Reversible changes in conformation of the 23-kDa protein of photosystem II and their relationship to the susceptibility of the protein to a proteinase from photosystem II membranes.
Reversible changes in conformation of the 23-kDa protein of photosystem II and their relationship to the susceptibility of the protein to a proteinase from photosystem II membranes.
复制标题
光系统 II 23-kDa 蛋白质构象的可逆变化及其与蛋白质对光系统 II 膜蛋白酶敏感性的关系。
DOI：
10.1093/oxfordjournals.pcp.a078785
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发表时间：
1995
影响因子：
4.9
通讯作者：
K. Suzuki
中科院分区：
文献类型：
--
作者：
T. Kuwabara;K. Suzuki
从菠菜的 PSII 膜中部分纯化天冬氨酸蛋白酶。 PSII 的 23-kDa 蛋白在其天然形式下对蛋白酶具有抗性，但在经过对氯汞苯磺酸 (pCMPS) 修饰、在 pH 3 下孵育以及在稀 SDS 中孵育后变得敏感。 pCMPS 引起的构象变化似乎仅限于局部区域，因为与未处理的蛋白质相比，修饰后的蛋白质重建水氧化复合物的效率略低。在三种蛋白水解条件下，裂解发生在 Asn-58-Leu-59 键处，表明每种情况下蛋白质都经历了类似的构象变化。二硫苏糖醇、pH 7 透析和中性去污剂分别抑制 pCMPS、pH 3 和 SDS 对蛋白水解的促进作用。随着敏感性的可逆变化，蛋白质的圆二色性在200-208 nm处也发生可逆变化。这些观察结果表明构象变化是可逆的并且底物的复性与敏感性的抑制相关。这些结果表明，易裂键响应环境变化而可逆地暴露并易受蛋白酶的影响。
An aspartic proteinase was partially purified from PSII membranes of spinach. The 23-kDa protein of PSII was resistant to the proteinase when in its native form but became susceptible upon modification by p-chloromercuriphenylsulfonic acid (pCMPS), upon incubation at pH 3, and upon incubation in dilute SDS. Conformational changes caused by pCMPS seemed to be restricted to a localized region since the modified protein reconstituted the water-oxidizing complex with slightly less efficiency as compared with the untreated protein. Under the three proteolytic conditions, cleavage occurred at the Asn-58-Leu-59 bond, suggesting that the protein underwent similar conformational changes in each case. Dithiothreitol, dialysis at pH 7, and neutral detergents suppressed the facilitative effects of pCMPS, pH 3, and SDS on proteolysis, respectively. With the reversible changes in susceptibility, reversible changes in circular dichroism of the protein also occurred at 200-208 nm. These observations indicate that the conformational changes are reversible and the renaturation of the substrate was associated with the suppression of the susceptibility. These results suggest that the scissile bond becomes reversibly exposed and susceptible to the proteinase in response to environmental changes.