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Title: Functional analyses of the digestive ß-Glucosidase of Formosan Subterranean Termites (Coptotermes formosanus)

Author
item Zhang, Dunhua
item Allen, April
item Lax, Alan

Submitted to: Journal of Insect Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2011
Publication Date: 1/7/2012
Citation: Zhang, D., Allen, A.B., Lax, A.R. 2012. Functional analyses of the digestive ß-Glucosidase of Formosan Subterranean Termites (Coptotermes formosanus). Journal of Insect Physiology. 58(1):205-210.

Interpretive Summary: Relative expression levels of a ß-glucosidase gene were examined among different castes and digestive tissues of Coptoterms formosanus. The recombinant ß-glucosidase had better affinity and activity toward cellobiose and cellotriose than other substrates tested. Conduritol B epoxide (CBE) strongly inhibited the activity of ß-glucosidase. Feeding termites with CBE reduced the glucose concentration in the midgut and resulted in body weight loss.

Technical Abstract: The research was to elucidate the function of the ß-glucosidase of Formosan subterranean termites in vitro and in vivo. Quantitative RT-PCR analyses indicated that the gene transcript was relatively more abundant in the foraging worker caste than in other castes and salivary glands were the major expression sites, suggesting that the ß-glucosidase was a digestive enzyme. Using recombinant ß-glucosidase produced in E. coli, the enzyme showed higher affinity and activity toward cellobiose and cellotriose than other substrates tested. In assessing impacts of specific inhibitors, we found that the ß-glucosidase could be irreversibly inactivated by conduritol B epoxide (CBE) but notgluconolactone. Feeding termites with these two inhibitors had the same effects. The CBE treatment reduced the glucose supply in the midgut and resulted in the body weight loss. These findings revealed that the ß-glucosidase has potential application for cellulose-based biofuel production while inactivation of digestive enzymes by specific inhibitors may Starve the termite.