title: Characterization and heterologous gene expression of a novel esterase from Lactobacillus casei CL96.
abstract: A novel esterase gene (estI) of Lactobacillus casei CL96 was localized on a 3.3-kb BamHI DNA fragment containing an open reading frame (ORF) of 1,800 bp. The ORF of estI was isolated by PCR and expressed in Escherichia coli, the methylotrophic bacterium Methylobacterium extorquens, and the methylotrophic yeast Pichia pastoris under the control of T7, methanol dehydrogenase (P(mxaF)), and alcohol oxidase (AOX1) promoters, respectively. The amino acid sequence of EstI indicated that the esterase is a novel member of the GHSMG family of lipolytic enzymes and that the enzyme contains a lipase-like catalytic triad, consisting of Ser325, Asp516, and His558. E. coli BL21(DE3)/pLysS containing estI expressed a novel 67.5-kDa protein corresponding to EstI in an N-terminal fusion with the S. tag peptide. The recombinant L. casei CL96 EstI protein was purified to electrophoretic homogeneity in a one-step affinity chromatography procedure on S-protein agarose. The optimum pH and temperature of the purified enzyme were 7.0 and 37 degrees C, respectively. Among the pNP (p-nitrophenyl) esters tested, the most selective substrate was pNP-caprylate (C(8)), with K(m) and k(cat) values of 14 +/- 1.08 microM and 1,245 +/- 42.3 S(-1), respectively.
authors.affiliation: Department of Food Science and Agricultural Chemistry, McGill University, Ste-Anne-de-Bellevue, Quebec, H9X 3V9, Canada.
authors.forename: Young J
authors.initials: YJ
authors.lastname: Choi
authors.forename: Carlos B
authors.initials: CB
authors.lastname: Miguez
authors.forename: Byong H
authors.initials: BH
authors.lastname: Lee
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D004950:Esterases / Q000235:genetics / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007780:Lacticaseibacillus casei / Q000201:enzymology* / Q000235:genetics; D020601:Methylobacterium extorquens / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D010843:Pichia / Q000201:enzymology* / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013696:Temperature
chemical_list: D011994:Recombinant Proteins; D004950:Esterases