HUMAN BETA-GLUCURONIDASE AT 2.6 A RESOLUTION
[BGLR_HUMAN] Defects in GUSB are the cause of mucopolysaccharidosis type 7 (MPS7) [MIM:253220]; also known as Sly syndrome. MPS7 is an autosomal recessive lysosomal storage disease characterized by inability to degrade glucuronic acid-containing glycosaminoglycans. The phenotype is highly variable, ranging from severe lethal hydrops fetalis to mild forms with survival into adulthood. Most patients with the intermediate phenotype show hepatomegaly, skeletal anomalies, coarse facies, and variable degrees of mental impairment.             Note=Mucopolysaccharidosis type 7 is associated with non-immune hydrops fetalis, a generalized edema of the fetus with fluid accumulation in the body cavities due to non-immune causes. Non-immune hydrops fetalis is not a diagnosis in itself but a symptom, a feature of many genetic disorders, and the end-stage of a wide variety of disorders.
[BGLR_HUMAN] Plays an important role in the degradation of dermatan and keratan sulfates.
Publication Abstract from PubMed
The X-ray structure of the homotetrameric lysosomal acid hydrolase, human beta-glucuronidase (332,000 Mr), has been determined at 2.6 A resolution. The tetramer has approximate dihedral symmetry and each promoter consists of three structural domains with topologies similar to a jelly roll barrel, an immunoglobulin constant domain and a TIM barrel respectively. Residues 179-204 form a beta-hairpin motif similar to the putative lysosomal targeting motif of cathepsin D, supporting the view that lysosomal targeting has a structural basis. The active site of the enzyme is formed from a large cleft at the interface of two monomers. Residues Glu 451 and Glu 540 are proposed to be important for catalysis. The structure establishes a framework for understanding mutations that lead to the human genetic disease mucopolysaccharidosis VII, and for using the enzyme in anti-cancer therapy.
Structure of human beta-glucuronidase reveals candidate lysosomal targeting and active-site motifs.,Jain S, Drendel WB, Chen ZW, Mathews FS, Sly WS, Grubb JH Nat Struct Biol. 1996 Apr;3(4):375-81. PMID:8599764
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.