セミナー情報

Although transposable elements (TEs) can potentially transpose in the host genomes, hosts have evolved many epigenetic mechanisms to repress transposition of TEs, such as DNA methylation. To counteract such repressing mechanisms, TEs seem to have evolved anti-silencing activities. We recently reported a novel TE-encoded gene, which can anti-silence the host repression mechanisms and re-activate TEs (Fu et al. 2013). In a mutant of Arabidopsis in which DNA methylation is abolished, we identified an atypical mobile Mutator-like element (Mule), Hiun (Hi). When a Hi transgene was introduced into the wild-type background, it induced excision of endogenous Hi copies, suggesting that Hi is an autonomously mobile copy. Interestingly, transgene of vanC, a gene encoding a non-conserved transposase in Hi, reduced DNA methylation level, activated transcripts and induced Hi excision in trans, demonstrating that vanC is an anti-silencing factor of Hi. Genome-wide DNA methylation analysis implied that vanC also reduced DNA methylation in other Mule copies, which have sequence similarity to Hi. Molecular mechanism and evolutionary contributions of vanC will be discussed.

Fu et al. EMBO J. 2013 (advance online publication)
http://www.nature.com/emboj/journal/vaop/ncurrent/full/emboj2013169a.html