title: A novel thermostable and glucose-tolerant β-glucosidase from Fervidobacterium islandicum.
abstract: An open reading frame (ORF) encoding the enzyme β-glucosidase from the extremely thermophilic bacterium Fervidobacterium islandicum has been identified, cloned and sequenced. The bgl1A gene was cloned in a pET-Blue1 vector and transformed in Escherichia coli, resulting in high-level expression of β-glucosidase FiBgl1A that was purified to homogeneity in a two-step purification. FiBgl1A is composed of 459 amino acid residues and showed high homology to glycoside hydrolase family 1 proteins. It exhibited highest activity towards p-nitrophenyl-β-D: -glucopyranoside with an optimum activity at pH 6.0 and 7.0 and at 90 °C. The enzyme is resistant to glucose inhibition. Furthermore, it did not require divalent cations for activity, nor was it affected by the addition of p-chloromercuribenzoate (10 mM), EDTA (10 mM), urea (10 mM) or dithiothreitol (10 mM). Addition of surfactants (with the exception of SDS) and a number of solvents enhanced the activity of FiBgl1A. It also displayed remarkable activity across a broad temperature range (80-100 °C). The thermoactivity and thermostability of FiBgl1A and its resistance to denaturing and reducing agents make this enzyme a potential candidate for industrial applications.
authors.affiliation: Institute of Technical Microbiology, Hamburg University of Technology, Kasernenstr. 12, 21073, Hamburg, Germany.
authors.forename: Dina
authors.initials: D
authors.lastname: Jabbour
authors.forename: Barbara
authors.initials: B
authors.lastname: Klippel
authors.forename: Garabed
authors.initials: G
authors.lastname: Antranikian
mesh_terms: D000595:Amino Acid Sequence; D001421:Bacteria, Anaerobic / Q000201:enzymology* / Q000235:genetics; D002413:Cations, Divalent / Q000378:metabolism; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D020536:Enzyme Activators; D004791:Enzyme Inhibitors / Q000378:metabolism; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D005947:Glucose / Q000378:metabolism; D005960:Glucosides / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D013696:Temperature; D001617:beta-Glucosidase / Q000235:genetics / Q000378:metabolism*
chemical_list: D002413:Cations, Divalent; D004269:DNA, Bacterial; D020536:Enzyme Activators; D004791:Enzyme Inhibitors; D005960:Glucosides; D011994:Recombinant Proteins; C025193:4-nitrophenyl beta-D-glucoside; D001617:beta-Glucosidase; D005947:Glucose