da Fonseca-Pereira Paula, Souza Paulo V L, Fernie Alisdair R, Timm Stefan, Daloso Danilo M, Araújo Wagner L
Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil.
Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, Fortaleza, Ceará, Brazil.
J Exp Bot. 2021 Sep 2;72(17):5987-6002. doi: 10.1093/jxb/erab098.
Thioredoxins (TRXs) are ubiquitous proteins engaged in the redox regulation of plant metabolism. Whilst the light-dependent TRX-mediated activation of Calvin-Benson cycle enzymes is well documented, the role of extraplastidial TRXs in the control of the mitochondrial (photo)respiratory metabolism has been revealed relatively recently. Mitochondrially located TRX o1 has been identified as a regulator of alternative oxidase, enzymes of, or associated with, the tricarboxylic acid (TCA) cycle, and the mitochondrial dihydrolipoamide dehydrogenase (mtLPD) involved in photorespiration, the TCA cycle, and the degradation of branched chain amino acids. TRXs are seemingly a major point of metabolic regulation responsible for activating photosynthesis and adjusting mitochondrial photorespiratory metabolism according to the prevailing cellular redox status. Furthermore, TRX-mediated (de)activation of TCA cycle enzymes contributes to explain the non-cyclic flux mode of operation of this cycle in illuminated leaves. Here we provide an overview on the decisive role of TRXs in the coordination of mitochondrial metabolism in the light and provide in silico evidence for other redox-regulated photorespiratory enzymes. We further discuss the consequences of mtLPD regulation beyond photorespiration and provide outstanding questions that should be addressed in future studies to improve our understanding of the role of TRXs in the regulation of central metabolism.
硫氧还蛋白（TRXs）是广泛存在的蛋白质，参与植物代谢的氧化还原调节。虽然光依赖的TRX介导的卡尔文-本森循环酶的激活已有充分记录，但质体外TRXs在控制线粒体（光）呼吸代谢中的作用直到最近才被揭示。位于线粒体的TRX o1已被确定为交替氧化酶、三羧酸（TCA）循环的酶或与之相关的酶以及参与光呼吸、TCA循环和支链氨基酸降解的线粒体二氢硫辛酰胺脱氢酶（mtLPD）的调节剂。TRXs似乎是代谢调节的一个主要关键点，负责激活光合作用并根据细胞内普遍存在的氧化还原状态调节线粒体光呼吸代谢。此外，TRX介导的TCA循环酶的（去）激活有助于解释该循环在光照叶片中的非循环通量运作模式。在此，我们概述了TRXs在光照下协调线粒体代谢中的决定性作用，并提供了其他氧化还原调节的光呼吸酶的计算机模拟证据。我们还进一步讨论了mtLPD调节在光呼吸之外的影响，并提出了未来研究中应解决的突出问题，以增进我们对TRXs在中心代谢调节中作用的理解。
