Abstract
A lichenase gene (mt-lic) was identified for the first time through function-based screening of a soil metagenomic library. Its deduced amino acid sequence exhibited a high degree of homology with endo-β-1,3-1,4-glucanase (having both lichenase and chitosanase activities), encoded by the bgc gene of Bacillus circulans WL-12. The recombinant lichenase overexpressed and purified from Escherichia coli was able to efficiently hydrolyze both barley β-glucan and lichenan. The enzyme showed maximal activity at a pH of 6.0 at 50°C, with Azo-barley-glucan as the substrate. The metal ions Mn(2+), Mg(2+), Ca(2+), and Fe(2+) enhanced the enzymatic activity, whereas the Cu(2+) and Zn(2+) ions inhibited the enzymatic activity. The Km and Vmax values of the purified lichenase were determined to be 0.45 mg/ml and 24.83 U/min/mg of protein, respectively.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Bacillus / genetics
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Cloning, Molecular
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Enzyme Activators / metabolism
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Enzyme Inhibitors / metabolism
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Enzyme Stability
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Escherichia coli / genetics
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Escherichia coli / metabolism
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Gene Expression
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Gene Library*
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Glucans / metabolism
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Glycoside Hydrolases / genetics
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Glycoside Hydrolases / isolation & purification*
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Glycoside Hydrolases / metabolism*
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Hydrogen-Ion Concentration
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Kinetics
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Metagenomics
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Metals / metabolism
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Molecular Sequence Data
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Recombinant Proteins / genetics
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Recombinant Proteins / isolation & purification
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Recombinant Proteins / metabolism
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Sequence Analysis, DNA
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Sequence Homology, Amino Acid
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Soil Microbiology*
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Substrate Specificity
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Temperature
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beta-Glucans / metabolism
Substances
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Enzyme Activators
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Enzyme Inhibitors
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Glucans
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Metals
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Recombinant Proteins
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beta-Glucans
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Glycoside Hydrolases
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licheninase
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lichenin