5tjh | pdb_00005tjh

hUGDH A136M Substitution

spinqualitylabelsall models 5tjh, resolution 2.05Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 5tjh is a 6 chain structure with sequence from Homo sapiens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.05Å Ligands: CL, POP, UPG Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function UGDH_HUMAN Involved in the biosynthesis of glycosaminoglycans; hyaluronan, chondroitin sulfate, and heparan sulfate. Publication Abstract from PubMed Human UDP-glucose dehydrogenase (hUGDH) is regulated by an atypical allosteric mechanism in which the feedback inhibitor UDP-xylose (UDP-Xyl) competes with the substrate for the active site. Binding of UDP-Xyl triggers the T131-loop/alpha6 allosteric switch, which converts the hexameric structure of hUGDH into an inactive, horseshoe-shaped complex (EOmega). This allosteric transition buries residue A136 in the protein core to produce a subunit interface that favors the EOmega structure. Here we use a methionine substitution to prevent the burial of A136 and trap the T131-loop/alpha6 switch 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 EOmega 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 EOmega 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/alpha6 switch is the source of the slow isomerization. This interpretation is supported by the 2.05 A resolution crystal structure of hUGDHA136M, which shows that the A136M substitution has stabilized the active conformation of the T131-loop/alpha6 allosteric switch. This work shows time that the T131-loop/alpha6 allosteric switch couples allostery and hysteresis in hUGDH. Allostery and Hysteresis Are Coupled in Human UDP-Glucose Dehydrogenase.,Beattie NR, Keul ND, Sidlo AM, Wood ZA Biochemistry. 2016 Dec 22. doi: 10.1021/acs.biochem.6b01044. PMID:27966912 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

Proteopedia Page Contributors and Editors (what is this?)

OCA