Conformational Selection and Folding-upon-binding of Intrinsically Disordered Protein CP12 Regulate Photosynthetic Enzymes Assembly
Conformational Selection and Folding-upon-binding of Intrinsically Disordered Protein CP12 Regulate Photosynthetic Enzymes Assembly
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DOI：
10.1074/jbc.m112.350355
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发表时间：
2012-06-15
影响因子：
4.8
通讯作者：
Trost, Paolo
中科院分区：
文献类型：
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作者：
Fermani, Simona;Trivelli, Xavier;Trost, Paolo
植物中的碳同化是通过特定蛋白质二硫化物在光照下的还原和在黑暗中的再氧化来调节的。氧化还原开关CP 12是一种本质上无序的蛋白质，可以形成两个二硫桥。在黑暗中，氧化的CP 12与甘油醛-3-磷酸脱氢酶（GAPDH）和磷酸核酮糖激酶（碳同化循环的两种酶）形成无活性的超分子复合物。在这里，我们表明，结合CP 12 GAPDH，三元复合物形成的第一步，遵循一个综合的机制，结合构象选择诱导折叠步骤。最初，通过GAPDH选择以包括C-末端二硫键的环状结构基序为特征的CP 12构象。随后，在GAPDH的活性位点中CP 12的柔性C-末端尾部的诱导折叠稳定二元复合物。几个氢键的形成补偿了CP 12固定的熵成本，并终止了有助于碳同化控制的相互作用机制。
Carbon assimilation in plants is regulated by the reduction of specific protein disulfides by light and their re-oxidation in the dark. The redox switch CP12 is an intrinsically disordered protein that can form two disulfide bridges. In the dark oxidized CP12 forms an inactive supramolecular complex with glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and phosphoribulokinase, two enzymes of the carbon assimilation cycle. Here we show that binding of CP12 to GAPDH, the first step of ternary complex formation, follows an integrated mechanism that combines conformational selection with induced folding steps. Initially, a CP12 conformation characterized by a circular structural motif including the C-terminal disulfide is selected by GAPDH. Subsequently, the induced folding of the flexible C-terminal tail of CP12 in the active site of GAPDH stabilizes the binary complex. Formation of several hydrogen bonds compensates the entropic cost of CP12 fixation and terminates the interaction mechanism that contributes to carbon assimilation control.