Structural basis for thioredoxin isoform-based fine-tuning of ferredoxin-thioredoxin reductase activity
Structural basis for thioredoxin isoform-based fine-tuning of ferredoxin-thioredoxin reductase activity
复制标题
基于硫氧还蛋白亚型的铁氧还蛋白-硫氧还蛋白还原酶活性微调的结构基础
DOI：
10.1002/pro.3964
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Kurisu G.
中科院分区：
文献类型：
--
作者：
Juniar L.;Tanaka H.;Yoshida K.;Hisabori T.;Kurisu G.
光合作用的电子传递发生在叶绿体的类囊体膜上。铁氧还蛋白（Fd）是电子传递链中的最终受体，将电子分配给几种Fd依赖性酶，包括Fd-硫氧还蛋白还原酶（FTR）。从Fd到FTR的级联反应进一步减少硫氧还蛋白（Trx），最终以光依赖性方式调节靶代谢酶的活性。我们先前报道了拟南芥中的10种Trx异构体可以根据FTR依赖性还原的动力学分为三类（高、中和低效率类）。在这项研究中，我们确定了FTR和Trx同种型的三种电子转移复合物的X射线结构，Trx-y1，Trx-f2和Trx-m2，作为每一类的代表性例子。具有/不具有Trx的FTR结构的叠加显示在复合物形成时没有主链结构变化。单一和复合Trx-m结构无显著构象变化。然而，FTR：Trx复合物的界面显示出显著的变化。三种结构的比较分析显示了两种类型的分子间相互作用;（i）所有三种复合物共有的共同相互作用和（ii）亚型特异性相互作用，这可能对微调FTR：Trx活性很重要。Trx亚型的微分静电势可能是亚型特异性相互作用的关键。
Photosynthetic electron transport occurs on the thylakoid membrane of chloroplasts. Ferredoxin (Fd), the final acceptor in the electron transport chain, distributes electrons to several Fd‐dependent enzymes including Fd‐thioredoxin reductase (FTR). A cascade from Fd to FTR further reduces Thioredoxin (Trx), which tunes the activity of target metabolic enzymes eventually in a light‐dependent manner. We previously reported that 10 Trx isoforms inArabidopsis thalianacan be clustered into three classes based on the kinetics of the FTR‐dependent reduction (high‐, middle‐, and low‐efficiency classes). In this study, we determined the X‐ray structure of three electron transfer complexes of FTR and Trx isoform, Trx‐y1, Trx‐f2, and Trx‐m2, as representative examples of each class. Superposition of the FTR structure with/without Trx showed no main chain structural changes upon complex formation. There was no significant conformational change for single and complexed Trx‐mstructures. Nonetheless, the interface of FTR:Trx complexes displayed significant variation. Comparative analysis of the three structures showed two types of intermolecular interactions; (i) common interactions shared by all three complexes and (ii) isoform‐specific interactions, which might be important for fine‐tuning FTR:Trx activity. Differential electrostatic potentials of Trx isoforms may be key to isoform‐specific interactions.