Abstracts (poster) - Wissenschaft Online

Lin XU, Rozenn MENARD, Alexandre BERR, Denise MEYER, Wen-Hui SHEN
Role of Histone Ubiquitination in Arabidopsis Development
Histone ubiquitination is a critical epigenetic mark conserved from yeast to human. H2B
mono-ubiquitination is involved in transcriptional activation whereas H2A monoubiquitination
is involved in gene silencing. Recently RING-domain proteins HUB1 and
HUB2, which show highest homologies with the yeast BRE1, were reported to act on H2B
ubiquitination and to be involved in regulation of G2-to-M transition of the cell cycle and
of seed germination (Fleury et al., Plant Cell. 2007 Feb;19(2):417-32; Liu et al., Plant
Cell. 2007 Feb;19(2):433-44). We identified AtUBC1 and AtUBC2 to encode proteins
showing highest homologies with the yeast Rad6. Rad6 is involved, together with BRE1,
in mono-ubiquitination of H2B in yeast. While the single mutant ubc1-1 or ubc2-1 has a
normal flowering phenotype, the double mutant ubc1-1 ubc2-1 showed an earlyflowering
phenotype. We found that hub1 and hub2 mutants also show an earlyflowering
phenotype, suggesting that AtUBC1/2 and HUB1/2 function together in
regulating flowering time through H2B ubiquitination. We also identified two novel genes
of the RING family, LOC1 and LOC2, as being required for the maintenance of the
restriction boundary of the shoot apical meristem (SAM) activity. We suggest that LOC1
and LOC2 repress transcription through a Polycomb-like pathway.
contact:
Dr. Lin XU
UNIVERSITE LOUIS PASTEUR
Institut de Biologie Moléculaire des Plantes du CNRS
lin.xu@ibmp-ulp.u-strasbg.fr
12 rue du Général ZIMMER
67084 STRASBOURG (France)