Corrigendum: Pentose sugars inhibit metabolism and increase expression of an AgrD-type cyclic pentapeptide in Clostridium thermocellum.
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ABSTRACT:
SUBMITTER: Verbeke TJ
PROVIDER: S-EPMC5532492 | biostudies-literature | 2017 Jul
REPOSITORIES: biostudies-literature
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Corrigendum: Pentose sugars inhibit metabolism and increase expression of an AgrD-type cyclic pentapeptide in Clostridium thermocellum.
Verbeke Tobin J TJ Giannone Richard J RJ Klingeman Dawn M DM Engle Nancy L NL Rydzak Thomas T Guss Adam M AM Tschaplinski Timothy J TJ Brown Steven D SD Hettich Robert L RL Elkins James G JG
Scientific reports 20170727
This corrects the article DOI: 10.1038/srep43355. ...[more]
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Project description:Clostridium thermocellum could potentially be used as a microbial biocatalyst to produce renewable fuels directly from lignocellulosic biomass due to its ability to rapidly solubilize plant cell walls. While the organism readily ferments sugars derived from cellulose, pentose sugars from xylan are not metabolized. Here, we show that non-fermentable pentoses inhibit growth and end-product formation during fermentation of cellulose-derived sugars. Metabolomic experiments confirmed that xylose is transported intracellularly and reduced to the dead-end metabolite xylitol. Comparative RNA-seq analysis of xylose-inhibited cultures revealed several up-regulated genes potentially involved in pentose transport and metabolism, which were targeted for disruption. Deletion of the ATP-dependent transporter, CbpD partially alleviated xylose inhibition. A putative xylitol dehydrogenase, encoded by Clo1313_0076, was also deleted resulting in decreased total xylitol production and yield by 41% and 46%, respectively. Finally, xylose-induced inhibition corresponds with the up-regulation and biogenesis of a cyclical AgrD-type, pentapeptide. Medium supplementation with the mature cyclical pentapeptide also inhibits bacterial growth. Together, these findings provide new foundational insights needed for engineering improved pentose utilizing strains of C. thermocellum and reveal the first functional Agr-type cyclic peptide to be produced by a thermophilic member of the Firmicutes.
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Project description:Differential RNA-Seq analyses to investigate the basis for metabolic inhibition of Clostridium thermocellum M1570 by xylose. The M1570 strain was developed in the C. thermocellum DSM 1313 Δhpt background strain. Lactate dehydrogenase (Ldh) and phosphotransacetylase (Pta) genes are deleted (Argyros DA, Tripathi SA, Barrett TF, Rogers SR, Feinberg LF, Olson DG, Foden JM, Miller BB, Lynd LR, Hogsett DA, Caiazza NC: High ethanol titers from cellulose by using metabolically engineered thermophilic, anaerobic microbes. Appl Environ Microbiol 2010, 77:8288-8294 )
2016-10-31 | GSE74918 | GEO
Project description:Cofactor specificities of glycolytic enzymes in Clostridium thermocellum were studied with cellobiose-grown cells from batch cultures. Intracellular glucose was phosphorylated by glucokinase using GTP rather than ATP. Although phosphofructokinase typically uses ATP as a phosphoryl donor, we found only pyrophosphate (PPi)-linked activity. Phosphoglycerate kinase used both GDP and ADP as phosphoryl acceptors. In agreement with the absence of a pyruvate kinase sequence in the C. thermocellum genome, no activity of this enzyme could be detected. Also, the annotated pyruvate phosphate dikinase (ppdk) is not crucial for the generation of pyruvate from phosphoenolpyruvate (PEP), as deletion of the ppdk gene did not substantially change cellobiose fermentation. Instead pyruvate formation is likely to proceed via a malate shunt with GDP-linked PEP carboxykinase, NADH-linked malate dehydrogenase, and NADP-linked malic enzyme. High activities of these enzymes were detected in extracts of cellobiose-grown cells. Our results thus show that GTP is consumed while both GTP and ATP are produced in glycolysis of C. thermocellum. The requirement for PPi in this pathway can be satisfied only to a small extent by biosynthetic reactions, in contrast to what is generally assumed for a PPi-dependent glycolysis in anaerobic heterotrophs. Metabolic network analysis showed that most of the required PPi must be generated via ATP or GTP hydrolysis exclusive of that which happens during biosynthesis. Experimental proof for the necessity of an alternative mechanism of PPi generation was obtained by studying the glycolysis in washed-cell suspensions in which biosynthesis was absent. Under these conditions, cells still fermented cellobiose to ethanol.
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Project description:Investigation of sulfur metabolism in Clostridium thermocellum DSM 1313 ∆hpt, to determine growth and gene expression when the organism is incubated with either the oxidized (i.e., sulfate) or the reduced and assimilated (i.e., cysteine) forms of sulfur. A sulfite reductase (∆hpt ∆SO3R) knockout mutant to limit sulfur assimilation was created to compare the resulting gene expression patterns by RNAseq transciptomics against the parental strain (∆hpt) when both are grown in the presence of sulfate. Additionally, we bypass the sulfate auxotrophy of the mutant by providing assimilated sulfur in the form of cysteine to determine whether growth is restored to normal and whether methionine can be biosynthesized by yet uncharacterized pathways in this organism.
2020-11-01 | GSE100047 | GEO
Project description:Homologues of the chaperonins Cpn60 and Cpn10 have been purified from the Gram-positive cellulolytic thermophile Clostridium thermocellum. The Cpn60 protein was purified by ATP-affinity chromatography and the Cpn10 protein was purified by gel-filtration, ion-exchange and hydrophobic interaction chromatographies. The identities of the proteins were confirmed by N-terminal sequence analysis and antigenic cross-reactivity. The Cpn60 homologue is a weak, thermostable ATPase (t1/2 at 70 decrees C more than 90 min) with optimum activity (Kcat 0.07 S-1) between 60 degrees C and 70 degrees C. The ATPase activity of the authentic Cpn60 was inhibited by Escherichia coli GroES. The catalytic properties of a recombinant C. thermocellum Cpn60 purified from a GST-Cpn60 fusion protein expressed in E. coli [Ciruela (1995) Ph.D. Thesis, University of Kent] were identical with those of the authentic C. thermocellum Cpn60. Gel-filtration studies show that at room temperature the Cpn60 migrates mainly as a heptamer. Electron microscopy confirms the presence of complexes showing 7-fold rotational symmetry and also reveals a small number of particles that seem to be tetradecamers with a similar structure to E. coli GroEL complexes.
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Project description:Clostridium thermocellum polynucleotide kinase-phosphatase (CthPnkp) catalyzes 5' and 3' end-healing reactions that prepare broken RNA termini for sealing by RNA ligase. The central phosphatase domain of CthPnkp belongs to the dinuclear metallophosphoesterase superfamily exemplified by bacteriophage lambda phosphatase (lambda-Pase). CthPnkp is a Ni(2+)/Mn(2+)-dependent phosphodiesterase-monoesterase, active on nucleotide and non-nucleotide substrates, that can be transformed toward narrower metal and substrate specificities via mutations of the active site. Here we characterize the Mn(2+)-dependent 2',3' cyclic nucleotide phosphodiesterase activity of CthPnkp, the reaction most relevant to RNA repair pathways. We find that CthPnkp prefers a 2',3' cyclic phosphate to a 3',5' cyclic phosphate. A single H189D mutation imposes strict specificity for a 2',3' cyclic phosphate, which is cleaved to form a single 2'-NMP product. Analysis of the cyclic phosphodiesterase activities of mutated CthPnkp enzymes illuminates the active site and the structural features that affect substrate affinity and k(cat). We also characterize a previously unrecognized phosphodiesterase activity of lambda-Pase, which catalyzes hydrolysis of bis-p-nitrophenyl phosphate. lambda-Pase also has cyclic phosphodiesterase activity with nucleoside 2',3' cyclic phosphates, which it hydrolyzes to yield a mixture of 2'-NMP and 3'-NMP products. We discuss our results in light of available structural and functional data for other phosphodiesterase members of the binuclear metallophosphoesterase family and draw inferences about how differences in active site composition influence catalytic repertoire.
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Project description:Large-scale production of lignocellulosic biofuel is a potential solution to sustainably meet global energy needs. One-step consolidated bioprocessing (CBP) is a potentially advantageous approach for the production of biofuels, but requires an organism capable of hydrolyzing biomass to sugars and fermenting the sugars to ethanol at commercially viable titers and yields. Clostridium thermocellum, a thermophilic anaerobe, can ferment cellulosic biomass to ethanol and organic acids, but low yield, low titer, and ethanol sensitivity remain barriers to industrial production. Here, we deleted the hypoxanthine phosphoribosyltransferase gene in ethanol tolerant strain of C. thermocellum adhE*(EA) in order to allow use of previously developed gene deletion tools, then deleted lactate dehydrogenase (ldh) to redirect carbon flux towards ethanol. Upon deletion of ldh, the adhE*(EA) ?ldh strain produced 30% more ethanol than wild type on minimal medium. The adhE*(EA) ?ldh strain retained tolerance to 5% v/v ethanol, resulting in an ethanol tolerant platform strain of C. thermocellum for future metabolic engineering efforts.
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Project description:We and others have shown the utility of long sequence reads to improve genome assembly quality. In this study, we generated PacBio DNA sequence data to improve the assemblies of draft genomes for Clostridium thermocellum AD2, Clostridium thermocellum LQRI, and Pelosinus fermentans R7.
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Project description:The ability of Clostridium thermocellum to rapidly degrade cellulose and ferment resulting hydrolysis products into ethanol makes it a promising platform organism for cellulosic biofuel production via consolidated bioprocessing. Currently, however, ethanol yield is far below theoretical maximum due to branched product pathways that divert carbon and electrons towards formate, H2, lactate, acetate, and secreted amino acids. To redirect carbon and electron flux away from formate, genes encoding pyruvate:formate lyase (pflB) and PFL-activating enzyme (pflA) were deleted. Formate production in the resulting ?pfl strain was eliminated and acetate production decreased by 50 % on both complex and defined medium. The growth rate of the ?pfl strain decreased by 2.9-fold on defined medium and biphasic growth was observed on complex medium. Supplementation of defined medium with 2 mM formate restored ?pfl growth rate to 80 % of the parent strain. The role of pfl in metabolic engineering strategies and C1 metabolism is discussed.
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Project description:Clostridium thermocellum is a major candidate for bioethanol production via consolidated bioprocessing. However, the low ethanol tolerance of the organism dramatically impedes its usage in industry. To explore the mechanism of ethanol tolerance in this microorganism, systematic metabolomics was adopted to analyse the metabolic phenotypes of a C. thermocellum wild-type (WT) strain and an ethanol-tolerant strain cultivated without (ET0) or with (ET3) 3% (v/v) exogenous ethanol. Metabolomics analysis elucidated that the levels of numerous metabolites in different pathways were changed for the metabolic adaption of ethanol-tolerant C. thermocellum. The most interesting phenomenon was that cellodextrin was significantly more accumulated in the ethanol-tolerant strain compared with the WT strain, although cellobiose was completely consumed in both the ethanol-tolerant and wild-type strains. These results suggest that the cellodextrin synthesis was active, which might be a potential mechanism for stress resistance. Moreover, the overflow of many intermediate metabolites, which indicates the metabolic imbalance, in the ET0 cultivation was more significant than in the WT and ET3 cultivations. This indicates that the metabolic balance of the ethanol-tolerant strain was adapted better to the condition of ethanol stress. This study provides additional insight into the mechanism of ethanol tolerance and is valuable for further metabolic engineering aimed at higher bioethanol production.
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