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Title: Dissociation of glucocerebrosidase dimer in solution by its co-factor, saposin C

Mutations in the gene for the lysosomal enzyme glucocerebrosidase (GCase) cause Gaucher disease and are the most common risk factor for Parkinson disease (PD). Analytical ultracentrifugation of 8 μM GCase shows equilibrium between monomer and dimer forms. However, in the presence of its co-factor saposin C (Sap C), only monomer GCase is seen. Isothermal calorimetry confirms that Sap C associates with GCase in solution in a 1:1 complex (Kd = 2.1 ± 1.1 μM). Saturation cross-transfer NMR determined that the region of Sap C contacting GCase includes residues 63–66 and 74–76, which is distinct from the region known to enhance GCase activity. Because α-synuclein (α-syn), a protein closely associated with PD etiology, competes with Sap C for GCase binding, its interaction with GCase was also measured by ultracentrifugation and saturation cross-transfer. Unlike Sap C, binding of α-syn to GCase does not affect multimerization. However, adding α-syn reduces saturation cross-transfer from Sap C to GCase, confirming displacement. To explore where Sap C might disrupt multimeric GCase, GCase x-ray structures were analyzed using the program PISA, which predicted stable dimer and tetramer forms. In conclusion, for the most frequently predicted multimer interface, the GCase active sites are partially buried, suggesting that Sapmore » C might disrupt the multimer by binding near the active site.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1]
  1. National Inst. of Health (NIH), Bethesda, MD (United States)
Publication Date:
Grant/Contract Number:
W-31-109-ENG-38
Type:
Accepted Manuscript
Journal Name:
Biochemical and Biophysical Research Communications
Additional Journal Information:
Journal Volume: 457; Journal Issue: 4; Journal ID: ISSN 0006-291X
Publisher:
Elsevier
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org:
USDOE; National Institutes of Health (NIH)
Country of Publication:
United States
Language:
ENGLISH
Subject:
59 BASIC BIOLOGICAL SCIENCES; Gaucher disease; Parkinson disease; NMR; AUC; α-synuclein
OSTI Identifier:
1225745
Alternate Identifier(s):
OSTI ID: 1233917