Redox-Dependent Conformational Dynamics of Decameric 2-Cysteine Peroxiredoxin and its Interaction with Cyclophilin 20-3
Redox-Dependent Conformational Dynamics of Decameric 2-Cysteine Peroxiredoxin and its Interaction with Cyclophilin 20-3
复制标题
DOI：
10.1093/pcp/pcw031
复制
发表时间：
2016-07-01
影响因子：
4.9
通讯作者：
Dietz, Karl-Josef
中科院分区：
文献类型：
--
作者：
Liebthal, Michael;Strueve, Marcel;Dietz, Karl-Josef
2-半胱氨酸过氧化物还毒素（2-CysPrxs）以氧化还原依赖的方式在巯基过氧化物酶、伴侣、相互作用伙伴和可能基于邻近的氧化酶之间转换功能。在光合作用的真核生物中，2-CysPrx定位于质体，在光合作用的背景下发挥作用，并使抗坏血酸过氧化物酶独立的水-水循环解毒H2O2。2-CysPrx的高度进化保守性表明，这种开关是将氧化还原信息传递到下游途径和调控所需的基本特征。该研究旨在探索2-CysPrx的解离行为及其与亲环蛋白的相互作用随体相条件的变化。等温滴定微热法（ITC）、动态光散射和粒径排除色谱法（SEC）证明了先前提出的模型，即低于临界过渡浓度（CTC）的2-CysPrx以二聚体状态存在，高于临界过渡浓度的2-CysPrx以十聚体状态存在。亲环蛋白20-3 （Cyp20-3）的存在影响了2-CysPrx十聚体的CTC，表明相互作用通过2-CysPrx与Cyp20-3的直接滴定和覆盖进一步量化。最后，催化失活实验表明，与pH 7.2相比，pH 8下2-CysPrx的催化效率更高，但也显示pH 8下高氧化的失活增加。有趣的是，在pH为8和pH为7.2的条件下，计算失活前的平均周转量得到的结果非常相似，分别为243和268个催化循环。这些定量数据支持一个模型，即2-CysPrx和Cyp20-3通过相互作用，在叶绿体中形成氧化还原敏感调节模块，该模块受光合作用相关的基质pH值、氧化还原状态和其他基质蛋白因子的控制。
2-Cysteine peroxiredoxins (2-CysPrxs) switch between functions as a thiol peroxidase, chaperone, an interaction partner and possibly a proximity-based oxidase in a redox-dependent manner. In photosynthetic eukaryotes, 2-CysPrx localizes to the plastid, functions in the context of photosynthesis and enables an ascorbate peroxidase-independent water-water cycle for detoxifying H2O2. The high degree of evolutionary conservation of 2-CysPrx suggests that the switching is an essential characteristic and needed to transduce redox information to downstream pathways and regulation. The study aimed at exploring the dissociation behavior of 2-CysPrx and its interactions with cyclophilin depending on bulk phase conditions. Isothermal titration microcalorimetry (ITC), dynamic light scattering and size exclusion chromatography (SEC) proved the previously suggested model that reduced 2-CysPrx below a critical transition concentration (CTC) exists in its dimeric state, and above the CTC adopts the decameric state. The presence of cyclophilin 20-3 (Cyp20-3) affected the CTC of a 2-CysPrx decamer suggesting interaction which was further quantified by direct titration of 2-CysPrx with Cyp20-3, and in overlays. Finally catalytic inactivation assays showed the higher catalytic efficiency of 2-CysPrx at pH 8 compared with pH 7.2, but also revealed increased inactivation by hyperoxidation at pH 8. Interestingly, calculation of the average turnover number until inactivation gave rather similar values of 243 and 268 catalytic cycles at pH 8 and pH 7.2, respectively. These quantitative data support a model where 2-CysPrx and Cyp20-3, by interaction, form a redox-sensitive regulatory module in the chloroplast which is under control of the photosynthesis-linked stromal pH value, the redox state and additional stromal protein factor(s).