Interaction of arylsulfatase-A (ASA) with its natural sulfoglycolipid substrates: a computational and site-directed mutagenesis study

Glycoconj J. 2009 Nov;26(8):1029-45. doi: 10.1007/s10719-008-9222-9.

Abstract

Arylsulfatase A (ASA) hydrolyzes sulfate esters with a pH optimum of 5. Interactions between p-nitrocatechol sulfate (NCS, artificial substrate) and active site residues of ASA are revealed from their co-crystal structure. Since equivalent ASA interactions with its natural substrates, sulfogalactosylceramide (SGC) and sulfogalactosylglycerolipid (SGG), are not known, we computationally docked SGC/SGG to the ASA crystal structure. Our dockings suggested that Cys69 was the active site residue, and Lys302 & Lys123 as residues anchoring the sulfate group of SGC/SGG to the active site, as observed for NCS. We further confirmed these results using 2 recombinant ASA mutants: C69A and CKK (Cys69, Lys302 and Lys123-all mutated to Ala). Both ASA mutants failed to desulfate SGC/SGG, and CKK showed minimal binding to [(14)C]SGC, although C69A still had affinity for this sulfoglycolipid. However, our dockings suggested additional intermolecular hydrogen bonding and hydrophobic interactions between ASA and SGC/SGG, thus contributing to the specificity of SGC/SGG as natural substrates.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acids / metabolism
  • Animals
  • CHO Cells
  • Carbohydrate Conformation
  • Catalytic Domain
  • Cerebroside-Sulfatase / metabolism*
  • Chromatography, Thin Layer
  • Computational Biology / methods*
  • Cricetinae
  • Cricetulus
  • Glycolipids / chemistry
  • Glycolipids / metabolism*
  • Hydrogen-Ion Concentration
  • Hydrophobic and Hydrophilic Interactions
  • Models, Molecular
  • Mutagenesis, Site-Directed / methods*
  • Recombinant Proteins / metabolism
  • Static Electricity
  • Substrate Specificity
  • Sulfates / chemistry
  • Sus scrofa

Substances

  • Amino Acids
  • Glycolipids
  • Recombinant Proteins
  • Sulfates
  • sulfoglycolipids
  • Cerebroside-Sulfatase