scholarly journals Utilization of Lactose and Galactose by Streptococcus mutans: Transport, Toxicity, and Carbon Catabolite Repression

2010 ◽  
Vol 192 (9) ◽  
pp. 2434-2444 ◽  
Author(s):  
Lin Zeng ◽  
Satarupa Das ◽  
Robert A. Burne
Keyword(s):  
Gene Expression ◽  
Streptococcus Mutans ◽  
Catabolite Repression ◽  
Dairy Products ◽  
Carbon Catabolite Repression ◽  
Human Tooth ◽  
Tooth Decay ◽  
Galactose Metabolism ◽  
Promoter Fusion ◽  
High Degree

ABSTRACT Abundant in milk and other dairy products, lactose is considered to have an important role in oral microbial ecology and can contribute to caries development in both adults and young children. To better understand the metabolism of lactose and galactose by Streptococcus mutans, the major etiological agent of human tooth decay, a genetic analysis of the tagatose-6-phosphate (lac) and Leloir (gal) pathways was performed in strain UA159. Deletion of each gene in the lac operon caused various alterations in expression of a PlacA -cat promoter fusion and defects in growth on either lactose (lacA, lacB, lacF, lacE, and lacG), galactose (lacA, lacB, lacD, and lacG) or both sugars (lacA, lacB, and lacG). Failure to grow in the presence of galactose or lactose by certain lac mutants appeared to arise from the accumulation of intermediates of galactose metabolism, particularly galatose-6-phosphate. The glucose- and lactose-PTS permeases, EIIMan and EIILac, respectively, were shown to be the only effective transporters of galactose in S. mutans. Furthermore, disruption of manL, encoding EIIABMan, led to increased resistance to glucose-mediated CCR when lactose was used to induce the lac operon, but resulted in reduced lac gene expression in cells growing on galactose. Collectively, the results reveal a remarkably high degree of complexity in the regulation of lactose/galactose catabolism.

scholarly journals Ethanolamine Utilization and Bacterial Microcompartment Formation Are Subject to Carbon Catabolite Repression

2019 ◽  
Vol 201 (10) ◽  
Author(s):  
Karan Gautam Kaval ◽  
Margo Gebbie ◽  
Jonathan R. Goodson ◽  
Melissa R. Cruz ◽  
Wade C. Winkler ◽  
...  
Keyword(s):  
Gene Expression ◽  
Enterococcus Faecalis ◽  
Small Rna ◽  
Catabolite Repression ◽  
Carbon Catabolite Repression ◽  
Bioinformatics Analysis ◽  
Maximum Efficiency ◽  
Gi Tract ◽  
Content Type ◽  
Regulatory Factors

ABSTRACT Ethanolamine (EA) is a compound prevalent in the gastrointestinal (GI) tract that can be used as a carbon, nitrogen, and/or energy source. Enterococcus faecalis, a GI commensal and opportunistic pathogen, contains approximately 20 ethanolamine utilization (eut) genes encoding the necessary regulatory, enzymatic, and structural proteins for this process. Here, using a chemically defined medium, two regulatory factors that affect EA utilization were examined. First, the functional consequences of loss of the small RNA (sRNA) EutX on the efficacy of EA utilization were investigated. One effect observed, as loss of this negative regulator causes an increase in eut gene expression, was a concomitant increase in the number of catabolic bacterial microcompartments (BMCs) formed. However, despite this increase, the growth of the strain was repressed, suggesting that the overall efficacy of EA utilization was negatively affected. Second, utilizing a deletion mutant and a complement, carbon catabolite control protein A (CcpA) was shown to be responsible for the repression of EA utilization in the presence of glucose. A predicted cre site in one of the three EA-inducible promoters, PeutS, was identified as the target of CcpA. However, CcpA was shown to affect the activation of all the promoters indirectly through the two-component system EutV and EutW, whose genes are under the control of the PeutS promoter. Moreover, a bioinformatics analysis of bacteria predicted to contain CcpA and cre sites revealed that a preponderance of BMC-containing operons are likely regulated by carbon catabolite repression (CCR). IMPORTANCE Ethanolamine (EA) is a compound commonly found in the gastrointestinal (GI) tract that can affect the behavior of human pathogens that can sense and utilize it, such as Enterococcus faecalis and Salmonella. Therefore, it is important to understand how the genes that govern EA utilization are regulated. In this work, we investigated two regulatory factors that control this process. One factor, a small RNA (sRNA), is shown to be important for generating the right levels of gene expression for maximum efficiency. The second factor, a transcriptional repressor, is important for preventing expression when other preferred sources of energy are available. Furthermore, a global bioinformatics analysis revealed that this second mechanism of transcriptional regulation likely operates on similar genes in related bacteria.

scholarly journals Intervening in Symbiotic Cross-Kingdom Biofilm Interactions: a Binding Mechanism-Based Nonmicrobicidal Approach

mBio ◽  
2021 ◽  
Vol 12 (3) ◽  
Author(s):  
H. E. Kim ◽  
A. Dhall ◽  
Y. Liu ◽  
M. Bawazir ◽  
H. Koo ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Streptococcus Mutans ◽  
Single Molecule ◽  
Mechanical Stability ◽  
Tooth Enamel ◽  
Oral Disease ◽  
Enzyme Treatment ◽  
Human Tooth ◽  
Tooth Decay ◽  
Content Type

ABSTRACT Early childhood caries is a severe oral disease that results in aggressive tooth decay. Particularly, a synergistic association between a fungus, Candida albicans, and a cariogenic bacterium, Streptococcus mutans, promotes the development of hard-to-remove and highly acidic biofilms, exacerbating the virulent damage. These interactions are largely mediated via glucosyltransferases (GtfB) binding to mannans on the cell wall of C. albicans. Here, we present an enzymatic approach to target GtfB-mannan interactions in this cross-kingdom consortium using mannan-degrading exo- and endo-enzymes. These exo- and endo-enzymes are highly effective in reducing biofilm biomass without killing microorganisms, as well as alleviating the production of an acidic pH environment conducive to tooth decay. To corroborate these results, we present biophysical evidence using single-molecule atomic force microscopy, biofilm shearing, and enamel surface topography analyses. Data show a drastic decrease in binding forces of GtfB to C. albicans (∼15-fold reduction) following enzyme treatment. Furthermore, enzymatic activity disrupted biofilm mechanical stability and significantly reduced human tooth enamel demineralization without cytotoxic effects on gingival keratinocytes. Our results represent significant progress toward a novel nonbiocidal therapeutic intervention against pathogenic bacterial-fungal biofilms by targeting the interkingdom receptor-ligand binding interactions. IMPORTANCE Biofilm formation is a key virulence factor responsible for various infectious diseases. Particularly, interactions between a fungus, Candida albicans, and a bacterium, Streptococcus mutans, have been known to play important roles in the pathogenesis of dental caries. Although some antimicrobials have been applied to treat fungal-involved biofilm-associated diseases, these often lack targeting polymicrobial interactions. Furthermore, these may not be appropriate for preventive measures because these antimicrobials may disrupt ecological microbiota and/or induce the prevalence of drug resistance over time. By specifically targeting the interaction mechanism whereby mannoproteins on the C. albicans surface mediate the cross-kingdom interaction, we demonstrated that mannoprotein-degrading enzymes can effectively disrupt biofilm interactions without microbiocidal effects or causing cytotoxicity to human cells. This suggests a potential application as a targeted approach for intervening a pathogenic cross-kingdom biofilm associated with a costly and unresolved oral disease.

Involvement of carbon catabolite repression on regulation of endopolygalacturonase gene expression in citrus fruit

2003 ◽  
Vol 69 (2) ◽  
pp. 120-125 ◽  
Author(s):  
Kouhei Ohtani ◽  
Atsunori Isshiki ◽  
Hiroshi Katoh ◽  
Hiroyuki Yamamoto ◽  
Kazuya Akimitsu
Keyword(s):  
Gene Expression ◽  
Catabolite Repression ◽  
Carbon Catabolite Repression ◽  
Citrus Fruit

scholarly journals Induction and Repression of Hydrolase Genes in Aspergillus oryzae

2021 ◽  
Vol 12 ◽  
Author(s):  
Mizuki Tanaka ◽  
Katsuya Gomi
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Aspergillus Oryzae ◽  
Catabolite Repression ◽  
Food Industry ◽  
Carbon Catabolite Repression ◽  
Proteolytic Enzymes ◽  
Current Knowledge ◽  
Glycosyl Hydrolase ◽  
Fermented Foods

The filamentous fungus Aspergillus oryzae, also known as yellow koji mold, produces high levels of hydrolases such as amylolytic and proteolytic enzymes. This property of producing large amounts of hydrolases is one of the reasons why A. oryzae has been used in the production of traditional Japanese fermented foods and beverages. A wide variety of hydrolases produced by A. oryzae have been used in the food industry. The expression of hydrolase genes is induced by the presence of certain substrates, and various transcription factors that regulate such expression have been identified. In contrast, in the presence of glucose, the expression of the glycosyl hydrolase gene is generally repressed by carbon catabolite repression (CCR), which is mediated by the transcription factor CreA and ubiquitination/deubiquitination factors. In this review, we present the current knowledge on the regulation of hydrolase gene expression, including CCR, in A. oryzae.

scholarly journals Regulation of Arabinose and Xylose Metabolism in Escherichia coli

2009 ◽  
Vol 76 (5) ◽  
pp. 1524-1532 ◽  
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.

Carbon catabolite repression of xylanase I (xyn1) gene expression in Trichoderma reesei

1996 ◽  
Vol 21 (6) ◽  
pp. 1273-1281 ◽  
Author(s):  
Robert L. Mach ◽  
Joseph Strauss ◽  
Susanne Zeilinger ◽  
Martin Schindler ◽  
Christian P. Kubicek
Keyword(s):  
Gene Expression ◽  
Trichoderma Reesei ◽  
Catabolite Repression ◽  
Carbon Catabolite Repression

Carbon Catabolite Repression Regulates Glyoxylate Cycle Gene Expression in Cucumber

1994 ◽  
Vol 6 (5) ◽  
pp. 761 ◽  
Author(s):  
Ian A. Graham ◽  
Katherine J. Denby ◽  
Christopher J. Leaver
Keyword(s):  
Gene Expression ◽  
Catabolite Repression ◽  
Carbon Catabolite Repression ◽  
Glyoxylate Cycle
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