Crystallization (Comment) | Organism |
---|---|
purified recombinant enzyme mutant T203I free and in complex with N4-(beta-N-acetylglucosaminyl)-L-asparagine, hanging drop vapor diffusion technique, mixing of 2mg/ml protein solution with reservoir oslution containing 0.2 M NaCl, 0.1 M bis-Tris, pH 6.5, and 25% PEG 3350, cryoprotection in solution containing 100 mM Tris-HCl, pH 8.0, and 20% glycerol, X-ray diffraction structure determination and analysis, molecular replacement using the structure of the wild-type enzyme (PDB ID 2GAW) as the starting model | Homo sapiens |
Protein Variants | Comment | Organism |
---|---|---|
C140S | the substitution is the causative mutation for enzyme deficiency. In addition to preventing the disulfide bond formation between C140 and C156, the C140S substitution also causes destabilization of the unique/longer loop structure in the human sequence and thus prevent dimerization of GA essential for autoproteolytic activation | Homo sapiens |
G172D | site-directed mutagenesis, the mutation causes a local conformational change, which in turn disrupts the requisite autoprocessing step to generate metabolically functional mature hydrolase | Homo sapiens |
G203D | naturally occuring mutation in Canadian population, causing aspartylglucosaminuria (AGU) | Homo sapiens |
G226D | naturally occuring mutation in Canadian population, causing aspartylglucosaminuria (AGU) | Homo sapiens |
additional information | construction of a model enzyme corresponding to a Finnish AGU allele, the naturally occuring T234I mutant variant. The Finnish variant is capable of a slow autoprocessing to generate detectible hydrolyzation activity of the natural substrate of the enzyme. Determination of a 1.6 A-resolution structure of the Finnish AGU model and construction of an enzyme-substrate complex to provide a structural basis for analyzing the negative effects of the point mutation on Km and kcat of the mature enzyme, overview | Homo sapiens |
R138Q | the single mutation does not affect either the enzyme's autoproteolysis or its hydrolase activity | Homo sapiens |
R138Q/C140S | naturally occuring mutation in Finnish population causing aspartylglucosaminuria (AGU). Due to a founder effect, AGU incidence in Finland is unexcelled, with one major allele (denoted AGUFIN) found in 98% of the AGU patients. The AGUFIN allele carries the two concurrent substitutions R138Q andC140S | Homo sapiens |
T122K | naturally occuring mutation in US-American population causing aspartylglucosaminuria (AGU) | Homo sapiens |
T203I | site-directed mutagenesis, corresponds to mutation T234I, the replacement of the conserved threonine with an isoleucine has negative impacts on both KM and, to a greater extent, kcat of hydrolase activity, the mutant is almost inactive. Structure comparison of mutant T203I with the wild-type enzyme. Mutant T203I is capable of autoprotolysis. In the T203I-substrate complex model, all the previously identified substrate binding residues (W11, F13, S50, T152, R180, D183, G204, G206) are in close contact distances from the substrate model, except the mutated residue Ile203 | Homo sapiens |
T234I | naturally occuring mutation in Canadian population,located at the rim of the substrate binding site , causing aspartylglucosaminuria (AGU). The mutatnt enzyme shows reduced autoprocessing capability compared to wild-type | Homo sapiens |
KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
additional information | - |
additional information | kinetics of mutant T203I and wild-type enzymes, the specificity constant (kcat/Km) of mutant T203I is decreased by more than 300fold when compared to the wild-type enzyme | Homo sapiens |
Localization | Comment | Organism | GeneOntology No. | Textmining |
---|---|---|---|---|
lysosome | - |
Homo sapiens | 5764 | - |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
N4-(beta-N-acetylglucosaminyl)-L-asparagine + H2O | Homo sapiens | - |
N-acetyl-D-glucosaminylamine + L-aspartate | - |
? |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Homo sapiens | P20933 | - |
- |
Posttranslational Modification | Comment | Organism |
---|---|---|
proteolytic modification | the enzyme is processed through autocatalytic cleavage. A subsequent autoprocessing results in a main-chain cleavage at the P-loop by a self-catalyzed peptide bond rearrangement via an N -> O acyl shift. This autoproteolysis event results in an active form of the hydrolase with separate alpha- and beta-subunits | Homo sapiens |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
aspartic acid beta-(4-nitroanilide) + H2O | - |
Homo sapiens | 4-nitroaniline + L-aspartate | - |
? | |
N4-(beta-N-acetylglucosaminyl)-L-asparagine + H2O | - |
Homo sapiens | N-acetyl-D-glucosaminylamine + L-aspartate | - |
? |
Subunits | Comment | Organism |
---|---|---|
heterotetramer | (alphabeta)2 | Homo sapiens |
Synonyms | Comment | Organism |
---|---|---|
AGA | - |
Homo sapiens |
aspartylglucosaminidase | - |
Homo sapiens |
glycosylasparaginase | - |
Homo sapiens |
General Information | Comment | Organism |
---|---|---|
malfunction | deficiency of the enzyme causes accumulation of glycoasparagines in lysosomes of cells, resulting in a genetic condition called aspartylglucosaminuria (AGU). AGU is a lysosomal storage disorder caused by defects of the hydrolase glycosylasparaginase. AGU mutations impair autoproteolysis of GA precursor and/or impair its hydrolase activity in lysosomes. This deficiency results in progressive mental decline of the patients, and leads to a lifelong condition affecting patient's appearance, cognition, adaptive skills, physical growth, personality, anatomical structure, and health. Early indicators of AGU include growth spurts in infants and the development of macrocephalia associated to hernias and respiratory infections | Homo sapiens |
additional information | structure comparison of mutant T203I with the wild-type enzyme | Homo sapiens |
physiological function | the enzyme is involved in protein degradation by cleaving Asn-linked glycoproteins in lysosomes. During the metabolic turnover of Asn-linked glycoproteins, autocleaved enzyme hydrolyzes glycoasparagine N4-(beta-N-acetylglucosaminyl)-L-asparagine (NAcGlc-Asn) that connects a carbohydrate to the side chain of an asparagine | Homo sapiens |