A cyclophilin links redox and light signals to cysteine biosynthesis and stress responses in chloroplasts
A cyclophilin links redox and light signals to cysteine biosynthesis and stress responses in chloroplasts
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DOI：
10.1073/pnas.0808204105
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发表时间：
2008-10-21
影响因子：
11.1
通讯作者：
Luan, Sheng
中科院分区：
文献类型：
--
作者：
Dominguez-Solis, Jose R.;He, Zengyong;Luan, Sheng
亲环素属于一个大家族的酶称为“肽基脯氨酰异构酶”，有助于蛋白质折叠和组装。亲环素CYP 20 -3（也称为“R 0 C4”）是位于叶绿体基质（可溶相）中的该组的唯一成员。在本研究中，我们分离出突变体拟南芥植物CYP 20 -3基因缺陷，发现它们是高敏感的氧化应激条件下创建的高光水平，玫瑰红，高盐水平，和渗透压休克。叶绿体丝氨酸乙酰转移酶（SAT 1）是半胱氨酸生物合成的限速酶，通过蛋白质相互作用分析，被鉴定为CYP 20 -3的相互作用伴侣。在本实验中，SAT 1活性增加显着的光和氧化应激条件下，在音乐会与野生型植物中的总硫醇。相比之下，这些参数在cyp 20 -3突变体的实验中仅略有变化，表明CYP 20 -3将光照和胁迫与SAT 1活性和半胱氨酸生物合成联系起来。为了进一步支持这一结论，我们的分析表明，盐过敏表型的突变体开发照明下，而不是在黑暗中。结合早期报道的CYP 20 -3折叠酶活性通过硫氧还蛋白介导的还原增强，我们的研究结果表明CYP 20 -3将光合电子传递和氧化还原调节与SAT 1的折叠联系起来，从而使基于半胱氨酸的巯基生物合成途径能够适应光照和胁迫条件。
Cyclophilins belong to a large family of enzymes called "peptidyl prolyl isomerases" that assist protein folding and assembly. The cyclophilin CYP20-3 (also known as "ROC4") is the only member of this group located in the stroma (soluble phase) of chloroplasts. In the present study we isolated mutant Arabidopsis plants defective in the CYP20-3 gene and found them to be hypersensitive to oxidative stress conditions created by high light levels, rose bengal, high salt levels, and osmotic shock. Chloroplast serine acetyltransferase (SAT1), a rate-limiting enzyme in cysteine biosynthesis, was identified as an interacting partner for CYP20-3 by protein interaction analyses. In the present experiments, SAT1 activity increased significantly under conditions of light and oxidative stress in concert with total thiols in wild-type plants. By contrast, these parameters changed only marginally in experiments with the cyp20-3 mutant, suggesting that CYP20-3 links light and stress to SAT1 activity and cysteine biosynthesis. In further support of this conclusion, our analyses showed that the salt-hypersensitive phenotype of the mutant developed under illumination and not in the dark. Together with the earlier report that CYP20-3 foldase activity is enhanced by thioredoxin-mediated reduction, our findings suggest that CYP20-3 links photosynthetic electron transport and redox regulation to the folding of SAT1, thereby enabling the cysteine-based thiol biosynthesis pathway to adjust to light and stress conditions.