First evidences of the existence of Glyoxalase I activity in durum wheat (Triticum durum Desf.) mitochondria and its activation under hyperosmotic stress conditions

Glyoxalase I (GloI) is a ubiquitous enzyme responsible for the primary defence against dicarbonyl glycation induced by methylglyoxal (MG), a toxic by-product of glycolysis and Calvin cycle. In plants, MG levels rise under various abiotic stresses, so GloI may play a crucial role in providing stress tolerance. GloI was demonstrated to localize in chloroplast, cytosol and nucleus. Moreover, a proteomic study suggested GloI existence also in mitochondria from potato tubers; nevertheless, so far, a mitochondrial GloI activity has never been measured. Here, for the first time GloI activity was assessed in highly purified mitochondria obtained from durum wheat (DWM). In particular, a high GloI activity was measured showing hyperbolic kinetics with Km and Vmax values equal to 225±15 μM and 0.134±0.002 U∙mg-1 of protein, respectively. Interestingly, an increase of GloI activity up to about 20% and 50% was obtained in DWM purified from salt- and osmotic-stressed seedlings, respectively, thus suggesting a key role of this enzyme in counteracting dicarbonyl glycation damage to DWM proteome. Identification of proteins target of dicarbonyl glycation in DWM merits further investigations