title: D-2-hydroxyglutarate metabolism is linked to photorespiration in the shm1-1 mutant.
abstract: 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 1.96 mm. 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.
authors.affiliation: Botanisches Institut, Biozentrum Köln, Universität zu Köln, Cologne, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Kuhn
authors.forename: M K M
authors.initials: MK
authors.lastname: Engqvist
authors.forename: E E W
authors.initials: EE
authors.lastname: Jansen
authors.forename: A P M
authors.initials: AP
authors.lastname: Weber
authors.forename: C
authors.initials: C
authors.lastname: Jakobs
authors.forename: V G
authors.initials: VG
authors.lastname: Maurino
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism / Q000494:pharmacology*; D019069:Cell Respiration; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism; D005977:Glutarates / Q000032:analysis / Q000378:metabolism*; D005998:Glycine / Q000378:metabolism; D012696:Glycine Hydroxymethyltransferase / Q000235:genetics* / Q000378:metabolism; D007438:Introns / Q000235:genetics; D007656:Ketoglutaric Acids / Q000378:metabolism; D008027:Light; D008239:Lysine / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D010788:Photosynthesis; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D022821:RNA Splice Sites / Q000235:genetics; D011994:Recombinant Proteins
chemical_list: D029681:Arabidopsis Proteins; D005977:Glutarates; D007656:Ketoglutaric Acids; D022821:RNA Splice Sites; D011994:Recombinant Proteins; D002245:Carbon Dioxide; C019417:alpha-hydroxyglutarate; D012696:Glycine Hydroxymethyltransferase; C509630:SHM1 protein, Arabidopsis; C402082:SAG12 protein, Arabidopsis; D003546:Cysteine Endopeptidases; D008239:Lysine; D005998:Glycine