Calcium sensing via EF-hand 4 enables thioredoxin activity in the sensor-responder protein calredoxin in the green alga Chlamydomonas reinhardtii
Calcium sensing via EF-hand 4 enables thioredoxin activity in the sensor-responder protein calredoxin in the green alga Chlamydomonas reinhardtii
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DOI：
10.1074/jbc.ra119.008735
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发表时间：
2020-01-03
影响因子：
4.8
通讯作者：
Kurisu, Genji
中科院分区：
文献类型：
--
作者：
Charoenwattanasatien, Ratana;Zinzius, Karen;Kurisu, Genji
钙（Ca 2+）和氧化还原信号使细胞能够快速适应不断变化的环境。来自绿色莱茵衣藻的信号蛋白钙氧还蛋白（CRX）是一种存在于叶绿体中的硫氧还蛋白，具有Ca 2+依赖性活性，并含有一个独特的EF-手结构域和一个典型的硫氧还蛋白折叠。使用小角X射线散射（SAXS），FRET和NMR技术，我们发现，Ca 2+结合不仅诱导EF-手域的构象变化，而且在硫氧还蛋白结构域，转化为硫氧还蛋白氧化还原活性的发病。CRX与基因改变的EF手的功能分析表明，EF手4是重要的介导的两个域之间的通信。此外，我们结晶的变体（C174 S）的CRX靶蛋白过氧化物氧还蛋白1（PRX 1）在2.4？分辨率，模拟了两种蛋白质的相互作用复合物，并通过交联和MS分析对其进行了分析，揭示了相互作用界面位于两种蛋白质的活性位点附近。我们的研究结果揭示了Ca 2+结合诱导的CRX结构在溶液中的整体蛋白质和单个结构域和残基的水平上的变化。
Calcium (Ca2+) and redox signaling enable cells to quickly adapt to changing environments. The signaling protein calredoxin (CRX) from the green alga Chlamydomonas reinhardtii is a chloroplast-resident thioredoxin having Ca2+-dependent activity and harboring a unique combination of an EF-hand domain connected to a typical thioredoxin-fold. Using small-angle X-ray scattering (SAXS), FRET, and NMR techniques, we found that Ca2+-binding not only induces a conformational change in the EF-hand domain, but also in the thioredoxin domain, translating into the onset of thioredoxin redox activity. Functional analyses of CRX with genetically altered EF-hands revealed that EF-hand 4 is important for mediating the communication between the two domains. Moreover, we crystallized a variant (C174S) of the CRX target protein peroxiredoxin 1 (PRX1) at 2.4 ? resolution, modeled the interaction complex of the two proteins, and analyzed it by cross-linking and MS analyses, revealing that the interaction interface is located close to the active sites of both proteins. Our findings shed light on the Ca2+ binding-induced changes in CRX structure in solution at the level of the overall protein and individual domains and residues.