López-Millán Ana F, Duy Daniela, Philippar Katrin
Department of Pediatrics, Children's Nutrition Research Center, Baylor College of Medicine, United States Department of Agriculture/Agricultural Research Service, Houston TX, USA.
Plastid Fatty Acid and Iron Transport - Plant Biochemistry and Physiology, Department Biology I, Ludwig-Maximilians-University of Munich Munich, Germany.
Front Plant Sci. 2016 Feb 19;7:178. doi: 10.3389/fpls.2016.00178. eCollection 2016.
Chloroplasts originated about three billion years ago by endosymbiosis of an ancestor of today's cyanobacteria with a mitochondria-containing host cell. During evolution chloroplasts of higher plants established as the site for photosynthesis and thus became the basis for all life dependent on oxygen and carbohydrate supply. To fulfill this task, plastid organelles are loaded with the transition metals iron, copper, and manganese, which due to their redox properties are essential for photosynthetic electron transport. In consequence, chloroplasts for example represent the iron-richest system in plant cells. However, improvement of oxygenic photosynthesis in turn required adaptation of metal transport and homeostasis since metal-catalyzed generation of reactive oxygen species (ROS) causes oxidative damage. This is most acute in chloroplasts, where radicals and transition metals are side by side and ROS-production is a usual feature of photosynthetic electron transport. Thus, on the one hand when bound by proteins, chloroplast-intrinsic metals are a prerequisite for photoautotrophic life, but on the other hand become toxic when present in their highly reactive, radical generating, free ionic forms. In consequence, transport, storage and cofactor-assembly of metal ions in plastids have to be tightly controlled and are crucial throughout plant growth and development. In the recent years, proteins for iron transport have been isolated from chloroplast envelope membranes. Here, we discuss their putative functions and impact on cellular metal homeostasis as well as photosynthetic performance and plant metabolism. We further consider the potential of proteomic analyses to identify new players in the field.
叶绿体起源于大约30亿年前，当时当今蓝细菌的一个祖先与一个含有线粒体的宿主细胞发生内共生。在进化过程中，高等植物的叶绿体成为光合作用的场所，从而成为所有依赖氧气和碳水化合物供应的生命的基础。为了完成这项任务，质体细胞器富含过渡金属铁、铜和锰，由于它们的氧化还原特性，这些金属对于光合电子传递至关重要。因此，例如叶绿体是植物细胞中含铁最丰富的系统。然而，提高光合放氧作用反过来需要适应金属运输和稳态，因为金属催化的活性氧（ROS）生成会导致氧化损伤。这在叶绿体中最为严重，在叶绿体中自由基和过渡金属并存，ROS的产生是光合电子传递的常见特征。因此，一方面，当与蛋白质结合时，叶绿体固有的金属是光合自养生命的先决条件，但另一方面，当以其高反应性、产生自由基的游离离子形式存在时会变得有毒。因此，质体中金属离子的运输、储存和辅因子组装必须受到严格控制，并且在植物的整个生长发育过程中都至关重要。近年来，已经从叶绿体包膜膜中分离出铁运输蛋白。在这里，我们讨论它们的假定功能以及对细胞金属稳态、光合性能和植物代谢的影响。我们还考虑了蛋白质组学分析在识别该领域新参与者方面的潜力。
