D-2-hydroxyglutarate metabolism is linked to photorespiration in the shm1-1 mutant
D-2-hydroxyglutarate metabolism is linked to photorespiration in the shm1-1 mutant
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DOI：
10.1111/plb.12020
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发表时间：
2013-07-01
期刊：
影响因子：
3.9
通讯作者：
Maurino, V. G.
中科院分区：
文献类型：
--
作者：
Kuhn, A.;Engqvist, M. K. M.;Maurino, V. G.
拟南芥突变体shm 1 -1是线粒体丝氨酸羟甲基转移酶1活性缺陷，并显示在环境CO2浓度下致死的光呼吸表型，但在高CO2正常生长。转移后高CO2生长的shm 1 -1植物环境CO2，年轻的叶片保持光合活性，而发达的叶片显示增加黄化和降低FV/FM值。从高CO2转移到环境空气中的植物的代谢物分析表明，大量的光依赖性（光呼吸）积累的甘氨酸，2-酮戊二酸（2 OG）和D-2-羟基戊二酸（D-2 HG）。衰老的氨基酸标志物积累在环境空气中的野生型和shm 1 -1植物保持在黑暗中，也建立在shm 1 -1在光。这与衰老标记物SAG 12在shm 1 -1中的增强的转录一起表明在光呼吸条件下shm 1 -1中衰老的开始。线粒体D-2 HG脱氢酶（D-2 HGDH）将D-2 HG转化为2 OG。体外研究表明，2 OG对D-2 HGDH具有竞争性抑制作用，Ki值为1.96mm。因此，2 OG是作为体内D-2 HGDH活性抑制剂的合适候选物，因为2 OG在线粒体中产生并积累。2 OG对D-2 HGDH的抑制可能是D-2 HG在shm 1 -1中积累的一种机制，但是不能排除D-2 HG也可能由于转移到光呼吸条件后在这些植物中启动的主动衰老程序而积累。因此，一种新的相互作用的光呼吸途径与细胞过程涉及D-2 HG已被确定。
The Arabidopsis mutant shm1-1 is defective in mitochondrial serine hydroxymethyltransferase 1 activity and displays a lethal photorespiratory phenotype at ambient CO2 concentration but grows normally at high CO2. After transferring high CO2-grown shm1-1 plants to ambient CO2, the younger leaves remain photosynthetically active while developed leaves display increased yellowing and decreased FV/FM values. Metabolite analysis of plants transferred from high CO2 to ambient air indicates a massive light-dependent (photorespiratory) accumulation of glycine, 2-oxoglutarate (2OG) and D-2-hydroxyglutarate (D-2HG). Amino acid markers of senescence accumulated in ambient air in wild-type and shm1-1 plants maintained in darkness and also build up in shm1-1 in the light. This, together with an enhanced transcription of the senescence marker SAG12 in shm1-1, suggests the initiation of senescence in shm1-1 under photorespiratory conditions. Mitochondrial D-2HG dehydrogenase (D-2HGDH) converts D-2HG into 2OG. In vitro studies indicate that 2OG exerts competitive inhibition on D-2HGDH with a Ki of 1.96mm. 2OG is therefore a suitable candidate as inhibitor of the in vivo D-2HGDH activity, as 2OG is produced and accumulates in mitochondria. Inhibition of the D-2HGDH by 2OG is likely a mechanism by which D-2HG accumulates in shm1-1, however it cannot be ruled out that D-2HG may also accumulate due to an active senescence programme that is initiated in these plants after transfer to photorespiratory conditions. Thus, a novel interaction of the photorespiratory pathway with cellular processes involving D-2HG has been identified.