1uj5

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spinqualitylabelsall models 1uj5, resolution 2.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal structure of Thermus thermophilus ribose-5-phosphate isomerase complexed with ribose-5-phosphate

Overview

Ribose-5-phosphate isomerase (Rpi) acts as a key enzyme in the oxidative, and reductive pentose-phosphate pathways for the conversion of, ribose-5-phosphate (R5P) to ribulose-5-phosphate and vice versa. We have, determined the crystal structures of Rpi from Thermus thermophilus HB8 in, complex with the open chain form of the substrate R5P and the open chain, form of the C2 epimeric inhibitor arabinose-5-phosphate as well as the apo, form at high resolution. The crystal structures of both complexes revealed, that these ring-opened epimers are bound in the active site in a mirror, symmetry binding mode. The O1 atoms are stabilized by an oxyanion hole, composed of the backbone amide nitrogens in the conserved motif. In the, structure of the Rpi.R5P complex, the conversion moiety O1-C1-C2-O2 in, cis-configuration interacts with the carboxyl oxygens of Glu-108 in a, water-excluded environment. Furthermore, the C2 hydroxyl group is presumed, to be highly polarized by short hydrogen bonding with the side chain of, Lys-99. R5P bound as the ring-opened reaction intermediate clarified the, high stereoselectivity of the catalysis and is consistent with an, aldose-ketose conversion by Rpi that proceeds via a cis-enediolate, intermediate.

About this Structure

1UJ5 is a Single protein structure of sequence from Thermus thermophilus with 5RP and CL as ligands. Active as Ribose-5-phosphate isomerase, with EC number 5.3.1.6 Full crystallographic information is available from OCA.

Reference

Oxyanion hole-stabilized stereospecific isomerization in ribose-5-phosphate isomerase (Rpi)., Hamada K, Ago H, Sugahara M, Nodake Y, Kuramitsu S, Miyano M, J Biol Chem. 2003 Dec 5;278(49):49183-90. Epub 2003 Sep 17. PMID:13679361

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