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Title: Characterization of a new endogenous endo-ß-1,4-glucanase of Formosan subterranean termite (Coptotermes formosanus)

Author
item Zhang, Dunhua
item Lax, Alan
item Bland, John

Submitted to: Journal of Insect Biochemistry and Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/7/2010
Publication Date: 3/4/2011
Citation: Zhang, D., Lax, A.R., Bland, J.M. 2011. Characterization of a new endogenous endo-ß-1,4-glucanase of Formosan subterranean termite (Coptotermes formosanus). Journal of Insect Biochemistry and Molecular Biology. 41:211-218.

Interpretive Summary: In this work we characterized a second endogenous cellulase (endo-ß-1,4-glucanase) gene and enzyme, CfEG4, from the Formosan subterranean termite (Coptotermes formosanus). As with first cellulase enzyme the transcript of CfEG4 was detected predominantly in the salivary gland based on quantitative RT-PCR. Recombinant CfEG4, produced in a bacterium, degraded filter-paper cellulose, resulting in mostly cellobiose and cellotriose. This enzyme will be used to discover possible new inhibitors for the development of target-specific and environment-friendly bio-termicides. This cellulose-degrading enzyme is another possible enzyme that may be useful for bioconversion of wood to simple sugars and production of biofuels.

Technical Abstract: The present work characterized a second endogenous cellulase (endo-ß-1,4-glucanase) gene, CfEG4, uncovered in the transcriptome of Formosan subterranean termite (Coptotermes formosanus). The full-length gene was cloned and sequenced. It is similar to the CfEG3a described earlier (Zhang et al. 2009) but not likely an allelic variant. GenomeWalker™ DNA walking analysis indicated that there may be one copy of CfEG4 and two copies of CfEG3a in the termite genome. As with CfEG3a, the transcript of CfEG4 was detected predominantly in the salivary gland based on quantitative RT-PCR. Phylogenetic analysis of translated amino acid sequence showed that the CfEG4 is more related to CaEG, derived from an Australian subterranean termite (C. acinaciformis), than CfEG3a and other cellulases from C. formosanus, Reticulitermes speratus, or R. flavipes. Recombinant CfEG4, produced in E. coli, was active against filter-paper cellulose, resulting in mostly cellobiose and cellotriose, similar to the enzymatic and biochemical properties of CfEG3a. These findings would lead to further investigation of both the evolutionary origin of eukaryotic cellulase genes and the evolutionary relationship of termite species. The cellulose-degrading enzyme is applicable for bioconversion of wood to simple sugars and production of biofuels. The recombinant cellulase should also be useful for designing and screening of inhibitors for the development of target-specific and environment-friendly bio-termicides