title: AtSAP18, an orthologue of human SAP18, is involved in the regulation of salt stress and mediates transcriptional repression in Arabidopsis.
abstract: In yeast and mammalian systems, it is well established that transcriptional down-regulation by DNA-binding repressors involves core histone deacetylation, mediated by their interaction within a complex containing histone deacetylase (e.g. HDA1), as well as various other proteins (e.g. SIN3, SAP18, SAP30, and RbAp46). Here we identify that a Arabidopsis thaliana gene related in sequence to SAP18, designated AtSAP18, functions in transcription regulation in plants subjected to salt stress. The AtSAP18 loss- of-function mutant is more sensitive to NaCl, and is impaired in chlorophyll synthesis as compared to the wild-type. Using GST pull-down, two-hybrid, and transient transcription assays, we have characterized SAP18 and HDA1 orthologues and provide evidence that SAP18 and HDA1 function as transcriptional repressors. We further demonstrate that they associate with Ethylene-Responsive Element binding Factors (ERFs) to create a hormone-sensitive multimeric repressor complex under conditions of environmental stress. Our results indicate that AtSAP18 functions to link the HDA complex to transcriptional repressors that are bound to chromatin in a sequence-specific manner, thereby providing the specificity of signal transduction accompanying transcriptional repression under stress conditions.
authors.affiliation: Department of Plant Sciences, University of Arizona, 303 Forbes Building, Tucson, AZ 85721, USA.
authors.forename: Chun-Peng
authors.initials: CP
authors.lastname: Song
authors.forename: David W
authors.initials: DW
authors.lastname: Galbraith
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000378:metabolism / Q000502:physiology*; D001483:Base Sequence; D002352:Carrier Proteins / Q000378:metabolism / Q000502:physiology*; D056970:Co-Repressor Proteins; D018076:DNA, Complementary; D006655:Histone Deacetylases / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D011485:Protein Binding; D018749:RNA, Plant / Q000235:genetics; D016601:RNA-Binding Proteins; D012492:Salts; D014158:Transcription, Genetic / Q000502:physiology*; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D056970:Co-Repressor Proteins; D018076:DNA, Complementary; D018749:RNA, Plant; D016601:RNA-Binding Proteins; C498650:SAP18 protein, human; D012492:Salts; D006655:Histone Deacetylases