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PMID:19769575

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Citation

Szostkiewicz, I, Richter, K, Kepka, M, Demmel, S, Ma, Y, Korte, A, Assaad, FF, Christmann, A and Grill, E (2010) Closely related receptor complexes differ in their ABA selectivity and sensitivity. Plant J. 61:25-35

Abstract

The recent discovery of a variety of receptors has led to new models for hormone perception in plants. In the case of the hormone abscisic acid (ABA), which regulates plant responses to abiotic stress, perception seems to occur both at the plasma membrane and in the cytosol. The cytosolic receptors for ABA have recently been identified as complexes between protein phosphatases 2C (PP2C) and regulatory components (RCAR/PYR/PYL) that bind ABA. Binding of ABA to the receptor complexes inactivates the PP2Cs, thereby activating the large variety of physiological processes regulated by ABA. The Arabidopsis genome encodes 13 homologues of RCAR1 and approximately 80 PP2Cs, of which six in clade A have been identified as negative regulators of ABA responses. In this study we characterize a novel member of the RCAR family, RCAR3. RCAR3 was identified in a screen for interactors of the PP2Cs ABI1 and ABI2, which are key regulators of ABA responses. RCAR3 was shown to repress ABI1 and ABI2 in vitro, and to stimulate ABA signalling in protoplast cells. RCAR3 conferred greater ABA sensitivity to the PP2C regulation than RCAR1, whereas stereo-selectivity for (S)-ABA was less stringent with RCAR3 as compared with RCAR1. In addition, regulation of the protein phosphatase activity by RCAR1 and RCAR3 was more sensitive to ABA for ABI1 than for ABI2. Based on the differences we have observed in transcriptional regulation and biochemical properties, we propose a model whereby differential expression of the co-receptors and combinatorial assembly of the receptor complexes act in concert to modulate and fine-tune ABA responses.

Links

PubMed Online version:10.1111/j.1365-313X.2009.04025.x

Keywords

Abscisic Acid/pharmacology; Arabidopsis/drug effects; Arabidopsis/genetics; Arabidopsis/metabolism; Arabidopsis Proteins/metabolism; Arabidopsis Proteins/physiology; Calorimetry; Carrier Proteins; Circular Dichroism; Gene Expression Regulation, Plant/genetics; Gene Expression Regulation, Plant/physiology; Phosphoprotein Phosphatases/metabolism; Plants, Genetically Modified/drug effects; Plants, Genetically Modified/genetics; Plants, Genetically Modified/metabolism; Protein Binding; Protoplasts/drug effects; Protoplasts/metabolism; Signal Transduction; Two-Hybrid System Techniques

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

ARATH:P2C77

enables

GO:0005515: protein binding

ECO:0000353: physical interaction evidence used in manual assertion

UniProtKB:Q9FGM1

F

Seeded From UniProt

complete

ARATH:P2C56

enables

GO:0005515: protein binding

ECO:0000353: physical interaction evidence used in manual assertion

UniProtKB:Q9FGM1

F

Seeded From UniProt

complete

ARATH:PYL8

enables

GO:0005515: protein binding

ECO:0000353: physical interaction evidence used in manual assertion

UniProtKB:O04719

F

Seeded From UniProt

complete

ARATH:PYL8

enables

GO:0005515: protein binding

ECO:0000353: physical interaction evidence used in manual assertion

UniProtKB:P49597

F

Seeded From UniProt

complete

ARATH:PYL8

involved_in

GO:0009738: abscisic acid-activated signaling pathway

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:PYL8

enables

GO:0038023: signaling receptor activity

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

ARATH:PYL8

acts_upstream_of_or_within

GO:0009738: abscisic acid-activated signaling pathway

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:PYL8

acts_upstream_of_or_within

GO:0009737: response to abscisic acid

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete


See also

References

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