Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.6.1 (sulfatase)
 3,205 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The lysosomal degradation of sulfatide requires the specific enzyme, arylsulfatase A, as well as a heat stable protein called sphingolipid activator protein-1 (SAP-1). While most patients with metachromatic leukodystrophy have defects in arylsulfatase A, some patients have defects in SAP-1. SAP-1 is coded for by a gene on human chromosome 10 that also codes for three other proposed SAP. Examination of the cDNA from two siblings with SAP-1 deficiency revealed a point mutation of nucleotide #650 (counting from the initiation ATG) which is in the SAP-1 coding domain. This C to T transition changed the codon from threonine (ACC) to one coding for isoleucine (ATC). This eliminated the only glycosylation site in mature SAP-1 and could explain the findings made at the protein level.
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PMID:Detection of a point mutation in sphingolipid activator protein-1 mRNA in patients with a variant form of metachromatic leukodystrophy. 230 19

Saposins are small, heat-stable glycoproteins required for the hydrolysis of sphingolipids by specific lysosomal hydrolases. Saposins A, B, C, and D are derived by proteolytic processing from a single precursor protein named prosaposin. Saposin B, previously known as SAP-1 and sulfatide activator, stimulates the hydrolysis of a wide variety of substrates including cerebroside sulfate, GM1 ganglioside, and globotriaosylceramide by arylsulfatase A, acid beta-galactosidase, and alpha-galactosidase, respectively. Human saposin B deficiency, transmitted as an autosomal recessive trait, results in tissue accumulation of cerebroside sulfate and a clinical picture resembling metachromatic leukodystrophy (activator-deficient metachromatic leukodystrophy). We have examined transformed lymphoblasts from the initially reported saposin B-deficient patient and found normal amounts of saposins A, C, and D. After preparing first-strand cDNA from lymphoblast total RNA, we used the polymerase chain reaction to amplify the prosaposin cDNA. The patient's mRNA differed from the normal sequence by only one C----T transition in the 23rd codon of saposin B, resulting in a threonine to isoleucine amino acid substitution. An affected male sibling has the same mutation as the proband and their heterozygous mother carries both the normal and mutant sequences, providing additional evidence that this base change is the disease-causing mutation. This base change results in the replacement of a polar amino acid (threonine) with a nonpolar amino acid (isoleucine) and, more importantly, eliminates the glycosylation signal in this activator protein. One explanation for the deficiency of saposin B in this disease is that the mutation may increase the degradation of saposin B by exposing a potential proteolytic cleavage site (arginine) two amino acids to the amino-terminal side of the glycosylation site when the carbohydrate side chain is absent.
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PMID:Characterization of a mutation in a family with saposin B deficiency: a glycosylation site defect. 232 May 74

Previous studies from this laboratory have demonstrated that arylsulfatase B (ASB) is phosphorylated by a protein kinase, which is the first finding of phosphorylation in lysosomal hydrolases. The present study was undertaken to characterize the sites of phosphorylation in ASB from transplanted human lung cancer and from normal human tissues, and to identify type of tumor protein kinase responsible for the phosphorylation of ASB. When ASB purified from liver and placenta was phosphorylated in vitro by a cAMP-dependent protein kinase, it gave a single tryptic phosphopeptide (X) and phosphothreonine. On the other hand, the tumor ASB which had been phosphorylated in vivo demonstrated two phosphopeptides X and Y. Since the tumor ASB had been shown to be phosphorylated both at threonine and serine residues, phosphorylation at threonine residue of peptide X, which is phosphorylated by a cAMP-dependent protein kinase, will be cancer-associated. Through photoaffinity labeling with a labeled cAMP analogue to detect regulatory subunits of cAMP-dependent protein kinase subtypes, it was found that the cAMP-dependent protein kinase in the transplanted lung tumor was largely type II which can be ascribed to the appearance of highly phosphorylated ASB in the tumor.
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PMID:Protein phosphorylation of human lysosomal arylsulfatase B from normal and cancer tissues. 338 98

An acidic variant form of arylsulfatase B from normal leukocytes and chronic myelogenous leukemia (CML) leukocytes was found to be phosphorylated at its serine and threonine residues through in vivo phosphorylation with 32Pi. However, the predominant phosphorylation site was serine in normal cells, in contrast to threonine in CML cells. A cyclic AMP-dependent protein kinase was responsible for phosphorylation of the sulfatase of CML cells.
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PMID:Protein phosphorylation of lysosomal arylsulfatase B in normal and leukemic leukocytes. 346 94

Human lung cancer transplanted into athymic mice contains predominantly an acidic variant (designated B1) of lysosomal arylsulfatase B. B1 enzyme was suggested to be phosphorylated and sialylated (Gasa, S., Makita, A., Kameya, T., Kodama, T., Koide, T., Tsumuraya, M., and Komai, T. (1981) Eur. J. Biochem. 116, 497-503). In order to determine the localization of phosphate in B1 enzyme, we labeled in vivo the transplanted tumor with [32P]H3PO4 or [3H]glucosamine and purified B1 enzyme by immunoprecipitation. Bio-Gel chromatography of the labeled B1 enzyme treated with endoglycosidase H demonstrated that both the excluded and included materials were labeled with 32P and 3H. From acid hydrolysate of the excluded materials, phosphorylated serine and threonine were detected. Protein phosphorylation of arylsulfatase was confirmed by in vitro labeling experiments with [gamma-32P]ATP. By incubation of the tumor homogenate with ATP followed by isolation of the enzymes, B1 enzyme had a significant amount of radioactivity, whereas the B enzyme had little; by exogenous protein kinase, partially purified B enzyme was phosphorylated 35 times more than B1 enzyme. Acid hydrolysate of the included materials in the Bio-Gel column demonstrated mannose 6-phosphate and an unknown phosphorylated compound which migrates more than Man-6-P on electrophoresis and chromatography.
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PMID:Phosphorylation on protein and carbohydrate moieties of a lysosomal arylsulfatase B variant in human lung cancer transplanted into athymic mice. 640 42

Metachromatic leukodystrophy (MLD) is an autosomal recessive lysosomal storage disorder caused by a deficiency of arylsulfatase A (ARSA; EC 3.1.6.8). The 8 ARSA exons and adjacent intron boundaries from a patient with late-infantile metachromatic leukodystrophy were polymerase chain reaction (PCR) amplified in seven discrete reactions. Amplified ARSA exons were analysed for the presence of sequence alterations by single-strand conformation polymorphism analysis, followed by direct sequencing of PCR products. The patient was found to be homozygous for a C-->T transition in exon IV that results in the substitution of a highly conserved threonine residue at amino acid 274 with a methionine (T274M). Analysis of a further 29 MLD patients revealed the presence of five additional homozygotes for T274M. All 6 T274M homozygotes (representing four families) were of Lebanese descent, and all were known to be the result of consanguineous marriages. The altered amino acid is rigidly conserved among 10 sulfatases from Escherichia coli to humans; therefore, it is most likely that the resultant mutant protein will have little or no enzyme activity. This is consistent with the very low ARSA activity measured in these patients and their uniformly severe clinical presentation.
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PMID:An arylsulfatase A (ARSA) missense mutation (T274M) causing late-infantile metachromatic leukodystrophy. 810 33

Sulfatases carry at their catalytic site a unique post-translational modification, an alpha-formylglycine residue that is essential for enzyme activity. Formylglycine is generated by oxidation of a conserved cysteine or, in some prokaryotic sulfatases, serine residue. In eukaryotes, this oxidation occurs in the endoplasmic reticulum during or shortly after import of the nascent sulfatase polypeptide. The modification of arylsulfatase A was studied in vitro and was found to be directed by a short linear sequence, CTPSR, starting with the cysteine to be modified. Mutational analyses showed that the cysteine, proline and arginine are the key residues within this motif, whereas formylglycine formation tolerated the individual, but not the simultaneous substitution of the threonine or serine. The CTPSR motif was transferred to a heterologous protein leading to low-efficient formylglycine formation. The efficiency reached control values when seven additional residues (AALLTGR) directly following the CTPSR motif in arylsulfatase A were present. Mutating up to four residues simultaneously within this heptamer sequence inhibited the modification only moderately. AALLTGR may, therefore, have an auxiliary function in presenting the core motif to the modifying enzyme. Within the two motifs, the key residues are fully, and other residues are highly conserved among all known members of the sulfatase family.
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PMID:Sequence determinants directing conversion of cysteine to formylglycine in eukaryotic sulfatases. 1020 63

The Sac3 gene product of Chlamydomonas positively and negatively regulates the responses of the cell to sulfur limitation. In wild-type cells, arylsulfatase activity is detected only during sulfur limitation. The sac3 mutant expresses arylsulfatase activity even when grown in nutrient-replete medium, which suggests that the Sac3 protein has a negative effect on the induction of arylsulfatase activity. In contrast to its effect on arylsulfatase activity, Sac3 positively regulates the high-affinity sulfate transport system-the sac3 mutant is unable to fully induce high-affinity sulfate transport during sulfur limitation. We have complemented the sac3 mutant and cloned a cDNA copy of the Sac3 gene. The deduced amino acid sequence of the Sac3 gene product is similar to the catalytic domain of the yeast Snf1 family of serine/threonine kinases and is therefore classified as a Snf1-related kinase (SnRK). Specifically, Sac3 falls within the SnRK2 subfamily of kinases from vascular plants. In addition to the 11 subdomains common to Snf1-like serine/threonine kinases, Sac3 and the plant kinases have two additional subdomains and a highly acidic C-terminal region. The role of Sac3 in the signal transduction system that regulates the responses of Chlamydomonas to sulfur limitation is discussed.
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PMID:Sac3, an Snf1-like serine/threonine kinase that positively and negatively regulates the responses of Chlamydomonas to sulfur limitation. 1036 87

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.
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PMID:Defective oligomerization of arylsulfatase a as a cause of its instability in lysosomes and metachromatic leukodystrophy. 1177 24

Staphylococcus aureus synthesizes polyglycerol-phosphate lipoteichoic acid (LTA) from phosphatidylglycerol. LtaS, a predicted membrane protein with 5 N-terminal transmembrane helices followed by a large extracellular part (eLtaS), is required for staphylococcal growth and LTA synthesis. Here, we report the first crystal structure of the eLtaS domain at 1.2-A resolution and show that it assumes a sulfatase-like fold with an alpha/beta core and a C-terminal part composed of 4 anti-parallel beta-strands and a long alpha-helix. Overlaying eLtaS with sulfatase structures identified active site residues, which were confirmed by alanine substitution mutagenesis and in vivo enzyme function assays. The cocrystal structure with glycerol-phosphate and the coordination of a Mn(2+) cation allowed us to propose a reaction mechanism, whereby the active site threonine of LtaS functions as nucleophile for phosphatidylglycerol hydrolysis and formation of a covalent threonine-glycerolphosphate intermediate. These results will aid in the development of LtaS-specific inhibitors for S. aureus and many other Gram-positive pathogens.
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PMID:Structure-based mechanism of lipoteichoic acid synthesis by Staphylococcus aureus LtaS. 1916 32


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