Submitted to: Insect Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2011
Publication Date: 1/16/2012
Citation: Zhang, D., Lax, A.R., Hennrisat, H., Coutinho, P., Katiya, N., Nierman, W.C., Fedorova, N. 2012. Carbohydrate active enzymes revealed in Coptotermes formosanus transcriptome. Insect Molecular Biology. 21(2):235-245. Interpretive Summary: Carbohydrate-active enzymes (CAZymes) involves in building and breaking complex carbohydrates (sugars and various polysaccharides) and glycoconjugates (sugar-linked proteins, lipids, nucleic acids, antibiotics, etc) that are essential for biological and biochemical activities. Categorization of CAZymes would help understand correlations between structures (amino acid sequences) and functions of individual enzymes (proteins). In this report, CAZymes in Formosan subterranean termites were analyzed; the results showed a characteristic feature of the wood-feeding insects. Many wood-degrading enzymes were uncovered, which are responsible for breakdown of lignocellulose. These wood-degrading enzymes have potential application in converting wood to glucose for glucose-based biofuel production and designing specific enzyme inhibitors for the development of next-generation termiticides. Characterization of other functional CAZymes would facilitate understanding the development, differentiation, and signaling among different castes of the termite.
Technical Abstract: A normalized cDNA library of Coptotermes formosanus was constructed using mixed RNA isolated from workers, soldiers, nymphs and alates of both sexes. Sequencing of this library generated 131,637 EST and 25,939 unigenes were assembled. Carbohydrate active enzymes (CAZymes) revealed in this library were analyzed in this report. There are a total of 509 putative CAZymes identified. Diverse lignocellulolytic enzymes were uncovered from both host termite and symbionts the termite harbored, which were most possibly attributed to the high efficiency of cellulose utilization. CAZymes associated with trehalose biosynthetic and metabolic pathway were also identified, which were key regulators of physiological activities of trehalose, the important insect blood sugar. Representative CAZyme coding genes in glycoside hydrolase family 1 (GH1) were quantitatively analyzed. The results showed that the five GH1 ß-glucosidase genes were expressed differentially among different castes and one of them was female alate specific. Overall, the normalized EST library, for the first time, provides a comprehensive genetic resource of C. formosanus and will serve a diverse range of research. The CAZymes represent one of the repositories of enzymes useful for physiological studies and applicable to sugar-based biofuel production.