Arylsulfatase

 

Sulfatase enzymes are a highly homologous enzyme family which catalyse the hydrolysis of sulphate-ester bonds.

 

Reference Protein and Structure

Sequence
P51691 UniProt (3.1.6.1) IPR017850 (Sequence Homologues) (PDB Homologues)
Biological species
Pseudomonas aeruginosa PAO1 (Bacteria) Uniprot
PDB
1hdh - Arylsulfatase from Pseudomonas aeruginosa (1.3 Å) PDBe PDBsum 1hdh
Catalytic CATH Domains
3.40.720.10 CATHdb (see all for 1hdh)
Cofactors
Calcium(2+) (1)
Click To Show Structure

Enzyme Reaction (EC:3.1.6.1)

water
CHEBI:15377ChEBI
+
phenyl sulfate
CHEBI:85289ChEBI
→
hydron
CHEBI:15378ChEBI
+
sulfate
CHEBI:16189ChEBI
+
phenol
CHEBI:15882ChEBI
Alternative enzyme names: 4-methylumbelliferyl sulfatase, p-nitrophenyl sulfatase, Arylsulfohydrolase, Estrogen sulfatase, Nitrocatechol sulfatase, Phenolsulfatase, Phenylsulfatase, Sulfatase, Aryl-sulfate sulphohydrolase,

Enzyme Mechanism

Introduction

The sulfate ester cleavage involves an aldehyde hydrate, a modified residue FGly 51, as the functional group that initiates the reaction through a nucleophilic attack on the sulphur atom of the substrate. Lys 113 and FGly 51 contribute to electron density withdrawal from the sulfate oxygen atoms to give increased electrophilicity at the sulphur centre. The nucleophilicity of the oxygen in the aldehyde hydrate is enhanced by coordination to the Ca cation and facilitated proton transfer by Asp 317. An alcohol is eliminated in an SN2 substitution reaction, and the pentacoordinate sulphur intermediate is stabilised by Lys 375, His 211 and the Ca cation - the His or the Lys can act as proton donors to the alcoholate depending on the pH conditions. Sulfate elimination regenerates the aldehyde, by deprotonation of FGly 51 with His 115 acting as a proton acceptor. The aldehyde is hydrated by water, with the C-O bond being polarised by His 115, Arg 55, Asn 318 and the Ca cation.

Catalytic Residues Roles

UniProt PDB* (1hdh)
Lys113 Lys113A Contributes to electron density withdrawal on substrate to increase electrophilicity of sulphur atom. increase electrophilicity, electrostatic stabiliser
His115, Arg55 His115A, Arg55A Activates aldehyde for hydration. proton acceptor, electrostatic stabiliser
His211 His211A Stabilises the transition state and may act as a base depending on the pH conditions. electrostatic stabiliser, proton donor
Asp317 Asp317A Increases the nucleophilicity of the aldehyde hydrate attacking oxygen by proton abstraction. increase nucleophilicity, activator, metal ligand, proton acceptor
Lys375 Lys375A Stabilises the transition state, and may act as a base depending on the pH conditions. electrostatic stabiliser
*PDB label guide - RESx(y)B(C) - RES: Residue Name; x: Residue ID in PDB file; y: Residue ID in PDB sequence if different from PDB file; B: PDB Chain; C: Biological Assembly Chain if different from PDB. If label is "Not Found" it means this residue is not found in the reference PDB.

Chemical Components

proton transfer, overall reactant used, overall product formed, bimolecular nucleophilic substitution, intermediate formation, heterolysis, unimolecular elimination by the conjugate base, intermediate terminated

References

  1. Boltes I et al. (2001), Structure, 9, 483-491. 1.3 Å Structure of Arylsulfatase from Pseudomonas aeruginosa Establishes the Catalytic Mechanism of Sulfate Ester Cleavage in the Sulfatase Family. DOI:10.1016/s0969-2126(01)00609-8. PMID:11435113.
  2. Marino T et al. (2013), Chemistry, 19, 2185-2192. Catalytic mechanism of the arylsulfatase promiscuous enzyme from Pseudomonas aeruginosa. DOI:10.1002/chem.201201943. PMID:23280779.
  3. Waldow A et al. (1999), J Biol Chem, 274, 12284-12288. Amino Acid Residues Forming the Active Site of Arylsulfatase A: ROLE IN CATALYTIC ACTIVITY AND SUBSTRATE BINDING. DOI:10.1074/jbc.274.18.12284. PMID:10212197.

Step 1. Asp317 activates the hydrate via deprotonation.

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Catalytic Residues Roles

Residue Roles
Lys375A electrostatic stabiliser
His211A electrostatic stabiliser
Lys113A electrostatic stabiliser
Arg55A electrostatic stabiliser
His115A electrostatic stabiliser
Asp317A increase nucleophilicity
Asp13A metal ligand
Asp14A metal ligand
X51A (ptm) metal ligand
Asp317A metal ligand
Asn318A metal ligand
Asp317A activator
X51A (ptm) proton donor
Asp317A proton acceptor

Chemical Components

proton transfer

Step 2. The activated hydrate attacks the sulfate group, and the bond between the sulfate and the phenol is cleaved.

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Catalytic Residues Roles

Residue Roles
X51A (ptm) nucleophile
Arg55A electrostatic stabiliser
Lys113A electrostatic stabiliser
His115A electrostatic stabiliser
His211A electrostatic stabiliser
Lys375A electrostatic stabiliser
Asp13A metal ligand
Asp14A metal ligand
X51A (ptm) metal ligand
Asp317A metal ligand
Asn318A metal ligand
X51A (ptm) covalently attached
X51A (ptm) increase electrophilicity
Lys113A increase electrophilicity
His211A proton donor

Chemical Components

overall reactant used, overall product formed, ingold: bimolecular nucleophilic substitution, intermediate formation, proton transfer

Step 3. The hydrate collapses into an aldehyde and sulfate is released.

Download: Image, Marvin File

Catalytic Residues Roles

Residue Roles
Asp13A metal ligand
Asp14A metal ligand
X51A (ptm) metal ligand
Asp317A metal ligand
Asn318A metal ligand
Arg55A electrostatic stabiliser
Lys113A electrostatic stabiliser
His115A electrostatic stabiliser
His211A electrostatic stabiliser
Lys375A electrostatic stabiliser
His115A proton acceptor

Chemical Components

overall product formed, heterolysis, ingold: unimolecular elimination by the conjugate base, intermediate terminated, proton transfer
Download: Image, Marvin File

Step 1. Asp317 activates the hydrate via deprotonation.

Step 2. The activated hydrate attacks the sulfate group, and the bond between the sulfate and the phenol is cleaved.

Step 3. The hydrate collapses into an aldehyde and sulfate is released.

Products.

Contributors

Gary McDowell, Gemma L. Holliday, James Willey