Cysteamine dioxygenase (ADO)

Cysteamine dioxygenase (ADO) is a non-heme iron-dependent enzyme that catalyzes the oxidation of cysteamine (2-aminoethanethiol) to hypotaurine, a key step in the biosynthesis of taurine. In addition to metabolizing small-molecule thiols, ADO can oxidize N-terminal cysteine in proteins, marking them for degradation via the N-degron pathway—a process important for oxygen sensing and hypoxia responses. ADO belongs to the cupin superfamily, exhibits a conserved 3-histidine Fe-binding motif, and has unique substrate flexibility that allows it to process both small molecules and protein substrates. Its biological roles include maintaining cellular sulfur/amino acid balance, preserving oxygen homeostasis, and mediating rapid protein turnover in response to hypoxic stress. Dysregulation of ADO activity is implicated in several disease processes, making it an emerging therapeutic target. Cysteamine dioxygenase (ADO) is an enzyme that catalyzes the oxygen-dependent oxidation of cysteamine to hypotaurine and plays a dual role as both a thiol-metabolizing enzyme and a contributor to oxygen sensing by post-translationally modifying proteins. There are no established therapeutics or clinical biomarkers for its activity yet, but it is an area of active research due to its central role in metabolic and stress-response pathways.

Other names

Cysteamine dioxygenaseADO2-aminoethanethiol dioxygenaseC10orf22 (previous symbol)

For hypothetical inhibitors: Inhibition of ADO would prevent the oxidation of cysteamine and N-terminal cysteine, affecting thiol metabolism and oxygen sensing pathways. No established small-molecule mechanism of action is documented for clinical agents