Dramatic performance of
            <i>Clostridium thermocellum</i>
            explained by its wide range of cellulase modalities

Xu, Qi; Resch, Michael G.; Podkaminer, Kara; Yang, Shihui; Baker, John O.; Donohoe, Bryon S.; Wilson, Charlotte M.; Klingeman, Dawn M.; Olson, Daniel G.; Decker, Stephen R.; Giannone, Richard J.; Hettich, Robert L.; Brown, Steven D.; Lynd, Lee R.; Bayer, Edward A.; Himmel, Michael E.; Bomble, Yannick J.

doi:10.1126/sciadv.1501254

Cited by 110 publications

(94 citation statements)

References 46 publications

(68 reference statements)

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“…Interestingly, the regulation of Clo1313_1398 (man5A) in the two, similar C. thermocellum strains ATCC 27405 and DSM1313 appears to differ. Cthe_0821, the homolog of Clo1313_1398, was one of the most highly expressed genes when the cells were grown on biomass (7) and was in the top 6% of expressed genes grown on cellulose (5), while Clo1313_1398 was only in the top 30% of expressed genes when DSM1313 was grown on cellulose (2). The genomic architecture of this region does differ between the two strains, with DSM1313 lacking two transposase genes immediately upstream of Cthe_0821.…”

Section: Discussionmentioning

confidence: 99%

“…These enzymes are bound to scaffoldins via type 1 cohesion-dockerin domain interactions, and this large complex is anchored to the cell wall by secondary scaffol-dins and type 2 cohesin-dockerin interations (1). In addition, the bacterium produces free enzymes and "cell-free" cellulosomes (2) and it is a candidate for cellulosic ethanol production (3). Wild-type C. thermocellum can utilize hexose sugars but not pentose sugars as fermentation substrates, despite having eight genes encoding xylanases (1).…”

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confidence: 99%

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LacI Transcriptional Regulatory Networks in Clostridium thermocellum DSM1313

Wilson

Klingeman

Schlachter

et al. 2017

Appl Environ Microbiol

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Organisms regulate gene expression in response to the environment to coordinate metabolic reactions. Clostridium thermocellum expresses enzymes for both lignocellulose solubilization and its fermentation to produce ethanol. One LacI regulator termed GlyR3 in C. thermocellum ATCC 27405 was previously identified as a repressor of neighboring genes with repression relieved by laminaribiose (a ␤-1,3 disaccharide). To better understand the three C. thermocellum LacI regulons, deletion mutants were constructed using the genetically tractable DSM1313 strain. DSM1313 lacI genes Clo1313_2023, Clo1313_0089, and Clo1313_0396 encode homologs of GlyR1, GlyR2, and GlyR3 from strain ATCC 27405, respectively. Growth on cellobiose or pretreated switchgrass was unaffected by any of the gene deletions under controlled-pH fermentations. Global gene expression patterns from time course analyses identified glycoside hydrolase genes encoding hemicellulases, including cellulosomal enzymes, that were highly upregulated (5-to 100-fold) in the absence of each LacI regulator, suggesting that these were repressed under wild-type conditions and that relatively few genes were controlled by each regulator under the conditions tested. Clo1313_2022, encoding lichenase enzyme LicB, was derepressed in a ΔglyR1 strain. Higher expression of Clo1313_1398, which encodes the Man5A mannanase, was observed in a ΔglyR2 strain, and ␣-mannobiose was identified as a probable inducer for GlyR2-regulated genes. For the ΔglyR3 strain, upregulation of the two genes adjacent to glyR3 in the celC-glyR3-licA operon was consistent with earlier studies. Electrophoretic mobility shift assays have confirmed LacI transcription factor binding to specific regions of gene promoters. IMPORTANCE Understanding C. thermocellum gene regulation is of importance for improved fundamental knowledge of this industrially relevant bacterium. Most LacI transcription factors regulate local genomic regions; however, a small number of those genes encode global regulatory proteins with extensive regulons. This study indicates that there are small specific C. thermocellum LacI regulons. The identification of LacI repressor activity for hemicellulase gene expression is a key result of this work and will add to the small body of existing literature on the area of gene regulation in C. thermocellum.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

LacI Transcriptional Regulatory Networks in Clostridium thermocellum DSM1313

Wilson

Klingeman

Schlachter

et al. 2017

Appl Environ Microbiol

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“…In fact, even those microorganisms that produce cell surface-anchored cellulosomes were found to produce free cellulosomes (14,(28)(29)(30).…”

Section: Discussionmentioning

confidence: 99%

The cohesin module is a major determinant of cellulosome mechanical stability

Galera‐Prat

Moraïs

Vazana

et al. 2018

Journal of Biological Chemistry

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“…CipA (primary scaffolding) has a significant role in cellulose degradation compared to other scaffoldings. Xu et al (2016) also reported that primary scaffolding (CipA) plays a key role in C. thermocellum for cellulose degradation.…”

Section: Cellulosementioning

confidence: 99%

“…Carbohydrateactive enzymes (CAZymes) play an important role in their activity and form large protein complexes (primary and secondary scaffoldings) that bond with the cell wall of bacteria. Xu et al (2016) studied the "cell-free" cellulosomal system and characterized two types of cellulosomal systems by using mutants with scaffolding gene deletions. CipA (primary scaffolding) has a significant role in cellulose degradation compared to other scaffoldings.…”

Section: Cellulosementioning

confidence: 99%

Review on the current status of polymer degradation: a microbial approach

Pathak

Bithel

2017

Bioresour. Bioprocess.

596

241

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Inertness and the indiscriminate use of synthetic polymers leading to increased land and water pollution are of great concern. Plastic is the most useful synthetic polymer, employed in wide range of applications viz. the packaging industries, agriculture, household practices, etc. Unpredicted use of synthetic polymers is leading towards the accumulation of increased solid waste in the natural environment. This affects the natural system and creates various environmental hazards. Plastics are seen as an environmental threat because they are difficult to degrade. This review describes the occurrence and distribution of microbes that are involved in the degradation of both natural and synthetic polymers. Much interest is generated by the degradation of existing plastics using microorganisms. It seems that biological agents and their metabolic enzymes can be exploited as a potent tool for polymer degradation. Bacterial and fungal species are the most abundant biological agents found in nature and have distinct degradation abilities for natural and synthetic polymers.

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Dramatic performance of Clostridium thermocellum explained by its wide range of cellulase modalities

Abstract: The multi–length scale nature of its glycoside hydrolase system explains the remarkable ability demonstrated by Clostridium thermocellum.

Cited by 110 publications

References 46 publications

LacI Transcriptional Regulatory Networks in Clostridium thermocellum DSM1313

LacI Transcriptional Regulatory Networks in Clostridium thermocellum DSM1313

The cohesin module is a major determinant of cellulosome mechanical stability

Review on the current status of polymer degradation: a microbial approach

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