1sq6

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spinqualitylabelsall models PDB ID 1sq6 Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image
, resolution 2.40Å
Ligands:	,
Gene:	PlasmoDB chr5.gen_243 (Plasmodium falciparum 3D7)
Activity:	Uridine phosphorylase, with EC number 2.4.2.3
Domains:	Udp
Resources:	FirstGlance, OCA, PDBsum, RCSB
Coordinates:	save as pdb, mmCIF, xml

Plasmodium falciparum homolog of Uridine phosphorylase/Purine nucleoside phosphorylase

Overview

Purine metabolism in the parasite Plasmodium has been identified as a promising target for antimalarial therapies. Purine nucleoside phosphorylase (PNP) is part of a salvage pathway for the biosynthesis of purines, which are essential for parasite survival. Two crystal structures of PNP from Plasmodium falciparum (PfPNP) in two space groups, each with a single subunit in the asymmetric unit, are described here. One structure, refined to 2.4 A, has an empty nucleoside-binding site and a sulfate ion bound in the phosphate-binding pocket. The second structure, refined to 2.0 A, has the substrate inosine bound to the active centre. Structure comparison reveals alterations in the active site upon ligand binding. The new structures presented here specifically highlight the likely roles of Asp206 and two loops flanking the active site: the beta7-alpha6 loop (residues approximately 161-169) and the beta9-alpha8 loop (residues approximately 208-223). Comparison with PNP in complex with transition-state inhibitors suggests that the purine substrate moves towards the phosphate substrate, rather than vice versa, upon forming the transition state. The single-substrate-containing PfPNP structures also appear to be more flexible than PfPNP bound to inhibitors. Together, these structures serve as a basis for better understanding of ligand binding and mechanism that can be further exploited to optimize the specificity of anti-PfPNP drugs.

About this Structure

1SQ6 is a Single protein structure of sequence from Plasmodium falciparum 3d7. Full crystallographic information is available from OCA.

Reference

Structures of Plasmodium falciparum purine nucleoside phosphorylase complexed with sulfate and its natural substrate inosine., Schnick C, Robien MA, Brzozowski AM, Dodson EJ, Murshudov GN, Anderson L, Luft JR, Mehlin C, Hol WG, Brannigan JA, Wilkinson AJ, Acta Crystallogr D Biol Crystallogr. 2005 Sep;61(Pt 9):1245-54. Epub 2005, Aug 16. PMID:16131758

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