Dataset Information

A two-component system (XydS/R) controls the expression of genes encoding CBM6-containing proteins in response to straw in Clostridium cellulolyticum.

ABSTRACT: The composition of the cellulosomes (multi enzymatic complexes involved in the degradation of plant cell wall polysaccharides) produced by Clostridium cellulolyticum differs according to the growth substrate. In particular, the expression of a cluster of 14 hemicellulase-encoding genes (called xyl-doc) seems to be induced by the presence of straw and not of cellulose. Genes encoding a putative two-component regulation system (XydS/R) were found upstream of xyl-doc. First evidence for the involvement of the response regulator, XydR, part of this two-component system, in the expression of xyl-doc genes was given by the analysis of the cellulosomes produced by a regulator overproducing strain when grown on cellulose. Nano-LC MS/MS analysis allowed the detection of the products of all xyl-doc genes and of the product of the gene at locus Ccel_1656 predicted to bear a carbohydrate binding domain targeting hemicellulose. RT-PCR experiments further demonstrated that the regulation occurs at the transcriptional level and that all xyl-doc genes are transcriptionally linked. mRNA quantification in a regulator knock-out strain and in its complemented derivative confirmed the involvement of the regulator in the expression of xyl-doc genes and of the gene at locus Ccel_1656 in response to straw. Electrophoretic mobility shift assays using the purified regulator further demonstrated that the regulator binds to DNA regions located upstream of the first gene of the xyl-doc gene cluster and upstream of the gene at locus Ccel_1656.

SUBMITTER: Celik H

PROVIDER: S-EPMC3572039 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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A two-component system (XydS/R) controls the expression of genes encoding CBM6-containing proteins in response to straw in Clostridium cellulolyticum.

Celik Hamza H Blouzard Jean-Charles JC Voigt Birgit B Becher Dörte D Trotter Valentine V Fierobe Henri-Pierre HP Tardif Chantal C Pagès Sandrine S de Philip Pascale P

PloS one 20130213 2

The composition of the cellulosomes (multi enzymatic complexes involved in the degradation of plant cell wall polysaccharides) produced by Clostridium cellulolyticum differs according to the growth substrate. In particular, the expression of a cluster of 14 hemicellulase-encoding genes (called xyl-doc) seems to be induced by the presence of straw and not of cellulose. Genes encoding a putative two-component regulation system (XydS/R) were found upstream of xyl-doc. First evidence for the involve ...[more]

PMID: 23418511

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Project description:Cellulolytic microorganisms play a key role in the global carbon cycle by decomposing structurally diverse plant biopolymers from dead plant matter. These microorganisms, in particular anaerobes such as Ruminiclostridium cellulolyticum that are capable of degrading and catabolizing several different polysaccharides, require a fine-tuned regulation of the biosynthesis of their polysaccharide-degrading enzymes. In this study, we present a bacterial regulatory system involved in the regulation of genes enabling the metabolism of the ubiquitous plant polysaccharide xyloglucan. The characterization of R. cellulolyticum knockout mutants suggests that the response regulator XygR and its cognate histidine kinase XygS are essential for growth on xyloglucan. Using in vitro and in vivo analyses, we show that XygR binds to the intergenic region and activates the expression of two polycistronic transcriptional units encoding an ABC transporter dedicated to the uptake of xyloglucan oligosaccharides and the two-component system itself together with three intracellular glycoside hydrolases responsible for the sequential intracellular degradation of the imported oligosaccharides into mono- and disaccharides. Interestingly, XygR also upregulates the expression of a distant gene coding for the most active extracellular cellulosomal xyloglucanase of R. cellulolyticum by binding to the upstream intergenic region.IMPORTANCE Ruminiclostridium cellulolyticum is a Gram-positive, mesophilic, anaerobic, cellulolytic, and hemicellulolytic bacterium. The last property qualifies this species as a model species for the study of hemicellulose degradation, import of degradation products, and overall regulation of these phenomena. In this study, we focus on the regulation of xyloglucan dextrin import and intracellular degradation and show that the two components of the two-component regulation system XygSR are essential for growth on xyloglucan and that the response regulator XygR regulates the transcription of genes involved in the extracellular degradation of the polysaccharide, the import of degradation products, and their intracellular degradation.

Dataset Information

A two-component system (XydS/R) controls the expression of genes encoding CBM6-containing proteins in response to straw in Clostridium cellulolyticum.

Publications

A two-component system (XydS/R) controls the expression of genes encoding CBM6-containing proteins in response to straw in Clostridium cellulolyticum.

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