Homeodomain protein ATHB6 is a target of the protein phosphatase ABI1 and regulates hormone responses in Arabidopsis

ABI1, a protein phosphatase 2C, is a key component of signal transduction in Arabidopsis. It regulates diverse responses to the phytohormone abscisic acid (ABA) such as stomatal closure, seed dormancy and inhibition of vegetative growth. By analysing proteins capable of interacting with ABI1, we hav...

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Published in:	The EMBO journal Vol. 21; no. 12; pp. 3029 - 3038
Main Authors:	Himmelbach, Axel, Hoffmann, Thomas, Leube, Martin, Höhener, Beat, Grill, Erwin
Format:	Journal Article
Language:	English
Published:	Chichester, UK John Wiley & Sons, Ltd 17-06-2002 Blackwell Publishing Ltd Oxford University Press
Subjects:	ABI1 abscisic acid Amino Acid Sequence Arabidopsis - physiology Arabidopsis Proteins - chemistry Arabidopsis Proteins - genetics Arabidopsis Proteins - metabolism ATHB6 Catalytic Domain Gene Expression Regulation, Plant Genes, Reporter Homeodomain Proteins homeodomain-leucine zipper protein Molecular Sequence Data Phosphoprotein Phosphatases - metabolism Plant Growth Regulators - metabolism Plants, Genetically Modified - genetics Plants, Genetically Modified - metabolism PP2C Promoter Regions, Genetic Protein Binding Recombinant Fusion Proteins - metabolism Signal Transduction - physiology Transcription Factors - chemistry Transcription Factors - genetics Transcription Factors - metabolism Transcription, Genetic Transgenic plants Two-Hybrid System Techniques
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Summary:	ABI1, a protein phosphatase 2C, is a key component of signal transduction in Arabidopsis. It regulates diverse responses to the phytohormone abscisic acid (ABA) such as stomatal closure, seed dormancy and inhibition of vegetative growth. By analysing proteins capable of interacting with ABI1, we have identified the homeodomain protein ATHB6 as a regulator of the ABA signal pathway. Critical for interaction between ATHB6 and ABI1 is an intact protein phosphatase domain and the N‐terminal domain of ATHB6 containing the DNA‐binding site. ATHB6 recognizes a cis‐element present in its promoter, which encompasses the core motif (CAATTATTA) that mediated ATHB6‐ and ABA‐dependent gene expression in protoplasts. In addition, transgenic plants containing a luciferase gene controlled by the ATHB6 promoter documented a strong ABA‐inducible expression of the reporter which was abrogated in the ABA‐insensitive abi1 mutant. Arabidopsis plants with constitutive expression of the transcriptional regulator revealed ABA insensitivity in a subset of ABI1‐dependent responses. Thus, the homeodomain protein ATHB6 seems to represent a negative regulator of the ABA signal pathway and to act downstream of ABI1.
Bibliography:	ArticleID:EMBJ7594522 istex:08ACCAD06D45F5E2885F92140BFFC8146CDD7B6B ark:/67375/WNG-FNKKJ6G3-G Supplementary data ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2
ISSN:	0261-4189 1460-2075 1460-2075
DOI:	10.1093/emboj/cdf316