背景回顾：Thioredoxin (Trx) is a protein that mediates the reducing power transfer from the photosynthetic electron transport system to target enzymes in chloroplasts and regulates their activities. Redox regulation governed by Trx is a system that is central to the adaptation of various chloroplast functions to the ever-changing light environment. 

提出问题：However, the factors involved in the opposite reaction (i.e., the oxidation of various enzymes) have yet to be revealed. 

研究基础：Recently, it has been suggested that Trx and Trx-like proteins could oxidize Trx-targeted proteins in vitro. 

研究目的与方法：To elucidate the in vivo function of these proteins as oxidation factors, we generated mutant plant lines deficient in Trx or Trx-like proteins and studied how the proteins are involved in oxidative regulation in chloroplasts. 

结果1：We found that f-type Trx and two types of Trx-like proteins, Trx-like 2 and atypical Cys His-rich Trx (ACHT), seemed to serve as oxidation factors for Trx-targeted proteins, such as fructose-1,6-bisphosphatase, Rubisco activase, and the γ-subunit of ATP synthase. 

结果2：In addition, ACHT was found to be involved in regulating nonphotochemical quenching, which is the mechanism underlying the thermal dissipation of excess light energy. 

结论：Overall, these results indicate that Trx and Trx-like proteins regulate chloroplast functions in concert by controlling the redox state of various photosynthesis-related proteins in vivo.

 摘 要 

硫氧还蛋白Trx是一类在叶绿体中介导从光合电子传递系统将还原力传递到目标酶的蛋白，调控着这些酶的活性。由Trx赋予的氧化还原调控是多个叶绿体功能适应不断改变的光环境的核心机制。但是，在叶绿体中参与酶的氧化反应的因素还不清楚。最近有研究显示，Trx和Trx-like蛋白能够在体外氧化Trx靶向的蛋白。为了进一步在体内验证这些蛋白是否同样行使氧化因子的功能，作者创制了Trx和Trx-like蛋白的突变体株系，研究这些蛋白如何在叶绿体中参与氧化调控。作者发现，f类Trx以及两个Trx-like蛋白Trx-like 2和ACHT似乎是Trx靶向蛋白的氧化因子，这些靶向蛋白包括果糖-1,6-双磷酸酶、Rubisco活化酶和ATP合酶的γ亚基。另外，ACHT被认为参与了非光化学猝灭的调控，这是过剩光能的热耗散机制。综上，本文的研究揭示了Trx和Trx-like蛋白通过控制体内多种光合相关蛋白的氧化还原状态，从而共同调节叶绿体的功能。