4LNC

Neutron structure of the cyclic glucose bound Xylose Isomerase E186Q mutant

Summary for 4LNC

• Entry DOI: 10.2210/pdb4lnc/pdb
• Descriptor: Xylose isomerase, alpha-D-glucopyranose, MANGANESE (II) ION, ... (5 entities in total)
• Functional Keywords: isomerase, mutant enzyme, metalloenzyme, two metal binding sites
• Biological source: Streptomyces rubiginosus
• Total number of polymer chains: 1
• Total formula weight: 43509.61

Authors

Munshi, P.,Meilleur, F.,Myles, D. (deposition date: 2013-07-11, release date: 2014-02-12, Last modification date: 2025-11-12)

Primary citation

Munshi, P.,Snell, E.H.,van der Woerd, M.J.,Judge, R.A.,Myles, D.A.,Ren, Z.,Meilleur, F.
Neutron structure of the cyclic glucose-bound xylose isomerase E186Q mutant.
Acta Crystallogr.,Sect.D, 70:414-420, 2014

PubMed Abstract: Ketol-isomerases catalyze the reversible isomerization between aldoses and ketoses. D-Xylose isomerase carries out the first reaction in the catabolism of D-xylose, but is also able to convert D-glucose to D-fructose. The first step of the reaction is an enzyme-catalyzed ring opening of the cyclic substrate. The active-site amino-acid acid/base pair involved in ring opening has long been investigated and several models have been proposed. Here, the structure of the xylose isomerase E186Q mutant with cyclic glucose bound at the active site, refined against joint X-ray and neutron diffraction data, is reported. Detailed analysis of the hydrogen-bond networks at the active site of the enzyme suggests that His54, which is doubly protonated, is poised to protonate the glucose O5 position, while Lys289, which is neutral, promotes deprotonation of the glucose O1H hydroxyl group via an activated water molecule. The structure also reveals an extended hydrogen-bonding network that connects the conserved residues Lys289 and Lys183 through three structurally conserved water molecules and residue 186, which is a glutamic acid to glutamine mutation.

PubMed: 24531475
DOI: 10.1107/S1399004713029684

Experimental method

NEUTRON DIFFRACTION (2.19 Å)
X-RAY DIFFRACTION (1.84 Å)