Carbon catabolite repression in bacteria: choice of the carbon source and autoregulatory limitation of sugar utilization

The effect of carbon source on the levels of three (1 → 3)-β-glucanases and a (1 → 6)-β-glucanase in the culture filtrates of the filamentous fungus Acremonium persicinum was investigated. All four enzymes were produced during growth of the fungus on (1 → 3)-, (1 → 6)-, and (1 → 3)(1 → 6)-β-glucans as well as β-linked oligoglucosides. However, only one (1 → 3)-β-glucanase and the (1 → 6)-β-glucanase were detected during growth on a range of other carbon sources including glucose, carboxymethylcellulose, and the α-glucan pullulan. The presence of glucose in the medium markedly decreased the production of all four glucanases, although the concentration required to effect complete repression of enzyme levels varied for the different enzymes. Similar repressive effects were also observed with sucrose, fructose, and galactose. The most likely explanations for these observations are that the synthesis of the (1 → 6)-β-glucanase and one of the (1 → 3)-β-glucanases is controlled by carbon catabolite repression, while the remaining two (1 → 3)-β-glucanases are inducible enzymes subject to carbon catabolite repression.Key words: (1 → 3)-β-glucanase, (1 → 6)-β-glucanase, Acremonium persicinum, regulation of synthesis, fungal β-glucanases.

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Regulation ofAspergillus nidulansCreA-Mediated Catabolite Repression by the F-Box Proteins Fbx23 and Fbx47

mBio ◽

10.1128/mbio.00840-18 ◽

2018 ◽

Vol 9 (3) ◽

Cited By ~ 15

Author(s):

Leandro José de Assis ◽

Mevlut Ulas ◽

Laure Nicolas Annick Ries ◽

Nadia Ali Mohamed El Ramli ◽

Ozlem Sarikaya-Bayram ◽

...

Keyword(s):

Carbon Source ◽

Aspergillus Nidulans ◽

Ubiquitin Ligase ◽

Catabolite Repression ◽

Carbon Catabolite Repression ◽

26S Proteasome ◽

Xylanase Production ◽

Content Type ◽

Regulatory Pathways ◽

Ubiquitin Ligase Complex

ABSTRACTThe attachment of one or more ubiquitin molecules by SCF (Skp–Cullin–F-box) complexes to protein substrates targets them for subsequent degradation by the 26S proteasome, allowing the control of numerous cellular processes. Glucose-mediated signaling and subsequent carbon catabolite repression (CCR) are processes relying on the functional regulation of target proteins, ultimately controlling the utilization of this carbon source. In the filamentous fungusAspergillus nidulans, CCR is mediated by the transcription factor CreA, which modulates the expression of genes encoding biotechnologically relevant enzymes. Although CreA-mediated repression of target genes has been extensively studied, less is known about the regulatory pathways governing CCR and this work aimed at further unravelling these events. The Fbx23 F-box protein was identified as being involved in CCR and the Δfbx23mutant presented impaired xylanase production under repressing (glucose) and derepressing (xylan) conditions. Mass spectrometry showed that Fbx23 is part of an SCF ubiquitin ligase complex that is bridged via the GskA protein kinase to the CreA-SsnF-RcoA repressor complex, resulting in the degradation of the latter under derepressing conditions. Upon the addition of glucose, CreA dissociates from the ubiquitin ligase complex and is transported into the nucleus. Furthermore, casein kinase is important for CreA function during glucose signaling, although the exact role of phosphorylation in CCR remains to be determined. In summary, this study unraveled novel mechanistic details underlying CreA-mediated CCR and provided a solid basis for studying additional factors involved in carbon source utilization which could prove useful for biotechnological applications.IMPORTANCEThe production of biofuels from plant biomass has gained interest in recent years as an environmentally friendly alternative to production from petroleum-based energy sources. Filamentous fungi, which naturally thrive on decaying plant matter, are of particular interest for this process due to their ability to secrete enzymes required for the deconstruction of lignocellulosic material. A major drawback in fungal hydrolytic enzyme production is the repression of the corresponding genes in the presence of glucose, a process known as carbon catabolite repression (CCR). This report provides previously unknown mechanistic insights into CCR through elucidating part of the protein-protein interaction regulatory system that governs the CreA transcriptional regulator in the reference organismAspergillus nidulansin the presence of glucose and the biotechnologically relevant plant polysaccharide xylan.

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Effect of deregulation of repressor-specific carbon catabolite repression on carbon source consumption in Escherichia coli

Applied Biological Chemistry ◽

10.1186/s13765-021-00627-0 ◽

2021 ◽

Vol 64 (1) ◽

Author(s):

Hyeon Jeong Seong ◽

Yu-Sin Jang

Keyword(s):

Escherichia Coli ◽

Carbon Source ◽

Catabolite Repression ◽

Sole Carbon Source ◽

Carbon Catabolite Repression ◽

Cell Factory ◽

Essential Information ◽

E Coli ◽

Marine Biomass ◽

Galactose Utilization

AbstractEscherichia coli has been used as a host to construct the cell factory for biobased production of chemicals from renewable feedstocks. Because galactose is found in marine biomass as a major component, the strategy for galactose utilization in E. coli has been gained more attention. Although galactose and glucose co-fermentation has been reported using the engineered E. coli strain, few reports have covered fermentation supplemented with galactose as a sole carbon source in the mutant lacking the repressor-specific carbon catabolite repression (CCR). Here, we report the effects of the deregulation of the repressor-specific CCR (galR− and galS−) in fermentation supplemented with galactose as a sole carbon source, using the engineered E. coli strains. In the fermentation using the galR− and galS− double mutant (GR2 strain), an increase of rates in sugar consumption and cell growth was observed compared to the parent strain. In the glucose fermentation, wild-type W3110 and its mutant GR2 and GR2PZ (galR−, galS−, pfkA−, and zwf−) consumed sugar at a higher rate than those values obtained from galactose fermentation. However, the GR2P strain (galR−, galS−, and pfkA−) showed no difference between fermentations using glucose and galactose as a sole carbon source. This study provides essential information for galactose fermentation using the CCR-deregulated E. coli strains.

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Staphylococcus aureus does not synthesize arginine from proline under physiological conditions

10.1101/2022.01.12.476138 ◽

2022 ◽

Author(s):

Taeok Bae ◽

Bohyun Jeong ◽

Majid Ali Shah ◽

Eunjung Roh ◽

Kyeong Kyu Kim ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Carbon Source ◽

Catabolite Repression ◽

Deletion Mutant ◽

Animal Experiment ◽

Carbon Catabolite Repression ◽

Ectopic Expression ◽

Proline Dehydrogenase ◽

Physiological Conditions ◽

Secondary Carbon

The Gram-positive pathogen Staphylococcus aureus is the only bacterium known to synthesize arginine from proline via the arginine-proline interconversion pathway, despite having genes for the well-conserved glutamate pathway. Since the proline-arginine interconversion pathway is repressed by CcpA-mediated carbon catabolite repression (CCR), CCR has been attributed to the arginine auxotrophy of S. aureus. Using ribose as a secondary carbon source, here, we demonstrate that S. aureus arginine auxotrophy is not due to CCR but due to the inadequate concentration of proline degradation product. Proline is degraded by proline dehydrogenase (PutA) into pyrroline-5-carboxylate (P5C). Although the PutA expression was fully induced by ribose, the P5C concentration remained insufficient to support arginine synthesis because P5C was constantly consumed by the P5C reductase ProC. When the P5C concentration was artificially increased by either PutA overexpression or proC-deletion, S. aureus could synthesize arginine from proline regardless of carbon source. In contrast, when the P5C concentration was reduced by overexpression of proC, it inhibited the growth of the ccpA-deletion mutant without arginine. Intriguingly, the ectopic expression of the glutamate pathway enzymes converted S. aureus into arginine prototroph. In an animal experiment, the arginine-proline interconversion pathway was not required for the survival of S. aureus. Based on these results, we concluded that S. aureus does not synthesize arginine from proline under physiological conditions. We also propose that arginine auxotrophy of S. aureus is not due to the CcpA-mediated CCR but due to the inactivity of the conserved glutamate pathway.

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Regulation of Arabinose and Xylose Metabolism in Escherichia coli

Applied and Environmental Microbiology ◽

10.1128/aem.01970-09 ◽

2009 ◽

Vol 76 (5) ◽

pp. 1524-1532 ◽

Cited By ~ 94

Author(s):

Tasha A. Desai ◽

Christopher V. Rao

Keyword(s):

Gene Expression ◽

Escherichia Coli ◽

Catabolite Repression ◽

Carbon Catabolite Repression ◽

Plant Biomass ◽

Xylose Metabolism ◽

Sugar Utilization ◽

E Coli ◽

Metabolic Genes ◽

Pentose Sugars

ABSTRACT Bacteria such as Escherichia coli will often consume one sugar at a time when fed multiple sugars, in a process known as carbon catabolite repression. The classic example involves glucose and lactose, where E. coli will first consume glucose, and only when it has consumed all of the glucose will it begin to consume lactose. In addition to that of lactose, glucose also represses the consumption of many other sugars, including arabinose and xylose. In this work, we characterized a second hierarchy in E. coli, that between arabinose and xylose. We show that, when grown in a mixture of the two pentoses, E. coli will consume arabinose before it consumes xylose. Consistent with a mechanism involving catabolite repression, the expression of the xylose metabolic genes is repressed in the presence of arabinose. We found that this repression is AraC dependent and involves a mechanism where arabinose-bound AraC binds to the xylose promoters and represses gene expression. Collectively, these results demonstrate that sugar utilization in E. coli involves multiple layers of regulation, where cells will consume first glucose, then arabinose, and finally xylose. These results may be pertinent in the metabolic engineering of E. coli strains capable of producing chemical and biofuels from mixtures of hexose and pentose sugars derived from plant biomass.

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Carbon Catabolite Repression and Impranil Polyurethane Degradation in Pseudomonas protegens Strain Pf-5

Applied and Environmental Microbiology ◽

10.1128/aem.01448-16 ◽

2016 ◽

Vol 82 (20) ◽

pp. 6080-6090 ◽

Cited By ~ 22

Author(s):

Chia-Suei Hung ◽

Sandra Zingarelli ◽

Lloyd J. Nadeau ◽

Justin C. Biffinger ◽

Carrie A. Drake ◽

...

Keyword(s):

Carbon Source ◽

Catabolite Repression ◽

Carbon Catabolite Repression ◽

Carbon Sources ◽

Regulatory Elements ◽

Dependent Manner ◽

Content Type ◽

Intergenic Sequences ◽

Degradation Activity ◽

The Impact

ABSTRACTPolyester polyurethane (PU) coatings are widely used to help protect underlying structural surfaces but are susceptible to biological degradation. PUs are susceptible to degradation byPseudomonasspecies, due in part to the degradative activity of secreted hydrolytic enzymes. Microorganisms often respond to environmental cues by secreting enzymes or secondary metabolites to benefit their survival. This study investigated the impact of exposing severalPseudomonasstrains to select carbon sources on the degradation of the colloidal polyester polyurethane Impranil DLN (Impranil). The prototypicPseudomonas protegensstrain Pf-5 exhibited Impranil-degrading activities when grown in sodium citrate but not in glucose-containing medium. Glucose also inhibited the induction of Impranil-degrading activity by citrate-fed Pf-5 in a dose-dependent manner. Biochemical and mutational analyses identified two extracellular lipases present in the Pf-5 culture supernatant (PueA and PueB) that were involved in degradation of Impranil. Deletion of thepueAgene reduced Impranil-clearing activities, whilepueBdeletion exhibited little effect. Removal of both genes was necessary to stop degradation of the polyurethane. Bioinformatic analysis showed that putative Cbr/Hfq/Crc-mediated regulatory elements were present in the intergenic sequences upstream of bothpueAandpueBgenes. Our results confirmed that both PueA and PueB extracellular enzymes act in concert to degrade Impranil. Furthermore, our data showed that carbon sources in the growth medium directly affected the levels of Impranil-degrading activity but that carbon source effects varied amongPseudomonasstrains. This study uncovered an intricate and complicated regulation ofP. protegensPU degradation activity controlled by carbon catabolite repression.IMPORTANCEPolyurethane (PU) coatings are commonly used to protect metals from corrosion. Microbiologically induced PU degradation might pose a substantial problem for the integrity of these coatings. Microorganisms from diverse genera, including pseudomonads, possess the ability to degrade PUs via various means. This work identified two extracellular lipases, PueA and PueB, secreted byP. protegensstrain Pf-5, to be responsible for the degradation of a colloidal polyester PU, Impranil. This study also revealed that the expression of the degradative activity by strain Pf-5 is controlled by glucose carbon catabolite repression. Furthermore, this study showed that the Impranil-degrading activity of many otherPseudomonasstrains could be influenced by different carbon sources. This work shed light on the carbon source regulation of PU degradation activity among pseudomonads and identified the polyurethane lipases inP. protegens.

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The Wide-Domain Carbon Catabolite Repressor CreA Indirectly Controls Expression of the Aspergillus nidulans xlnBGene, Encoding the Acidic Endo-β-(1,4)-Xylanase X24

Journal of Bacteriology ◽

10.1128/jb.183.5.1517-1523.2001 ◽

2001 ◽

Vol 183 (5) ◽

pp. 1517-1523 ◽

Cited By ~ 26

Author(s):

Margarita Orejas ◽

Andrew P. MacCabe ◽

JoséAntonio Pérez-González ◽

Sudeep Kumar ◽

Daniel Ramón

Keyword(s):

Carbon Source ◽

Aspergillus Nidulans ◽

Catabolite Repression ◽

Sole Carbon Source ◽

Carbon Catabolite Repression ◽

Target Sites ◽

Wide Domain ◽

Catabolite Repressor ◽

Functional Analyses

ABSTRACT The Aspergillus nidulans xlnB gene, which encodes the acidic endo-β-(1,4)-xylanase X24, is expressed when xylose is present as the sole carbon source and repressed in the presence of glucose. That the mutation creAd30results in considerably elevated levels of xlnB mRNA indicates a role for the wide-domain repressor CreA in the repression of xlnB promoter (xlnBp) activity. Functional analyses of xlnBp::goxC reporter constructs show that none of the four CreA consensus target sites identified in xlnBp are functional in vivo. The CreA repressor is thus likely to exert carbon catabolite repression via an indirect mechanism rather than to influence xlnB expression by acting directly on xlnB.

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