8UAN

The crystal structure of cobalt-bound human ADO C18S C239S variant at 1.99 Angstrom

Summary for 8UAN

• Entry DOI: 10.2210/pdb8uan/pdb
• Related: 8U9J
• Descriptor: 2-aminoethanethiol dioxygenase, COBALT (II) ION, GLYCEROL, ... (4 entities in total)
• Functional Keywords: cysteamine dioxygenase; cobalt-bound human ado, oxidoreductase
• Biological source: Homo sapiens (human)
• Total number of polymer chains: 1
• Total formula weight: 30535.39

Authors

Liu, A.,Li, J.,Duan, R.,Shin, I. (deposition date: 2023-09-21, release date: 2024-07-17, Last modification date: 2024-07-24)

Primary citation

Li, J.,Duan, R.,Liu, A.
Cobalt(II)-Substituted Cysteamine Dioxygenase Oxygenation Proceeds through a Cobalt(III)-Superoxo Complex.
J.Am.Chem.Soc., 146:18292-18297, 2024

PubMed Abstract: We investigated the metal-substituted catalytic activity of human cysteamine dioxygenase (ADO), an enzyme pivotal in regulating thiol metabolism and contributing to oxygen homeostasis. Our findings demonstrate the catalytic competence of cobalt(II)- and nickel(II)-substituted ADO in cysteamine oxygenation. Notably, Co(II)-ADO exhibited superiority over Ni(II)-ADO despite remaining significantly less active than the natural enzyme. Structural analyses through X-ray crystallography and cobalt K-edge excitation confirmed successful metal substitution with minimal structural perturbations. This provided a robust structural basis, supporting a conserved catalytic mechanism tailored to distinct metal centers. This finding challenges the proposed high-valent ferryl-based mechanism for thiol dioxygenases, suggesting a non-high-valent catalytic pathway in the native enzyme. Further investigation of the cysteamine-bound or a peptide mimic of -terminus RGS5 bound Co(II)-ADO binary complex revealed the metal center's high-spin ( = 3/2) state. Upon reaction with O, a kinetically and spectroscopically detectable intermediate emerged with a ground spin state of = 1/2. This intermediate exhibits a characteristic Co hyperfine splitting ( = 67 MHz) structure in the EPR spectrum alongside UV-vis features, consistent with known low-spin Co(III)-superoxo complexes. This observation, unique for protein-bound thiolate-ligated cobalt centers in a protein, unveils the capacities for O activation in such metal environments. These findings provide valuable insights into the non-heme iron-dependent thiol dioxygenase mechanistic landscape, furthering our understanding of thiol metabolism regulation. The exploration of metal-substituted ADO sheds light on the intricate interplay between metal and catalytic activity in this essential enzyme.

PubMed: 38941563
DOI: 10.1021/jacs.4c01871

Experimental method

X-RAY DIFFRACTION (1.99 Å)