1NXC

Structure of mouse Golgi alpha-1,2-mannosidase IA reveals the molecular basis for substrate specificity among Class I enzymes (family 47 glycosidases)

Summary for 1NXC

• Entry DOI: 10.2210/pdb1nxc/pdb
• Descriptor: Mannosyl-oligosaccharide 1,2-alpha-mannosidase IA, alpha-D-mannopyranose-(1-6)-alpha-D-mannopyranose-(1-3)-[alpha-D-mannopyranose-(1-3)-[alpha-D-mannopyranose-(1-6)]alpha-D-mannopyranose-(1-6)]beta-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, CALCIUM ION, ... (4 entities in total)
• Functional Keywords: mannosidase, glycosidase, structural genomics, psi, protein structure initiative, southeast collaboratory for structural genomics, secsg, hydrolase
• Biological source: Mus musculus (house mouse)
• Total number of polymer chains: 1
• Total formula weight: 55977.46

Authors

Tempel, W.,Liu, Z.-J.,Karaveg, K.,Rose, J.,Moremen, K.W.,Wang, B.-C.,Southeast Collaboratory for Structural Genomics (SECSG) (deposition date: 2003-02-10, release date: 2004-05-04, Last modification date: 2020-07-29)

Primary citation

Tempel, W.,Karaveg, K.,Liu, Z.-J.,Rose, J.,Wang, B.-C.,Moremen, K.W.
Structure of mouse Golgi alpha-mannosidase IA reveals the molecular basis for substrate specificity among class 1 (family 47 glycosylhydrolase) alpha1,2-mannosidases
J.Biol.Chem., 279:29774-29786, 2004

PubMed Abstract: Three subfamilies of mammalian Class 1 processing alpha1,2-mannosidases (family 47 glycosidases) play critical roles in the maturation of Asn-linked glycoproteins in the endoplasmic reticulum (ER) and Golgi complex as well as influencing the timing and recognition for disposal of terminally unfolded proteins by ER-associated degradation. In an effort to define the structural basis for substrate recognition among Class 1 mannosidases, we have crystallized murine Golgi mannosidase IA (space group P2(1)2(1)2(1)), and the structure was solved to 1.5-A resolution by molecular replacement. The enzyme assumes an (alphaalpha)(7) barrel structure with a Ca(2+) ion coordinated at the base of the barrel similar to other Class 1 mannosidases. Critical residues within the barrel structure that coordinate the Ca(2+) ion or presumably bind and catalyze the hydrolysis of the glycone are also highly conserved. A Man(6)GlcNAc(2) oligosaccharide attached to Asn(515) in the murine enzyme was found to extend into the active site of an adjoining protein unit in the crystal lattice in a presumed enzyme-product complex. In contrast to an analogous complex previously isolated for Saccharomyces cerevisiae ER mannosidase I, the oligosaccharide in the active site of the murine Golgi enzyme assumes a different conformation to present an alternate oligosaccharide branch into the active site pocket. A comparison of the observed protein-carbohydrate interactions for the murine Golgi enzyme with the binding cleft topologies of the other family 47 glycosidases provides a framework for understanding the structural basis for substrate recognition among this class of enzymes.

PubMed: 15102839
DOI: 10.1074/jbc.M403065200

Experimental method

X-RAY DIFFRACTION (1.51 Å)