Molecular Biology of Plant Organelles, Ruhr-University Bochum, Universitätsstraße 150, 44780, Bochum, Germany.
Photosynth Res. 2018 Dec;138(3):303-313. doi: 10.1007/s11120-018-0544-6. Epub 2018 Jun 28.
The light-harvesting chlorophyll a/b binding proteins (LHCP) belong to a large family of membrane proteins. They form the antenna complexes of photosystem I and II and function in light absorption and transfer of the excitation energy to the photosystems. As nuclear-encoded proteins, the LHCPs are imported into the chloroplast and further targeted to their final destination-the thylakoid membrane. Due to their hydrophobicity, the formation of the so-called 'transit complex' in the stroma is important to prevent their aggregation in this aqueous environment. The posttranslational LHCP targeting mechanism is well regulated through the interaction of various soluble and membrane-associated protein components and includes several steps: the binding of the LHCP to the heterodimeric cpSRP43/cpSRP54 complex to form the soluble transit complex; the docking of the transit complex to the SRP receptor cpFtsY and the Alb3 translocase at the membrane followed by the release and integration of the LHCP into the thylakoid membrane in a GTP-dependent manner. This review summarizes the molecular mechanisms and dynamics behind the posttranslational LHCP targeting to the thylakoid membrane of Arabidopsis thaliana.
捕光叶绿素 a/b 结合蛋白（LHCP）属于膜蛋白大家族。它们构成光系统 I 和 II 的天线复合物，在吸收光和将激发能传递到光系统中发挥作用。作为核编码蛋白，LHCP 被导入叶绿体，并进一步靶向其最终目的地——类囊体膜。由于其疏水性，在这个水相环境中，形成所谓的“转运复合物”对于防止它们聚集是很重要的。通过各种可溶性和膜相关蛋白成分的相互作用，LHCP 的翻译后靶向机制得到了很好的调节，包括几个步骤：LHCP 与异二聚体 cpSRP43/cpSRP54 复合物结合形成可溶性转运复合物；转运复合物与 SRP 受体 cpFtsY 和膜上的 Alb3 易位酶对接，然后以 GTP 依赖性方式将 LHCP 释放并整合到类囊体膜中。本综述总结了拟南芥 LHCP 向类囊体膜的翻译后靶向的分子机制和动力学。
