title: A novel thermostable carboxylesterase from Geobacillus thermodenitrificans: evidence for a new carboxylesterase family.
abstract: A novel gene encoding an esterase from Geobacillus thermodenitrificans strain CMB-A2 was cloned, sequenced and functionally expressed in Escherichia coli M15. Sequence analysis revealed an open reading frame of 747 bp corresponding to a polypeptide of 249 amino acid residues (named EstGtA2). After purification, a specific activity of 2.58 U mg(-1) was detected using p-NP caprylate (C8) at 50 degrees C and pH 8.0 (optimal conditions). The enzyme catalyses the hydrolysis of triglycerides (tributyrin) and a variety of p-nitrophenyl esters with different fatty acyl chain length (C4-C16). The enzyme has potential for various industrial applications since it is characterized by its activity under a wide range of pH, from 25 to 65 degrees C. Using Geobacillus stearothermophilus Est30 esterase structure as template, a model of EstGtA2 was built using ESyPred3D. Analysis of this structural model allowed identifying putative sequence features that control EstGtA2 enzymatic properties. Based on sequence properties, multiple sequence comparisons and phylogenetic analyses, this enzyme appears to belong to a new family of carboxylesterases.
authors.affiliation: Département de chimie-biologie, Université du Québec à Trois-Rivières, 3351 Boul. Des Forges, C.P. 500 Trois-Rivières (Québec) G9A 5H7, Canada.
authors.forename: David M
authors.initials: DM
authors.lastname: Charbonneau
authors.forename: Fatma
authors.initials: F
authors.lastname: Meddeb-Mouelhi
authors.forename: Marc
authors.initials: M
authors.lastname: Beauregard
mesh_terms: D001483:Base Sequence; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D004795:Enzyme Stability; D056506:Geobacillus / Q000201:enzymology*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008958:Models, Molecular; D010802:Phylogeny; D011487:Protein Conformation; D017422:Sequence Analysis, DNA; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D002265:Carboxylic Ester Hydrolases