Journal Article

Cloning and sequencing of the gene for cellobiose 2-epimerase from a ruminal strain of <i>Eubacterium cellulosolvens</i>

Hidenori Taguchi, Takeshi Senoura, Shigeki Hamada, Hirokazu Matsui, Yasuo Kobayashi, Jun Watanabe, Jun Wasaki and Susumu Ito

in FEMS Microbiology Letters

Volume 287, issue 1, pages 34-40
Published in print October 2008 |
Published online September 2008 | e-ISSN: 1574-6968 | DOI: http://dx.doi.org/10.1111/j.1574-6968.2008.01281.x

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Abstract

Cellobiose 2-epimerase (CE; EC 5.1.3.11) is known to catalyze the reversible epimerization of cellobiose to 4-O-β-d-glucopyranosyl-d-mannose in Ruminococcus albus cells. Here, we report a CE in a ruminal strain of Eubacterium cellulosolvens for the first time. The nucleotide sequence of the CE had an ORF of 1218 bp (405 amino acids; 46 963.3 Da). The CE from E. cellulosolvens showed 44–54% identity to N-acyl-d-glucosamine 2-epimerase-like hypothetical proteins in the genomes of Coprococcus eutactus, Faecalibacterium prausnitzii, Clostridium phytofermentans, Caldicellulosiruptor saccharolyticus, and Eubacterium siraeum. Surprisingly, it exhibited only 46% identity to a CE from R. albus. The recombinant enzyme expressed in Escherichia coli was purified by two-step chromatography. The purified enzyme had a molecular mass of 46.7 kDa and exhibited optimal activity at around 35 °C and pH 7.0–8.5. In addition to cello-oligosaccharides, it converted lactose to epilactose (4-O-β-d-galactopyranosyl-d-mannose).

Keywords: Eubacterium; rumen; cellobiose 2-epimerase; N-acyl-d-glucosamine 2-epimerase; epilactose

Journal Article.  3755 words.  Illustrated.

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