Department of Biological and Environmental Sciences, University of Gothenburg, 40530, Gothenburg, Sweden.
Cell Mol Life Sci. 2014 Mar;71(6):979-98. doi: 10.1007/s00018-013-1412-3. Epub 2013 Jul 9.
Chloroplasts from land plants and algae originated from an endosymbiotic event, most likely involving an ancestral photoautotrophic prokaryote related to cyanobacteria. Both chloroplasts and cyanobacteria have thylakoid membranes, harboring pigment-protein complexes that perform the light-dependent reactions of oxygenic photosynthesis. The composition, function and regulation of these complexes have thus far been the major topics in thylakoid membrane research. For many decades, we have also accumulated biochemical and electrophysiological evidence for the existence of solute transthylakoid transport activities that affect photosynthesis. However, research dedicated to molecular identification of the responsible proteins has only recently emerged with the explosion of genomic information. Here we review the current knowledge about channels and transporters from the thylakoid membrane of Arabidopsis thaliana and of the cyanobacterium Synechocystis sp. PCC 6803. No homologues of these proteins have been characterized in algae, although similar sequences could be recognized in many of the available sequenced genomes. Based on phylogenetic analyses, we hypothesize a host origin for most of the so far identified Arabidopsis thylakoid channels and transporters. Additionally, the shift from a non-thylakoid to a thylakoid location appears to have occurred at different times for different transport proteins. We propose that closer control of and provision for the thylakoid by products of the host genome has been an ongoing process, rather than a one-step event. Some of the proteins recruited to serve in the thylakoid may have been the result of the increased specialization of its pigment-protein composition and organization in green plants.
叶绿体起源于陆地植物和藻类的内共生事件，最有可能涉及与蓝细菌有关的原始光合原核生物。叶绿体和蓝细菌都有类囊体膜，其中含有执行放氧光合作用的光依赖反应的色素-蛋白复合物。因此，这些复合物的组成、功能和调控一直是类囊体膜研究的主要课题。几十年来，我们还积累了关于影响光合作用的溶质跨类囊体转运活性存在的生化和电生理学证据。然而，随着基因组信息的爆炸式增长，专门用于鉴定负责蛋白的分子研究才刚刚出现。在这里，我们回顾了目前关于拟南芥和集胞藻 6803 的类囊体膜中的通道和转运蛋白的知识。虽然在许多已测序的基因组中可以识别出类似的序列，但藻类中尚未鉴定出这些蛋白的同源物。基于系统发育分析，我们假设迄今为止鉴定出的大多数拟南芥类囊体通道和转运蛋白都具有宿主起源。此外，不同的转运蛋白从非类囊体到类囊体的位置转移似乎发生在不同的时间。我们提出，宿主基因组产物对类囊体的更紧密控制和供应是一个持续的过程，而不是一个一步到位的事件。一些被招募到类囊体中发挥作用的蛋白可能是由于其色素-蛋白组成和组织在绿色植物中的专业化增加的结果。
