3K43

Crystal structure of sCD-MPR mutant E19Q/K137M pH 6.5

Summary for 3K43

• Entry DOI: 10.2210/pdb3k43/pdb
• Related: 3K41 3K42
• Descriptor: Cation-dependent mannose-6-phosphate receptor, 2-acetamido-2-deoxy-beta-D-glucopyranose, SULFATE ION, ... (6 entities in total)
• Functional Keywords: transport, lysosome, mannose, receptor, sugar binding, glycoprotein, membrane, phosphoprotein, transmembrane, protein transport, sugar binding protein
• Biological source: Bos taurus (bovine,cow,domestic cattle,domestic cow)
• Cellular location: Lysosome membrane ; Single-pass type I membrane protein : P11456
• Total number of polymer chains: 2
• Total formula weight: 35747.96

Authors

Olson, L.J.,Sun, G.,Bohnsack, R.N.,Peterson, F.C.,Dahms, N.M.,Kim, J.J.P. (deposition date: 2009-10-05, release date: 2009-11-24, Last modification date: 2024-10-30)

Primary citation

Olson, L.J.,Sun, G.,Bohnsack, R.N.,Peterson, F.C.,Dahms, N.M.,Kim, J.J.
Intermonomer interactions are essential for lysosomal enzyme binding by the cation-dependent mannose 6-phosphate receptor.
Biochemistry, 49:236-246, 2010

PubMed Abstract: The 46 kDa cation-dependent mannose 6-phosphate receptor (CD-MPR) plays a key role in the delivery of lysosomal enzymes to the lysosome by binding newly synthesized mannose 6-phosphate (Man-6-P)-containing acid hydrolases and diverting them from the secretory pathway. Previous studies on a truncated form of the receptor comprised of only the soluble extracellular region (sCD-MPR, residues 1-154) have shown that the CD-MPR exists as a homodimer and exhibits two distinct conformations in the ligand-bound versus ligand-unbound states, involving changes in quaternary structure and positioning of loop D, the residues of which form a side of the binding pocket in the presence of ligand. To determine the role of intermonomer contacts in the functioning of the sCD-MPR, site-directed mutagenesis was used to generate a construct lacking a salt bridge (Glu19-Lys137) that tethers the N-terminal alpha-helix of one subunit to loop D of the other subunit in the ligand-bound form. Here we show by surface plasmon resonance analyses and NMR spectroscopy that the elimination of this intermonomer salt bridge significantly decreases the binding affinity of the mutant receptor (E19Q/K137M) toward lysosomal enzymes and Man-6-P. Analyses of the E19Q/K137M mutant receptor crystallized under various conditions revealed an altered quaternary structure that is intermediate between those observed in the ligand-bound and ligand-unbound states. Taken together, the results demonstrate a key role for intermonomer interactions in the structure and functioning of the CD-MPR.

PubMed: 19928875
DOI: 10.1021/bi901725x

Experimental method

X-RAY DIFFRACTION (2 Å)