Crystal structure of Arabidopsis thaliana glutamyl-tRNA(Glu) reductase in complex with NADPH and glutamyl-tRNA(Glu) reductase binding protein.
Crystal structure of Arabidopsis thaliana glutamyl-tRNA(Glu) reductase in complex with NADPH and glutamyl-tRNA(Glu) reductase binding protein.
复制标题
拟南芥谷氨酰-tRNA(Glu)还原酶与NADPH和谷氨酰-tRNA(Glu)还原酶结合蛋白复合物的晶体结构。
DOI：
10.1007/s11120-018-0518-8
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发表时间：
2018
影响因子：
3.7
通讯作者：
Han Feng
中科院分区：
文献类型：
--
作者：
Zhao Aiguo;Han Feng
在高等植物中，四吡咯生物合成途径始于限速酶谷氨酰-tRNAGlu还原酶（GTR）催化的反应。在拟南芥中，GTR受转录后调节因子如GTR结合蛋白（GBP）的控制，GBP刺激AtGTR活性。AtGTR的NADPH结合结构域在GBP结合后发生了实质性的移动。本文报道了AtGTR-NADPH-GBP三元复合物的晶体结构。与AtGTR-GBP二元复合物相比，NADPH结合引起轻微的结构变化，并可能占据底物谷氨酰-tRNAGlu所需的部分空间。活性位点残基Cys 144的高活性巯基显示出明显的旋转，这可能有助于从NADPH到硫酯中间体的氢化物转移，形成谷氨酸-1-半醛。GBP的赖氨酸271、赖氨酸274、丝氨酸275、天冬酰胺278和谷氨酰胺282参与了AtGTR与GBP的相互作用，当这些残基全部突变为丙氨酸时，GBP的刺激作用减弱。当AtGTR的Cys 144突变为Ser时，即使在GBP存在下也不能检测到AtGTR活性。
In higher plants, the tetrapyrrole biosynthesis pathway starts from the reaction catalyzed by the rate-limiting enzyme, glutamyl-tRNAGlureductase (GTR). InArabidopsis thaliana, GTR is controlled by post-transcriptional regulators such as GTR binding protein (GBP), which stimulatesAtGTR activity. The NADPH-binding domain ofAtGTR undergoes a substantial movement upon GBP binding. Here, we report the crystal structure ofAtGTR-NADPH-GBP ternary complex. NADPH binding causes slight structural changes compared with theAtGTR-GBP binary complex, and possibly take a part of the space needed by the substrate glutamyl-tRNAGlu. The highly reactive sulfhydryl group of the active-site residue Cys144 shows an obvious rotation, which may facilitate the hydride transfer from NADPH to the thioester intermediate to form glutamate-1-semialdehyde. Furthermore, Lys271, Lys274, Ser275, Asn278, and Gln282 of GBP participate in the interaction betweenAtGTR and GBP, and the stimulating effect of GBP decreased when all of these residues were mutated to Ala. When the Cys144 ofAtGTR was mutated to Ser,AtGTR activity could not be detected even in the presence of GBP.