3g6w

From Proteopedia

Asymetric GTP bound structure of UPRTase from Sulfolobus solfataricus containing PRPP-mg2+ in half of the active sites and R5P and PPi in the other half

PDB ID 3g6w

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Structural highlights

3g6w is a 4 chain structure with sequence from Saccharolobus solfataricus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 2.9Å
Ligands:	, , , ,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

UPP_SACS2 Catalyzes the conversion of uracil and 5-phospho-alpha-D-ribose 1-diphosphate (PRPP) to UMP and diphosphate.^[1]

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

Publication Abstract from PubMed

Uracil phosphoribosyltransferase catalyzes the conversion of 5-phosphoribosyl-alpha-1-diphosphate (PRPP) and uracil to uridine monophosphate (UMP) and diphosphate (PP(i)). The tetrameric enzyme from Sulfolobus solfataricus has a unique type of allosteric regulation by cytidine triphosphate (CTP) and guanosine triphosphate (GTP). Here we report two structures of the activated state in complex with GTP. One structure (refined at 2.8-A resolution) contains PRPP in all active sites, while the other structure (refined at 2.9-A resolution) has PRPP in two sites and the hydrolysis products, ribose-5-phosphate and PP(i), in the other sites. Combined with three existing structures of uracil phosphoribosyltransferase in complex with UMP and the allosteric inhibitor cytidine triphosphate (CTP), these structures provide valuable insight into the mechanism of allosteric transition from inhibited to active enzyme. The regulatory triphosphates bind at a site in the center of the tetramer in a different manner and change the quaternary arrangement. Both effectors contact Pro94 at the beginning of a long beta-strand in the dimer interface, which extends into a flexible loop over the active site. In the GTP-bound state, two flexible loop residues, Tyr123 and Lys125, bind the PP(i) moiety of PRPP in the neighboring subunit and contribute to catalysis, while in the inhibited state, they contribute to the configuration of the active site for UMP rather than PRPP binding. The C-terminal Gly216 participates in a hydrogen-bond network in the dimer interface that stabilizes the inhibited, but not the activated, state. Tagging the C-terminus with additional amino acids generates an endogenously activated enzyme that binds GTP without effects on activity.

Structural and kinetic studies of the allosteric transition in Sulfolobus solfataricus uracil phosphoribosyltransferase: Permanent activation by engineering of the C-terminus.,Christoffersen S, Kadziola A, Johansson E, Rasmussen M, Willemoes M, Jensen KF J Mol Biol. 2009 Oct 23;393(2):464-77. Epub 2009 Aug 14. PMID:19683539^[2]

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

References

↑ Jensen KF, Arent S, Larsen S, Schack L. Allosteric properties of the GTP activated and CTP inhibited uracil phosphoribosyltransferase from the thermoacidophilic archaeon Sulfolobus solfataricus. FEBS J. 2005 Mar;272(6):1440-53. PMID:15752360 doi:http://dx.doi.org/10.1111/j.1742-4658.2005.04576.x
↑ Christoffersen S, Kadziola A, Johansson E, Rasmussen M, Willemoes M, Jensen KF. Structural and kinetic studies of the allosteric transition in Sulfolobus solfataricus uracil phosphoribosyltransferase: Permanent activation by engineering of the C-terminus. J Mol Biol. 2009 Oct 23;393(2):464-77. Epub 2009 Aug 14. PMID:19683539 doi:10.1016/j.jmb.2009.08.019