Michel François, Costa Maria, Westhof Eric
Centre de Génétique Moléculaire du CNRS, 1 Avenue de la Terrasse, 91190 Gif-sur-Yvette, France.
Trends Biochem Sci. 2009 Apr;34(4):189-99. doi: 10.1016/j.tibs.2008.12.007. Epub 2009 Mar 18.
Group II introns contain a large ribozyme, which catalyzes self-splicing, and the coding sequence of a reverse transcriptase, the function of which is to cooperate with the ribozyme to achieve genomic mobility. Despite its lack of substrates for both steps of the splicing process, the crystal structure of a group II ribozyme reveals the location of two metal ions most likely to be involved in catalysis; the RNA structure that binds to these ions results from the bending of a local motif by the folding of the rest of the ribozyme. The stage is now set to determine where the intron-encoded protein binds to its partner and whether the spliceosome uses a counterpart of the group II catalytic center to excise nuclear pre-messenger introns.
II类内含子包含一个大型核酶，它催化自我剪接，以及一个逆转录酶的编码序列，其功能是与核酶协同作用以实现基因组移动性。尽管剪接过程的两个步骤都缺乏底物，但II类核酶的晶体结构揭示了最有可能参与催化的两个金属离子的位置；与这些离子结合的RNA结构是由核酶其余部分的折叠导致局部基序弯曲而形成的。现在已经具备了确定内含子编码蛋白与其伙伴结合的位置以及剪接体是否使用II类催化中心的对应物来切除核前信使内含子的条件。
