酵母丝氨酰-tRNA合成酶：ATP结合位点与tRNASer及L-丝氨酸结合位点之间的相互作用
Yeast seryl tRNA synthetase: interactions between the ATP binding site and the sites for tRNASer and L-serine.
作者信息
Pachmann U, Zachau H G
出版信息
Nucleic Acids Res. 1978 Mar;5(3):975-85. doi: 10.1093/nar/5.3.975.
T1 ribonuclease digestion of yeast tRNASer in the presence of seryl tRNA synthetase was used for monitoring the relationship between the substrate binding sites on the synthetase. It was found that (a) ATP displaces the tRNA from the synthetase with an effector affinity constant corresponding to the Km for ATP of 10 micron; (b) AMP and a number of nucleoside triphosphates, while influencing the rate of aminoacylation, do not displace the tRNA from the enzyme; (c) ADP and PPi inhibit the aminoacylation and the binding of tRNASer; (d) adenylyl diphosphonate is bound to the synthetase and lowers the protection of the tRNA against the nuclease attack in a similar way as does ATP; (e) interactions between the sites of L-serine and tRNASer could only be shown when both sites for serine were saturated and, in addition, the ATP analog or ADP was present. It is concluded that in seryl tRNA synthetase binding sites for ATP interact with the ones for tRNA as well as with the ones for serine. These findings contribute to the understanding of the mechanism of aminoacylation.
在丝氨酰 - tRNA合成酶存在的情况下，用T1核糖核酸酶消化酵母tRNASer，以此监测合成酶上底物结合位点之间的关系。结果发现：（a）ATP以对应于10微摩尔ATP的Km的效应亲和力常数将tRNA从合成酶上置换下来；（b）AMP和一些核苷三磷酸虽然影响氨酰化速率，但不会将tRNA从酶上置换下来；（c）ADP和PPi抑制氨酰化以及tRNASer的结合；（d）腺苷二磷酸酯与合成酶结合，并以与ATP类似的方式降低tRNA对核酸酶攻击的保护作用；（e）只有当丝氨酸的两个位点都饱和，并且此外还存在ATP类似物或ADP时，才能显示出L - 丝氨酸位点与tRNASer位点之间的相互作用。得出的结论是，在丝氨酰 - tRNA合成酶中，ATP的结合位点与tRNA的结合位点以及丝氨酸的结合位点相互作用。这些发现有助于理解氨酰化机制。
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