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ISME J. 2009 Sep;3(9):1070-81. doi: 10.1038/ismej.2009.48. Epub 2009 May 21.

Insights into bacterial cellulose biosynthesis by functional metagenomics on Antarctic soil samples.

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1
Laboratory of Biological Macromolecules, Centre d'Ingéniérie des Proteines, University of Liège, Institut de Chimie B6a, Liège, Sart-Tilman, Belgium.

Abstract

In this study, the mining of an Antarctic soil sample by functional metagenomics allowed the isolation of a cold-adapted protein (RBcel1) that hydrolyzes only carboxymethyl cellulose. The new enzyme is related to family 5 of the glycosyl hydrolase (GH5) protein from Pseudomonas stutzeri (Pst_2494) and does not possess a carbohydrate-binding domain. The protein was produced and purified to homogeneity. RBcel1 displayed an endoglucanase activity, producing cellobiose and cellotriose, using carboxymethyl cellulose as a substrate. Moreover, the study of pH and the thermal dependence of the hydrolytic activity shows that RBcel1 was active from pH 6 to pH 9 and remained significantly active when temperature decreased (18% of activity at 10 degrees C). It is interesting that RBcel1 was able to synthetize non-reticulated cellulose using cellobiose as a substrate. Moreover, by a combination of bioinformatics and enzyme analysis, the physiological relevance of the RBcel1 protein and its mesophilic homologous Pst_2494 protein from P. stutzeri, A1501, was established as the key enzymes involved in the production of cellulose by bacteria. In addition, RBcel1 and Pst_2494 are the two primary enzymes belonging to the GH5 family involved in this process.

PMID:
19458657
DOI:
10.1038/ismej.2009.48
[Indexed for MEDLINE]
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