Marchetti Giulia Maria, Füsser Friederike, Singh Rohit Kumar, Brummel Monika, Koch Oliver, Kümmel Daniel, Hippler Michael
Institute of Plant Biology and Biotechnology, University of Münster, 48143 Münster, Germany.
Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, 48149 Münster, Germany; German Center for Infection Research, University of Münster, 48149 Münster, Germany; Institute of Biochemistry, University of Münster, 48149 Münster, Germany.
J Struct Biol. 2022 Mar;214(1):107829. doi: 10.1016/j.jsb.2021.107829. Epub 2021 Dec 30.
In plant chloroplasts, thiol regulation is driven by two systems. One relies on the activity of thioredoxins through their light dependent reduction by ferredoxin via a ferredoxin-thioredoxin reductase (FTR). In the other system, a NADPH-dependent redox regulation is driven by a NADPH-thioredoxin reductase C (NTRC). While the thioredoxin system has been deeply studied, a more thorough understanding of the function of this plant specific NTRC is desirable. NTRC is a single polypeptide harbouring a thioredoxin domain (Trx) at the C-terminus of a NADPH-dependent Thioredoxin reductase (TrxR). To provide functional and structural insights, we studied the crystal structure of the TrxR domain of the NTRC from Chlamydomonas reinhardtii (CrNTRC, Cre01.g054150.t1.2) and its Cys136Ser (C136S) mutant, which is characterized by the mutation of the resolving cysteine in the active site of the TrxR domain. Furthermore, we confirmed the role of NTRC as electron donor for 2-Cys peroxiredoxin (PRX) also in C. reinhardtii. The structural data of TrxR were employed to develop a scheme of action which addresses electron transfer between TrxR and Trx of NTRC and between NTRC and its substrates.
在植物叶绿体中，硫醇调节由两个系统驱动。一个系统依赖于硫氧还蛋白的活性，通过铁氧还蛋白-硫氧还蛋白还原酶（FTR），使其在光依赖下被铁氧还蛋白还原。另一个系统中，NADPH依赖的氧化还原调节由NADPH-硫氧还蛋白还原酶C（NTRC）驱动。虽然硫氧还蛋白系统已得到深入研究，但仍需要更全面地了解这种植物特有的NTRC的功能。NTRC是一种单一多肽，在NADPH依赖的硫氧还蛋白还原酶（TrxR）的C末端含有一个硫氧还蛋白结构域（Trx）。为了提供功能和结构方面的见解，我们研究了莱茵衣藻（CrNTRC，Cre01.g054150.t1.2）的NTRC的TrxR结构域及其Cys136Ser（C136S）突变体的晶体结构，该突变体的特征是TrxR结构域活性位点中的裂解半胱氨酸发生突变。此外我们还证实了在莱茵衣藻中，NTRC作为2-半胱氨酸过氧化物酶（PRX）的电子供体的作用。利用TrxR的结构数据制定了一个作用方案，该方案涉及NTRC的TrxR与Trx之间以及NTRC与其底物之间的电子转移。
