Structural highlights
FunctionPublication Abstract from PubMedGlutamate dehydrogenases (GDHs) are key enzymes at the crossroads of N and C metabolism in plants. Legumes, whose N metabolism is particularly intricate, possess a unique type of GDH. This study presents an analysis of a legume-type GDH (isoform 2) from Medicago truncatula (MtGDH2). We measured MtGDH2 activity in both the Glu --> 2-oxoglutarate (2OG) and 2OG --> Glu reaction directions and obtained kinetic parameters for Glu, 2OG, NAD(+), and NADH. Inhibition assays revealed that compounds possessing di- or tricarboxylates act as inhibitors of plant GDHs. Interestingly, 2,6-pyridinedicarboxylate (PYR) weakly inhibits MtGDH2 compared to Arabidopsis thaliana homologs. Furthermore, we explored tetrazole derivatives to discover 3-(1H-tetrazol-5-yl)benzoic acid (TBA) as an MtGDH2 inhibitor. The kinetic experiments are supported by six crystal structures, solved as: (i) unliganded enzyme, (ii) trapping the reaction intermediate 2-amino-2-hydroxyglutarate and NAD(+), and also complexed with NAD(+) and inhibitors such as (iii) citrate, (iv) PYR, (v) isophthalate, and (vi) TBA. The complex with TBA revealed a new mode of action that, in contrast to other inhibitors, prevents domain closure. This discovery points to TBA as a starting point for the development of novel GDH inhibitors to study the functions of GDH in plants and potentially boost biomass production. Legume-type glutamate dehydrogenase: Structure, activity, and inhibition studies.,Grzechowiak M, Sliwiak J, Link A, Ruszkowski M Int J Biol Macromol. 2024 Aug 12;278(Pt 2):134648. doi: , 10.1016/j.ijbiomac.2024.134648. PMID:39142482[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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