Crystal structure of a ribonuclease for rRNA processing, FAU-1, from Pyrococcus furiosus was determined with the resolution of 2.57 Å in a homo-trimeric form. The monomer structure consists of two domains, N-terminal and C-terminal domains. C-terminal domain forms trimer and each N-terminal domain locates outside of the trimer core. In the obtained crystal, a dinucleotide, pApUp, was bound to the N-terminal domain, indicating that N-terminal domain has the RNA-binding ability. The affinities to RNA of FAU-1 and a fragment corresponding to the N-terminal domain, FAU-ΔC, were confirmed by PAGE and NMR. Interestingly, well dispersed NMR signals were observed at 318 K, indicating that the FAU-ΔC-F18 complex form an ordered structure at higher temperature. As predicted in our previous works, FAU-1 and RNase E show a structural similarity in their RNA binding regions. However, structural similarity between RNase E and FAU-1 could be found in the limited regions of the N-terminal domain. On the other hand, structural similarity between C-terminal domain and some proteins including a phosphatase was found. Thus, it is possible that the catalytic site is located in C-terminal domain.

中文翻译：

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用于 rRNA 加工的核糖核酸酶 FAU-1（来自激烈火球菌）的同源三聚体结构

来自激烈热球菌的用于 rRNA 加工的核糖核酸酶 FAU-1 的晶体结构以同源三聚体形式确定，分辨率为 2.57 Å。单体结构由两个结构域组成，即N端结构域和C端结构域。 C 端结构域形成三聚体，每个 N 端结构域位于三聚体核心外部。在获得的晶体中，二核苷酸pApUp与N末端结构域结合，表明N末端结构域具有RNA结合能力。通过 PAGE 和 NMR 证实了 FAU-1 和对应于 N 末端结构域的片段 FAU-ΔC 对 RNA 的亲和力。有趣的是，在 318 K 下观察到分散良好的 NMR 信号，表明 FAU-ΔC-F18 复合物在较高温度下形成有序结构。正如我们之前的工作所预测的，FAU-1 和 RNase E 在它们的 RNA 结合区域显示出结构相似性。然而，RNase E 和 FAU-1 之间的结构相似性可以在 N 端结构域的有限区域中发现。另一方面，发现 C 端结构域与包括磷酸酶在内的一些蛋白质之间的结构相似性。因此，催化位点可能位于C端结构域。