BIOCHEMICAL BASIS OF SULFATASE ACTIVITY

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Mammalian sulfatases are a diverse group of enzymes which hydrolize steroid, mucopolysaccharide and glycolipid sulfates. The sulfatase deficiency disorders include a number of lysosomal storage diseases, and are a significant cause of mental retardation and/or physical deformities. Multiple sulfatase deficiency (MSD) is a unique genetic disorder resulting from deficiencies of at least seven distinct sulfatases and appears to result from increased degradation of cellular sulfatases. These investigations are aimed at the definition of various controls of sulfatase activity and causes of defects at various levels, including transcription, translation and post-translational processes. The elucidation of the defect in MSD is likely to demonstrate new levels of control of cellular hydrolases. Antibody and cDNA probes for steroid sulfatase, iduronate sulfatase (Id-S) and arylsulfatase B (ASB) will be used to study the various levels of control of study the molecular basis of the genetic variation of ASB activity in mouse strains with high or low ASB activity. Synthesis and processing of ASB in these mice using immunoprecipitation and pulse-chase labeling will also be studied to detect the effect of regulatory genes on mouse ASB. cDNA clones and antibodies for human ASB and human Id-S will be isolated and used to characterize the mRNA and newly synthesized polypeptides in ASB deficient Maroteaux-Lamy syndrome and Id-S deficient Hunter disease. These probes plus those for steroid sulfatase will be used to characterize the synthesis and processing of sulfatase in MSD. cDNA for sulfatase will be transfected into MSD and normal cells, and the translation and processing of the transfected STS will be followed. The subcellular compartmentalization and degradation of microinjected STS from normal and MSD cells will be evaluated. Immunoprecipitated labeled sulfatases from normal and MSD cells will be compared by isoelectric focussing, peptide mapping, oligosaccharide content and subcellular location. The role of cellular stabilization factors for sulfatases will be investigated. The route and location of post-translational processing and the role of the Golgi complex in sulfatase processing, including degradation, will be determined. The understanding of all these processes will be important in devising strategies for the treatment of enzyme deficiency diseases.