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See detailEtude de l'implication de cellulases dans la voie de biosynthèse de cellulose chez les bactéries
Delsaute, Maud ULg

Doctoral thesis (2014)

By definition, cellulases are enzymes that catalyze the degradation of cellulose. However, their involvement in cellulose biosynthesis by bacteria and plants has been reported, although their exact ... [more ▼]

By definition, cellulases are enzymes that catalyze the degradation of cellulose. However, their involvement in cellulose biosynthesis by bacteria and plants has been reported, although their exact contribution remains unclear. In the present study, we have investigated the involvement of cellulases from glycoside hydrolase family 5 (GH5) in cellulose synthesis. In particular, we have functionally and structurally characterized the Ps_Cel5A cellulase from Pseudomonas stutzeri and its metagenome-derived homolog RBcel1, which both belong to the GH5 family and are suspected to be involved in cellulose biosynthesis. In addition, we have also compared these enzymes with the well-characterized Ta_Cel5A cellulase from the cellulolytic fungus Thermoascus aurantiacus. The first part of the work was devoted to the description of the tridimensional structure of RBcel1, in comparison with other glycoside hydrolases from GH5. In the second part of the study, we focused on the functional and structural comparison between RBcel1, Ps_CelA and Ta_Cel5A. Biochemical analysis has highlighted that, besides their hydrolytic activity, RBcel1 and Ps_Cel5A were able to catalyze transglycosylation in vitro. This synthesis reaction was not detected for Ta_Cel5A, which seemed to remain hydrolytic only. Determination of the structure of RBcel1 in complex with cellobiose has revealed distinct features in the aglycone substrate binding sites compared to Ta_Cel5A which could potentially explain the observed differences in their activities in vitro. Finally, the involvement of Ps_Cel5A in cellulose production by P. stutzeri was confirmed, by analysis the ability of P. stutzeri-ΔPs_Cel5A to produce the polymer. Complementation of this mutant strain by the three cellulases was also performed and discussed. [less ▲]

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See detailLa production de cellulose chez les plantes et les bactéries
Delsaute, Maud ULg

Scientific conference (2013, May 03)

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See detailEtude de l'implication de cellulases dans la synthèse de cellulose bactérienne
Delsaute, Maud ULg

Scientific conference (2012)

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See detailCellulase involvement in the bacterial cellulose biosynthesis
Delsaute, Maud ULg; Berlemont, Renaud ULg; Bauvois, Cédric et al

Poster (2012)

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See detailCellulase involvement in the cellulose biosynthesis of Pseudomonas stutzeri
Delsaute, Maud ULg; Berlemont, Renaud ULg; Paulus, Virginie et al

Poster (2011)

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See detailExploring the Antarctic soil metagenome as a source of novel cold-adapted enzymes and genetic mobile elements
Berlemont, Renaud ULg; Pipers; Delsaute, Maud ULg et al

in Revista Argentina de Microbiologia (2011)

Metagenomic library PP1 was obtained from Antarctic soil samples. Both functional and genotypic metagenomic screening were used for the isolation of novel cold-adapted enzymes with potential applications ... [more ▼]

Metagenomic library PP1 was obtained from Antarctic soil samples. Both functional and genotypic metagenomic screening were used for the isolation of novel cold-adapted enzymes with potential applications, and for the detection of genetic elements associated with gene mobilization, respectively. Fourteen lipase/esterase-, 14 amylase-, 3 protease-, and 11 cellulase-producing clones were detected by activity-driven screening, with apparent maximum activities around 35 °C for both amylolytic and lipolytic enzymes, and 35-55 °C for cellulases, as observed for other cold-adapted enzymes. However, the behavior of at least one of the studied cellulases is more compatible to that observed for mesophilic enzymes. These enzymes are usually still active at temperatures above 60 °C, probably resulting in a psychrotolerant behavior in Antarctic soils. Metagenomics allows to access novel genes encoding for enzymatic and biophysic properties from almost every environment with potential benefits for biotechnological and industrial applications. Only intI- and tnp-like genes were detected by PC R, encoding for proteins with 58-86%, and 58-73% amino acid identity with known entries, respectively. Two clones, BAC 27A-9 and BAC 14A-5, seem to present unique syntenic organizations, suggesting the occurrence of gene rearrangements that were probably due to evolutionary divergences within the genus or facilitated by the association with transposable elements. The evidence for genetic elements related to recruitment and mobilization of genes (transposons/integrons) in an extreme environment like Antarctica reinforces the hypothesis [less ▲]

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See detailEtude de l'implication de cellulases dans la synthèse de cellulose bactérienne
Delsaute, Maud ULg

Scientific conference (2011)

Detailed reference viewed: 25 (17 ULg)
See detailInsights into the metagenomic approach : identification and characterization of cellulases involved in bacterial cellulose synthesis
Berlemont, Renaud ULg; Delsaute, Maud ULg; Galleni, Moreno ULg

Conference (2010, March 22)

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 ... [more ▼]

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 1C). 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. [less ▲]

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See detailCellulases catalysed cellulose polymerisation
Delsaute, Maud ULg; Berlemont, Renaud ULg; Renson, Thomas ULg et al

Poster (2010)

Detailed reference viewed: 33 (26 ULg)
See detailLes années métagénomiques au CIP, état des lieux et perspectives
Berlemont, Renaud ULg; Delsaute, Maud ULg

Scientific conference (2010)

Detailed reference viewed: 32 (15 ULg)
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See detailInsights into bacterial cellulose biosynthesis by functional metagenomics on Antarctic soil samples.
Berlemont, Renaud ULg; Delsaute, Maud ULg; Pipers, Delphine ULg et al

in ISME Journal (The) (2009), 3(9), 1070-1081

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 ... [more ▼]

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.The ISME Journal advance online publication, 21 May 2009; doi:10.1038/ismej.2009.48. [less ▲]

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