Crystal structures of leucyl/phenylalanyl-tRNA-protein transferase and its complex with an aminoacyl-tRNA analog
Crystal structures of leucyl/phenylalanyl-tRNA-protein transferase and its complex with an aminoacyl-tRNA analog
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DOI：
10.1038/sj.emboj.7601433
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发表时间：
2006-12-13
期刊：
影响因子：
11.4
通讯作者：
Tomita, Kozo
中科院分区：
文献类型：
--
作者：
Suto, Kyoko;Shimizu, Yoshihiro;Tomita, Kozo
真细菌亮氨酰/苯丙氨酰-tRNA 蛋白转移酶（L/F-转移酶）由 aat 基因编码，使用 Leu-tRNA Leu 或 Phe-tRNA Phe 作为底物，将亮氨酸或苯丙氨酸缀合到蛋白质的 N 末端 Arg 或 Lys 残基上。由此产生的 N 端 Leu 或 Phe 充当 ClpS-ClpAP 介导的 N 端规则蛋白降解途径的降解信号。在这里，我们展示了大肠杆菌 L/F-转移酶及其与氨酰基-tRNA 类似物嘌呤霉素的复合物的晶体结构。 L/F 转移酶的 C 末端结构域由 GCN5 相关的 N-乙酰转移酶折叠组成，常见于乙酰转移酶超家族中。嘌呤霉素的对甲氧基苄基，对应于Leu-tRNA（Leu）或Phe-tRNA（Phe）的Leu或Phe侧链，容纳在高度疏水性口袋中，其形状和大小适合缺乏支链b碳的疏水性氨基酸残基，例如亮氨酸和苯丙氨酸。 L/F-转移酶基于结构的诱变揭示了其底物特异性。此外，我们提出了 L/F 转移酶复合物的模型，其中包含 tRNA 和带有 N 末端 Arg 或 Lys 的底物蛋白。
Eubacterial leucyl/phenylalanyl-tRNA protein transferase (L/F- transferase), encoded by the aat gene, conjugates leucine or phenylalanine to the N-terminal Arg or Lys residue of proteins, using Leu-tRNA Leu or Phe-tRNA Phe as a substrate. The resulting N-terminal Leu or Phe acts as a degradation signal for the ClpS-ClpAP-mediated N-end rule protein degradation pathway. Here, we present the crystal structures of Escherichia coli L/F-transferase and its complex with an aminoacyl-tRNA analog, puromycin. The C-terminal domain of L/F-transferase consists of the GCN5-related N-acetyltransferase fold, commonly observed in the acetyltransferase superfamily. The p-methoxybenzyl group of puromycin, corresponding to the side chain of Leu or Phe of Leu-tRNA(Leu) or Phe-tRNA(Phe), as accommodated in a highly hydrophobic pocket, with a shape and size suitable for hydrophobic amino-acid residues lacking a branched b-carbon, such as leucine and phenylalanine. Structure-based mutagenesis of L/F-transferase revealed its substrate specificity. Furthermore, we present a model of the L/F-transferase complex with tRNA and substrate proteins bearing an N-terminal Arg or Lys.