Endonuclease Associations with Three Distinct Editosomes in Trypanosoma brucei
Endonuclease Associations with Three Distinct Editosomes in Trypanosoma brucei
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DOI：
10.1074/jbc.m111.228965
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发表时间：
2011-06-03
影响因子：
4.8
通讯作者：
Stuart, Kenneth
中科院分区：
文献类型：
--
作者：
Carnes, Jason;Soares, Carmen Zelaya;Stuart, Kenneth
三种不同的编辑体，以相互排斥的KREN 1，KREN 2或KREN 3内切核酸酶为代表，是布氏锥虫线粒体RNA编辑所必需的。三种编辑体在底物内切核糖核酸裂解特异性方面不同，这可能反映了大量需要插入或缺失尿苷核苷酸（Us）的编辑位点。每个编辑体需要每个内切核酸酶中的单个RNase III结构域进行催化。本文报道的研究表明，编辑核酸内切酶不形成同源二聚体结构域，因此可能与KREPB 4和/或KREPB 5起分子间异源二聚体的作用。通过与KREPB 6、KREPB 7或KREPB 8融合的TAP标签分离的编辑体具有一组共同的12种蛋白质。此外，KREN 3仅在KREPB 6编辑体中发现，KREN 2仅在KREPB 7编辑体中发现，KREN 1仅在KREPB 8编辑体中发现。这些是先前在通过TAP标记的核酸内切酶KREN 1、KREN 2或KREN 3分离的编辑体中发现的相同关联。此外，从细胞中分离的TAP标记的KREPB 6、KREPB 7和KREPB 8复合物被破坏，并且缺乏异源三聚体插入子复合物（KRET 2、KREPA 1和KREPA 2），在所述细胞中，它们各自的核酸内切酶的表达被敲低。这些结果和已发表的数据表明，KREPB 6，KREPB 7和KREPB 8与缺失亚复合物相关，而KREN 1，KREN 2和KREN 3内切核酸酶与插入亚复合物相关。
Three distinct editosomes, typified by mutually exclusive KREN1, KREN2, or KREN3 endonucleases, are essential for mitochondrial RNA editing in Trypanosoma brucei. The three editosomes differ in substrate endoribonucleolytic cleavage specificity, which may reflect the vast number of editing sites that need insertion or deletion of uridine nucleotides (Us). Each editosome requires the single RNase III domain in each endonuclease for catalysis. Studies reported here show that the editing endonucleases do not form homodimeric domains, and may therefore function as intermolecular heterodimers, perhaps with KREPB4 and/or KREPB5. Editosomes isolated via TAP tag fused to KREPB6, KREPB7, or KREPB8 have a common set of 12 proteins. In addition, KREN3 is only found in KREPB6 editosomes, KREN2 is only found in KREPB7 editosomes, and KREN1 is only found in KREPB8 editosomes. These are the same associations previously found in editosomes isolated via the TAP-tagged endonucleases KREN1, KREN2, or KREN3. Furthermore, TAP-tagged KREPB6, KREPB7, and KREPB8 complexes isolated from cells in which expression of their respective endonuclease were knocked down were disrupted and lacked the heterotrimeric insertion subcomplex (KRET2, KREPA1, and KREL2). These results and published data suggest that KREPB6, KREPB7, and KREPB8 associate with the deletion subcomplex, whereas the KREN1, KREN2, and KREN3 endonucleases associate with the insertion subcomplex.