濡木研公開ラボセミナー
Molecular basis for catalytic mechanisms of ribozymes
Benoit Masquida（University of Strasbourg CNRS Doctor of Philosophy）
2023年10月24日(火) 14:00-15:00 理学部1号館中央棟341号室
The intron inserted in the small ribosomal subunit gene of the myxomycete Didymium iridis is made up of at least three different functional RNAs, a self-splicing group I intron (GIR2) leading to exon ligation, a branching ribozyme inserted within GIR2. The branching ribozyme catalyses the formation of a 3-nt lariat that ultimately caps the 5’ end of the downstream intronic ORF encoding a homing endonuclease. The latter is responsible for intron spreading within the myxomycete population. These three RNAs cross-talk since the cleavage patterns differ according to environmental conditions. When starving, the branching ribozyme cleaves first leaving the exons unligated, leading to strong decrease of translation rates and further cyst formation pointing to a trade-off between splicing and ribozyme activities.
We have published in 2014 the Crystal structure of the 200-nt branching ribozyme. In order to better understand the molecular basis of the cross-talk between the two ribozymes, we aim at solving the cry-EM structure of the ribozyme ensemble. Moreover, cry-EM would also allow observing the various catalytic intermediates shading light on the whole process. This is a unique example of two ribozymes working in concert, although the coupling between splicing and RNA catalysis may be a more general control gate with another known example provided by the CPEB3 ribozyme expressed in the human brain.
担当：東京大学大学院理学系研究科・生物科学専攻・濡木理
※学内限定
