Poterszman A, Delarue M, Thierry J C, Moras D
Laboratoire de Biologie Structurale, I.B.M.C. du C.N.R.S., Strasbourg, France.
J Mol Biol. 1994 Nov 25;244(2):158-67. doi: 10.1006/jmbi.1994.1716.
The crystal structures of Thermus thermophilus aspartyl-tRNA synthetase and of its complex with ATP, Mg2+ and aspartic acid, show in situ formation of the amino acid adenylate and furnish experimental evidence for the modes of recognition of aspartic acid and ATP. The amino acid fits in a predefined specific site in which it replaces water molecules without significant conformational changes of the binding residues. This mode of selection is reminiscent of the lock and key concept. The pocket is closed by the movement of a histidine side chain from a neighbouring loop acting as a valve. ATP binding is driven by the stacking of the adenine upon the otherwise fixed aromatic ring of the class-II-invariant phenylalanine Phe235. Specific recognition is achieved by interactions with the flexible side chains of other class-II-conserved residues. Conformational changes have been identified which allow the description of a reaction pathway including both lock-and-key and induced-fit interactions. This pathway can presumably be extended to all class II aaRS.
嗜热栖热菌天冬氨酸 - tRNA合成酶及其与ATP、Mg2+和天冬氨酸复合物的晶体结构，显示了氨基酸腺苷酸的原位形成，并为天冬氨酸和ATP的识别模式提供了实验证据。氨基酸适配于一个预定义的特定位点，在该位点它取代水分子，而结合残基没有明显的构象变化。这种选择模式让人联想到锁钥概念。口袋通过来自相邻环的组氨酸侧链作为阀门的移动而关闭。ATP的结合是由腺嘌呤堆积在II类不变苯丙氨酸Phe235原本固定的芳香环上驱动的。通过与其他II类保守残基的柔性侧链相互作用实现特异性识别。已经确定了构象变化，这使得能够描述包括锁钥和诱导契合相互作用的反应途径。这条途径大概可以扩展到所有II类氨酰 - tRNA合成酶。
