PDBsum entry 1vst

Transferase

PDB id: 1vst

Contents

Protein chain

215 a.a. *

Ligands

GTP

PRP

Metals

_MG

Waters ×10

* Residue conservation analysis

PDB id:

1vst

Name:

Transferase

Title:

Symmetric sulfolobus solfataricus uracil phosphoribosyltransferase with bound prpp and gtp

Structure:

Uracil phosphoribosyltransferase. Chain: a. Synonym: ump pyrophosphorylase, uprtase. Engineered: yes

Source:

Sulfolobus solfataricus. Organism_taxid: 2287. Gene: sso0231, upp. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.80Å R-factor: 0.226 R-free: 0.277

Authors:

A.Kadziola

Key ref:

S.Christoffersen et al. (2009). Structural and kinetic studies of the allosteric transition in Sulfolobus solfataricus uracil phosphoribosyltransferase: Permanent activation by engineering of the C-terminus. J Mol Biol, 393, 464-477. PubMed id: 19683539

Date:

09-Feb-09 Release date: 01-Sep-09

Protein chain

Q980Q4  (UPP_SULSO) -  Uracil phosphoribosyltransferase from Saccharolobus solfataricus (strain ATCC 35092 / DSM 1617 / JCM 11322 / P2)

Seq: 216 a.a.

Struc: 215 a.a.

Enzyme reactions

• Enzyme class: E.C.2.4.2.9 - uracil phosphoribosyltransferase.
• Reaction: UMP + diphosphate = 5-phospho-alpha-D-ribose 1-diphosphate + uracil

UMP + diphosphate (Bound ligand (Het Group name = GTP) matches with 60.61% similarity) = 5-phospho-alpha-D-ribose 1-diphosphate (Bound ligand (Het Group name = PRP) corresponds exactly) + uracil

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

J Mol Biol 393:464-477 (2009)

PubMed id: 19683539

Structural and kinetic studies of the allosteric transition in Sulfolobus solfataricus uracil phosphoribosyltransferase: Permanent activation by engineering of the C-terminus.

S.Christoffersen, A.Kadziola, E.Johansson, M.Rasmussen, M.Willemoës, K.F.Jensen.

ABSTRACT

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.