1E2S

Crystal structure of an Arylsulfatase A mutant C69A

Summary for 1E2S

• Entry DOI: 10.2210/pdb1e2s/pdb
• Related: 1AUK 1E33 1E3C
• Descriptor: Arylsulfatase A, 2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, MAGNESIUM ION, ... (5 entities in total)
• Functional Keywords: hydrolase, cerebroside-3-sulfate hydrolysis, lysosomal enzyme, formylglycine
• Biological source: Homo sapiens (Human)
• Total number of polymer chains: 1
• Total formula weight: 52610.63

Authors

von Buelow, R.,Schmidt, B.,Dierks, T.,von Figura, K.,Uson, I. (deposition date: 2000-05-24, release date: 2000-12-06, Last modification date: 2024-10-23)

Primary citation

von Bulow, R.,Schmidt, B.,Dierks, T.,von Figura, K.,Uson, I.
Crystal structure of an enzyme-substrate complex provides insight into the interaction between human arylsulfatase A and its substrates during catalysis.
J. Mol. Biol., 305:269-277, 2001

PubMed Abstract: Arylsulfatase A (ASA) belongs to the sulfatase family whose members carry a C(alpha)-formylglycine that is post-translationally generated by oxidation of a conserved cysteine or serine residue. The crystal structures of two arylsulfatases, ASA and ASB, and kinetic studies on ASA mutants led to different proposals for the catalytic mechanism in the hydrolysis of sulfate esters. The structures of two ASA mutants that lack the functional C(alpha)-formylglycine residue 69, in complex with a synthetic substrate, have been determined in order to unravel the reaction mechanism. The crystal structure of the inactive mutant C69A-ASA in complex with p-nitrocatechol sulfate (pNCS) mimics a reaction intermediate during sulfate ester hydrolysis by the active enzyme, without the covalent bond to the key side-chain FGly69. The structure shows that the side-chains of lysine 123, lysine 302, serine 150, histidine 229, the main-chain of the key residue 69 and the divalent cation in the active center are involved in sulfate binding. It is proposed that histidine 229 protonates the leaving alcoholate after hydrolysis.C69S-ASA is able to bind covalently to the substrate and hydrolyze it, but is unable to release the resulting sulfate. Nevertheless, the resulting sulfation is low. The structure of C69S-ASA shows the serine side-chain in a single conformation, turned away from the position a substrate occupies in the complex. This suggests that the double conformation observed in the structure of wild-type ASA is more likely to correspond to a formylglycine hydrate than to a twofold disordered aldehyde oxo group, and accounts for the relative inertness of the C69S-ASA mutant. In the C69S-ASA-pNCS complex, the substrate occupies the same position as in the C69A-ASA-pNCS complex, which corresponds to the non-covalently bonded substrate. Based on the structural data, a detailed mechanism for sulfate ester cleavage is proposed, involving an aldehyde hydrate as the functional group.

PubMed: 11124905
DOI: 10.1006/jmbi.2000.4297

Experimental method

X-RAY DIFFRACTION (2.35 Å)