Some properties of uridine diphosphoglucose dehydrogenase

Maxwell, Elizabeth S.; Kalckar, Herman Μ.; Strominger, Jack L.

doi:10.1016/0003-9861(56)90171-0

Cited by 58 publications

(6 citation statements)

References 9 publications

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“…The same hypothesis has been reached for the enzyme catalysing the oxidation of L-histidinol to L-histidine (Adams, 1955). Other properties of the pea enzyme are quite similar to those of the enzyme purified from calf liver (Strominger et al 1957;Maxwell, Kalckar & Strominger, 1956). SUMMARY 1.…”

Section: I957mentioning

confidence: 57%

Uridine diphosphoglucose dehydrogenase of pea seedlings

Strominger¹,

Mapson

1957

Biochemical Journal

108

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Section: I957mentioning

confidence: 57%

Uridine diphosphoglucose dehydrogenase of pea seedlings

Strominger¹,

Mapson

1957

Biochemical Journal

108

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“…9–11 UDP-GlcA is produced by UDP-glucose dehydrogenase (UGDH), which uses two molecules of NAD + to oxidize the C6 hydroxyl of UDP-glucose (UDP-Glc). 12 The downstream metabolite UDP-xylose (UDP-Xyl) acts as an allosteric feedback inhibitor to control the activity of hUGDH. 13, 14 Understanding the allosteric mechanism of UGDH is an important goal in developing strategies to control glucuronidation.…”

Section: Introductionmentioning

confidence: 99%

Hysteresis and Allostery in Human UDP-Glucose Dehydrogenase Require a Flexible Protein Core

et al. 2018

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Human UDP-glucose dehydrogenase (hUGDH) oxidizes UDP-glucose to UDP-glucuronic acid, an essential substrate in the phase II metabolism of drugs. The activity of hUGDH is regulated by the conformation of a buried allosteric switch (T131-loop/α6 helix). Substrate binding induces the allosteric switch to slowly isomerize from an inactive E* conformation to the active E state, which can be observed as enzyme hysteresis. When the feedback inhibitor UDP-xylose binds, the allosteric switch and surrounding residues in the protein core repack, converting the hexamer into an inactive, horseshoe-shaped complex (EΩ). This allosteric transition is facilitated by large cavities and declivities in the protein core that provide the space required to accommodate the alternate packing arrangements. Here, we have used the A104L substitution to fill a cavity in the E state and sterically prevent repacking of the core into the EΩ state. Steady state analysis shows that hUGDHA104L binds UDP-xylose with lower affinity and that the inhibition is no longer cooperative. This means that the allosteric transition to the high UDP-xylose affinity EΩ state is blocked by the substitution. The crystal structures of hUGDHA104L show that the allosteric switch still adopts the E and E* states, albeit with a more rigid protein core. However, the progress curves of hUGDHA104L do not show hysteresis, which suggests that the E* and E states are now in rapid equilibrium. Our data suggests that hysteresis in native hUGDH originates from the conformational entropy of the E* state protein core.

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“…It is possible to inhibit glucuronidation by limiting the availability of the essential substrate, UDP-glucuronic acid 9–11 . UDP-glucose dehydrogenase (UGDH) catalyzes the NAD + dependent oxidation of UDP-glucose (UDP-Glc) to produce UDP-glucuronic acid 12–15 . Understanding how UGDH activity is regulated is an important goal in developing new strategies to control glucuronidation-dependent drug resistance.…”

Section: Introductionmentioning

confidence: 99%

Allostery and Hysteresis Are Coupled in Human UDP-Glucose Dehydrogenase

et al. 2016

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Human UDP-glucose dehydrogenase (hUGDH) is regulated by an atypical allosteric mechanism in which the feedback inhibitor UDP-xylose (UDP-Xyl) competes with substrate for the active site. Binding of UDP-Xyl triggers the T131-Loop/α6 allosteric switch, which converts the hexameric structure of hUGDH into an inactive, horseshoe-shaped complex (EΩ). This allosteric transition buries residue A136 in the protein core to produce a subunit interface that favors the EΩ structure. Here we use a methionine substitution to prevent the burial of A136 and trap the T131-Loop/α6 in the active conformation. We show that hUGDHA136M does not exhibit substrate cooperativity, which is strong evidence that the methionine substitution prevents the formation of the low UDP-Glc affinity EΩ state. In addition, the inhibitor affinity of hUGDHA136M is reduced 14 fold, which most likely represents the Ki for competitive inhibition in the absence of the allosteric transition to the higher affinity EΩ state. hUGDH also displays a lag in progress curves, which is caused by a slow, substrate-induced isomerization that activates the enzyme. Stopped flow analysis shows that hUGDHA136M does not exhibit hysteresis, which suggests that the T131-Loop/α6 switch is the source of the slow isomerization. This interpretation is supported by the 2.05 Å resolution crystal structure of hUGDHA136M, which shows that the A136M substitution has stabilized the active conformation of the T131-loop/α6 allosteric switch. This work shows that the T131-Loop/α6 allosteric switch couples allostery and hysteresis in hUGDH.

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Some properties of uridine diphosphoglucose dehydrogenase

Cited by 58 publications

References 9 publications

Uridine diphosphoglucose dehydrogenase of pea seedlings

Uridine diphosphoglucose dehydrogenase of pea seedlings

Hysteresis and Allostery in Human UDP-Glucose Dehydrogenase Require a Flexible Protein Core

Allostery and Hysteresis Are Coupled in Human UDP-Glucose Dehydrogenase

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