9dh0

Publication Abstract from PubMed

Human UDP-glucose dehydrogenase (hUGDH) catalyzes the oxidation of UDP-glucose into UDP-glucuronic acid, an essential substrate in the Phase II metabolism of drugs. hUGDH is a hexamer that exists in an equilibrium between an active (E) state and an inactive (E(Omega)) state, with the latter being stabilized by the binding of the allosteric inhibitor UDP-xylose (UDP-Xyl). The allosteric transition between E(Omega) and E is slow and can be observed as a lag in progress curves. Previous analysis of the lag suggested that unliganded hUGDH exists mainly as E(Omega), but two unique crystal forms suggest that the enzyme favors the E state. Resolving this discrepancy is necessary to fully understand the allosteric mechanism of hUGDH. Here, we used cryo-EM to show that recombinant hUGDH expressed in Escherichia coli copurifies with UDP-4-keto-xylose (UX4O), which mimics the UDP-Xyl inhibitor and favors the E(Omega) state. Cryo-EM studies show that removing UX4O from hUGDH shifts the ensemble to favor the E state. This shift is consistent with progress curve analysis, which shows the absence of a lag for unliganded hUGDH. Inhibition studies show that hUGDH has similar affinities for UDP-Xyl and UX4O. The discovery that UX4O inhibits allosteric hUGDH suggests that UX4O may be the physiologically relevant inhibitor of allosteric UGDHs in bacteria that do not make UDP-Xyl.

Cryo-EM Structure of Recombinantly Expressed hUGDH Unveils a Hidden, Alternative Allosteric Inhibitor.,O'Brien JH, Kadirvelraj R, Tseng PS, Ross-Kemppinen N, Crich D, Walsh RM Jr, Wood ZA Biochemistry. 2025 Jan 7;64(1):92-104. doi: 10.1021/acs.biochem.4c00555. Epub , 2024 Dec 16. PMID:39680853^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.