1ci9

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spinqualitylabelsall models 1ci9, resolution 1.800Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

DFP-INHIBITED ESTERASE ESTB FROM BURKHOLDERIA GLADIOLI

Overview

Esterases form a diverse class of enzymes of largely unknown physiological, role. Because many drugs and pesticides carry ester functions, the, hydrolysis of such compounds forms at least one potential biological, function. Carboxylesterases catalyze the hydrolysis of short chain, aliphatic and aromatic carboxylic ester compounds. Esterases, D-alanyl-D-alanine-peptidases (DD-peptidases) and beta-lactamases can be, grouped into two distinct classes of hydrolases with different folds and, topologically unrelated catalytic residues, the one class comprising of, esterases, the other one of beta-lactamases and DD-peptidases. The, chemical reactivities of esters and beta-lactams towards hydrolysis are, quite similar, which raises the question of which factors prevent, esterases from displaying beta-lactamase activity and vice versa. Here we, describe the crystal structure of EstB, an esterase isolated from, Burkholderia gladioli. It shows the protein to belong to a novel class of, esterases with homology to Penicillin binding proteins, notably, DD-peptidase and class C beta-lactamases. Site-directed mutagenesis and, the crystal structure of the complex with diisopropyl-fluorophosphate, suggest Ser75 within the "beta-lactamase" Ser-x-x-Lys motif to act as, catalytic nucleophile. Despite its structural homology to beta-lactamases, EstB shows no beta-lactamase activity. Although the nature and arrangement, of active-site residues is very similar between EstB and homologous, beta-lactamases, there are considerable differences in the shape of the, active site tunnel. Modeling studies suggest steric factors to account for, the enzyme's selectivity for ester hydrolysis versus beta-lactam cleavage.

About this Structure

1CI9 is a Single protein structure of sequence from Burkholderia gladioli with DFP as ligand. Active as Carboxylesterase, with EC number 3.1.1.1 Full crystallographic information is available from OCA.

Reference

EstB from Burkholderia gladioli: a novel esterase with a beta-lactamase fold reveals steric factors to discriminate between esterolytic and beta-lactam cleaving activity., Wagner UG, Petersen EI, Schwab H, Kratky C, Protein Sci. 2002 Mar;11(3):467-78. PMID:11847270

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