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Molecular cloning and characterization of an endogenous digestive β-glucosidase from the midgut of the fungus-growing termite Macrotermes barneyi

Authors


Correspondence: Jinfeng Ni, State Key Laboratory of Microbial Technology, Shandong University, 27 Shandanan Road, Jinan, Shandong 250100, China. Tel.: +86-531-88363323; fax: +86 531 88362928; e-mail: jinfgni@sdu.edu.cn

Abstract

β-glucosidase from the midgut of the fungus-growing termite Macrotermes barneyi was first cloned and characterized to gain a better understanding of cellulolytic systems in fungus-growing termites. β-glucosidase activity was proven to present primarily in the midgut of M. barneyi and two β-glucosidases were partially purified from the midgut. Based on the N-terminus sequence of one of the β-glucosidases, a full-length cDNA fragment of 1708 bp was obtained. This sequence encodes a 493 amino acid protein belonging to glycoside hydrolase family 1. Quantitative real-time PCR analysis proved that the β-glucosidase gene was primarily expressed in the midgut. β-glucosidase was expressed heterologously and biochemically characterized. Results indicate that β-glucosidase is an endogenous, midgut-origin termite digestive enzyme. It may have applications in understanding the mechanism of lignocellulose degradation in fungus-growing termites.

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