Cavarelli J, Rees B, Ruff M, Thierry J C, Moras D
Laboratoire de Biologie Structurale, IBMC Strasbourg, France.
Nature. 1993 Mar 11;362(6416):181-4. doi: 10.1038/362181a0.
Aminoacyl-RNA synthetases can be divided into two classes according to structural features inferred from sequence alignments. This classification correlates almost perfectly with the attachment of the amino acid to the 2'-OH (class I) or 3'-OH (class II) group of the terminal adenosine. Six subgroups of higher homology can be inferred from sequence analysis. The five aminoacyl-tRNA synthetases whose crystal structures are known (MetRS, TyrRS and GlnRS in class I, SerRS and AspRS in class II) belong to different subgroups. Two of them, GlnRS and AspRS, have been cocrystallized with their cognate tRNA. AspRS, like six other members of class II, is an alpha 2 dimer. Yeast tRNA(Asp) exhibits five identity determinants: the three anticodon bases, the discriminator base G73 and the base pair G10-U25. We report here that the refined crystal structure of AspRS complexed with tRNA(Asp) at 2.9 A resolution reveals three regions of contact, each involving a domain of AspRS and at least one identity determinant of tRNA(Asp). The mode of binding of the acceptor stem of tRNA(Asp) by AspRS can be generalized to class II aminoacyl-tRNA synthetases, whereas the deciphering of the anticodon, which involves a large conformational change of the loop and the formation of a bulge, is more specific to the aspartic system.
根据序列比对推断出的结构特征，氨酰 - tRNA合成酶可分为两类。这种分类与氨基酸连接到末端腺苷的2'-OH（I类）或3'-OH（II类）基团几乎完全相关。从序列分析中可以推断出六个同源性较高的亚组。已知晶体结构的五种氨酰 - tRNA合成酶（I类中的MetRS、TyrRS和GlnRS，II类中的SerRS和AspRS）属于不同的亚组。其中两种，GlnRS和AspRS，已与其同源tRNA共结晶。AspRS与II类的其他六个成员一样，是一个α2二聚体。酵母tRNA（Asp）表现出五个识别决定因素：三个反密码子碱基、判别碱基G73和碱基对G10 - U25。我们在此报告，以2.9 Å分辨率解析的AspRS与tRNA（Asp）复合的晶体结构揭示了三个接触区域，每个区域都涉及AspRS的一个结构域和tRNA（Asp）的至少一个识别决定因素。AspRS与tRNA（Asp）受体茎的结合模式可以推广到II类氨酰 - tRNA合成酶，而反密码子的解读涉及环的大构象变化和凸起的形成，这对天冬氨酸系统更具特异性。
