title: Repression of the floral transition via histone H2B monoubiquitination.
abstract: The Rad6-Bre1 complex monoubiquitinates histone H2B in target gene chromatin, and plays an important role in positively regulating gene expression in yeast. Here, we show that the Arabidopsis relatives of the yeast Rad6, ubiquitin-conjugating enzyme 1 (UBC1) and UBC2, redundantly mediate histone H2B monoubiquitination, and upregulate the expression of FLOWERING LOCUS C (FLC; a central flowering repressor in Arabidopsis) and FLC relatives, and also redundantly repress flowering, the developmental transition from a vegetative to a reproductive phase that is critical in the plant life cycle. Moreover, we have found that Arabidopsis relatives of the yeast Bre1, including HISTONE MONOUBIQUITINATION 1 (HUB1) and HUB2, also upregulate the expression of FLC and FLC relatives, and that HUB1 genetically interacts with UBC1 and UBC2 to repress the floral transition. These findings are consistent with a model in which HUB1 and HUB2 specifically interact with and direct UBC1 and UBC2 to monoubiquitinate H2B in developmental genes, and thus regulate developmental processes in plants.
authors.affiliation: Department of Biological Sciences, National University of Singapore, Singapore.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Gu
authors.forename: Danhua
authors.initials: D
authors.lastname: Jiang
authors.forename: Yuqi
authors.initials: Y
authors.lastname: Wang
authors.forename: Andreas
authors.initials: A
authors.lastname: Bachmair
authors.forename: Yuehui
authors.initials: Y
authors.lastname: He
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D035264:Flowers / Q000201:enzymology / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D006657:Histones / Q000378:metabolism*; D026161:MADS Domain Proteins / Q000378:metabolism*; D018749:RNA, Plant / Q000235:genetics; D044763:Ubiquitin-Conjugating Enzymes / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D054875:Ubiquitination
chemical_list: D029681:Arabidopsis Proteins; C418902:At5g10140 protein, Arabidopsis; D006657:Histones; D026161:MADS Domain Proteins; D018749:RNA, Plant; C489357:UBC1 protein, Arabidopsis; D044763:Ubiquitin-Conjugating Enzymes; C521255:HUB1 protein, Arabidopsis; C521256:HUB2 protein, Arabidopsis; D044767:Ubiquitin-Protein Ligases