Arabidopsis COMPASS-like complexes mediate histone H3 lysine-4 trimethylation to control floral transition and plant development

• Published in: PLoS genetics Vol. 7; no. 3; p. e1001330
• Main Authors: Jiang, Danhua, Kong, Nicholas C, Gu, Xiaofeng, Li, Zicong, He, Yuehui
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01.03.2011; Public Library of Science (PLoS)
• Subjects: Animals; Arabidopsis; Arabidopsis - genetics; Arabidopsis - physiology; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Carrier Proteins - genetics; Carrier Proteins - metabolism; Chromatin; Chromatin - metabolism; Chromosomal Proteins, Non-Histone - genetics; Chromosomal Proteins, Non-Histone - metabolism; Flowers - genetics; Flowers - physiology; Gene expression; Gene Expression Regulation, Developmental; Genetic aspects; Genetics; Genetics and Genomics/Gene Expression; Genetics and Genomics/Plant Genetics and Gene Expression; Genomes; Histones; Histones - metabolism; Insects; Leaves; Life sciences; MADS Domain Proteins - genetics; MADS Domain Proteins - metabolism; Methylation; Methyltransferases - metabolism; Multiprotein Complexes - metabolism; Phylogeny; Physiological aspects; Plant Biology/Plant Genetics and Gene Expression; Plant Biology/Plant Growth and Development; Plant Leaves - genetics; Plant Leaves - growth & development; Protein Binding; Proteins; Repressor Proteins - genetics; Repressor Proteins - metabolism; RNA Interference; Seeds - genetics; Seeds - physiology; Two-Hybrid System Techniques; Yeast; Singapore
• ISSN: 1553-7404; 1553-7390; 1553-7404
• DOI: 10.1371/journal.pgen.1001330

Histone H3 lysine-4 (H3K4) methylation is associated with transcribed genes in eukaryotes. In Drosophila and mammals, both di- and tri-methylation of H3K4 are associated with gene activation. In contrast to animals, in Arabidopsis H3K4 trimethylation, but not mono- or di-methylation of H3K4, has been implicated in transcriptional activation. H3K4 methylation is catalyzed by the H3K4 methyltransferase complexes known as COMPASS or COMPASS-like in yeast and mammals. Here, we report that Arabidopsis homologs of the COMPASS and COMPASS-like complex core components known as Ash2, RbBP5, and WDR5 in humans form a nuclear subcomplex during vegetative and reproductive development, which can associate with multiple putative H3K4 methyltransferases. Loss of function of ARABIDOPSIS Ash2 RELATIVE (ASH2R) causes a great decrease in genome-wide H3K4 trimethylation, but not in di- or mono-methylation. Knockdown of ASH2R or the RbBP5 homolog suppresses the expression of a crucial Arabidopsis floral repressor, FLOWERING LOCUS C (FLC), and FLC homologs resulting in accelerated floral transition. ASH2R binds to the chromatin of FLC and FLC homologs in vivo and is required for H3K4 trimethylation, but not for H3K4 dimethylation in these loci; overexpression of ASH2R causes elevated H3K4 trimethylation, but not H3K4 dimethylation, in its target genes FLC and FLC homologs, resulting in activation of these gene expression and consequent late flowering. These results strongly suggest that H3K4 trimethylation in FLC and its homologs can activate their expression, providing concrete evidence that H3K4 trimethylation accumulation can activate eukaryotic gene expression. Furthermore, our findings suggest that there are multiple COMPASS-like complexes in Arabidopsis and that these complexes deposit trimethyl but not di- or mono-methyl H3K4 in target genes to promote their expression, providing a molecular explanation for the observed coupling of H3K4 trimethylation (but not H3K4 dimethylation) with active gene expression in Arabidopsis.