This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.
Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.
1krf
From Proteopedia
OCA (Talk | contribs)
(New page: 200px<br /><applet load="1krf" size="450" color="white" frame="true" align="right" spinBox="true" caption="1krf, resolution 2.20Å" /> '''STRUCTURE OF P. CITR...)
Next diff →
Revision as of 17:37, 20 November 2007
|
STRUCTURE OF P. CITRINUM ALPHA 1,2-MANNOSIDASE REVEALS THE BASIS FOR DIFFERENCES IN SPECIFICITY OF THE ER AND GOLGI CLASS I ENZYMES
Overview
Class I alpha1,2-mannosidases (glycosylhydrolase family 47) are key, enzymes in the maturation of N-glycans. This protein family includes two, distinct enzymatically active subgroups. Subgroup 1 includes the yeast and, human endoplasmic reticulum (ER) alpha1,2-mannosidases that primarily trim, Man(9)GlcNAc(2) to Man(8)GlcNAc(2) isomer B whereas subgroup 2 includes, mammalian Golgi alpha1,2-mannosidases IA, IB, and IC that trim, Man(9)GlcNAc(2) to Man(5)GlcNAc(2) via Man(8)GlcNAc(2) isomers A and C., The structure of the catalytic domain of the subgroup 2, alpha1,2-mannosidase from Penicillium citrinum has been determined by, molecular replacement at 2.2-A resolution. The fungal alpha1,2-mannosidase, is an (alphaalpha)(7)-helix barrel, very similar to the subgroup 1 yeast, (Vallee, F., Lipari, F., Yip, P., Sleno, B., Herscovics, A., and Howell, P. L. (2000) EMBO J. 19, 581-588) and human (Vallee, F., Karaveg, K., Herscovics, A., Moremen, K. W., and Howell, P. L. (2000) J. Biol. Chem., 275, 41287-41298) ER enzymes. The location of the conserved acidic, residues of the catalytic site and the binding of the inhibitors, kifunensine and 1-deoxymannojirimycin, to the essential calcium ion are, conserved in the fungal enzyme. However, there are major structural, differences in the oligosaccharide binding site between the two, alpha1,2-mannosidase subgroups. In the subgroup 1 enzymes, an arginine, residue plays a critical role in stabilizing the oligosaccharide, substrate. In the fungal alpha1,2-mannosidase this arginine is replaced by, glycine. This replacement and other sequence variations result in a more, spacious carbohydrate binding site. Modeling studies of interactions, between the yeast, human and fungal enzymes with different Man(8)GlcNAc(2), isomers indicate that there is a greater degree of freedom to bind the, oligosaccharide in the active site of the fungal enzyme than in the yeast, and human ER alpha1,2-mannosidases.
About this Structure
1KRF is a Single protein structure of sequence from Penicillium citrinum with CA and KIF as ligands. Active as Mannosyl-oligosaccharide 1,2-alpha-mannosidase, with EC number 3.2.1.113 Full crystallographic information is available from OCA.
Reference
Structure of Penicillium citrinum alpha 1,2-mannosidase reveals the basis for differences in specificity of the endoplasmic reticulum and Golgi class I enzymes., Lobsanov YD, Vallee F, Imberty A, Yoshida T, Yip P, Herscovics A, Howell PL, J Biol Chem. 2002 Feb 15;277(7):5620-30. Epub 2001 Nov 19. PMID:11714724
Page seeded by OCA on Tue Nov 20 19:44:39 2007
