Insights into bacterial cellulose biosynthesis by functional metagenomics on Antarctic soil samples.
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.
Berlemont
Renaud
R
Laboratory of Biological Macromolecules, Centre d'Ingéniérie des Proteines, University of Liège, Institut de Chimie B6a, Liège, Sart-Tilman, Belgium.
Delsaute
Maud
M
Pipers
Delphine
D
D'Amico
Salvino
S
Feller
Georges
G
Galleni
Moreno
M
Power
Pablo
P
D000595:Amino Acid Sequence; D000864:Antarctic Regions; D002266:Carboxymethylcellulose Sodium / Q000378:metabolism*; D002475:Cellobiose / Q000378:metabolism; D002480:Cellulase / Q000235:genetics* / Q000302:isolation & purification; D002482:Cellulose / Q000096:biosynthesis; D004269:DNA, Bacterial / Q000235:genetics* / Q000302:isolation & purification; D004795:Enzyme Stability; D005798:Genes, Bacterial; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012988:Soil Microbiology; D013379:Substrate Specificity; D013696:Temperature
D004269:DNA, Bacterial; D002475:Cellobiose; D002482:Cellulose; D002480:Cellulase; D002266:Carboxymethylcellulose Sodium