scholarly journals Two Gene Clusters Coordinate Galactose and Lactose Metabolism in Streptococcus gordonii

2012 ◽  
Vol 78 (16) ◽  
pp. 5597-5605 ◽  
Author(s):  
Lin Zeng ◽  
Nicole C. Martino ◽  
Robert A. Burne
Keyword(s):  
Gene Clusters ◽  
Selective Advantage ◽  
Streptococcus Gordonii ◽  
Phosphotransferase System ◽  
Content Type ◽  
High Affinity ◽  
Oral Biofilms ◽  
Genes Encoding ◽  
Complex Regulation ◽  
Galactose Utilization

ABSTRACTStreptococcus gordoniiis an early colonizer of the human oral cavity and an abundant constituent of oral biofilms. Two tandemly arranged gene clusters, designatedlacandgal, were identified in theS. gordoniiDL1 genome, which encode genes of the tagatose pathway (lacABCD) and sugar phosphotransferase system (PTS) enzyme II permeases. Genes encoding a predicted phospho-β-galactosidase (LacG), a DeoR family transcriptional regulator (LacR), and a transcriptional antiterminator (LacT) were also present in the clusters. Growth and PTS assays supported that the permease designated EIILactransports lactose and galactose, whereas EIIGaltransports galactose. The expression of the gene for EIIGalwas markedly upregulated in cells growing on galactose. Using promoter-catfusions, a role for LacR in the regulation of the expressions of both gene clusters was demonstrated, and thegalcluster was also shown to be sensitive to repression by CcpA. The deletion oflacTcaused an inability to grow on lactose, apparently because of its role in the regulation of the expression of the genes for EIILac, but had little effect on galactose utilization.S. gordoniimaintained a selective advantage overStreptococcus mutansin a mixed-species competition assay, associated with its possession of a high-affinity galactose PTS, althoughS. mutanscould persist better at low pHs. Collectively, these results support the concept that the galactose and lactose systems ofS. gordoniiare subject to complex regulation and that a high-affinity galactose PTS may be advantageous whenS. gordoniiis competing against the caries pathogenS. mutansin oral biofilms.

scholarly journals Vibrio Iron Transport: Evolutionary Adaptation to Life in Multiple Environments

2015 ◽  
Vol 80 (1) ◽  
pp. 69-90 ◽  
Author(s):  
Shelley M. Payne ◽  
Alexandra R. Mey ◽  
Elizabeth E. Wyckoff
Keyword(s):  
Regulatory Networks ◽  
Iron Transport ◽  
Horizontal Transmission ◽  
Essential Element ◽  
Transport Systems ◽  
Iron Binding ◽  
Content Type ◽  
High Affinity ◽  
Wide Range ◽  
Genes Encoding

SUMMARYIron is an essential element forVibriospp., but the acquisition of iron is complicated by its tendency to form insoluble ferric complexes in nature and its association with high-affinity iron-binding proteins in the host. Vibrios occupy a variety of different niches, and each of these niches presents particular challenges for acquiring sufficient iron.Vibriospecies have evolved a wide array of iron transport systems that allow the bacteria to compete for this essential element in each of its habitats. These systems include the secretion and uptake of high-affinity iron-binding compounds (siderophores) as well as transport systems for iron bound to host complexes. Transporters for ferric and ferrous iron not complexed to siderophores are also common toVibriospecies. Some of the genes encoding these systems show evidence of horizontal transmission, and the ability to acquire and incorporate additional iron transport systems may have allowedVibriospecies to more rapidly adapt to new environmental niches. While too little iron prevents growth of the bacteria, too much can be lethal. The appropriate balance is maintained in vibrios through complex regulatory networks involving transcriptional repressors and activators and small RNAs (sRNAs) that act posttranscriptionally. Examination of the number and variety of iron transport systems found inVibriospp. offers insights into how this group of bacteria has adapted to such a wide range of habitats.

scholarly journals Amino Sugars Modify Antagonistic Interactions between Commensal Oral Streptococci andStreptococcus mutans

2019 ◽  
Vol 85 (10) ◽  
Author(s):  
Lulu Chen ◽  
Brinta Chakraborty ◽  
Jing Zou ◽  
Robert A. Burne ◽  
Lin Zeng
Keyword(s):  
Streptococcus Mutans ◽  
Arginine Deiminase ◽  
Clinical Isolates ◽  
Amino Sugars ◽  
Oral Streptococci ◽  
Streptococcus Gordonii ◽  
Content Type ◽  
Oral Biofilms ◽  
Passage Number ◽  
Low Passage

ABSTRACTN-Acetylglucosamine (GlcNAc) and glucosamine (GlcN) enhance the competitiveness of the laboratory strain DL1 ofStreptococcus gordoniiagainst the caries pathogenStreptococcus mutans. Here, we examine how amino sugars affect the interaction of five low-passage-number clinical isolates of abundant commensal streptococci withS. mutansby utilizing a dual-species biofilm model. Compared to that for glucose, growth on GlcN or GlcNAc significantly reduced the viability ofS. mutansin cocultures with most commensals, shifting the proportions of species. Consistent with these results, production of H2O2was increased in most commensals when growing on amino sugars, and inhibition ofS. mutansbyStreptococcus cristatus,Streptococcus oralis, orS. gordoniiwas enhanced by amino sugars on agar plates. All commensals exceptS. oralishad higher arginine deiminase activities when grown on GlcN and, in some cases, GlcNAc. Inex vivobiofilms formed using pooled cell-containing saliva (CCS), the proportions ofS. mutanswere drastically diminished when GlcNAc was the primary carbohydrate. Increased production of H2O2could account in large part for the inhibitory effects of CCS biofilms. Surprisingly, amino sugars appeared to improve mutacin production byS. mutanson agar plates, suggesting that the commensals have mechanisms to actively subvert antagonism byS. mutansin cocultures. Collectively, these findings demonstrate that amino sugars can enhance the beneficial properties of low-passage-number commensal oral streptococci and highlight their potential for moderating the cariogenicity of oral biofilms.IMPORTANCEDental caries is driven by dysbiosis of oral biofilms in which dominance by acid-producing and acid-tolerant bacteria results in loss of tooth mineral. Our previous work demonstrated the beneficial effects of amino sugars GlcNAc and GlcN in promoting the antagonistic properties of a health-associated oral bacterium,Streptococcus gordonii, in competition with the major caries pathogenStreptococcus mutans. Here, we investigated 5 low-passage-number clinical isolates of the most common streptococcal species to establish how amino sugars may influence the ecology and virulence of oral biofilms. Using multiplein vitromodels, including a human saliva-derived microcosm biofilm, experiments showed significant enhancement by at least one amino sugar in the ability of most of these bacteria to suppress the caries pathogen. Therefore, our findings demonstrated the mechanism of action by which amino sugars may affect human oral biofilms to promote health.

scholarly journals Distribution and Functions of Phosphotransferase System Genes in the Genome of the Lactic Acid Bacterium Oenococcus oeni

2013 ◽  
Vol 79 (11) ◽  
pp. 3371-3379 ◽  
Author(s):  
Zohra Jamal ◽  
Cécile Miot-Sertier ◽  
François Thibau ◽  
Lucie Dutilh ◽  
Aline Lonvaud-Funel ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacterium ◽  
Oenococcus Oeni ◽  
Phosphotransferase System ◽  
Content Type ◽  
Low Concentrations ◽  
Perfect Adaptation ◽  
Form Part ◽  
Genes Encoding ◽  
Enzyme I

ABSTRACTOenococcus oeni, the lactic acid bacterium primarily responsible for malolactic fermentation in wine, is able to grow on a large variety of carbohydrates, but the pathways by which substrates are transported and phosphorylated in this species have been poorly studied. We show that the genes encoding the general phosphotransferase proteins, enzyme I (EI) and histidine protein (HPr), as well as 21 permease genes (3 isolated ones and 18 clustered into 6 distinct loci), are highly conserved among the strains studied and may form part of theO. oenicore genome. Additional permease genes differentiate the strains and may have been acquired or lost by horizontal gene transfer events. The coreptsgenes are expressed, and permease gene expression is modulated by the nature of the bacterial growth substrate. DecryptifiedO. oenicells are able to phosphorylate glucose, cellobiose, trehalose, and mannose at the expense of phosphoenolpyruvate. These substrates are present at low concentrations in wine at the end of alcoholic fermentation. The phosphotransferase system (PTS) may contribute to the perfect adaptation ofO. oenito its singular ecological niche.

scholarly journals Degradation of Benzene by Pseudomonas veronii 1YdBTEX2 and 1YB2 Is Catalyzed by Enzymes Encoded in Distinct Catabolism Gene Clusters

2015 ◽  
Vol 82 (1) ◽  
pp. 167-173 ◽  
Author(s):  
Daiana de Lima-Morales ◽  
Diego Chaves-Moreno ◽  
Melissa L. Wos-Oxley ◽  
Ruy Jáuregui ◽  
Ramiro Vilchez-Vargas ◽  
...  
Keyword(s):  
Gene Clusters ◽  
Contaminated Site ◽  
Degradation Pathways ◽  
Content Type ◽  
Benzene Degradation ◽  
Semialdehyde Dehydrogenase ◽  
Genes Encoding ◽  
Aromatic Degradation ◽  
Pseudomonas Veronii ◽  
Encoding Gene

ABSTRACTPseudomonas veronii1YdBTEX2, a benzene and toluene degrader, andPseudomonas veronii1YB2, a benzene degrader, have previously been shown to be key players in a benzene-contaminated site. These strains harbor unique catabolic pathways for the degradation of benzene comprising a gene cluster encoding an isopropylbenzene dioxygenase where genes encoding downstream enzymes were interrupted by stop codons. Extradiol dioxygenases were recruited from gene clusters comprising genes encoding a 2-hydroxymuconic semialdehyde dehydrogenase necessary for benzene degradation but typically absent from isopropylbenzene dioxygenase-encoding gene clusters. The benzene dihydrodiol dehydrogenase-encoding gene was not clustered with any other aromatic degradation genes, and the encoded protein was only distantly related to dehydrogenases of aromatic degradation pathways. The involvement of the different gene clusters in the degradation pathways was suggested by real-time quantitative reverse transcription PCR.

scholarly journals Lactobacillus casei Ferments theN-Acetylglucosamine Moiety of Fucosyl-α-1,3-N-Acetylglucosamine and Excretes l-Fucose

2012 ◽  
Vol 78 (13) ◽  
pp. 4613-4619 ◽  
Author(s):  
Jesús Rodríguez-Díaz ◽  
Antonio Rubio-del-Campo ◽  
María J. Yebra
Keyword(s):  
Carbon Source ◽  
Lactobacillus Casei ◽  
Genomic Sequence ◽  
Protein A ◽  
Physiological Role ◽  
Gene Clusters ◽  
Transcriptional Analysis ◽  
Phosphotransferase System ◽  
Content Type

ABSTRACTWe have previously characterized fromLactobacillus caseiBL23 three α-l-fucosidases, AlfA, AlfB, and AlfC, which hydrolyzein vitronatural fucosyl-oligosaccharides. In this work, we have shown thatL. caseiis able to grow in the presence of fucosyl-α-1,3-N-acetylglucosamine (Fuc-α-1,3-GlcNAc) as a carbon source. Interestingly,L. caseiexcretes thel-fucose moiety during growth on Fuc-α-1,3-GlcNAc, indicating that only theN-acetylglucosamine moiety is being metabolized. Analysis of the genomic sequence ofL. caseiBL23 shows that downstream fromalfB, which encodes the α-l-fucosidase AlfB, a gene,alfR, that encodes a transcriptional regulator is present. Divergently fromalfB, three genes,alfEFG, that encode proteins with homology to the enzyme IIAB (EIIAB), EIIC, and EIID components of a mannose-class phosphoenolpyruvate:sugar phosphotransferase system (PTS) are present. Inactivation of eitheralfBoralfFabolishes the growth ofL. caseion Fuc-α-1,3-GlcNAc. This proves that AlfB is involved in Fuc-α-1,3-GlcNAc metabolism and that the transporter encoded byalfEFGparticipates in the uptake of this disaccharide. A mutation in the PTS general component enzyme I does not eliminate the utilization of Fuc-α-1,3-GlcNAc, suggesting that the transport via the PTS encoded byalfEFGis not coupled to phosphorylation of the disaccharide. Transcriptional analysis withalfRandccpAmutants shows that the two gene clustersalfBRandalfEFGare regulated by substrate-specific induction mediated by the inactivation of the transcriptional repressor AlfR and by carbon catabolite repression mediated by the catabolite control protein A (CcpA). This work reports for the first time the characterization of the physiological role of an α-l-fucosidase in lactic acid bacteria and the utilization of Fuc-α-1,3-GlcNAc as a carbon source for bacteria.

scholarly journals Genetic Analysis Reveals the Identity of the Photoreceptor for Phototaxis in Hormogonium Filaments of Nostoc punctiforme

2014 ◽  
Vol 197 (4) ◽  
pp. 782-791 ◽  
Author(s):  
Elsie L. Campbell ◽  
Kari D. Hagen ◽  
Rui Chen ◽  
Douglas D. Risser ◽  
Daniela P. Ferreira ◽  
...  
Keyword(s):  
Mutational Analysis ◽  
Transcriptional Start Site ◽  
Gene Clusters ◽  
Gliding Motility ◽  
Transcriptional Analysis ◽  
Nostoc Punctiforme ◽  
Recognition Sequence ◽  
Content Type ◽  
Wide Range ◽  
Genes Encoding

In cyanobacterialNostocspecies, substratum-dependent gliding motility is confined to specialized nongrowing filaments called hormogonia, which differentiate from vegetative filaments as part of a conditional life cycle and function as dispersal units. Here we confirm thatNostoc punctiformehormogonia are positively phototactic to white light over a wide range of intensities.N. punctiformecontains two gene clusters (clusters 2 and 2i), each of which encodes modular cyanobacteriochrome–methyl-accepting chemotaxis proteins (MCPs) and other proteins that putatively constitute a basic chemotaxis-like signal transduction complex. Transcriptional analysis established that all genes in clusters 2 and 2i, plus two additional clusters (clusters 1 and 3) with genes encoding MCPs lacking cyanobacteriochrome sensory domains, are upregulated during the differentiation of hormogonia. Mutational analysis determined that only genes in cluster 2i are essential for positive phototaxis inN. punctiformehormogonia; here these genes are designatedptx(forphototaxis) genes. The cluster is unusual in containing complete or partial duplicates of genes encoding proteins homologous to the well-described chemotaxis elements CheY, CheW, MCP, and CheA. The cyanobacteriochrome-MCP gene (ptxD) lacks transmembrane domains and has 7 potential binding sites for bilins. The transcriptional start site of theptxgenes does not resemble a sigma 70 consensus recognition sequence; moreover, it is upstream of two genes encoding gas vesicle proteins (gvpAandgvpC), which also are expressed only in the hormogonium filaments ofN. punctiforme.

scholarly journals Effects of Arginine on Streptococcus mutans Growth, Virulence Gene Expression, and Stress Tolerance

2017 ◽  
Vol 83 (15) ◽  
Author(s):  
Brinta Chakraborty ◽  
Robert A. Burne
Keyword(s):  
Dental Caries ◽  
Streptococcus Mutans ◽  
Environmental Stresses ◽  
Arginine Deiminase ◽  
Pathogenic Potential ◽  
Content Type ◽  
Chemically Defined Media ◽  
Defined Media ◽  
Oral Biofilms ◽  
Genes Encoding

ABSTRACT Streptococcus mutans is a common constituent of oral biofilms and a primary etiologic agent of human dental caries. The bacteria associated with dental caries have potent abilities to produce organic acids from dietary carbohydrates and to grow and metabolize in acidic conditions. By contrast, many commensal bacteria produce ammonia through the arginine deiminase system (ADS), which moderates the pH of oral biofilms. Arginine metabolism by the ADS is a significant deterrent to the initiation and progression of dental caries. In this study, we observed how exogenously provided l-arginine affects the growth, the virulence properties, and the tolerance of environmental stresses of S. mutans. Supplementation with 1.5% arginine (final concentration) had an inhibitory effect on the growth of S. mutans in complex and chemically defined media, particularly when cells were exposed to acid or oxidative stress. The genes encoding virulence factors required for attachment/accumulation (gtfB and spaP), bacteriocins (nlmA, nlmB, nlmD, and cipB), and the sigma factor required for competence development (comX) were downregulated during growth with 1.5% arginine. Deep sequencing of RNA (RNA-Seq) comparing the transcriptomes of S. mutans growing in chemically defined media with and without 1.5% arginine revealed differential expression of genes encoding ATP-binding cassette transporters, metal transporters, and constituents required for survival, metabolism, and biofilm formation. Therefore, the mechanisms of action by which arginine inhibits dental caries include direct adverse effects on multiple virulence-related properties of the most common human dental caries pathogen. IMPORTANCE Metabolism of the amino acid arginine by the arginine deiminase system (ADS) of certain oral bacteria raises the pH of dental plaque and provides a selective advantage to health-associated bacteria, thereby protecting the host from dental caries (cavities). Here, we examine the effects of arginine on the cavity-causing bacterium Streptococcus mutans. We find that arginine negatively impacts the growth, the pathogenic potential, and the tolerance of environmental stresses in a way that is likely to compromise the ability of S. mutans to cause disease. Using genetic and genomic techniques, multiple mechanisms by which arginine exerts its influence on virulence-related properties of S. mutans are discovered. This report demonstrates that a primary mechanism of action by which arginine inhibits the initiation and progression of dental caries may be by reducing the pathogenic potential of S. mutans.

scholarly journals In Salmonella enterica, Ethanolamine Utilization Is Repressed by 1,2-Propanediol To Prevent Detrimental Mixing of Components of Two Different Bacterial Microcompartments

2015 ◽  
Vol 197 (14) ◽  
pp. 2412-2421 ◽  
Author(s):  
Ryan Sturms ◽  
Nicholas A. Streauslin ◽  
Shouqiang Cheng ◽  
Thomas A. Bobik
Keyword(s):  
Protein Interactions ◽  
Regulatory Protein ◽  
Gene Clusters ◽  
Content Type ◽  
Bacterial Microcompartments ◽  
Shell Protein ◽  
Bacterial Microcompartment ◽  
Genes Encoding ◽  
Shell Proteins ◽  
High Conservation

ABSTRACTBacterial microcompartments (MCPs) are a diverse family of protein-based organelles composed of metabolic enzymes encapsulated within a protein shell. The function of bacterial MCPs is to optimize metabolic pathways by confining toxic and/or volatile metabolic intermediates. About 20% of bacteria produce MCPs, and there are at least seven different types. Different MCPs vary in their encapsulated enzymes, but all have outer shells composed of highly conserved proteins containing bacterial microcompartment domains. Many organisms have genes encoding more than one type of MCP, but given the high homology among shell proteins, it is uncertain whether multiple MCPs can be functionally expressed in the same cell at the same time. In these studies, we examine the regulation of the 1,2-propanediol (1,2-PD) utilization (Pdu) and ethanolamine utilization (Eut) MCPs inSalmonella. Studies showed that 1,2-PD (shown to induce the Pdu MCP) represses transcription of the Eut MCP and that the PocR regulatory protein is required. The results indicate that repression of the Eut MCP by 1,2-PD is needed to prevent detrimental mixing of shell proteins from the Eut and Pdu MCPs. Coexpression of both MCPs impaired the function of the Pdu MCP and resulted in the formation of hybrid MCPs composed of Eut and Pdu MCP components. We also show that plasmid-based expression of individual shell proteins from the Eut MCP or the β-carboxysome impaired the function of Pdu MCP. Thus, the high conservation among bacterial microcompartment (BMC) domain shell proteins is problematic for coexpression of the Eut and Pdu MCPs and perhaps other MCPs as well.IMPORTANCEBacterial MCPs are encoded by nearly 20% of bacterial genomes, and almost 40% of those genomes contain multiple MCP gene clusters. In this study, we examine how the regulation of two different MCP systems (Eut and Pdu) is integrated inSalmonella. Our findings indicate that 1,2-PD (shown to induce the Pdu MCP) represses the Eut MCP to prevent detrimental mixing of Eut and Pdu shell proteins. These findings suggest that numerous organisms which produce more than one type of MCP likely need some mechanism to prevent aberrant shell protein interactions.

scholarly journals Genetic Analysis of Capsular Polysaccharide Synthesis Gene Clusters from All Serotypes of Streptococcus suis: Potential Mechanisms for Generation of Capsular Variation

2013 ◽  
Vol 79 (8) ◽  
pp. 2796-2806 ◽  
Author(s):  
Masatoshi Okura ◽  
Daisuke Takamatsu ◽  
Fumito Maruyama ◽  
Takashi Nozawa ◽  
Ichiro Nakagawa ◽  
...  
Keyword(s):  
Capsular Polysaccharide ◽  
Single Gene ◽  
Streptococcus Suis ◽  
Gene Clusters ◽  
Small Scale ◽  
Specific Gene ◽  
Chromosomal Locus ◽  
Content Type ◽  
Comprehensive Information ◽  
Genes Encoding

ABSTRACTStreptococcus suisstrains are classified into 35 serotypes on the basis of the antigenicity of their capsular polysaccharides (CPs). CP synthesis genes are known to be clustered on the chromosome (cpsgene cluster). The entirecpsgene clusters ofS. suishave so far been sequenced in 15 serotypes and found to be located betweenorfZandaroA. In this study, to provide comprehensive information aboutS. suisCPs, we sequenced the entirecpsgene clusters of the remaining serotypes and analyzed the complete set ofS. suiscpsgene clusters. Among the 35cpsgene clusters, 22 were located betweenorfZandaroA, whereas the other 13 were flanked by other gene(s) on the chromosomes, and the chromosomal locus was classified into five patterns. By clustering analysis, the predicted products ofcpsgenes found in the 35 serotypes were assigned into 291 homology groups, and all serotypes possessed a serotype-specific gene, except for serotypes 1, 2, 1/2, and 14. Because of the presence of genes encoding flippase (wzx) and polymerase (wzy), CPs of all serotypes were thought to be synthesized by the Wzx/Wzy pathway. Our data also implied the possibility of the transfer of the entire or partialcpsgene clusters amongS. suisstrains, as well as the influence of spontaneous mutations in a single gene or a few genes on the antigenicity of some serotypes. Accumulation of these gene transfers and small-scale mutations may have generated the antigenic diversity ofS. suisCPs.

scholarly journals Diversity in Robustness of Lactococcus lactis Strains during Heat Stress, Oxidative Stress, and Spray Drying Stress

2013 ◽  
Vol 80 (2) ◽  
pp. 603-611 ◽  
Author(s):  
Annereinou R. Dijkstra ◽  
Meily C. Setyawati ◽  
Jumamurat R. Bayjanov ◽  
Wynand Alkema ◽  
Sacha A. F. T. van Hijum ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Spray Drying ◽  
Lactococcus Lactis ◽  
Comparative Genomic ◽  
Phosphotransferase System ◽  
Culture Collections ◽  
Content Type ◽  
Stress Survival ◽  
Genes Encoding ◽  
And Oxidative Stress

ABSTRACTIn this study we tested 39Lactococcus lactisstrains isolated from diverse habitats for their robustness under heat and oxidative stress, demonstrating high diversity in survival (up to 4 log units). Strains with anL. lactissubsp.lactisphenotype generally displayed more-robust phenotypes than strains with anL. lactissubsp.cremorisphenotype, whereas the habitat from which the strains had been isolated did not appear to influence stress survival. Comparison of the stress survival phenotypes with already available comparative genomic data sets revealed that the absence or presence of specific genes, including genes encoding a GntR family transcriptional regulator, a manganese ABC transporter permease, a cellobiose phosphotransferase system (PTS) component, the FtsY protein, and hypothetical proteins, was associated with heat or oxidative stress survival. Finally, 14 selected strains also displayed diversity in survival after spray drying, ranging from 20% survival for the most robust strains, which appears acceptable for industrial application, to 0.1% survival for the least-tolerant strains. The high and low levels of survival upon spray drying correlated clearly with the combined robustness under heat and oxidative stress. These results demonstrate the relevance of screening culture collections for robustness under heat and oxidative stress on top of the typical screening for acidifying and flavor-forming properties.

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