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D ‐2‐hydroxyglutarate metabolism is linked to photorespiration in the shm1‐1 mutant
Author(s) -
Kuhn A.,
Engqvist M. K. M.,
Jansen E. E. W.,
Weber A. P. M.,
Jakobs C.,
Maurino V. G.
Publication year - 2013
Publication title -
plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 1435-8603
DOI - 10.1111/plb.12020
Subject(s) - photorespiration , biology , serine hydroxymethyltransferase , biochemistry , senescence , mutant , photosynthesis , metabolism , metabolite , glycine , dehydrogenase , botany , amino acid , enzyme , microbiology and biotechnology , gene
The A rabidopsis mutant shm1‐1 is defective in mitochondrial serine hydroxymethyltransferase 1 activity and displays a lethal photorespiratory phenotype at ambient CO 2 concentration but grows normally at high CO 2 . After transferring high CO 2 ‐grown shm1‐1 plants to ambient CO 2 , the younger leaves remain photosynthetically active while developed leaves display increased yellowing and decreased F V / F M values. Metabolite analysis of plants transferred from high CO 2 to ambient air indicates a massive light‐dependent (photorespiratory) accumulation of glycine, 2‐oxoglutarate (2 OG ) and D ‐2‐hydroxyglutarate ( D ‐2 HG ). 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 SAG 12 in shm1‐1 , suggests the initiation of senescence in shm1‐1 under photorespiratory conditions. Mitochondrial D ‐2 HG dehydrogenase ( D ‐2 HGDH ) converts D ‐2 HG into 2 OG . In vitro studies indicate that 2 OG exerts competitive inhibition on D ‐2 HGDH with a K i of 1.96 m m . 2 OG is therefore a suitable candidate as inhibitor of the in vivo D‐2HGDH activity, as 2 OG is produced and accumulates in mitochondria. Inhibition of the D ‐2 HGDH by 2 OG 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.