1nr7
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Crystal structure of apo bovine glutamate dehydrogenase
OverviewOverview
Glutamate dehydrogenase (GDH) is found in all organisms and catalyzes the, reversible oxidative deamination of L-glutamate to 2-oxoglutarate. Unlike, GDH from bacteria, mammalian GDH exhibits negative cooperativity with, respect to coenzyme, activation by ADP, and inhibition by GTP. Presented, here are the structures of apo bovine GDH, bovine GDH complexed with ADP, and the R463A mutant form of human GDH (huGDH) that is insensitive to ADP, activation. In the absence of active site ligands, the catalytic cleft is, in the open conformation, and the hexamers form long polymers in the, crystal cell with more interactions than found in the abortive complex, crystals. This is consistent with the fact that ADP promotes aggregation, in solution. ADP is shown to bind to the second, inhibitory, NADH site yet, causes activation. The beta-phosphates of the bound ADP interact with R459, (R463 in huGDH) on the pivot helix. The structure of the ADP-resistant, R463A mutant of human GDH is identical to native GDH with the exception of, the truncated side chain on the pivot helix. Together, these results, strongly suggest that ADP activates by facilitating the opening of the, catalytic cleft. From alignment of GDH from various sources, it is likely, that the antenna evolved in the protista prior to the formation of purine, regulatory sites. This suggests that there was some selective advantage of, the antenna itself and that animals evolved new functions for GDH through, the addition of allosteric regulation.
About this StructureAbout this Structure
1NR7 is a Single protein structure of sequence from Bos taurus. Active as Glutamate dehydrogenase (NAD(P)(+)), with EC number 1.4.1.3 Full crystallographic information is available from OCA.
ReferenceReference
Structural studies on ADP activation of mammalian glutamate dehydrogenase and the evolution of regulation., Banerjee S, Schmidt T, Fang J, Stanley CA, Smith TJ, Biochemistry. 2003 Apr 1;42(12):3446-56. PMID:12653548
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