2i3c | pdb_00002i3c
Crystal Structure of an Aspartoacylase from Homo Sapiens
Structural highlights
DiseaseACY2_HUMAN Defects in ASPA are the cause of Canavan disease (CAND) [MIM:271900; also known as spongy degeneration of the brain. CAND is a rare neurodegenerative condition of infancy or childhood characterized by white matter vacuolization and demeylination that gives rise to a spongy appearance. The clinical features are onset in early infancy, atonia of neck muscles, hypotonia, hyperextension of legs and flexion of arms, blindness, severe mental defect, megalocephaly, and death by 18 months on the average.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] FunctionACY2_HUMAN Catalyzes the deacetylation of N-acetylaspartic acid (NAA) to produce acetate and L-aspartate. NAA occurs in high concentration in brain and its hydrolysis NAA plays a significant part in the maintenance of intact white matter. In other tissues it act as a scavenger of NAA from body fluids. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedAspartoacylase catalyzes hydrolysis of N-acetyl-l-aspartate to aspartate and acetate in the vertebrate brain. Deficiency in this activity leads to spongiform degeneration of the white matter of the brain and is the established cause of Canavan disease, a fatal progressive leukodystrophy affecting young children. We present crystal structures of recombinant human and rat aspartoacylase refined to 2.8- and 1.8-A resolution, respectively. The structures revealed that the N-terminal domain of aspartoacylase adopts a protein fold similar to that of zinc-dependent hydrolases related to carboxypeptidases A. The catalytic site of aspartoacylase shows close structural similarity to those of carboxypeptidases despite only 10-13% sequence identity between these proteins. About 100 C-terminal residues of aspartoacylase form a globular domain with a two-stranded beta-sheet linker that wraps around the N-terminal domain. The long channel leading to the active site is formed by the interface of the N- and C-terminal domains. The C-terminal domain is positioned in a way that prevents productive binding of polypeptides in the active site. The structures revealed that residues 158-164 may undergo a conformational change that results in opening and partial closing of the channel entrance. We hypothesize that the catalytic mechanism of aspartoacylase is closely analogous to that of carboxypeptidases. We identify residues involved in zinc coordination, and propose which residues may be involved in substrate binding and catalysis. The structures also provide a structural framework necessary for understanding the deleterious effects of many missense mutations of human aspartoacylase. Structure of aspartoacylase, the brain enzyme impaired in Canavan disease.,Bitto E, Bingman CA, Wesenberg GE, McCoy JG, Phillips GN Jr Proc Natl Acad Sci U S A. 2007 Jan 9;104(2):456-61. Epub 2006 Dec 28. PMID:17194761[13] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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