6BVQ
Crystal structure of 3-hydroxyanthranilate-3,4-dioxygenase N27A from Cupriavidus metallidurans in complex with 4-Cl-3-HAA
Summary for 6BVQ
| Entry DOI | 10.2210/pdb6bvq/pdb |
| Descriptor | 3-hydroxyanthranilate 3,4-dioxygenase, FE (II) ION, 4-CHLORO-3-HYDROXYANTHRANILIC ACID, ... (5 entities in total) |
| Functional Keywords | complex structure, dioxygenase, mutant n27a, oxidoreductase |
| Biological source | Cupriavidus metallidurans (Ralstonia metallidurans) |
| Total number of polymer chains | 1 |
| Total formula weight | 22968.76 |
| Authors | |
| Primary citation | Yang, Y.,Liu, F.,Liu, A. Adapting to oxygen: 3-Hydroxyanthrinilate 3,4-dioxygenase employs loop dynamics to accommodate two substrates with disparate polarities. J. Biol. Chem., 293:10415-10424, 2018 Cited by PubMed Abstract: 3-Hydroxyanthranilate 3,4-dioxygenase (HAO) is an iron-dependent protein that activates O and inserts both oxygen atoms into 3-hydroxyanthranilate (3-HAA). An intriguing question is how HAO can rapidly bind O, even though local O concentrations and diffusion rates are relatively low. Here, a close inspection of the HAO structures revealed that substrate- and inhibitor-bound structures exhibit a closed conformation with three hydrophobic loop regions moving toward the catalytic iron center, whereas the ligand-free structure is open. We hypothesized that these loop movements enhance O binding to the binary complex of HAO and 3-HAA. We found that the carboxyl end of 3-HAA triggers changes in two loop regions and that the third loop movement appears to be driven by an H-bond interaction between Asn and Ile Mutational analyses revealed that N27A, I142A, and I142P variants cannot form a closed conformation, and steady-state kinetic assays indicated that these variants have a substantially higher for O than WT HAO. This observation suggested enhanced hydrophobicity at the iron center resulting from the concerted loop movements after the binding of the primary substrate, which is hydrophilic. Given that O is nonpolar, the increased hydrophobicity at the iron center of the binary complex appears to be essential for rapid O binding and activation, explaining the reason for the 3-HAA-induced loop movements. Because substrate binding-induced open-to-closed conformational changes are common, the results reported here may help further our understanding of how oxygen is enriched in nonheme iron-dependent dioxygenases. PubMed: 29784877DOI: 10.1074/jbc.RA118.002698 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (2.084 Å) |
Structure validation
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