Ishii Ryohei, Minagawa Asako, Takaku Hiroaki, Takagi Masamichi, Nashimoto Masayuki, Yokoyama Shigeyuki
Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
J Biol Chem. 2005 Apr 8;280(14):14138-44. doi: 10.1074/jbc.M500355200. Epub 2005 Jan 27.
The maturation of the tRNA 3' end is catalyzed by a tRNA 3' processing endoribonuclease named tRNase Z (RNase Z or 3'-tRNase) in eukaryotes, Archaea, and some bacteria. The tRNase Z generally cuts the 3' extra sequence from the precursor tRNA after the discriminator nucleotide. In contrast, Thermotoga maritima tRNase Z cleaves the precursor tRNA precisely after the CCA sequence. In this study, we determined the crystal structure of T. maritima tRNase Z at 2.6-A resolution. The tRNase Z has a four-layer alphabeta/betaalpha sandwich fold, which is classified as a metallo-beta-lactamase fold, and forms a dimer. The active site is located at one edge of the beta-sandwich and is composed of conserved motifs. Based on the structure, we constructed a docking model with the tRNAs that suggests how tRNase Z may recognize the substrate tRNAs.
在真核生物、古细菌和一些细菌中，tRNA 3' 末端的成熟是由一种名为tRNase Z（RNase Z或3'-tRNase）的tRNA 3' 加工内切核糖核酸酶催化的。tRNase Z通常在鉴别核苷酸之后从前体tRNA上切割掉3' 额外序列。相比之下，嗜热栖热菌的tRNase Z在CCA序列之后精确切割前体tRNA。在本研究中，我们测定了嗜热栖热菌tRNase Z分辨率为2.6埃的晶体结构。tRNase Z具有四层αβ/βα三明治折叠结构，属于金属β-内酰胺酶折叠类型，并形成二聚体。活性位点位于β-三明治的一侧边缘，由保守基序组成。基于该结构，我们构建了与tRNA的对接模型，该模型揭示了tRNase Z可能如何识别底物tRNA。
