title: Crystal structure of a covalent intermediate of endogenous human arylsulfatase A.
abstract: The structures of human arylsulfatase A crystals soaked in solutions containing 4-methylumbelliferyl phosphate and O-phospho-DL-tyrosine have been determined at 2.7- and 3.2-A resolution, respectively. The formylglycine in position 69, a residue crucial for catalytic activity, was unambiguously identified in both structures as forming a covalent bond to the phosphate moiety. A hydroxyl group is present at the Cbeta of residue 69 and the formation of one out of two possible stereomeric forms is strongly favoured. The structures confirm the importance of the gem-diol intermediate in the arylsulfatase's catalytic mechanism. The presence of an apparently stable covalent bond is consistent with the weak phosphatase activity observed for human arylsulfatase A. The structures of the complexes suggest that phosphate ions and phosphate esters inhibit arylsulfatase in non-covalent and covalent modes, respectively. The metal ion present in the active site of arylsulfatase A isolated from human placenta is Ca(2+) and not Mg(2+) as was found in the structure of the recombinant enzyme.
authors.affiliation: Faculty of Chemistry, Jagiellonian University, ul. Ingardena 3, 30-060, Krakow, Poland.
authors.forename: Maksymilian
authors.initials: M
authors.lastname: Chruszcz
authors.forename: Piotr
authors.initials: P
authors.lastname: Laidler
authors.forename: Maciej
authors.initials: M
authors.lastname: Monkiewicz
authors.forename: Eric
authors.initials: E
authors.lastname: Ortlund
authors.forename: Lukasz
authors.initials: L
authors.lastname: Lebioda
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Lewinski
mesh_terms: D001665:Binding Sites; D002118:Calcium / Q000032:analysis / Q000737:chemistry; D002553:Cerebroside-Sulfatase / Q000737:chemistry*; D003460:Crystallization; D006801:Humans; D008274:Magnesium / Q000032:analysis / Q000737:chemistry; D015394:Molecular Structure; D010710:Phosphates / Q000737:chemistry; D010920:Placenta / Q000201:enzymology; D011487:Protein Conformation
chemical_list: D010710:Phosphates; D002553:Cerebroside-Sulfatase; D008274:Magnesium; D002118:Calcium