title: The WD40 Domain Protein MSI1 Functions in a Histone Deacetylase Complex to Fine-Tune Abscisic Acid Signaling.
abstract: MSI1 belongs to a family of histone binding WD40-repeat proteins. Arabidopsis thaliana contains five genes encoding MSI1-like proteins, but their functions in diverse chromatin-associated complexes are poorly understood. Here, we show that MSI1 is part of a histone deacetylase complex. We copurified HISTONE DEACETYLASE19 (HDA19) with MSI1 and transcriptional regulatory SIN3-like proteins and provide evidence that MSI1 and HDA19 associate into the same complex in vivo. These data suggest that MSI1, HDA19, and HISTONE DEACETYLATION COMPLEX1 protein form a core complex that can integrate various SIN3-like proteins. We found that reduction of MSI1 or HDA19 causes upregulation of abscisic acid (ABA) receptor genes and hypersensitivity of ABA-responsive genes. The MSI1-HDA19 complex fine-tunes ABA signaling by binding to the chromatin of ABA receptor genes and by maintaining low levels of acetylation of histone H3 at lysine 9, thereby affecting the expression levels of ABA receptor genes. Reduced MSI1 or HDA19 levels led to increased tolerance to salt stress corresponding to the increased ABA sensitivity of gene expression. Together, our results reveal the presence of an MSI1-HDA19 complex that fine-tunes ABA signaling in Arabidopsis.
authors.affiliation: Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, SE-75007 Uppsala, Sweden.
authors.forename: Saher
authors.identifier: http://orcid.org/0000-0003-4602-9821
authors.initials: S
authors.lastname: Mehdi
authors.affiliation: Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, SE-75007 Uppsala, Sweden Department of Biology and Zurich-Basel Plant Science Center, ETH Zurich, CH-8092 Zurich, Switzerland.
authors.forename: Maria
authors.identifier: http://orcid.org/0000-0001-8355-6546
authors.initials: M
authors.lastname: Derkacheva
authors.affiliation: Department of Chemistry, Analytical Chemistry and Science for Life Laboratory, Uppsala University, SE-75124 Uppsala, Sweden.
authors.forename: Margareta
authors.identifier: http://orcid.org/0000-0003-1471-7291
authors.initials: M
authors.lastname: Ramström
authors.affiliation: Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, SE-75007 Uppsala, Sweden.
authors.forename: Lejon
authors.identifier: http://orcid.org/0000-0002-8154-9315
authors.initials: L
authors.lastname: Kralemann
authors.affiliation: Department of Chemistry, Analytical Chemistry and Science for Life Laboratory, Uppsala University, SE-75124 Uppsala, Sweden.
authors.forename: Jonas
authors.initials: J
authors.lastname: Bergquist
authors.affiliation: Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, SE-75007 Uppsala, Sweden lars.hennig@slu.se.
authors.forename: Lars
authors.identifier: http://orcid.org/0000-0002-6645-1862
authors.initials: L
authors.lastname: Hennig
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism* / Q000494:pharmacology; D000107:Acetylation / Q000187:drug effects; D000222:Adaptation, Physiological / Q000187:drug effects / Q000235:genetics; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D006655:Histone Deacetylases / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D008239:Lysine / Q000378:metabolism; D008954:Models, Biological; D011485:Protein Binding / Q000187:drug effects; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D029681:Arabidopsis Proteins; D002843:Chromatin; D006657:Histones; C475821:MSI1 protein, Arabidopsis; D021122:Protein Subunits; D012333:RNA, Messenger; D012965:Sodium Chloride; D000040:Abscisic Acid; C507152:HDA19 protein, Arabidopsis; D006655:Histone Deacetylases; D008239:Lysine