Biochemistry and Molecular Biology International 1998-02-01

Cloning and expression of a Clostridium thermocellum xylanase gene in Escherichia coli.

K H Jung, K M Lee, H Kim, K H Yoon, S H Park, M Y Pack

Index: Biochem. Mol. Biol. Int. 44(2) , 283-92, (1998)

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Abstract

A Clostridium thermocellum xylanase gene, designated xynX, was cloned in Escherichia coli and was categorized a novel gene as a result of the comparison of restriction patterns of the C. thermocellum xylanase genes so far reported. The xynX gene encodes a xylanase having the molecular weight of 105 kilodaltons. A number of smaller truncated proteins with activities towards 4-methylumbelliferyl-beta-D-cellobioside and xylan were also produced. The enzyme hydrolyzed xylan to xylo-oligosaccharide, indicating typical activity of endo-beta-1,4-xylanase. This endoxylanase hydrolyzed carboxymethylcellulose without notable reduction of the viscosity as an exo-beta-1,4-glucanase, even though the enzyme exhibited very low levels of activity against other soluble and insoluble cellulosic substrates.