HUB1, a homolog of BRE1 in Saccharomyces cerevisiae, plays a role in flowering time controlling in Arabidopsis
Date Issued
2008
Date
2008
Author(s)
Liang, Shih-Chieh
Abstract
FLOWERING LOCUS C (FLC), a central floral repressor in Arabidopsis thaliana, inhibits the expression of flowering genens, such as FLOWERING LOCUS T (FT) and SUPPRESSOR OF CONSTANT1 (SOC1). One of the mechanisms regulating FLC expression is epigenetic control, which includes histone modifications in gene’s promoter region. We isolated HISTONE MONO-UBIQUITINATION(HUB1) gene from Arabidopsis thaliana, which is a homolog of BRE1 in Saccharomyces cerevisiae. HUB1, with a RING-finger domain in its C-terminus, has E3 ligase activity, while its target, as that of BRE1 in yeast, is histone H2B. In yeast model, ubiquitination on H2B might induce H3K4 tri-methylation via COMPASS complex, and activate gene expression. T-DNA insertion plant with hub1 mutant shows early flowering. Besides, FLC expression level decreases, and its downstream flowering genes, FT and SOC1 are activated in hub1. Furthermore, Chromatin immunoprecipitation (ChIP) was performed, and a dramatic decrease in H3K4 tri-methylation and ubiquitylation was observed in FLC promoter. We propose that HUB1-mediated H2B ubiquitination might induce tri-methylation on H3K4, and consequently activate FLC expression
Subjects
epigenetic regulation
FLC
histone modification
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