Heterologous expression and characterization of a glycoside hydrolase family 45 endo-β-1,4-glucanase from a symbiotic protist of the lower termite, Reticulitermes speratus

Appl Biochem Biotechnol. 2013 Mar;169(6):1910-8. doi: 10.1007/s12010-012-9992-1. Epub 2013 Jan 25.

Abstract

The termite symbiotic system is one of the efficient lignocellulose degradation systems. We tried to express and characterize a novel cellulolytic enzyme from this system. Here, we report the isolation of an endo-β-1,4-glucanase gene homolog of glycoside hydrolase family 45 from a symbiotic protistan community of Reticulitermes speratus. Heterologous expression of this gene was performed using the expression system of Aspergillus oryzae. Analysis of enzymatic properties revealed 786 μmol/min/mg protein in specific activity, a V max of 833.0 units/mg protein, and a K m value of 2.58 mg/ml with carboxymethyl cellulose as the substrate. Thin-layer chromatography analysis showed that RsSymEG2 produces cellobiose from cellodextrins larger than cellohexaose. This enzyme showed high specific activity like other endo-β-1,4-glucanases from the symbiotic system of termites. It means that the termite symbiotic system is a good resource for highly active endo-β-1,4-glucanases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Aspergillus oryzae / genetics
  • Cellulase / chemistry
  • Cellulase / genetics*
  • Cellulase / isolation & purification
  • Cellulase / metabolism*
  • Gene Expression
  • Isoptera / microbiology*
  • Molecular Sequence Data
  • Substrate Specificity
  • Symbiosis*

Substances

  • Cellulase