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13 results on '"Abdou, Laetitia"'

2. Transcriptional regulation of the Clostridium cellulolyticum cip-cel operon: a complex mechanism involving a catabolite-responsive element

Author

Abdou, Laetitia, Boileau, Celine, de Philip, Pascale, Pages, Sandrine, Fierobe, Henri-Pierre, and Tardif, Chantal

Subjects
Cellulose -- Genetic aspects, Clostridium -- Physiological aspects, Clostridium -- Genetic aspects, Biological sciences
Abstract

The cip-cel cluster of genes plays an important role in the catabolism of the substrate cellulose by Clostridium cellulolyticum. It encodes several key components of the cellulosomes, including the scaffolding protein CipC and the major cellulase Ce148F. All the genes of this cluster display linked transcription, focusing attention on the promoter upstream from the first gene, cipC. We analyzed the regulation of the cipC promoter using a transcriptional fusion approach. A single promoter is located between nucleotides -671 and -643 with respect to the ATG start codon, and the large mRNA leader sequence is processed at position -194. A catabolite-responsive element (CRE) 414 nucleotides downstream from the transcriptional start site has been shown to be involved in regulating this operon by a carbon catabolite repression mechanism. This CRE is thought to bind a CcpA-like regulator complexed with a P-Ser-Crh-like protein. Sequences surrounding the promoter sequence may also be involved in direct (sequencedependent DNA curvature) or indirect (unknown regulator binding) regulation.

Published
2008

3. Transcriptional analysis of the cip-cel gene cluster from Clostridium cellulolyticum

Author

Maamar, Hedia, Abdou, Laetitia, Boileau, Celine, Valette, Odile, and Tardif, Chantal

Subjects
Gene mutations -- Research, Genetic transcription -- Research, Genetic research, Biological sciences
Abstract

Twelve genes encoding key components of Clostridium celhdolyticum cellulosomes are clustered. Among them, the first, second, and fifth genes encode the assembly factor CipC and the two major cellulases Cel48F and Cel9E, respectively. Cellulolytic clones were selected from the noncellulolytic cipC insertional mutant transcomplemented with a cipC expression vector, in which one homologous recombination event between the 3' end of the chromosomal cipC gene and the plasmidic cipC gene has restored the cluster continuity. The absence of the enzymes encoded by the cluster in the cipC mutant was thus only due to a strong polar effect, indicating that all genes were transcriptionally linked. Two large transcripts were detected in cellulose-grown cells by Northern hybridization: a 14-kb messenger which carries the cipC-cel48F-cel8C-cel9G-cel9E coding sequences and, in a smaller amount, a 12-kb messenger which carries the genes located in the 3' part of the cluster. Four smaller transcripts were found in large amounts: a cipC-cel48F bicistronie one and three monocistronie ones, cipC, cel48F, and cel9E. The cipC-cel48F and cel48F messengers were shown to be stable. Analysis by reverse transcription-PCR suggested transcriptional linkage of all of the open reading frames. The production of a primary very large transcript covering the entire cluster was hypothesized. Primer extension analysis has identified two putative transcriptional start sites located 638/637 and 194 nucleotides upstream of the cipC translational start. The processing of the primary transcript would lead to the production of several secondary messengers displaying different stabilities, contributing to fine tuning of expression of individual genes of the operon.

Published
2006

4. A rhamnogalacturonan lyase in the Clostridium cellulolyticum cellulosome

Author

Pages, Sandrine, Valette, Odile, Abdou, Laetitia, Belaich, Anne, and Belaich, Jean-Pierre

Subjects
Prolactin -- Physiological aspects, Lyases -- Genetic aspects, Polysaccharides -- Physiological aspects, Biodegradation -- Genetic aspects, Biodegradation -- Physiological aspects, Gene expression -- Physiological aspects, Secretion -- Genetic aspects, Clostridium -- Genetic aspects, Plant cells and tissues -- Genetic aspects, Bacteriology -- Research, Biological sciences
Abstract

Clostridium cellulolyticum secretes large multienzymatic complexes with plant cell wail-degrading activities named cellulosomes. Most of the genes encoding cellulosomal components are located in a large gene cluster: cipC-cel48F-cel8C-cel9G-cel9E-orfX-cel9H-cel9J-man5K-cel9M. Downstream of the cel9M gene, a new open reading frame was discovered and named rgl11Y. Amino acid sequence analysis indicates that this gene encodes a multidomain pectinase, Rgl11Y, containing an N-terminal signal sequence, a catalytic domain belonging to family 11 of the polysaccharide lyases, and a C-terminal dockerin domain. The present report describes the biochemical characterization of a recombinant form of Rgl11Y. Rgl11Y cleaves the [alpha]-L-Rhap-(1[vector]4)-[alpha]-D-GalpA glycosidic bond in the backbone of rhamnogalacturonan I (RGI) via a [beta]-elimination mechanism. Its specific activity on potato pectic galactan and rhamnogalacturonan was found to be 28 and 3.6 IU/mg, respectively, indicating that Rgl11Y requires galactan decoration of the RGI backbone. The optimal pH of Rgl11Y is 8.5 and calcium is required for its activity. Rgl11Y was shown to be incorporated in the C. cellulolyticum cellulosome through a typical cohesin-dockerin interaction. Rgl11Y from C. cellulolyticum is the first cellulosomal rhamnogalacturonase characterized.

Published
2003

5. Interplay between the catabolite repression control protein Crc, Hfq and RNA in Hfq-dependent translational regulation in Pseudomonas aeruginosa

Author

Sonnleitner, Elisabeth, primary, Wulf, Alexander, additional, Campagne, Sébastien, additional, Pei, Xue-Yuan, additional, Wolfinger, Michael T, additional, Forlani, Giada, additional, Prindl, Konstantin, additional, Abdou, Laetitia, additional, Resch, Armin, additional, Allain, Frederic H -T, additional, Luisi, Ben F, additional, Urlaub, Henning, additional, and Bläsi, Udo, additional

Published
2017
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9. Interplay between the catabolite repression control protein Crc, Hfq and RNA in Hfq-dependent translational regulation in Pseudomonas aeruginosa

Author

Sonnleitner, Elisabeth, Wulf, Alexander, Campagne, Sébastien, Pei, Xue-Yuan, Wolfinger, Michael T., Forlani, Giada, Prindl, Konstantin, Abdou, Laetitia, Resch, Armin, Allain, Frédéric H.-T., Luisi, Ben F., Urlaub, Henning, and Bläsi, Udo

Subjects
neoplasms, digestive system diseases, 3. Good health
Abstract

In Pseudomonas aeruginosa the RNA chaperone Hfq and the catabolite repression control protein (Crc) act as post-transcriptional regulators during carbon catabolite repression (CCR). In this regard Crc is required for full-fledged Hfq-mediated translational repression of catabolic genes. RNAseq based transcriptome analyses revealed a significant overlap between the Crc and Hfq regulons, which in conjunction with genetic data supported a concerted action of both proteins. Biochemical and biophysical approaches further suggest that Crc and Hfq form an assembly in the presence of RNAs containing A-rich motifs, and that Crc interacts with both, Hfq and RNA. Through these interactions, Crc enhances the stability of Hfq/Crc/RNA complexes, which can explain its facilitating role in Hfq-mediated translational repression. Hence, these studies revealed for the first time insights into how an interacting protein can modulate Hfq function. Moreover, Crc is shown to interfere with binding of a regulatory RNA to Hfq, which bears implications for riboregulation. These results are discussed in terms of a working model, wherein Crc prioritizes the function of Hfq toward utilization of favored carbon sources., Nucleic Acids Research, 46 (3), ISSN:1362-4962, ISSN:0301-5610

10. Regulation of cel genes of C. cellulolyticum: identification of GlyR2, a transcriptional regulator regulating cel5D gene expression

Author

Fendri, Imen, Abdou, Laetitia, Trotter, Valentine, Dedieu, Luc, Maamar, Hédia, Minton, Nigel P., Tardif, Chantal, Fendri, Imen, Abdou, Laetitia, Trotter, Valentine, Dedieu, Luc, Maamar, Hédia, Minton, Nigel P., and Tardif, Chantal

Abstract

Transcription and expression regulation of some individual cel genes (cel5A, cel5I, cel5D and cel44O) of Clostridium cellulolyticum were investigated. Unlike the cip-cel operon, these genes are transcribed as monocistronic units of transcription, except cel5D. The location of the transcription initiation sites was determined using RT-PCR and the mRNA 5′-end extremities were detected using primer extension experiments. Similarly to the cip-cel operon, cel5A and cel5I expressions are regulated by a carbon catabolite repression mechanism, whereas cel44O and cel5D expressions do not seem to be submitted to this regulation. The role of the putative transcriptional regulator GlyR2 in the regulation of cel5D expression was investigated. The recombinant protein GlyR2 was produced and was shown to bind in vitro to the cel5D and glyR2 promoter regions, suggesting that besides regulating its own expression, GlyR2 may regulate cel5D expression. To test this hypothesis in vivo, an insertional glyR2 mutant was generated and the effect of this disruption on cel5D expression was evaluated. Levels of cel5D mRNAs in the mutant were 16 fold lower than that of the wild-type strain suggesting that GlyR2 acts as an activator of cel5D expression.

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11. Regulation of cel genes of C. cellulolyticum: identification of GlyR2, a transcriptional regulator regulating cel5D gene expression

Author

Fendri, Imen, Abdou, Laetitia, Trotter, Valentine, Dedieu, Luc, Maamar, Hédia, Minton, Nigel P., Tardif, Chantal, Fendri, Imen, Abdou, Laetitia, Trotter, Valentine, Dedieu, Luc, Maamar, Hédia, Minton, Nigel P., and Tardif, Chantal

Abstract

Transcription and expression regulation of some individual cel genes (cel5A, cel5I, cel5D and cel44O) of Clostridium cellulolyticum were investigated. Unlike the cip-cel operon, these genes are transcribed as monocistronic units of transcription, except cel5D. The location of the transcription initiation sites was determined using RT-PCR and the mRNA 5′-end extremities were detected using primer extension experiments. Similarly to the cip-cel operon, cel5A and cel5I expressions are regulated by a carbon catabolite repression mechanism, whereas cel44O and cel5D expressions do not seem to be submitted to this regulation. The role of the putative transcriptional regulator GlyR2 in the regulation of cel5D expression was investigated. The recombinant protein GlyR2 was produced and was shown to bind in vitro to the cel5D and glyR2 promoter regions, suggesting that besides regulating its own expression, GlyR2 may regulate cel5D expression. To test this hypothesis in vivo, an insertional glyR2 mutant was generated and the effect of this disruption on cel5D expression was evaluated. Levels of cel5D mRNAs in the mutant were 16 fold lower than that of the wild-type strain suggesting that GlyR2 acts as an activator of cel5D expression.

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12. Regulation of cel genes of C. cellulolyticum: identification of GlyR2, a transcriptional regulator regulating cel5D gene expression

Author

Fendri, Imen, Abdou, Laetitia, Trotter, Valentine, Dedieu, Luc, Maamar, Hédia, Minton, Nigel P., Tardif, Chantal, Fendri, Imen, Abdou, Laetitia, Trotter, Valentine, Dedieu, Luc, Maamar, Hédia, Minton, Nigel P., and Tardif, Chantal

Abstract

Transcription and expression regulation of some individual cel genes (cel5A, cel5I, cel5D and cel44O) of Clostridium cellulolyticum were investigated. Unlike the cip-cel operon, these genes are transcribed as monocistronic units of transcription, except cel5D. The location of the transcription initiation sites was determined using RT-PCR and the mRNA 5′-end extremities were detected using primer extension experiments. Similarly to the cip-cel operon, cel5A and cel5I expressions are regulated by a carbon catabolite repression mechanism, whereas cel44O and cel5D expressions do not seem to be submitted to this regulation. The role of the putative transcriptional regulator GlyR2 in the regulation of cel5D expression was investigated. The recombinant protein GlyR2 was produced and was shown to bind in vitro to the cel5D and glyR2 promoter regions, suggesting that besides regulating its own expression, GlyR2 may regulate cel5D expression. To test this hypothesis in vivo, an insertional glyR2 mutant was generated and the effect of this disruption on cel5D expression was evaluated. Levels of cel5D mRNAs in the mutant were 16 fold lower than that of the wild-type strain suggesting that GlyR2 acts as an activator of cel5D expression.

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13. Regulation of cel genes of C. cellulolyticum: identification of GlyR2, a transcriptional regulator regulating cel5D gene expression

Author

Fendri, Imen, Abdou, Laetitia, Trotter, Valentine, Dedieu, Luc, Maamar, Hédia, Minton, Nigel P., Tardif, Chantal, Fendri, Imen, Abdou, Laetitia, Trotter, Valentine, Dedieu, Luc, Maamar, Hédia, Minton, Nigel P., and Tardif, Chantal

Abstract

Transcription and expression regulation of some individual cel genes (cel5A, cel5I, cel5D and cel44O) of Clostridium cellulolyticum were investigated. Unlike the cip-cel operon, these genes are transcribed as monocistronic units of transcription, except cel5D. The location of the transcription initiation sites was determined using RT-PCR and the mRNA 5′-end extremities were detected using primer extension experiments. Similarly to the cip-cel operon, cel5A and cel5I expressions are regulated by a carbon catabolite repression mechanism, whereas cel44O and cel5D expressions do not seem to be submitted to this regulation. The role of the putative transcriptional regulator GlyR2 in the regulation of cel5D expression was investigated. The recombinant protein GlyR2 was produced and was shown to bind in vitro to the cel5D and glyR2 promoter regions, suggesting that besides regulating its own expression, GlyR2 may regulate cel5D expression. To test this hypothesis in vivo, an insertional glyR2 mutant was generated and the effect of this disruption on cel5D expression was evaluated. Levels of cel5D mRNAs in the mutant were 16 fold lower than that of the wild-type strain suggesting that GlyR2 acts as an activator of cel5D expression.

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