Summary auto-generated
Researchers identified and characterized an arylsulphatase enzyme from the marine bacterium Alteromonas carrageenovora, an organism known to degrade sulfated seaweed polysaccharides. Unlike most arylsulphatases from other bacteria, this enzyme was not repressed by sulfate ions, which is consistent with the high sulfate concentration in marine environments. The researchers cloned and sequenced the arylsulphatase gene (atsA), revealing a 984-base-pair open reading frame encoding a 328-amino-acid protein with a molecular mass of approximately 35,800 Daltons. The purified enzyme from both native bacteria and recombinant E. coli exhibited identical biochemical properties: an isoelectric point of 5.5, a Michaelis constant of 68 micromolar, and molecular mass of approximately 35,000 Daltons. Structural analysis using hydrophobic cluster analysis revealed similar folding domains between this enzyme and putative sulfatases from pathogenic bacteria Mycobacterium leprae and Porphyromonas gingivalis, suggesting these proteins may function as glycosulfhydrolases involved in degrading sulfated polysaccharides.
Key findings
- Arylsulphatase from A. carrageenovora is not repressed by sulfate, unlike most microbial arylsulphatases, reflecting adaptation to sulfate-rich marine environments
- The atsA gene encodes a 328-amino-acid protein processed to 304 amino acids with a signal peptide, indicating periplasmic localization
- Native and recombinant enzymes have identical kinetic properties: Km of 68 micromolar for the substrate methylumbelliferyl sulfate and pH optimum of 8.5
- Structural homology analysis indicates the enzyme shares conserved folding domains with putative sulfatases from pathogenic bacteria, suggesting a role in degrading sulfated glycosaminoglycans
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Abstract
Summary: Arylsulphatase activity was identified in cultures of the marine bacterium Alteromonas carrageenovora, using methylumbelliferyl sulphate as substrate. In contrast with most other microbial arylsulphatases, arylsulphatase production in A. carrageenovora was not repressed by sulphate. The structural gene of arylsulphatase (atsA) was cloned and sequenced. An ORF of 984 bp was found, specifying a primary translation product of 328 amino acids with a molecular mass of 35797 Da. Arylsulphatase was partially purified from cell extracts of both A. carrageenovora and recombinant Escherichia coli. Both the recombinant and native enzymes exhibited a pl of 5-5, a Michaelis constant for methylumbelliferyl sulphate of 68 µM, and a molecular mass of approximately 35000 Da in SDS-PAGE analysis. Secondary structure comparisons using hydrophobic cluster analysis suggest functional analogies between the arylsulphatase of A. carrageenovora, that of Mycobacterium leprae and a 33-5 kDa protein from Porphyromonas gingivalis. It is speculated that these proteins are all glycosulphohydrolases, involved with desulphatation of sulphated polysaccharides.