X-ray structure of human acid-beta-glucosidase covalently bound to conduritol B epoxide (1y7v)
(see also Treatment of Gaucher disease)
Publication Abstract from PubMed
Gaucher disease is an inherited metabolic disorder caused by mutations in the lysosomal enzyme acid-beta-glucosidase (GlcCerase). We recently determined the x-ray structure of GlcCerase to 2.0 A resolution (Dvir, H., Harel, M., McCarthy, A. A., Toker, L., Silman, I., Futerman, A. H., and Sussman, J. L. (2003) EMBO Rep.4, 704-709) and have now solved the structure of Glc-Cerase conjugated with an irreversible inhibitor, conduritol-B-epoxide (CBE). The crystal structure reveals that binding of CBE to the active site does not induce a global conformational change in GlcCerase and confirms that Glu340 is the catalytic nucleophile. However, only one of two alternative conformations of a pair of flexible loops (residues 345-349 and 394-399) located at the entrance to the active site in native GlcCerase is observed in the GlcCerase-CBE structure, a conformation in which the active site is accessible to CBE. Analysis of the dynamics of these two alternative conformations suggests that the two loops act as a lid at the entrance to the active site. This possibility is supported by a cluster of mutations in loop 394-399 that cause Gaucher disease by reducing catalytic activity. Moreover, in silico mutational analysis demonstrates that all these mutations stabilize the conformation that limits access to the active site, thus providing a mechanistic explanation of how mutations in this loop result in Gaucher disease.
X-ray structure of human acid-beta-glucosidase covalently bound to conduritol-B-epoxide. Implications for Gaucher disease.,Premkumar L, Sawkar AR, Boldin-Adamsky S, Toker L, Silman I, Kelly JW, Futerman AH, Sussman JL J Biol Chem. 2005 Jun 24;280(25):23815-9. Epub 2005 Apr 6. PMID:15817452[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
The crystal structure of the human acid-β-glucosidase (acid-beta-glucosidase, glucocerebrosidase, , E.C. 3.2.1.45, colored yellow with covalently bound irreversible inhibitor (conduritol-B-epoxide; CBE; shown in cyan with its hydroxyl groups are in red) was solved. This structure reveals that binding of CBE to the active site does not induce a global conformational change in GlcCerase and confirms that Glu340 is the active-site catalytic nucleophile, because the between the cyclohexitol C1 atom and Glu340 Oε2 is 1.43 Å. The comparison between the active sites of and another representative of the glycohydrolase family - plant (1iev), reveals that CBE bound with this plant enzyme adopted the "chair" conformation, while with human , it is observed in a "boat" conformation, with hydrogen bonds to Asn234 Oδ1 and Nδ2, Glu340 Oε1, Trp179 Nε1, and Asp127 Oδ1 and Oδ2.
Only one of two of a pair of flexible loops (L1: Ser345–Glu349, and L2: Val394–Asp399) located at the entrance to the active site in native GlcCerase (1ogs) is observed in the GlcCerase-CBE structure, a conformation in which the active site is accessible to CBE (colored blue), while these loops in the second (closed) conformation are colored magenta. In , a major structural change is observed in the positions of , and in a more limited difference is observed in the conformations of . Analysis of the dynamics of these two alternative conformations suggests that the two loops act as a lid at the entrance to the active site. The movies 1 and 2 illustrate the dynamics of the movement of these two loops [2][3].
