Bartlam M

References (2)

Title : Crystal structure of methyl parathion hydrolase from Pseudomonas sp. WBC-3 - Dong_2005_J.Mol.Biol_353_655
Author(s) : Dong YJ , Bartlam M , Sun L , Zhou YF , Zhang ZP , Zhang CG , Rao Z , Zhang XE
Ref : Journal of Molecular Biology , 353 :655 , 2005
Abstract : Methyl parathion hydrolase (MPH, E.C.3.1.8.1), isolated from the soil-dwelling bacterium Pseudomonas sp. WBC-3, is a Zn(II)-containing enzyme that catalyzes the degradation of the organophosphate pesticide methyl parathion. We have determined the structure of MPH from Pseudomonas sp. WBC-3 to 2.4 angstroms resolution. The enzyme is dimeric and each subunit contains a mixed hybrid binuclear zinc center, in which one of the zinc ions is replaced by cadmium. In both subunits, the more solvent-exposed beta-metal ion is substituted for Cd2+ due to high cadmium concentration in the crystallization condition. Both ions are surrounded by ligands in an octahedral arrangement. The ions are separated by 3.5 angstroms and are coordinated by the amino acid residues His147, His149, Asp151, His152, His234 and His302 and a water molecule. Asp255 and a water molecule serve to bridge the zinc ions together. MPH is homologous with other metallo-beta-lactamases but does not show any similarity to phosphotriesterase that can also catalyze the degradation of methyl parathion with lower rate, despite the lack of sequence homology. Trp179, Phe196 and Phe119 form an aromatic cluster at the entrance of the catalytic center. Replacement of these three amino acids by alanine resulted in a significant increase of K(m) and loss of catalytic activity, indicating that the aromatic cluster has an important role to facilitate affinity of enzyme to the methyl parathion substrates.
ESTHER : Dong_2005_J.Mol.Biol_353_655
PubMedSearch : Dong_2005_J.Mol.Biol_353_655
PubMedID: 16181636

Title : Crystal Structure of an Acylpeptide Hydrolase\/Esterase from Aeropyrum pernix K1. - Bartlam_2004_Structure.(Camb)_12_1481
Author(s) : Bartlam M , Wang G , Yang H , Gao R , Zhao X , Xie G , Cao S , Feng Y , Rao Z
Ref : Structure(Camb) , 12 :1481 , 2004
Abstract : Acylpeptide hydrolases (APH; also known as acylamino acid releasing enzyme) catalyze the removal of an N-acylated amino acid from blocked peptides. The crystal structure of an APH from the thermophilic archaeon Aeropyrum pernix K1 to 2.1 A resolution confirms it to be a member of the prolyl oligopeptidase family of serine proteases. The structure of apAPH is a symmetric homodimer with each subunit comprised of two domains. The N-terminal domain is a regular seven-bladed beta-propeller, while the C-terminal domain has a canonical alpha/beta hydrolase fold and includes the active site and a conserved Ser445-Asp524-His556 catalytic triad. The complex structure of apAPH with an organophosphorus substrate, p-nitrophenyl phosphate, has also been determined. The complex structure unambiguously maps out the substrate binding pocket and provides a basis for substrate recognition by apAPH. A conserved mechanism for protein degradation from archaea to mammals is suggested by the structural features of apAPH.
ESTHER : Bartlam_2004_Structure.(Camb)_12_1481
PubMedSearch : Bartlam_2004_Structure.(Camb)_12_1481
PubMedID: 15296741
Gene_locus related to this paper: aerpe-APE1547