title: Requirement of histone acetyltransferases HAM1 and HAM2 for epigenetic modification of FLC in regulating flowering in Arabidopsis.
abstract: Histone acetylation is an important posttranslational modification associated with gene activation. In Arabidopsis, two MYST histone acetyltransferases HAM1 and HAM2 work redundantly to acetylate histone H4 lysine 5 (H4K5ace) in vitro. The double mutant ham1/ham2 is lethal, which suggests the critical role of HAM1 and HAM2 in development. Here, we used an artificial microRNA (amiRNA) strategy in Arabidopsis to uncover a novel function of HAM1 and HAM2. The amiRNA-HAM1/2 transgenic plants showed early flowering and reduced fertility. In addition, they responded normally to photoperiod, gibberellic acid treatment, and vernalization. The expression of flowering-repressor FLOWERING LOCUS C (FLC) and its homologues, MADS-box Affecting Flowering genes 3/4 (MAF3/4), were decreased in amiRNA-HAM1/2 lines. HAM1 overexpression caused late flowering and elevated expression of FLC and MAF3/4. Mutation of FLC almost rescued the late flowering with HAM1 overexpression, which suggests that HAM1 regulation of flowering time depended on FLC. Global H4 acetylation was decreased in amiRNA-HAM1/2 lines, but increased in HAM1-OE lines, which further confirmed the acetyltransferase activity of HAM1 in vivo. Chromatin immunoprecipitation revealed that H4 hyperacetylation and H4K5ace at FLC and MAF3/4 were less abundant in amiRNA-HAM1/2 lines than the wild type, but were enriched in HAM1-OE lines. Thus, HAM1 and HAM2 may affect flowering time by epigenetic modification of FLC and MAF3/4 chromatins at H4K5 acetylation.
authors.affiliation: Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Xiao
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.forename: Lijing
authors.initials: L
authors.lastname: Xing
authors.forename: Shujuan
authors.initials: S
authors.lastname: Xu
authors.forename: Huanhuan
authors.initials: H
authors.lastname: Liu
authors.forename: Kang
authors.initials: K
authors.lastname: Chong
authors.forename: Yunyuan
authors.initials: Y
authors.lastname: Xu
mesh_terms: D000107:Acetylation; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D044127:Epigenesis, Genetic; D035264:Flowers / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D051548:Histone Acetyltransferases / Q000235:genetics* / Q000378:metabolism*; D026161:MADS Domain Proteins / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C418902:At5g10140 protein, Arabidopsis; D026161:MADS Domain Proteins; D010937:Plant Growth Regulators; C582654:HAM1 protein, Arabidopsis; C582655:HAM2 protein, Arabidopsis; D051548:Histone Acetyltransferases