2008年10月10日, 北京生命科学研究所马力耕实验室在 The Plant Cell 杂志上在线发表题为Histone H2B Monoubiquitination in the Chromatin of FLOWERING LOCUS C Regulates Flowering Time in Arabidopsis的文章, 报道了FLC(FLOWERING LOCUS C) 染色质的一种新的修饰方式-H2B单泛素化调节FLC基因表达和拟南芥开花时间。
植物由营养生长向生殖生长转化是植物的一个重要的发育过程。这种转化发生在顶端分生组织细胞,细胞分化的决定受多种因素调控,其中转录因子FLC抑制营养生长向生殖生长的转化,抑制程度与其表达水平成正相关。目前已知多种因素通过调控FLC染色质的甲基化和乙酰化来调控其表达,而且FLC已经成为植物体系中研究组蛋白修饰和基因表达调控之间关系的模型。该论文鉴定了参与拟南芥组蛋白H2B单泛素化的E2和E3,并证明FLC及其同源基因的染色质H2B被单泛素化,H2B被单泛素化后进一步增强H3K4和H3K36的甲基化,进而激活FLC及其同源基因的表达,并导致开花延迟。这些E2和E3基因的突变导致植物开花提前。该论文的研究结果证实FLC (FLOWERING LOCUS C) 染色质的一种新的修饰-H2B单泛素化调节FLC基因表达并因此调控拟南芥开花时间。
博士研究生曹颖和博士后戴艳为该文的共同第一作者。河北师范大学的崔素娟博士为本论文的合作者。马力耕博士为本文通讯作者。 此项研究为科技部863和北京市科委资助课题,主要工作在北京生命科学研究所完成。(生物谷Bioon.com)
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Plant Cell Published on October 10, 2008; 10.1105/tpc.108.062760
Histone H2B Monoubiquitination in the Chromatin of FLOWERING LOCUS C Regulates Flowering Time in Arabidopsis
Ying Cao 1, Yan Dai 2, Sujuan Cui 3, and Ligeng Ma 2
1 Institute of Molecular Cellular Biology, Hebei Key Laboratory of Molecular and Cellular Biology, Hebei Normal University, Shijiazhuang 050016, China; National Institute of Biological Sciences, Beijing 102206, China
2 National Institute of Biological Sciences, Beijing 102206, China
3 Institute of Molecular Cellular Biology, Hebei Key Laboratory of Molecular and Cellular Biology, Hebei Normal University, Shijiazhuang 050016, China
Ubiquitination is one of many known histone modifications that regulate gene expression. Here, we examine theArabidopsis thaliana homologs of the yeast E2 and E3 enzymes responsible for H2B monoubiquitination (H2Bub1).Arabidopsis has two E3 homologs (HISTONE MONOUBIQUITINATION1 [HUB1] and HUB2) and three E2 homologs (UBIQUITIN CARRIER PROTEIN [UBC1] to UBC3). hub1 and hub2 mutants show the loss of H2Bub1 and early flowering. By contrast, single ubc1, ubc2, or ubc3 mutants show no flowering defect; only ubc1 ubc2 double mutants, and not double mutants with ubc3, show early flowering and H2Bub1 defects. This suggests that ubc1 and ubc2 are redundant, but ubc3 is not involved in flowering time regulation. Protein interaction analysis showed that HUB1 and HUB2 interact with each other and with UBC1 and UBC2, as well as self-associating. The expression of FLOWERING LOCUS C (FLC) and its homologs was repressed in hub1, hub2, and ubc1 ubc2 mutant plants. Association of H2Bub1 with the chromatin of FLC clade genes depended on UBC1,2 and HUB1,2, as did the dynamics of methylated histones H3K4me3 and H3K36me2. The monoubiquitination of H2B via UBC1,2 and HUB1,2 represents a novel form of histone modification that is involved in flowering time regulation.