Oshikane Hiroyuki, Sheppard Kelly, Fukai Shuya, Nakamura Yuko, Ishitani Ryuichiro, Numata Tomoyuki, Sherrer R Lynn, Feng Liang, Schmitt Emmanuelle, Panvert Michel, Blanquet Sylvain, Mechulam Yves, Söll Dieter, Nureki Osamu
Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama-shi, Kanagawa 226-8501, Japan.
Science. 2006 Jun 30;312(5782):1950-4. doi: 10.1126/science.1128470.
Glutaminyl-transfer RNA (Gln-tRNA(Gln)) in archaea is synthesized in a pretranslational amidation of misacylated Glu-tRNA(Gln) by the heterodimeric Glu-tRNA(Gln) amidotransferase GatDE. Here we report the crystal structure of the Methanothermobacter thermautotrophicus GatDE complexed to tRNA(Gln) at 3.15 angstroms resolution. Biochemical analysis of GatDE and of tRNA(Gln) mutants characterized the catalytic centers for the enzyme's three reactions (glutaminase, kinase, and amidotransferase activity). A 40 angstrom-long channel for ammonia transport connects the active sites in GatD and GatE. tRNA(Gln) recognition by indirect readout based on shape complementarity of the D loop suggests an early anticodon-independent RNA-based mechanism for adding glutamine to the genetic code.
古菌中的谷氨酰胺转运RNA（Gln - tRNA(Gln)）是由异源二聚体谷氨酰胺 - tRNA(Gln)氨基转移酶GatDE在错酰化的谷氨酸 - tRNA(Gln)的翻译前酰胺化过程中合成的。在此，我们报道了嗜热栖热甲烷杆菌GatDE与tRNA(Gln)复合物在3.15埃分辨率下的晶体结构。对GatDE和tRNA(Gln)突变体的生化分析确定了该酶三个反应（谷氨酰胺酶、激酶和氨基转移酶活性）的催化中心。一条用于氨转运的40埃长通道连接了GatD和GatE中的活性位点。基于D环形状互补性的间接读出对tRNA(Gln)的识别表明，在遗传密码中添加谷氨酰胺存在一种早期的不依赖反密码子的基于RNA的机制。
