6N43

Crystal structure of cysteine, nitric oxide-bound ferrous form of the crosslinked human cysteine dioxygenase in the anaerobic condition

6N43 の概要

• エントリーDOI: 10.2210/pdb6n43/pdb
• 分子名称: Cysteine dioxygenase type 1, CYSTEINE, FE (III) ION, ... (6 entities in total)
• 機能のキーワード: cysteine, cys-tyr cofactor, iron, oxidoreductase
• 由来する生物種: Homo sapiens (Human)
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 23440.95

構造登録者

Liu, A.,Li, J. (登録日: 2018-11-16, 公開日: 2019-04-17, 最終更新日: 2024-10-09)

主引用文献

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

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: 30946568
DOI: 10.1021/acs.biochem.9b00006

実験手法

X-RAY DIFFRACTION (2.289 Å)