6E87
Crystal structure of ferrous form of the crosslinked human cysteine dioxygenase in the anaerobic condition
Summary for 6E87
| Entry DOI | 10.2210/pdb6e87/pdb |
| Descriptor | Cysteine dioxygenase type 1, FE (II) ION, SULFATE ION, ... (5 entities in total) |
| Functional Keywords | cysteine, cys-tyr cofactor, iron, unnatural amino acid, oxidoreductase |
| Biological source | Homo sapiens (Human) |
| Total number of polymer chains | 1 |
| Total formula weight | 23658.17 |
| Authors | |
| Primary citation | Li, J.,Koto, T.,Davis, I.,Liu, A. Probing the Cys-Tyr Cofactor Biogenesis in Cysteine Dioxygenase by the Genetic Incorporation of Fluorotyrosine. Biochemistry, 58:2218-2227, 2019 Cited by PubMed Abstract: Cysteine dioxygenase (CDO) is a nonheme iron enzyme that adds two oxygen atoms from dioxygen to the sulfur atom of l-cysteine. Adjacent to the iron site of mammalian CDO, there is a post-translationally generated Cys-Tyr cofactor, whose presence substantially enhances the oxygenase activity. The formation of the Cys-Tyr cofactor in CDO is an autocatalytic process, and it is challenging to study by traditional techniques because the cross-linking reaction is a side, uncoupled, single-turnover oxidation buried among multiple turnovers of l-cysteine oxygenation. Here, we take advantage of our recent success in obtaining a purely uncross-linked human CDO due to site-specific incorporation of 3,5-difluoro-l-tyrosine (F-Tyr) at the cross-linking site through the genetic code expansion strategy. Using EPR spectroscopy, we show that nitric oxide (NO), an oxygen surrogate, similarly binds to uncross-linked F-Tyr157 CDO as in wild-type human CDO. We determined X-ray crystal structures of uncross-linked F-Tyr157 CDO and mature wild-type CDO in complex with both l-cysteine and NO. These structural data reveal that the active site cysteine (Cys93 in the human enzyme), rather than the generally expected tyrosine (i.e., Tyr157), is well-aligned to be oxidized should the normal oxidation reaction uncouple. This structure-based understanding is further supported by a computational study with models built on the uncross-linked ternary complex structure. Together, these results strongly suggest that the first target to oxidize during the iron-assisted Cys-Tyr cofactor biogenesis is Cys93. Based on these data, a plausible reaction mechanism implementing a cysteine radical involved in the cross-link formation is proposed. PubMed: 30946568DOI: 10.1021/acs.biochem.9b00006 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1.952 Å) |
Structure validation
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