Transport of photorespiratory intermediates between cellular compartments

细胞区室之间光呼吸中间体的运输

• 批准号: 134778026
• 负责人: Professor Dr. Andreas P.M. Weber
• 金额: --
• 依托单位: Institut für Biochemie der Pflanzen
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2009
• 资助国家: 德国
• 起止时间: 2008-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/134778026?language=en
• 关键词: Transport; photorespiratory; intermediates; between; cellular

Photorespiratory metabolism is a highly compartmentalized pathway, comprising chloroplasts, peroxisomes, mitochondria and cytosol. At least 14 different transport steps are necessary to allow for effective shuttling of photorespiratory intermediates in between the different compartments. In contrast to the well-characterized photorespiratory enzymes the situation for the metabolite transporters is rather poor. The aim of this project was and is to identify those transporters and thus close a major gap in knowledge about photorespiration. We could establish a crucial function of the metabolite transporters BOU1 and MEP1 in photorespiration. Corresponding Arabidopsis mutants showed a typical photorespiratory phenotype. We suggest that the mitochondrial carrier protein BOU1 transports a substrate that is essential for glycine decarboxylase complex activity. The gene mep1 encodes for a chloroplast metabolite transporter required for the transport of glycolate and glycerate across the plastid envelope membrane. Since transporter activities could not be demonstrated by in vitro assays, we will follow an in vivo approach in the next funding period. Additionally, we could recently show that the Arabidopsis dicarboxylate transporter DiT1 is required for photorespiration. To identify further novel photorespiratory transporters we are continuing with screening Arabidopsis mutants selected on the basis of transcript co-expression analyses. With At1g78620 and ucp1-3 four new candidate genes could be detected. Mutants in these genes are currently under investigation. The aim of the PROMICS joined “Central experiment” is to unravel new insights into photorespiratory metabolism, associated pathways and C/N signalling. We could establish the workflow for successful sample preparation and transcriptomic analysis. In the next round we will expand the sample input and concentrate on the evaluation of the full dataset. We believe that we can use the integrated transriptomic and metabolic data to run a computational model aimed at improving the efficiency of the photosynthetic pathway.

光呼吸代谢是一种高度区域化的代谢途径，由叶绿体、过氧化物体、线粒体和胞浆组成。至少需要14个不同的运输步骤，才能在不同隔间之间有效地穿梭光呼吸中间体。与特性良好的光呼吸酶相比，代谢物转运蛋白的情况相当糟糕。该项目的目的是确定这些转运体，从而弥合关于光呼吸作用知识的一个重大空白。我们可以确定代谢物转运蛋白BOU1和MEP1在光呼吸中的重要作用。相应的拟南芥突变体表现出典型的光呼吸表型。我们认为线粒体载体蛋白BOU1运输甘氨酸脱羧酶复合体活性所必需的底物。Mep1基因编码一种叶绿体代谢物转运体，该转运体是乙醇酸和甘油酸跨叶绿体被膜运输所必需的。由于转运蛋白的活性不能通过体外测试来证明，我们将在下一个资助期采用体内方法。此外，我们最近还发现拟南芥的二羧酸转运蛋白DiT1是光呼吸所必需的。为了进一步确定新的光呼吸转运蛋白，我们继续筛选根据转录共表达分析筛选出的拟南芥突变体。利用AT1g78620和UCP1-3可以检测到4个新的候选基因。这些基因的突变目前正在调查中。PROMICS联合“中心实验”的目的是揭开对光呼吸代谢、相关途径和C/N信号的新见解。我们可以建立成功的样品制备和转录分析的工作流程。在下一轮中，我们将扩展样本输入，并专注于对整个数据集的评估。我们相信，我们可以使用整合的跨分裂和代谢数据来运行一个旨在提高光合作用途径效率的计算模型。