Inhibition and Crystal Structure of the Human DHTKD1-Thiamin Diphosphate Complex

DHTKD1
is the E1 component of the 2-oxoadipate dehydrogenase complex,
which is an enzyme involved in the catabolism of (hydroxy-)­lysine
and tryptophan. Mutations in DHTKD1 have been associated with 2-aminoadipic
and 2-oxoadipic aciduria, Charcot–Marie–Tooth disease
type 2Q and eosinophilic esophagitis, but the pathophysiology of these
clinically distinct disorders remains elusive. Here, we report the
identification of adipoylphosphonic acid and tenatoprazole as DHTKD1
inhibitors using targeted and high throughput screening, respectively.
We furthermore elucidate the DHTKD1 crystal structure with thiamin
diphosphate bound at 2.25 Å. We also report the impact of 10
disease-associated missense mutations on DHTKD1. Whereas the majority
of the DHTKD1 variants displayed impaired folding or reduced thermal
stability in combination with absent or reduced enzyme activity, three
variants showed no abnormalities. Our work provides chemical and structural
tools for further understanding of the function of DHTKD1 and its
role in several human pathologies.