Manganese stabilizing protein of photosystem II is a thermostable, natively unfolded polypeptide.
Manganese stabilizing protein of photosystem II is a thermostable, natively unfolded polypeptide.
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DOI：
10.1021/bi981847z
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发表时间：
1999-01
期刊：
影响因子：
2.9
通讯作者：
N. Lydakis-Simantiris;R. S. Hutchison;S. Betts;B. Barry;C. Yocum
中科院分区：
文献类型：
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作者：
N. Lydakis-Simantiris;R. S. Hutchison;S. Betts;B. Barry;C. Yocum
通过生化和光谱技术检测了光系统II的锰稳定蛋白的热稳定性。天然和重组菠菜锰稳定蛋白样品在 90°C 下孵育，然后冷却至 25°C，能够重新结合并重新激活已去除天然蛋白的光系统 II 膜的 O2 放出活性。使用远紫外圆二色性和傅立叶变换红外光谱分析加热锰稳定蛋白的结构后果。从这些技术获得的数据表明，加热导致蛋白质二级结构完全丧失，这是一种可逆的非合作现象。冷却后，热处理蛋白质的二级结构恢复到与天然未加热对照相似但不相同的状态。通过尺寸排阻色谱法和近紫外圆二色性证实了近天然三级结构的恢复。本文报道的锰稳定蛋白的功能和结构热稳定性，结合该蛋白的其他已知特性（酸性 pI、高无规卷曲和转角含量、异常流体动力学行为），将锰稳定蛋白鉴定为天然未折叠蛋白 [Weinreb 等人，2017]。 (1996) 生物化学 35, 13709-13715]。尽管这些蛋白质缺乏氨基酸序列同一性，但它们在生理条件下的功能性溶液构象据说是“天然展开的”。我们认为，与该蛋白质家族的其他成员一样，锰稳定蛋白的天然未折叠结构促进了高效的蛋白质-蛋白质相互作用，这是其组装成光系统 II 所必需的。
The thermostability of manganese stabilizing protein of photosystem II was examined by biochemical and spectroscopic techniques. Samples of both native and recombinant spinach manganese stabilizing protein incubated at 90 degreesC and then cooled to 25 degreesC were capable of rebinding to, and of reactivating, the O2-evolution activity of photosystem II membranes from which the native protein had been removed. Far-UV circular dichroism and FT-IR spectroscopies were used to analyze the structural consequences of heating manganese stabilizing protein. The data obtained from these techniques show that heating causes a complete loss of the protein's secondary structure, and that this is a reversible, noncooperative phenomenon. Upon cooling, the secondary structures of the heat-treated proteins return to a state similar to, but not identical with, that of the native, unheated controls. Restoration of a near-native tertiary structure is confirmed both by size-exclusion chromatography and by near-UV circular dichroism. The functional and structural thermostability of manganese stabilizing protein reported here, in conjunction with additional known properties of this protein (acidic pI, high random coil and turn content, anomalous hydrodynamic behavior), identifies manganese stabilizing protein as a natively unfolded protein [Weinreb et al. (1996) Biochemistry 35, 13709-13715]. Although these proteins lack amino acid sequence identity, their functional solution conformations under physiological conditions are said to be "natively unfolded". We suggest that, as with other members of this family of proteins, the natively unfolded structure of manganese stabilizing protein facilitates the highly effective protein-protein interactions that are necessary for its assembly into photosystem II.