 2+ channels, which mediate the influx of external Ca 2+ to increase the cytosolic Ca 2+ concentration (Pei et al, 2000;Allen et al, 2001Allen et al, , 2002. It has also been reported that KAT1 can be inhibited through phosphorylation by kinases and that the C terminus of KAT1 is the main targeting site for this phosphorylation event (Mori et al, 2000;Sato et al, 2009Sato et al, , 2010Acharya et al, 2013). All these diverse regulators are involved in KAT1 regulation, which may be slow and consume energy.…”

Section: Drought Stress Induces a Significant Upregulation Of The Expmentioning

confidence: 99%

S-type Anion Channels SLAC1 and SLAH3 Function as Essential Negative Regulators of Inward K+ Channels and Stomatal Opening in Arabidopsis

et al. 2016

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Drought stress induces stomatal closure and inhibits stomatal opening simultaneously. However, the underlying molecular mechanism is still largely unknown. Here, we show that the slow-type (S-type) anion channels SLAC1 and SLAH3 mainly inhibit the inward-rectifying K + channel KAT1 by protein-protein interaction and consequently prevent stomatal opening in Arabidopsis thaliana. Voltage-clamp results demonstrated that SLAC1 inhibited KAT1 dramatically but did not inhibit KAT2. SLAH3 inhibited KAT1 to a lesser extent than did SLAC1. Both the N and C termini of SLAC1 inhibited KAT1, but the inhibition by the N terminus was stronger. The C terminus was essential for SLAC1-mediated inhibition of KAT1. Furthermore, drought stress strongly upregulated the expression of SLAC1 and SLAH3 in Arabidopsis guard cells, and the overexpression of wildtype and truncated SLAC1 dramatically impaired inward K + (K + in ) currents of guard cells and light-induced stomatal opening. Additionally, the inhibition of KAT1 by SLAC1 and KC1 only partially overlapped, suggesting that SLAC1 and KC1 inhibited K + in channels via different molecular mechanisms. Taken together, these findings reveal a novel regulatory mechanism for stomatal movement, in which signaling pathways for stomatal closure and opening are directly coupled by protein-protein interaction between SLAC1/SLAH3 and KAT1 in Arabidopsis.

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Open Stomata 1 (OST1) is limiting in abscisic acid responses of Arabidopsis guard cells

Cited by 171 publications

References 101 publications

CPK13, a Noncanonical Ca2+-Dependent Protein Kinase, Specifically Inhibits KAT2 and KAT1 Shaker K+ Channels and Reduces Stomatal Opening

CPK13, a Noncanonical Ca2+-Dependent Protein Kinase, Specifically Inhibits KAT2 and KAT1 Shaker K+ Channels and Reduces Stomatal Opening

Identification of Open Stomata1-Interacting Proteins Reveals Interactions with Sucrose Non-fermenting1-Related Protein Kinases2 and with Type 2A Protein Phosphatases That Function in Abscisic Acid Responses

S-type Anion Channels SLAC1 and SLAH3 Function as Essential Negative Regulators of Inward K+ Channels and Stomatal Opening in Arabidopsis

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