Expression profiling of Cellvibrio japonicus using either glucose or xylan
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ABSTRACT:
ORGANISM(S): Cellvibrio japonicus
PROVIDER: GSE108095 | GEO | 2018/01/15
SECONDARY ACCESSION(S): PRJNA422442
REPOSITORIES: GEO
Similar Datasets
Project description:Chitin utilization by microbes plays a significant role in cycling of carbon and nitrogen in the biosphere, and the study of the microbial approaches used to degrade chitin will facilitate our understanding of bacterial strategies to degrade this recalcitrant polysaccharide. The early stages of chitin depolymerization by the bacterium Cellvibrio japonicus have been characterized and are dependent on one chitin-specific lytic polysaccharide monooxygenase and non-redundant glycoside hydrolases from the family GH18 to generate chito-oligosaccharides for entry into metabolism. Here, we describe the mechanisms for the latter stages of chitin utilization by C. japonicus with an emphasis on the fate of chito-oligosaccharides. Our systems biology approach combined transcriptomics, bacterial genetics, and complex environmental substrates to determine the essential mechanisms for chito-oligosaccharide transport and catabolism in Cellvibrio japonicus. Using RNAseq analysis we found not only the up-regulation of genes that encode CAZymes specific for chitin metabolism but also a coordinated expression of non-chitin specific CAZyme genes. Furthermore, we used mutational analysis to characterize the hex20B gene product, predicted to encode a hexosaminidase, and found that it is required for efficient utilization of chito-oligosaccharides. Surprisingly, two additional gene loci (CJA_0353 and CJA_1157), which encode putative TonB-dependent transporters, were essential for shuttling chito-oligosaccharides into the periplasmic space. Here we propose naming these loci cttA (chito-oligosaccharides transporter A) and cttB respectively. This study further develops our model of how C. japonicus can derive nutrients from recalcitrant chitin-containing substrates and may be potentially useful for other environmentally or industrially important bacteria.
2020-04-30 | GSE149593 | GEO
Project description:Plant mannans are a component of lignocellulose that may possess diverse compositions changing both in terms of its backbone and side-chain substitutions. Consequently, the degradation of mannan substrates requires a cadre of enzymes for complete reduction to substituent monosaccharides, specifically mannose, galactose, and/or glucose. One bacterium that possesses this suite of enzymes is the Gram-negative saprophyte Cellvibrio japonicus, which has ten predicted mannanases from the Glycoside Hydrolase (GH) families 5, 26, and 27. Here we describe a systems biology approach to identify and characterize the essential components of the mannan degradation apparatus in this bacterium. Transcriptomic analysis uncovered significant changes in gene expression for most mannanases, as well as many genes that encode Carbohydrate Active Enzymes (CAZymes) when mannan substrates were actively being degraded. A comprehensive mutational analysis characterized 54 CAZyme genes in the context of mannan utilization. Growth analysis of the mutant strains indicated that the man26C, aga27A, and man5D genes, which encode a mannobiohydrolase, α- galactosidase, and mannosidase, respectively, were influential to the deconstruction of galactomannan. Furthermore, our updated model of mannan degradation in C. japonicus proposes that the removal of galactose sidechains from substituted mannans constitutes a crucial step for the efficient and complete degradation of this hemicellulose by bacteria.
2022-06-28 | GSE206864 | GEO
Project description:Degradation of polysaccharides forms an essential arc in the carbon cycle, provides a percentage of our daily caloric intake, and is a major driver in the renewable chemical industry. Microorganisms proficient at degrading insoluble polysaccharides possess large numbers of carbohydrate active enzymes, many of which have been categorized as functionally redundant. Here we present data that suggests that carbohydrate active enzymes that have overlapping enzymatic activities can have unique, non-overlapping biological functions in the cell. Our comprehensive study to understand cellodextrin utilization in the soil saprophyte Cellvibrio japonicus found that only one of four predicted b-glucosidases is required in a physiological context. Gene deletion analysis indicated that only the cel3B gene product is essential for efficient cellodextrin utilization in C. japonicus and is constitutively expressed at high levels. Interestingly, expression of individual b-glucosidases in Escherichia coli K-12 enabled this non-cellulolytic bacterium to be fully capable of using cellobiose as a sole carbon source. Furthermore, enzyme kinetic studies indicated that the Cel3A enzyme is significantly more active than the Cel3B enzyme on the oligosaccharides but not disaccharides. Our approach for parsing related carbohydrate active enzymes to determine actual physiological roles in the cell can be applied to other polysaccharide-degradation systems.
2017-01-01 | GSE90955 | GEO
Project description:Understanding the strategies used by bacteria to degrade polysaccharides constitutes an invaluable tool for biotechnological applications Bacteria are major mediators of polysaccharide degradation in nature, however the complex mechanisms used to detect, degrade, and consume these substrates are not well understood, especially for recalcitrant polysaccharides such as chitin It has been previously shown that the model bacterial saprophyte Cellvibrio japonicus is able to catabolize chitin, but little is known about the enzymatic machinery underlying this capability Previous analyses of the C japonicus genome and proteome indicated the presence of four family 18 Glycoside Hydrolase (GH18) enzymes, and studies of the proteome indicated that all are involved in chitin utilization Using a combination of in vitro and in vivo approaches, we have studied the roles of these four chitinases in chitin bioconversion Genetic analyses showed that only the chi18D gene product is essential for the degradation of chitin substrates Biochemical characterization of the four enzymes showed functional differences and synergistic effects during chitin degradation, indicating non-redundant roles in the cell Transcriptomic studies revealed complex regulation of the chitin degradation machinery of C japonicus and confirmed the importance of CjChi18D and CjLPMO10A, a previously characterized chitin-active enzyme With this systems biology approach, we deciphered the physiological relevance of the GH18 enzymes for chitin degradation in C japonicus, and the combination of in vitro and in vivo approaches provided a comprehensive understanding of the initial stages of chitin degradation by this bacterium
2018-01-24 | GSE108935 | GEO
Project description:Background: Xyloglucan (XyG) is a ubiquitous and fundamental polysaccharide of plant cell walls. Due to its structural complexity, XyG requires a combination of backbone-cleaving and sidechain-debranching enzymes for complete deconstruction into its component monosaccharides. The soil saprophyte Cellvibrio japonicus has emerged as a genetically tractable model system to study biomass saccharification, in part due to an innate capacity to utilize a wide range of plant polysaccharides for growth. Whereas the downstream debranching enzymes of the xyloglucan utilization system of C. japonicus have been functionally characterized, the requisite backbone-cleaving endo-xyloglucanases were unresolved. Results: Combined bioinformatic and transcriptomic analyses implicated three Glycoside Hydrolase Family 5 Subfamily 4 (GH5_4) members, with distinct modular organization, as potential keystone endo-xyloglucanases in C. japonicus. Detailed biochemical and enzymatic characterization of the GH5_4 modules of all three recombinant proteins confirmed particularly high specificities for the XyG polysaccharide versus a panel of other cell wall glycans, including mixed-linkage beta-glucan and cellulose. Moreover, product analysis demonstrated that all three enzymes generated XyG oligosaccharides required for subsequent saccharification by known exo-glycosidases. Crystallographic analysis of GH5D, which was the only GH5_4 member specifically and highly upregulated during growth on XyG, in free, product-complex, and active-site affinity-labelled forms revealed the molecular basis for the exquisite XyG specificity among these GH5_4 enzymes. Strikingly, exhaustive reverse-genetic analysis of all three GH5_4 members and a previously biochemically characterized GH74 member failed to reveal a growth defect, thereby indicating functional compensation in vivo, both among members of this cohort and by other, yet unidentified, xyloglucanases in C. japonicus. Our systems-based analysis indicates distinct substrate-sensing (GH74, GH5E, GH5F) and attack-mounting (GH5D) functions for the endo-xyloglucanases characterized here. Conclusions: Through a multi-faceted, molecular systems-based approach, this study provides a new insight into the saccharification pathway of xyloglucan utilization system of C. japonicus. The detailed structural-functional characterization of three distinct GH5_4 endo-xyloglucanases will inform future bioinformatics predictions across species, and provides new CAZymes with defined specificity that may be harnessed in industrial and other biotechnological applications.
2018-01-25 | GSE109594 | GEO
Project description:Investigation of whole genome gene expression level changes in Cellvibrio japonicus wild-type, comparing glucose vs cellulose. Study was purposed with determining changes in polysaccharide degradation pathways during utilization of insoluble cellulose.
2014-10-07 | GSE62106 | GEO
Project description:Dietary fiber degradation is a key function of the human gut microbiota. The aim of this study was to increase our knowledge on the degradation of plant cell wall polysaccharide degradation by a prominent human gut bacterial species, Bacteroides xylanisolvens. The transcriptome analysis of B. xylanisolvens XB1AT revealed the existence of six and two genomic loci dedicated to the degradation of pectins and xylan, respectively. These loci or PUL ("Polysaccharide Utilization Loci") are known to encode enzyme systems in Bacteroides that are specific to a particular polysaccharide. Simple two-way comparisons between pectin or xylan sources (treatment) and glucose or xylose (control), collected during mid- and late-log phase. Three replicates per condition.
2015-10-28 | E-GEOD-74379 | biostudies-arrayexpress
Project description:Extremely thermophilic bacteria from the genus Caldicellulosiruptor can degrade various polysaccharide components of plant cell walls. Previous experimental studies identified a variety of carbohydrate-active enzymes in model species C. saccharolyticus and C.bescii, while prior transcriptomic experiments identified their putative carbohydrate uptake transporters. We investigated the mechanisms of transcriptional regulation of carbohydrate utilization genes using a comparative genomics approach applied to fourteen Caldicellulosiruptor species. The reconstruction of carbohydrate utilization regulatory network includes the predicted binding sites for 34 mostly local regulators and point to the regulatory mechanisms controlling expression of genes involved in degradation of plant biomass. The Rex and CggR regulons control the central glycolytic and primary redox reactions. The identified transcription factor binding sites and regulons were validated with transcriptomic and transcription start site data for C. bescii grown on cellulose, cellobiose, glucose, xylan, and xylose. The XylR and XynR regulons control xylan-induced transcriptional response of genes involved in degradation of xylan and xylose utilization. The reconstructed regulons informed the carbohydrate utilization reconstruction analysis and improved functional annotations of 51 transporters and 11 catabolic enzymes. Using gene deletion, we confirmed that the shared ATPase component MsmK is essential for growth on oligo- and polysaccharides but not for the utilization of monosaccharides. By elucidating the carbohydrate utilization framework in C. bescii, strategies for metabolic engineering can be pursued to optimize yields of bio-based fuels and chemicals from lignocellulose.
2021-02-23 | GSE163472 | GEO
Project description:Extremely thermophilic bacteria from the genus Caldicellulosiruptor can degrade various polysaccharide components of plant cell walls. Previous experimental studies identified a variety of carbohydrate-active enzymes in model species C. saccharolyticus and C.bescii, while prior transcriptomic experiments identified their putative carbohydrate uptake transporters. We investigated the mechanisms of transcriptional regulation of carbohydrate utilization genes using a comparative genomics approach applied to fourteen Caldicellulosiruptor species. The reconstruction of carbohydrate utilization regulatory network includes the predicted binding sites for 34 mostly local regulators and point to the regulatory mechanisms controlling expression of genes involved in degradation of plant biomass. The Rex and CggR regulons control the central glycolytic and primary redox reactions. The identified transcription factor binding sites and regulons were validated with transcriptomic and transcription start site data for C. bescii grown on cellulose, cellobiose, glucose, xylan, and xylose. The XylR and XynR regulons control xylan-induced transcriptional response of genes involved in degradation of xylan and xylose utilization. The reconstructed regulons informed the carbohydrate utilization reconstruction analysis and improved functional annotations of 51 transporters and 11 catabolic enzymes. Using gene deletion, we confirmed that the shared ATPase component MsmK is essential for growth on oligo- and polysaccharides but not for the utilization of monosaccharides. By elucidating the carbohydrate utilization framework in C. bescii, strategies for metabolic engineering can be pursued to optimize yields of bio-based fuels and chemicals from lignocellulose.
2021-02-23 | GSE163473 | GEO
Project description:Plant biomass holds tremendous potential as a renewable feedstock in the production of biofuels and biochemicals. The effective co-utilization of the main components cellulose and hemicellulose in plant lignocellulose is critical to the economic viability of lignocellulosic biorefineries. Here, we found that the thermophilic cellulolytic fungi Myceliophthora thermophila can utilize cellulose and hemicellulose synchronously. To investigate the underlying molecular mechanisms, we firstly checked the soluble carbohydrate of the culture using plant biomass (corncob) as sole carbon source and revealed the presence of various oligosaccharides including cellodextrin and xylodextrin, both intracellularly and extracellularly in the cultures, in addition to glucose or xylose. Based on these, intracellular oligosaccharide metabolism was proposed and confirmed by identification of cellodextrin and xylodextrin metabolism pathway. Furthermore, sugar consumption assay showed that contrasting with synchronous utilization of mixed cello-/xylo-dextrin, the inhibition effect of glucose for the metabolism of xylose and cello-/xylo-dextrin exists in this fungus, suggesting Carbon Catabolite Repression (CCR) is largely avoided at the form of oligosaccharides. Transporter MtCDT-2 showing preference to xylobiose and the tolerance of cellobiose inhibition also helps to bypass metabolic inhibition. Finally, the expression of cellulase and hemicellulase genes, were found orthogonal induction by cellobiose/Avicel and xylobiose/xylan, which conferred the ability of the strain to synchronously utilize cellulose and hemicellulose. Taken together, the orthogonal oligosaccharide catabolic pathway in this fungus establishes the molecular basis for the synchronous utilization of cellulose and hemicellulose, which sheds new light on understanding the plant biomass degradation by fungi and provides alternative paradigm for development of lignocellulose biorefinery such as consolidated bioprocessing in the future.
2024-02-28 | GSE222371 | GEO