We report the cloning and functional characterization of an endo-β-1,3-glucanase from the pinewood nematode Bursaphelenchus xylophilus acquired by horizontal gene transfer from bacteria. This is the first gene of this type from any nematode species. We show that a similar cDNA is also present in another closely related species B. mucronatus, but that similar sequences are not present in any other nematode studied to date. The B. xylophilus gene is expressed solely in the oesophageal gland cells of the nematode and the protein is present in the nematode's secretions. The deduced amino acid sequence of the gene is very similar to glycosyl hydrolase family 16 proteins. The recombinant protein, expressed in Escherichia coli, preferentially hydrolysed the β-1,3-glucan laminarin, and had very low levels of activity on β-1,3-1,4-glucan, lichenan and barley β-glucan. Laminarin was degraded in an endoglucanase mode by the enzyme. The optimal temperature and pH for activity of the recombinant enzyme were 65 °C and pH 4.9. The protein is probably important in allowing the nematodes to feed on fungi. Sequence comparisons suggest that the gene encoding the endo-β-1,3-glucanase was acquired by horizontal gene transfer from bacteria. B. xylophilus therefore contains genes that have been acquired by this process from both bacteria and fungi. These findings support the idea that multiple independent horizontal gene transfer events have helped in shaping the evolution of several different life strategies in nematodes.
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Research Article|
June 21 2005
Molecular and biochemical characterization of an endo-β-1,3-glucanase from the pinewood nematode Bursaphelenchus xylophilus acquired by horizontal gene transfer from bacteria
Taisei KIKUCHI;
Taisei KIKUCHI
1
*Forestry and Forest Products Research Institute, Tsukuba, Ibaraki 305-8687, Japan
1To whom correspondence should be addressed (email kikuchit@affrc.go.jp).
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Hajime SHIBUYA;
Hajime SHIBUYA
*Forestry and Forest Products Research Institute, Tsukuba, Ibaraki 305-8687, Japan
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John T. JONES
John T. JONES
†Plant–Pathogen Interactions Programme, Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, Scotland, U.K.
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Publisher: Portland Press Ltd
Received:
December 09 2004
Revision Received:
February 17 2005
Accepted:
February 23 2005
Accepted Manuscript online:
February 23 2005
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London
2005
Biochem J (2005) 389 (1): 117–125.
Article history
Received:
December 09 2004
Revision Received:
February 17 2005
Accepted:
February 23 2005
Accepted Manuscript online:
February 23 2005
Citation
Taisei KIKUCHI, Hajime SHIBUYA, John T. JONES; Molecular and biochemical characterization of an endo-β-1,3-glucanase from the pinewood nematode Bursaphelenchus xylophilus acquired by horizontal gene transfer from bacteria. Biochem J 1 July 2005; 389 (1): 117–125. doi: https://doi.org/10.1042/BJ20042042
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