...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Biochemistry >Light-induced trimer to monomer transition in the main light-harvesting antenna complex of plants: thermo-optic mechanism
【24h】

Light-induced trimer to monomer transition in the main light-harvesting antenna complex of plants: thermo-optic mechanism

机译：植物主要光收集天线复合体中光诱导的三聚体向单体的转变：热光机理

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The main chlorophyll a/b light-harvesting complex of photosystem II,LHCIIb, has earlier been shown to be capable of undergoing light-induced reversible structural changes and chlorophyll a fluorescence quenching in a way resembling those observed in granal thylakoids when exposed to excess light [Barzda. et al. (1996) Biochemistry 35, 8981-8985]. The nature and mechanism of this unexpected structural flexibility has not been elucidated. In this work, by using density gradient centrifugation and nondenaturing green gel electrophoresis, as well as absorbance and circular dichroic spectroscopy, we show that light induces a significant degree of monomerization, which is in contrast with the preferentially trimeric organization of the isolated complexes in the dark. Monomerization is accompanied by a reversible release of Mg ions, most likely from the outer loop of the complexes. These data, as well as the built-in thermal and light instability of the trimeric organization, are explained in terms of a simple theoretical model of thermo-optic mechanism, effect of fast thermal transients (local T-jumps) due to dissipated photon energies in the vicinity of the cation binding sites, which lead to thermally assisted elementary structural transitions. Disruption of trimers to monomers by excess light is not confined to isolated trimers and lamellar aggregates of LHCII but occurs in photosystem II-enriched grana membranes, intact thylakoid membranes, and whole plants. As indicated by differences in the quenching capability of trimers and monomers, the appearance of monomers could facilitate the nonphotochemical quenching of the singlet excited state of chlorophyll a. The light-induced formation of monomers may also be important in regulated proteolytic degradation of the complexes. Structural changes driven by thermo-optic mechanisms may therefore provide plants with a novel mechanism for regulation of light harvesting in excess light.
机译：先前已证明，光系统II的主要叶绿素a / b光捕获复合物LHCIIb能够经历光诱导的可逆结构变化，并且叶绿素a荧光猝灭的方式类似于在暴露于过量光的粒状类囊体中观察到的方式。 [巴兹达。等。 （1996）Biochemistry 35，8981-8985]。这种意外的结构柔性的性质和机理尚未阐明。在这项工作中，通过使用密度梯度离心和非变性绿色凝胶电泳，以及吸光度和圆二色光谱，我们显示光诱导了很大程度的单体化，这与分离的复合物中优先的三聚体组织形成对比。黑暗。单体化伴随着Mg离子的可逆释放，很可能是从络合物的外环释放出来的。这些数据以及三聚体组织固有的热和光不稳定性，通过简单的热光机理理论模型，由于光子能量耗散引起的快速热瞬变（局部T跃迁）的影响进行了解释。在阳离子结合位点附近，这导致热辅助的基本结构转变。三聚体被过量的光破坏不局限于分离的三聚体和LHCII的层状聚集体，而是发生在富含光系统II的颗粒膜，完整类囊体膜和整个植物中。正如三聚体和单体的猝灭能力的差异所表明的那样，单体的出现可以促进叶绿素a单线激发态的非光化学猝灭。光诱导的单体形成在调节复合物的蛋白水解降解中也可能是重要的。因此，由热光机制驱动的结构变化可以为植物提供一种用于调节过量光中光收集的新颖机制。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号