PLGG1, a plastidic glycolate glycerate transporter, is required for photorespiration and defines a unique class of metabolite transporters
PLGG1, a plastidic glycolate glycerate transporter, is required for photorespiration and defines a unique class of metabolite transporters
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DOI：
10.1073/pnas.1215142110
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发表时间：
2013-02-19
影响因子：
11.1
通讯作者：
Weber, Andreas P. M.
中科院分区：
文献类型：
--
作者：
Pick, Thea R.;Braeutigam, Andrea;Weber, Andreas P. M.
光呼吸碳通量高达光合通量的三分之一，对全球碳循环贡献巨大。该途径使乙醇酸-2-磷酸（RubisCO反应中最丰富的副产物）分解。RubisCO的这种氧化反应和随后的光呼吸显著限制了许多作物植物的生物量增益。虽然光呼吸是一个区室化的过程，在叶绿体，过氧化物酶体，线粒体和细胞质中的酶反应，没有转运所需的核心光呼吸循环已被确定在分子水平上。使用转录共表达分析，我们确定质体乙醇酸甘油酸转运蛋白1（PLGG 1）作为候选核心光呼吸转运蛋白。相关基因在古生菌、细菌、真菌和所有古质体的基因组中编码，并且先前与程序性细胞死亡中的功能相关。PLGG 1缺陷的突变体仅在升高的二氧化碳气氛中显示WT样生长。突变体积累乙醇酸和甘油酸，导致假设PLGG 1是乙醇酸/甘油酸转运蛋白。体内和体外转运试验和O-18（2）-代谢通量分析验证并支持了这一假设。我们的研究结果表明，PLGG 1是叶绿体乙醇酸/甘油酸转运蛋白，这是所需的光呼吸循环的功能。PLGG 1转运功能的鉴定将有助于解开类似蛋白在细菌，古细菌和真菌中的作用。
Photorespiratory carbon flux reaches up to a third of photosynthetic flux, thus contributes massively to the global carbon cycle. The pathway recycles glycolate-2-phosphate, the most abundant byproduct of RubisCO reactions. This oxygenation reaction of RubisCO and subsequent photorespiration significantly limit the biomass gains of many crop plants. Although photorespiration is a compartmentalized process with enzymatic reactions in the chloroplast, the peroxisomes, the mitochondria, and the cytosol, no transporter required for the core photorespiratory cycle has been identified at the molecular level to date. Using transcript coexpression analyses, we identified Plastidal glycolate glycerate translocator 1 (PLGG1) as a candidate core photorespiratory transporter. Related genes are encoded in the genomes of archaea, bacteria, fungi, and all Archaeplastida and have previously been associated with a function in programmed cell-death. A mutant deficient in PLGG1 shows WT-like growth only in an elevated carbon dioxide atmosphere. The mutant accumulates glycolate and glycerate, leading to the hypothesis that PLGG1 is a glycolate/glycerate transporter. This hypothesis was tested and supported by in vivo and in vitro transport assays and O-18(2)-metabolic flux profiling. Our results indicate that PLGG1 is the chloroplastidic glycolate/glycerate transporter, which is required for the function of the photorespiratory cycle. Identification of the PLGG1 transport function will facilitate unraveling the role of similar proteins in bacteria, archaea, and fungi in the future.