1fo2

From Proteopedia

Revision as of 10:40, 21 February 2008

CRYSTAL STRUCTURE OF HUMAN CLASS I ALPHA1,2-MANNOSIDASE IN COMPLEX WITH 1-DEOXYMANNOJIRIMYCIN

Overview

Endoplasmic reticulum (ER) class I alpha1,2-mannosidase (also known as ER alpha-mannosidase I) is a critical enzyme in the maturation of N-linked oligosaccharides and ER-associated degradation. Trimming of a single mannose residue acts as a signal to target misfolded glycoproteins for degradation by the proteasome. Crystal structures of the catalytic domain of human ER class I alpha1,2-mannosidase have been determined both in the presence and absence of the potent inhibitors kifunensine and 1-deoxymannojirimycin. Both inhibitors bind to the protein at the bottom of the active-site cavity, with the essential calcium ion coordinating the O-2' and O-3' hydroxyls and stabilizing the six-membered rings of both inhibitors in a (1)C(4) conformation. This is the first direct evidence of the role of the calcium ion. The lack of major conformational changes upon inhibitor binding and structural comparisons with the yeast alpha1, 2-mannosidase enzyme-product complex suggest that this class of inverting enzymes has a novel catalytic mechanism. The structures also provide insight into the specificity of this class of enzymes and provide a blueprint for the future design of novel inhibitors that prevent degradation of misfolded proteins in genetic diseases.

About this Structure

1FO2 is a Single protein structure of sequence from Homo sapiens with , and as ligands. Active as Alpha-mannosidase, with EC number 3.2.1.24 Full crystallographic information is available from OCA.

Reference

Structural basis for catalysis and inhibition of N-glycan processing class I alpha 1,2-mannosidases., Vallee F, Karaveg K, Herscovics A, Moremen KW, Howell PL, J Biol Chem. 2000 Dec 29;275(52):41287-98. PMID:10995765

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