title: ABI5-binding proteins (AFPs) alter transcription of ABA-induced genes via a variety of interactions with chromatin modifiers.
abstract: Overexpression of ABI5/ABF binding proteins (AFPs) results in extreme ABA resistance of seeds via multiple mechanisms repressing ABA response, including interactions with histone deacetylases and the co-repressor TOPLESS. Several ABI5/ABF binding proteins (AFPs) inhibit ABA response, resulting in extreme ABA resistance in transgenic Arabidopsis overexpression lines, but their mechanism of action has remained obscure. By analogy to the related Novel Interactor of JAZ (NINJA) protein, it was suggested that the AFPs interact with the co-repressor TOPLESS to inhibit ABA-regulated gene expression. This study shows that the AFPs that inhibit ABA response have intrinsic repressor activity in a heterologous system, which does not depend on the domain involved in the interaction with TOPLESS. This domain is also not essential for repressing ABA response in transgenic plants, but does contribute to stronger ABA resistance. Additional interactions between some AFPs and histone deacetylase subunits were observed in yeast two-hybrid and bimolecular fluorescence assays, consistent with a more direct mechanism of AFP-mediated repression of gene expression. Chemical inhibition of histone deacetylase activity by trichostatin A suppressed AFP effects on a small fraction of the ABI5-regulated genes tested. Collectively, these results suggest that the AFPs participate in multiple mechanisms modulating ABA response, including both TOPLESS-dependent and -independent chromatin modification.
authors.affiliation: Molecular, Cellular, and Developmental Biology Department, University of California at Santa Barbara, Santa Barbara, CA, 93106, USA.
authors.forename: Tim J
authors.initials: TJ
authors.lastname: Lynch
authors.affiliation: Biomolecular Science and Engineering Program, University of California at Santa Barbara, Santa Barbara, CA, 93106, USA.
authors.forename: B Joy
authors.initials: BJ
authors.lastname: Erickson
authors.affiliation: Biomolecular Science and Engineering Program, University of California at Santa Barbara, Santa Barbara, CA, 93106, USA.|Chemistry Department, Vanderbilt University, Nashville, TN, 37235, USA.
authors.forename: Dusty R
authors.initials: DR
authors.lastname: Miller
authors.affiliation: Molecular, Cellular, and Developmental Biology Department, University of California at Santa Barbara, Santa Barbara, CA, 93106, USA. finkelst@lifesci.ucsb.edu.
authors.forename: Ruth R
authors.identifier: http://orcid.org/0000-0001-7702-3778
authors.initials: RR
authors.lastname: Finkelstein
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D002843:Chromatin / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D006655:Histone Deacetylases / Q000235:genetics / Q000378:metabolism; D015151:Immunoblotting; D047908:Intracellular Signaling Peptides and Proteins; D008856:Microscopy, Fluorescence; D010937:Plant Growth Regulators / Q000494:pharmacology; D030821:Plants, Genetically Modified; D011485:Protein Binding; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020798:Two-Hybrid System Techniques
chemical_list: D000040:Abscisic Acid; D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D002352:Carrier Proteins; D002843:Chromatin; D006655:Histone Deacetylases; D047908:Intracellular Signaling Peptides and Proteins; D010937:Plant Growth Regulators; C409743:ABI5 protein, Arabidopsis; C000616520:AFP1 protein, Arabidopsis; C000616521:AFP2 protein, Arabidopsis; C511291:At1g15750 protein, Arabidopsis
keywords: ABA-INSENSITIVE(ABI5); AFP; Arabidopsis; Chromatin; Germination; Histone deacetylase