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Kato T, Kato Z, Kuratsubo I, Tanaka N, Ishigami T, Kajihara JI, Sukegawa-Hayasaka K, Orii K, Isogai K, Fukao T, Shimozawa N, Orii T, Kondo N, Suzuki Y. Mutational and structural analysis of Japanese patients with mucopolysaccharidosis type II. J Hum Genet 2005; 50:395-402. [PMID: 16133661 DOI: 10.1007/s10038-005-0266-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2005] [Accepted: 06/03/2005] [Indexed: 11/26/2022]
Abstract
We investigated mutations of the iduronate-2-sulfatase (I2S) gene and structural characteristics of I2S to clarify genotype/phenotype relationships in 18 Japanese patients with mucopolysaccharidosis type II. The I2S gene was analyzed in five patients with a severe phenotype and in 13 patients with an attenuated phenotype. The tertiary structural model of the human I2S was constructed by homology modeling using the arylsulfatase structure as a template. We identified four missense mutations and a nonsense mutation in the severe phenotype; four missense, two nonsense, three frame shifts, and one each of splice and amino acid deletion in the attenuated phenotype. Seven of them (L73del, Q75X, G140R, C171R, V401 fs, C422 fs, and H441 fs) were novel mutations. Structural analysis indicated that the residues of the mutations found in the severe phenotype would have direct interactions with the active site residues or should break the hydrophobic core domain of I2S, whereas residues of the missense mutations found in the attenuated phenotype were located in the peripheral region. In addition, effects by deletion or frameshift mutations could also be interpreted by the structure. Structural analysis of mutant proteins would help in understanding the genotype/phenotype relationships of Hunter disease.
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Affiliation(s)
- Tomomi Kato
- Department of Pediatrics, Gifu University Graduate School of Medicine, Gifu, Japan.
- Medical Education Development Center, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan.
| | - Zenichiro Kato
- Department of Pediatrics, Gifu University Graduate School of Medicine, Gifu, Japan
| | - Izumi Kuratsubo
- Department of Pediatrics, Gifu University Graduate School of Medicine, Gifu, Japan
| | - Noboru Tanaka
- Research Center, Japan Chemical Research Pharmaceuticals Co. Ltd., Kobe, Japan
| | - Tabito Ishigami
- Research Center, Japan Chemical Research Pharmaceuticals Co. Ltd., Kobe, Japan
| | - Jun-Ichi Kajihara
- Research Center, Japan Chemical Research Pharmaceuticals Co. Ltd., Kobe, Japan
| | | | - Koji Orii
- Department of Pediatrics, Gifu University Graduate School of Medicine, Gifu, Japan
| | - Koji Isogai
- Department of Pediatrics, Gifu University Graduate School of Medicine, Gifu, Japan
| | - Toshiyuki Fukao
- Department of Pediatrics, Gifu University Graduate School of Medicine, Gifu, Japan
| | - Nobuyuki Shimozawa
- Division of Genomic Research, Life Science Research Center, Gifu University, Gifu, Japan
| | | | - Naomi Kondo
- Department of Pediatrics, Gifu University Graduate School of Medicine, Gifu, Japan
| | - Yasuyuki Suzuki
- Department of Pediatrics, Gifu University Graduate School of Medicine, Gifu, Japan
- Medical Education Development Center, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan
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Villani GR, Daniele A, Balzano N, Di Natale P. Expression of five iduronate-2-sulfatase site-directed mutations. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1501:71-80. [PMID: 10838181 DOI: 10.1016/s0925-4439(00)00006-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Five point mutations (R88H, R88P, T118I, 959delT, R468Q) previously identified in the iduronate-2-sulfatase (IDS) gene of Italian Hunter patients were expressed in COS cells to evaluate their functional consequence on enzyme activity, processing and intracellular localization. The 88 arginine residue belongs to the CXPSR pentapeptide conserved in all human sulfatases, where cysteine modification to formylglycine is required for enzyme activity. Substitution of arginine with histidine residue resulted in 13.7% residual enzyme activity, with an apparent K(m) value (133 microM) lower than that found for the normal enzyme (327 microM), indicating a higher affinity for the substrate; substitution of arginine with proline resulted in total absence of residual activity, in agreement with the phenotypes observed in patients carrying R88H and R88P mutations. For the four missense mutations, pulse-chase labelling experiments showed an apparently normal maturation; however, subcellular fractionation demonstrated poor transport to lysosomes. Therefore, residues 88, 118 and 468 appear to be not essential for processing but important for IDS conformation.
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Affiliation(s)
- G R Villani
- Department of Biochemistry and Medical Biotechnologies, Medical School, University of Naples 'Federico II', Via S. Pansini 5, 80131, Naples, Italy
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Abstract
Mucopolysaccharidosis type II (Hunter disease) is an X-linked disorder due to deficiency of the lysosomal enzyme iduronate 2-sulphatase. Here we report an update of molecular studies in 31 Spanish families with Hunter disease. We found a total of 22 novel small mutations (7 reported previously by our group), and 4 large deletions or rearrangements. Particularly relevant are two mutations, one showing an alternatively spliced product although the normal splice site is conserved; the other mutation results in an amino acid change that most likely modifies regulation of expression of the IDS gene. Except for large gene alterations and for the G374sp mutation already described, we could not establish a clear phenotype-genotype correlation. Mutation G374sp is the point mutation most frequent in our population (10%) and is always associated with mild phenotype. Our molecular analyses carried out in a relatively large series of patients with Hunter disease contribute to the identification of new mutations and reinforce the conclusions drawn in other populations about the genotype-phenotype correlation and the gene distribution of mutations.
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Affiliation(s)
- L Gort
- Institut de Bioquímica Clínica, C/Mejía Lequerica, Barcelona, Spain
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