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.
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.
Biomass Research Platform Team, Biomass Engineering Program, Research Cluster for Innovation, RIKEN, 1-7-29 Suehiro-cho, Tsurumi-ward, Yokohama, Kanagawa, Japan. masatoo@riken.jp
Masato
M
Otagiri
Crisanto M
CM
Lopez
Katsuhiko
K
Kitamoto
Manabu
M
Arioka
Toshiaki
T
Kudo
Shigeharu
S
Moriya
D000595:Amino Acid Sequence; D000818:Animals; D001236:Aspergillus oryzae / Q000235:genetics; D002480:Cellulase / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D015870:Gene Expression; D020049:Isoptera / Q000382:microbiology*; D008969:Molecular Sequence Data; D013379:Substrate Specificity; D013559:Symbiosis
D002480:Cellulase