Comparison of the thermodynamic landscapes of unfolding and formation of the energy dissipative state in the isolated light harvesting complex II.
Comparison of the thermodynamic landscapes of unfolding and formation of the energy dissipative state in the isolated light harvesting complex II.
复制标题
孤立光收集复合体 II 中能量耗散态展开和形成的热力学景观的比较。
DOI：
10.1016/j.bpj.2009.06.005
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发表时间：
2009
影响因子：
3.4
通讯作者：
Santabarbara S
中科院分区：
文献类型：
--
作者：
Santabarbara S
在生物化学和细胞生物学中，了解生理过程调节的分子机制被认为是最终目标。在高等植物中，叶绿体类囊体膜的捕光复合物（LHCII）是研究最广泛的调控过程之一。在有限的光子通量密度下，LHCII以高效率收集阳光。当入射辐射的强度达到接近光合作用饱和的水平时，光捕获的效率被称为非光化学猝灭（NPQ）的过程降低，该过程通过非辐射耗散过程增强单重激发态失活。已知LHCII中的构象重排在体外和体内促进和控制NPQ中至关重要。在这篇文章中，我们解决的热力学性质的构象重排，促进和控制NPQ在孤立的LHCII。一个组合的，线性的反应方案，其中折叠，淬灭状态代表一个稳定的中间体展开途径被用来描述与叶绿素荧光淬灭和LHCII的二级结构基序的损失的光谱特征的温度依赖性。热力学模型需要考虑LHCII的猝灭和未猝灭状态以及展开和猝灭状态之间的吉布斯自由能差对温度的依赖性。即使相同的反应方案是足够的描述淬灭和展开过程中的LHCII单体和三聚体，他们的热力学特性被发现是显着不同的。热力学分析的结果揭示了LHCII的三聚体状态在稳定有效的光捕获模式以及防止蛋白质的猝灭构象展开方面的生理重要性。此外，三聚体中向淬灭构象的转变显示出比单体更大程度的协同性，这可以用小的特征熵（ΔHq= 85 ± 3 kJ mol− 1，而单体中为125 ± 5 kJ mol − 1）来解释，这使得体内非光化学淬灭的微调成为可能。
In biochemistry and cell biology, understanding the molecular mechanisms by which physiological processes are regulated is regarded as an ultimate goal. In higher plants, one of the most widely investigated regulatory processes occurs in the light harvesting complexes (LHCII) of the chloroplast thylakoid membranes. Under limiting photon flux densities, LHCII harvests sunlight with high efficiency. When the intensity of incident radiation reaches levels close to the saturation of the photosynthesis, the efficiency of light harvesting is decreased by a process referred to as nonphotochemical quenching (NPQ), which enhances the singlet-excited state deactivation via nonradiative dissipative processes. Conformational rearrangements in LHCII are known to be crucial in promoting and controlling NPQ in vitro and in vivo. In this article, we address the thermodynamic nature of the conformational rearrangements promoting and controlling NPQ in isolated LHCII. A combined, linear reaction scheme in which the folded, quenched state represents a stable intermediate on the unfolding pathway was employed to describe the temperature dependence of the spectroscopic signatures associated with the chlorophyll fluorescence quenching and the loss of secondary structure motifs in LHCII. The thermodynamic model requires considering the temperature dependence of Gibbs free energy difference between the quenched and the unquenched states, as well as the unfolded and quenched states, of LHCII. Even though the same reaction scheme is adequate to describe the quenching and the unfolding processes in LHCII monomers and trimers, their thermodynamic characteristics were found to be markedly different. The results of the thermodynamic analysis shed light on the physiological importance of the trimeric state of LHCII in stabilizing the efficient light harvesting mode as well as preventing the quenched conformation of the protein from unfolding. Moreover, the transition to the quenched conformation in trimers reveals a larger degree of cooperativity than in monomers, explained by a small characteristic entropy (ΔHq= 85 ± 3 kJ mol−1compared to 125 ± 5 kJ mol−1in monomers), which enables the fine-tuning of nonphotochemical quenching in vivo.
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影响因子：
--
作者：
J. M. Beechem
通讯作者：
J. M. Beechem
影响因子：
6.8
作者：
Dobson, Christopher M.;Karplus, Martin
通讯作者：
Karplus, Martin
高等植物光系统中的天线结构和能量传递
DOI：
--
发表时间：
1996
期刊：
影响因子：
--
作者：
R. Jennings;R. Bassi;G. Zucchelli
通讯作者：
G. Zucchelli
通过超快吸收瞬变监测 LHCII 复合物中的非平衡加热。
影响因子：
2.9
作者：
V. Gulbinas;R. Karpicz;G. Garab;L. Valkunas
通讯作者：
L. Valkunas
光系统II中激发态布居对光抑制引起的叶绿素荧光参数变化的影响
DOI：
--
发表时间：
1999
期刊：
Biochimica et Biophysica Acta
影响因子：
--
作者：
Santabarbara;Garlaschi;Zucchelli;Jennings
通讯作者：
Jennings