Abstract

Human phytanoyl-CoA dioxygenase domain-containing 1 (PHYHD1) is a 2-oxoglutarate (2OG)-dependent dioxygenase implicated in Alzheimer’s disease, some cancers, and immune cell functions. The substrate, kinetic and inhibitory properties, function and subcellular localization of PHYHD1 are unknown. We used recombinant expression and enzymatic, biochemical, biophysical, cellular and microscopic assays for their determination. The apparent K_m values of PHYHD1 for 2OG, Fe²⁺ and O₂ were 27, 6 and > 200 μm, respectively. PHYHD1 activity was tested in the presence of 2OG analogues, and it was found to be inhibited by succinate and fumarate but not R-2-hydroxyglutarate, whereas citrate acted as an allosteric activator. PHYHD1 bound mRNA, but its catalytic activity was inhibited upon interaction. PHYHD1 was found both in the nucleus and cytoplasm. Interactome analyses linked PHYHD1 to cell division and RNA metabolism, while phenotype analyses linked it to carbohydrate metabolism. Thus, PHYHD1 is a potential novel oxygen sensor regulated by mRNA and citrate.