Structure and function of the polymerase core of TRAMP, a RNA surveillance complex
Structure and function of the polymerase core of TRAMP, a RNA surveillance complex
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DOI：
10.1073/pnas.1003505107
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发表时间：
2010-08-24
影响因子：
11.1
通讯作者：
Reinisch, Karin M.
中科院分区：
文献类型：
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作者：
Hamill, Stephanie;Wolin, Sandra L.;Reinisch, Karin M.
Trf4p/Air2p/Mtr4p多聚腺苷化（TRAMP）复合物识别酿酒酵母中的异常rna并将其靶向降解。由核苷酸转移酶Pol β超家族中的非规范聚(A) RNA聚合酶Trf4p和锌指节蛋白Air2p组成的TRAMP亚复合物介导初始底物识别。Trf4p和相关的真核多聚(A)和多聚(U)聚合酶与Pol β超家族中的其他特征酶在序列和缺乏可识别的核酸结合基序方面都有所不同。在2.7埃分辨率下，我们报告了Trf4p与Air2p片段的配合物结构，其中Air2p片段包含两个锌关节基元。Trf4p由催化结构域和中心结构域组成，其折叠方式与其他非规范Pol β RNA聚合酶相似，并且Air2p的两个锌关节基序与Trf4p中心结构域相互作用。Trf4p上的相互作用表面在真核生物中是高度保守的，这表明Trf4p/Air2p复合体在高等真核生物和酵母中都是保守的，并且TRAMP复合体也可能在高等真核生物中具有RNA监视功能。我们发现，Air2p，特别是在其N端附近包含锌节基序的序列，可以调节Trf4p的活性，并且我们提供的数据支持该锌节在RNA结合中的作用。最后，我们发现RNA 3'端在底物识别中起作用。
The Trf4p/Air2p/Mtr4p polyadenylation (TRAMP) complex recognizes aberrant RNAs in Saccharomyces cerevisiae and targets them for degradation. A TRAMP subcomplex consisting of a noncanonical poly(A) RNA polymerase in the Pol beta superfamily of nucleotidyl transferases, Trf4p, and a zinc knuckle protein, Air2p, mediates initial substrate recognition. Trf4p and related eukaryotic poly(A) and poly(U) polymerases differ from other characterized enzymes in the Pol beta superfamily both in sequence and in the lack of recognizable nucleic acid binding motifs. Here we report, at 2.7-angstrom resolution, the structure of Trf4p in complex with a fragment of Air2p comprising two zinc knuckle motifs. Trf4p consists of a catalytic and central domain similar in fold to those of other noncanonical Pol beta RNA polymerases, and the two zinc knuckle motifs of Air2p interact with the Trf4p central domain. The interaction surface on Trf4p is highly conserved across eukaryotes, providing evidence that the Trf4p/Air2p complex is conserved in higher eukaryotes as well as in yeast and that the TRAMP complex may also function in RNA surveillance in higher eukaryotes. We show that Air2p, and in particular sequences encompassing a zinc knuckle motif near its N terminus, modulate Trf4p activity, and we present data supporting a role for this zinc knuckle in RNA binding. Finally, we show that the RNA 3' end plays a role in substrate recognition.