Characterization of a novel beta-glucosidase-like activity from a soil metagenome

J Microbiol. 2009 Oct;47(5):542-8. doi: 10.1007/s12275-009-0024-y. Epub 2009 Oct 24.

Abstract

We report the cloning of a novel beta-glucosidase-like gene by function-based screening of a metagenomic library from uncultured soil microorganisms. The gene was named bgllC and has an open reading frame of 1,443 base pairs. It encodes a 481 amino acid polypeptide with a predicted molecular mass of about 57.8 kDa. The deduced amino acid sequence did not show any homology with known beta-glucosidases. The putative beta-glucosidase gene was subcloned into the pETBlue-2 vector and overexpressed in E. coli Tuner (DE3) pLacI; the recombinant protein was purified to homogeneity. Functional characterization with a high performance liquid chromatography method demonstrated that the recombinant BgllC protein hydrolyzed D-glucosyl-beta-(l-4)-D-glucose to glucose. The maximum activity for BgllC protein occurred at pH 8.0 and 42 degrees C using p-nitrophenyl-beta-D-glucoside as the substrate. A CaCl(2) concentration of 1 mM was required for optimal activity. The putative beta-glucosidase had an apparent K(m) value of 0.19 mM, a V(max) value of 4.75 U/mg and a k (cat) value of 316.7/min under the optimal reaction conditions. The biochemical characterization of BgllC has enlarged our understanding of the novel enzymes that can be isolated from the soil metagenome.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cloning, Molecular
  • Enzyme Stability
  • Escherichia coli / genetics
  • Gene Expression
  • Hydrogen-Ion Concentration
  • Kinetics
  • Metagenome*
  • Metagenomics / methods
  • Molecular Sequence Data
  • Molecular Weight
  • Open Reading Frames
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid
  • Soil Microbiology*
  • Substrate Specificity
  • Temperature
  • beta-Glucosidase / chemistry
  • beta-Glucosidase / genetics*
  • beta-Glucosidase / isolation & purification
  • beta-Glucosidase / metabolism*

Substances

  • beta-Glucosidase

Associated data

  • GENBANK/EU678637