8YT2
Crystal structure of ACMSD mutant W194A
Summary for 8YT2
| Entry DOI | 10.2210/pdb8yt2/pdb |
| Descriptor | 2-amino-3-carboxymuconate 6-semialdehyde decarboxylase, ZINC ION (3 entities in total) |
| Functional Keywords | kynurenine, decarboxylase, nad homeostasis, tryptophan metabolism, metalloenzyme, lyase |
| Biological source | Pseudomonas fluorescens |
| Total number of polymer chains | 3 |
| Total formula weight | 111401.62 |
| Authors | |
| Primary citation | Yang, Y.,Davis, I.,Altman, R.A.,Liu, A. alpha-Amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase catalyzes enol/keto tautomerization of oxaloacetate. J.Biol.Chem., 300:107878-107878, 2024 Cited by PubMed Abstract: ACMSD (α-amino-β-carboxymuconate-ε-semialdehyde decarboxylase) is a key metalloenzyme critical for regulating de novo endogenous NAD/NADH biosynthesis through the tryptophan-kynurenine pathway. This decarboxylase is a recognized target implicated in mitochondrial diseases and neurodegenerative disorders. However, unraveling its enzyme-substrate complex has been challenging due to its high catalytic efficiency. Here, we present a combined biochemical and structural study wherein we determined the crystal structure of ACMSD in complex with malonate. Our analysis revealed significant rearrangements in the active site, particularly in residues crucial for ACMS decarboxylation, including Arg51, Arg239∗ (a residue from an adjacent subunit), His228, and Trp194. Docking modeling studies proposed a putative ACMS binding mode. Additionally, we found that ACMSD catalyzes oxaloacetic acid (OAA) tautomerization at a rate of 6.51 ± 0.42 s but not decarboxylation. The isomerase activity of ACMSD on OAA warrants further investigation in future biological studies. Subsequent mutagenesis studies and crystallographic analysis of the W194A variant shed light on the roles of specific second-coordination sphere residues. Our findings indicate that Arg51 and Arg239∗ are crucial for OAA tautomerization. Moreover, our comparative analysis with related isomerase superfamily members underscores a general strategy employing arginine residues to promote OAA isomerization. Given the observed isomerase activity of ACMSD on OAA and its structural similarity to ACMS, we propose that ACMSD may facilitate isomerization to ensure ACMS is in the optimal tautomeric form for subsequent decarboxylation initiated by the zinc-bound hydroxide ion. Overall, these findings deepen the understanding of the structure and function of ACMSD, offering insights into potential therapeutic interventions. PubMed: 39395800DOI: 10.1016/j.jbc.2024.107878 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (2.02 Å) |
Structure validation
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