1e33
|
CRYSTAL STRUCTURE OF AN ARYLSULFATASE A MUTANT P426L
OverviewOverview
In one of the most common mutations causing metachromatic leukodystrophy, the P426L-allele of arylsulfatase A (ASA), the deficiency of ASA results, from its instability in lysosomes. Inhibition of lysosomal cysteine, proteinases protects the P426L-ASA and restores the sulfatide catabolism, in fibroblasts of the patients. P426L-ASA, but not wild type ASA, was, cleaved by purified cathepsin L at threonine 421 yielding 54- and 9-kDa, fragments. X-ray crystallography at 2.5-A resolution showed that cleavage, is not due to a difference in the protein fold that would expose the, peptide bond following threonine 421 to proteases. Octamerization, which, depends on protonation of Glu-424, was impaired for P426L-ASA. The, mutation lowers the pH for the octamer/dimer equilibrium by 0.6 pH units, from pH 5.8 to 5.2. A second oligomerization mutant (ASA-A464R) was, generated that failed to octamerize even at pH 4.8. A464R-ASA was degraded, in lysosomes to catalytically active 54-kDa intermediate. In cathepsin, L-deficient fibroblasts, degradation of P426L-ASA and A464R-ASA to the, 54-kDa fragment was reduced, while further degradation was blocked. This, indicates that defective oligomerization of ASA allows degradation of ASA, to a catalytically active 54-kDa intermediate by lysosomal cysteine, proteinases, including cathepsin L. Further degradation of the 54-kDa, intermediate critically depends on cathepsin L and is modified by the, structure of the 9-kDa cleavage product.
DiseaseDisease
Known disease associated with this structure: Metachromatic leukodystrophy OMIM:[607574]
About this StructureAbout this Structure
1E33 is a Single protein structure of sequence from Homo sapiens with MG as ligand. Active as Cerebroside-sulfatase, with EC number 3.1.6.8 Full crystallographic information is available from OCA.
ReferenceReference
Defective oligomerization of arylsulfatase a as a cause of its instability in lysosomes and metachromatic leukodystrophy., von Bulow R, Schmidt B, Dierks T, Schwabauer N, Schilling K, Weber E, Uson I, von Figura K, J Biol Chem. 2002 Mar 15;277(11):9455-61. Epub 2002 Jan 2. PMID:11777924
Page seeded by OCA on Mon Nov 12 16:39:15 2007