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Jeon K, Andoy NMO, Dufour D, Yang JYC, Lévesque CM, Sullan RMA. Cocktail Approach with Polyserotonin Nanoparticles and Peptides for Treatment of Streptococcus mutans. ACS Infect Dis 2024. [PMID: 39158205 DOI: 10.1021/acsinfecdis.4c00107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/20/2024]
Abstract
Dental plaque, formed by a Streptococcus mutans biofilm, is a major contributor to cavity formation. While antimicrobial strategies exist, the growing risk of antibiotic resistance necessitates alternative therapeutic solutions. Polyserotonin nanoparticles (PSeNPs), recently recognized for their photothermal property and promising biomedical applications, open up a new avenue for antimicrobial use. Here, we introduced a UV-initiated synthetic route for PSeNPs with improved yield. Using these PSeNPs, a cocktail treatment to reduce the viability of this cavity-causing bacteria was developed. This cocktail comprises an S. mutans-targeting antimicrobial peptide (GH12), an intraspecies competence-stimulating peptide that triggers altruistic cell death in S. mutans, and laser-activated heating of PSeNPs. The "peptide + PSeNP + laser" combination effectively inhibits S. mutans growth in both planktonic and biofilm states. Moreover, the cocktail approach remains effective in reducing the viability of S. mutans in a more virulent dual-species biofilm with Candida albicans. Overall, our results reinforce the utility of a multipronged therapeutic strategy to reduce cariogenic bacteria in the complex model oral biofilm.
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Affiliation(s)
- Keuna Jeon
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1065 Military Trail, Toronto, Ontario M1C 1A4, Canada
- Department of Chemistry, University of Toronto, 80 Street George Street, Toronto, Ontario M5S 3H6, Canada
| | - Nesha May O Andoy
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1065 Military Trail, Toronto, Ontario M1C 1A4, Canada
| | - Delphine Dufour
- Faculty of Dentistry, University of Toronto, 124 Edward Street, Toronto, Ontario M5G 1G6, Canada
| | - Jessica Y C Yang
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1065 Military Trail, Toronto, Ontario M1C 1A4, Canada
| | - Céline M Lévesque
- Faculty of Dentistry, University of Toronto, 124 Edward Street, Toronto, Ontario M5G 1G6, Canada
| | - Ruby May A Sullan
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1065 Military Trail, Toronto, Ontario M1C 1A4, Canada
- Department of Chemistry, University of Toronto, 80 Street George Street, Toronto, Ontario M5S 3H6, Canada
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Pandey SD, Biswas I. Clp ATPases differentially affect natural competence development in Streptococcus mutans. Microbiologyopen 2022; 11:e1288. [PMID: 35765180 PMCID: PMC9108599 DOI: 10.1002/mbo3.1288] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 04/27/2022] [Indexed: 11/25/2022] Open
Abstract
In naturally competent bacteria, DNA transformation through horizontal gene transfer is an evolutionary mechanism to receive extracellular DNA. Bacteria need to maintain a state of competence to accept foreign DNA, and this is an energy-driven phenomenon that is tightly controlled. In Streptococcus, competence development is a complex process that is not fully understood. In this study, we used Streptococcus mutans, an oral bacterium, to determine how cell density affects competence development. We found that in S. mutans the transformation efficiency is maximum when the transforming DNA was added at low cell density and incubated for 2.5 h before selecting for transformants. We also found that S. mutans cells remain competent until the mid-logarithmic phase, after which the competence decreases drastically. Surprisingly, we observed that individual components of Clp proteolytic complexes differentially regulate competence. If the transformation is carried out at the early growth phase, both ClpP protease and ClpX ATPase are needed for competence. In contrast, we found that both ClpC and ClpE negatively affect competence. We also found that if the transformation is carried out at the mid-logarithmic growth phase ClpX is still required for competence, but ClpP negatively affects competence. While the exact reason for this differential effect of ClpP and ClpX on transformation is currently unknown, we found that both ClpC and ClpE have a negative effect on transformation, which was not reported before.
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Affiliation(s)
- Satya D. Pandey
- Department of MicrobiologyUniversity of Kansas Medical CenterKansas CityKansasUSA
| | - Indranil Biswas
- Department of MicrobiologyUniversity of Kansas Medical CenterKansas CityKansasUSA
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Expression of an Extracellular Protein (SMU.63) Is Regulated by SprV in Streptococcus mutans. Appl Environ Microbiol 2020; 86:AEM.01647-20. [PMID: 32978138 DOI: 10.1128/aem.01647-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 09/20/2020] [Indexed: 12/19/2022] Open
Abstract
In Streptococcus mutans, SprV (SMU.2137) is a pleiotropic regulator that differentially regulates genes related to competence, mutacin production, biofilm formation, and the stress tolerance response, along with some other pathways. In this study, we established a link between SprV and an ∼67-kDa protein in the culture supernatant of strain UA159 that was later confirmed as SMU.63 by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis. We discovered that SprV downregulates the transcription and translation of SMU.63. We found that the seven amino acids from the C-terminal region of SprV were also crucial for the expression of SMU.63. Deletion of smu.63 led to increased sucrose-independent biofilm formation and competence. The sprV deletion also increased biofilm formation although this could be partially attributed to the downregulation of smu.63 In an smu.63 sprV double mutant, a synergistic effect was observed in biofilm formation in contrast to effects on competence development. We found that low or excess magnesium ion repressed sprV transcription that, in turn, affected the expression of smu.63 As expected, a magnesium ion-dependent effect of competence and biofilm formation was observed in the UA159 strain. We also replicated the results of SMU.63 expression and competence in S. mutans GS5 that encodes both SprV and SMU.63 homologs and found that the GS5 strain behaves similarly to the UA159 strain, indicating that SprV's effect is strain independent.IMPORTANCE We previously identified a pleiotropic regulator, SprV, in Streptococcus mutans This regulator appears to be highly conserved among streptococci. Here, we showed that SprV regulates the expression of a secreted protein encoded by SMU.63 in S. mutans SMU.63 has been known to impact biofilm formation and genetic competence, two important characteristics that help in colonization of the organism. SMU.63 is also unique since it is known to form amyloid fiber. We found that SprV regulates the expression of SMU.63 at both the transcriptional and translational levels. We also found that the expression of SprV is regulated by magnesium ion concentration. Interestingly, both low and high magnesium ion concentrations affected biofilm formation and genetic competence. Since SMU.63 is also highly conserved among streptococci, we hypothesized that SprV will have a similar effect on its expression.
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Bikash CR, Tal-Gan Y. Structure Activity Relationship Study of the XIP Quorum Sensing Pheromone in Streptococcus mutans Reveal Inhibitors of the Competence Regulon. ACS Chem Biol 2020; 15:2833-2841. [PMID: 32946208 DOI: 10.1021/acschembio.0c00650] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The dental cariogenic pathogen Streptococcus mutans coordinates competence for genetic transformation via two peptide pheromones, competence stimulating peptide (CSP) and comX-inducing peptide (XIP). CSP is sensed by the comCDE system and induces competence indirectly, whereas XIP is sensed by the comRS system and induces competence directly. In chemically defined media (CDM), after uptake by oligopeptide permease, XIP interacts with the cytosolic receptor ComR to form the XIP::ComR complex that activates the expression of comX, an alternative sigma factor that initiates the transcription of late-competence genes. In this study, we set out to determine the molecular mechanism of XIP::ComR interaction. To this end, we performed systematic replacement of the amino acid residues in the XIP pheromone and assessed the ability of the mutated analogs to modulate the competence regulon in CDM. We were able to identify structural features that are important to ComR binding and activation. Our structure-activity relationship insights led us to construct multiple XIP-based inhibitors of the comRS pathway. Furthermore, when comCDE and comRS were both stimulated with CSP and XIP, respectively, a lead XIP-based inhibitor was able to maintain the inhibitory activity. Last, phenotypic assays were used to highlight the potential of XIP-based inhibitors to attenuate pathogenicity in S. mutans and to validate the specificity of these compounds to the comRS pathway within the competence regulon. The XIP-based inhibitors developed in this study can be used as lead scaffolds for the design and development of potential therapeutics against S. mutans infections.
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Affiliation(s)
- Chowdhury Raihan Bikash
- Department of Chemistry, University of Nevada, Reno, 1664 North Virginia Street, Reno, Nevada 89557, United States
| | - Yftah Tal-Gan
- Department of Chemistry, University of Nevada, Reno, 1664 North Virginia Street, Reno, Nevada 89557, United States
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Rocha FR, Regis WFM, Duarte S, Muniz FWMG, Rodrigues LKA. Effect of bioactive compounds on the regulation of quorum sensing network-associated genes and virulence in Streptococcus mutans-A systematic review. Arch Oral Biol 2020; 119:104893. [PMID: 32961379 DOI: 10.1016/j.archoralbio.2020.104893] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 08/23/2020] [Accepted: 08/25/2020] [Indexed: 12/15/2022]
Abstract
OBJECTIVE The aim of this study was to systematically review the literature on the effect of bioactive compounds and their regulation of quorum sensing (QS)-related and/or -regulated-virulence genes expression in Streptococcus mutans. DESIGN The search strategy was conducted through the electronic databases Pubmed, Scopus, and Web of Science for studies reporting the effects of natural and synthetic bioactive compounds on the regulation of QS-associated and/or -regulated genes of S. mutans. RESULTS After full-text reading, 19 studies met the inclusion criteria, in most of them, QS-inhibitors from synthetic origin were evaluated, 16 articles described the effect of the compounds on biofilm formation cultivated in vitro and five studies described these effects on adhesion of biofilm-producing cells. Only 2 studies analyzed the potential target-component of the QS. CONCLUSIONS Mostly, the bioactive compounds affected the expression of QS-associated and/or -regulated genes and virulence traits (e.g. adhesion, biofilm formation, acid stress tolerance) of S. mutans. Further studies are necessary to elucidate the target-specific QS-system constituent used by bioactive compounds to achieve QS inhibition as well as validate the use of these compounds in controlling dental caries.
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Affiliation(s)
- Francisco R Rocha
- Department of Pathology and Legal Medicine, Postgraduate Program in Medical Microbiology, Federal University of Ceará, Fortaleza, CE, Zip Code: 60430-270, Brazil
| | - Wanessa F M Regis
- Faculty of Pharmacy, Dentistry, and Nursing, Federal University of Ceará, Fortaleza, Ceará, Brazil
| | - Simone Duarte
- Department of Cariology, Operative Dentistry and Dental Public Health, Indiana University School of Dentistry, Indianapolis, IN, United States
| | - Francisco W M G Muniz
- Department of Periodontology, School of Dentistry, Federal University of Pelotas, Pelotas, RS, Brazil
| | - Lidiany K A Rodrigues
- Department of Operative Dentistry, Faculty of Pharmacy, Dentistry and Nursing, Federal University of Ceará, Fortaleza, CE, Zip Code: 60430-170, Brazil.
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Barran-Berdon AL, Ocampo S, Haider M, Morales-Aparicio J, Ottenberg G, Kendall A, Yarmola E, Mishra S, Long JR, Hagen SJ, Stubbs G, Brady LJ. Enhanced purification coupled with biophysical analyses shows cross-β structure as a core building block for Streptococcus mutans functional amyloids. Sci Rep 2020; 10:5138. [PMID: 32198417 PMCID: PMC7083922 DOI: 10.1038/s41598-020-62115-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 02/14/2020] [Indexed: 11/10/2022] Open
Abstract
Streptococcus mutans is an etiologic agent of human dental caries that forms dental plaque biofilms containing functional amyloids. Three amyloidogenic proteins, P1, WapA, and Smu_63c were previously identified. C123 and AgA are naturally occurring amyloid-forming fragments of P1 and WapA, respectively. We determined that four amyloidophilic dyes, ThT, CDy11, BD-oligo, and MK-H4, differentiate C123, AgA, and Smu_63c amyloid from monomers, but non-specific binding to bacterial cells in the absence of amyloid precludes their utility for identifying amyloid in biofilms. Congo red-induced birefringence is a more specific indicator of amyloid formation and differentiates biofilms formed by wild-type S. mutans from a triple ΔP1/WapA/Smu_63c mutant with reduced biofilm forming capabilities. Amyloid accumulation is a late event, appearing in older S. mutans biofilms after 60 hours of growth. Amyloid derived from pure preparations of all three proteins is visualized by electron microscopy as mat-like structures. Typical amyloid fibers become evident following protease digestion to eliminate non-specific aggregates and monomers. Amyloid mats, similar in appearance to those reported in S. mutans biofilm extracellular matrices, are reconstituted by co-incubation of monomers and amyloid fibers. X-ray fiber diffraction of amyloid mats and fibers from all three proteins demonstrate patterns reflective of a cross-β amyloid structure.
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Affiliation(s)
- Ana L Barran-Berdon
- Department of Oral Biology, University of Florida, Gainesville, Florida, USA
| | - Sebastian Ocampo
- Department of Oral Biology, University of Florida, Gainesville, Florida, USA
| | - Momin Haider
- Department of Physics, University of Florida, Gainesville, Florida, USA
| | | | - Gregory Ottenberg
- Department of Oral Biology, University of Florida, Gainesville, Florida, USA
| | - Amy Kendall
- Department of Biological Sciences and Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - Elena Yarmola
- Department of Oral Biology, University of Florida, Gainesville, Florida, USA
| | - Surabhi Mishra
- Department of Oral Biology, University of Florida, Gainesville, Florida, USA
| | - Joanna R Long
- Department of Biochemistry, University of Florida, Gainesville, Florida, USA
| | - Stephen J Hagen
- Department of Physics, University of Florida, Gainesville, Florida, USA
| | - Gerald Stubbs
- Department of Biological Sciences and Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - L Jeannine Brady
- Department of Oral Biology, University of Florida, Gainesville, Florida, USA.
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Ricomini Filho AP, Khan R, Åmdal HA, Petersen FC. Conserved Pheromone Production, Response and Degradation by Streptococcus mutans. Front Microbiol 2019; 10:2140. [PMID: 31572344 PMCID: PMC6753979 DOI: 10.3389/fmicb.2019.02140] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 08/30/2019] [Indexed: 01/27/2023] Open
Abstract
Streptococcus mutans, a bacterium with high cariogenic potential, coordinates competence for natural transformation and bacteriocin production via the XIP and CSP pheromones. CSP is effective in inducing bacteriocin responses but not competence in chemically defined media (CDM). This is in contrast to XIP, which is a strong inducer of competence in CDM but can also stimulate bacteriocin genes as a late response. Interconnections between the pathways activated by the two pheromones have been characterized in certain detail in S. mutans UA159, but it is mostly unknown whether such findings are representative for the species. In this study, we used bioassays based on luciferase reporters for the bacteriocin gene cipB and the alternative sigma factor sigX to investigate various S. mutans isolates for production and response to CSP and XIP pheromones in CDM. Similar to S. mutans UA159, endogenous CSP was undetectable in the culture supernatants of all tested strains. During optimization of the bioassay using the cipB reporter, we discovered that the activity of exogenous CSP used as a standard was reduced over time during S. mutans growth. Using a FRET-CSP reporter peptide, we found that S. mutans UA159 was able to degrade CSP, and that such activity was not significantly different in isogenic mutants with deletion of the protease gene htrA or the competence genes sigX, oppD, and comR. CSP cleavage was also detected in all the wild type strains, indicating that this is a conserved feature in S. mutans. For the XIP pheromone, endogenous production was observed in the supernatants of all 34 tested strains at peak concentrations in culture supernatants that varied between 200 and 26000 nM. Transformation in the presence of exogenous XIP was detected in all but one of the isolates. The efficiency of transformation varied, however, among the different strains, and for those with the highest transformation rates, endogenous XIP peak concentrations in the supernatants were above 2000 nM XIP. We conclude that XIP production and inducing effect on transformation, as well as the ability to degrade CSP, are conserved functions among different S. mutans isolates. Understanding the functionality and conservation of pheromone systems in S. mutans may lead to novel strategies to prevent or treat unbalances in oral microbiomes that may favor diseases.
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Affiliation(s)
| | - Rabia Khan
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - Heidi Aarø Åmdal
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - Fernanda C. Petersen
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
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8
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Bedoya-Correa CM, Rincón Rodríguez RJ, Parada-Sanchez MT. Genomic and phenotypic diversity of Streptococcus mutans. J Oral Biosci 2019; 61:22-31. [DOI: 10.1016/j.job.2018.11.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 10/29/2018] [Accepted: 11/05/2018] [Indexed: 02/03/2023]
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9
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Hagen SJ, Son M. Origins of heterogeneity in Streptococcus mutans competence: interpreting an environment-sensitive signaling pathway. Phys Biol 2017; 14:015001. [PMID: 28129205 PMCID: PMC5336344 DOI: 10.1088/1478-3975/aa546c] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Bacterial pathogens rely on chemical signaling and environmental cues to regulate disease-causing behavior in complex microenvironments. The human pathogen Streptococcus mutans employs a particularly complex signaling and sensing scheme to regulate genetic competence and other virulence behaviors in the oral biofilms it inhabits. Individual S. mutans cells make the decision to enter the competent state by integrating chemical and physical cues received from their microenvironment along with endogenously produced peptide signals. Studies at the single-cell level, using microfluidics to control the extracellular environment, provide physical insight into how the cells process these inputs to generate complex and often heterogeneous outputs. Fine changes in environmental stimuli can dramatically alter the behavior of the competence circuit. Small shifts in pH can switch the quorum sensing response on or off, while peptide-rich media appear to switch the output from a unimodal to a bimodal behavior. Therefore, depending on environmental cues, the quorum sensing circuitry can either synchronize virulence across the population, or initiate and amplify heterogeneity in that behavior. Much of this complex behavior can be understood within the framework of a quorum sensing system that can operate both as an intercellular signaling mechanism and intracellularly as a noisy bimodal switch.
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Affiliation(s)
- Stephen J. Hagen
- University of Florida, Physics Department, PO Box 118440, Gainesville FL 32611
| | - Minjun Son
- University of Florida, Physics Department, PO Box 118440, Gainesville FL 32611
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10
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Salvadori G, Junges R, Khan R, Åmdal HA, Morrison DA, Petersen FC. Natural Transformation of Oral Streptococci by Use of Synthetic Pheromones. Methods Mol Biol 2017; 1537:219-232. [PMID: 27924597 DOI: 10.1007/978-1-4939-6685-1_13] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The discovery that Streptococcus pneumoniae uses a competence-stimulating peptide (CSP) to induce competence for natural transformation, and that other species of the mitis and the anginosus streptococcal groups use a similar system, has expanded the tools to explore gene function and regulatory pathways in streptococci. Two other classes of pheromones have been discovered since then, comprising the bacteriocin-inducing peptide class found in Streptococcus mutans (also named CSP, although different from the former) and the SigX-inducing peptides (XIP), in the mutans, salivarius, bovis, and pyogenes groups of streptococci. The three classes of peptide pheromones can be ordered from peptide synthesis services at affordable prices, and used in transformation assays to obtain competent cultures consistently at levels usually higher than those achieved during spontaneous competence. In this chapter, we present protocols for natural transformation of oral streptococci that are based on the use of synthetic pheromones, with examples of conditions optimized for transformation of S. mutans and Streptococcus mitis.
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Affiliation(s)
- Gabriela Salvadori
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, P.O. Box 1052, Blindern, Oslo, 0316, Norway
| | - Roger Junges
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, P.O. Box 1052, Blindern, Oslo, 0316, Norway
| | - Rabia Khan
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, P.O. Box 1052, Blindern, Oslo, 0316, Norway
| | - Heidi A Åmdal
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, P.O. Box 1052, Blindern, Oslo, 0316, Norway
| | - Donald A Morrison
- Department of Biological Sciences, College of Liberal Arts and Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - Fernanda C Petersen
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, P.O. Box 1052, Blindern, Oslo, 0316, Norway.
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11
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Zaccaria E, Wels M, van Baarlen P, Wells JM. Temporal Regulation of the Transformasome and Competence Development in Streptococcus suis. Front Microbiol 2016; 7:1922. [PMID: 28066332 PMCID: PMC5167698 DOI: 10.3389/fmicb.2016.01922] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 11/16/2016] [Indexed: 11/19/2022] Open
Abstract
In S. suis the ComX-inducing peptide (XIP) pheromone regulates ComR-dependent transcriptional activation of comX (or sigX) the regulator of the late competence regulon. The aims of this study were to identify the ComR-regulated genes and in S. suis using genome-wide transcriptomics and identify their function based on orthology and the construction of specific knockout mutants. The ComX regulon we identified, includes all homologs of the “transformasome” a type 4-like pilus DNA binding and transport apparatus identified in Streptococcus pneumoniae, Streptococcus mutans, and Streptococcus thermophilus. A conserved CIN-box (YTACGAAYW), predicted to be bound by ComX, was found in the promoters of operons encoding genes involved in expression of the transformasome. Mutants lacking the major pilin gene comYC were not transformable demonstrating that the DNA uptake pilus is indeed required for competence development in S. suis. Competence was a transient state with the comX regulon shut down after ~15 min even when transcription of comX had not returned to basal levels, indicating other mechanisms control the exit from competence. The ComX regulon also included genes involved in DNA repair including cinA which we showed to be required for high efficiency transformation. In contrast to S. pneumoniae and S. mutans the ComX regulon of S. suis did not include endA which converts the transforming DNA into ssDNA, or ssbA, which protects the transforming ssDNA from degradation. EndA appeared to be essential in S. suis so we could not generate mutants and confirm its role in DNA transformation. Finally, we identified a putative homolog of fratricin, and a putative bacteriocin gene cluster, that were also part of the CIN-box regulon and thus may play a role in DNA release from non-competent cells, enabling gene transfer between S. suis pherotypes or S. suis and other species. S. suis mutants of oppA, the binding subunit of the general oligopeptide transporter were not transformable, suggesting that it is required for the import of XIP.
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Affiliation(s)
- Edoardo Zaccaria
- Host-Microbe Interactomics, Animal Sciences, Wageningen University Wageningen, Netherlands
| | | | - Peter van Baarlen
- Host-Microbe Interactomics, Animal Sciences, Wageningen University Wageningen, Netherlands
| | - Jerry M Wells
- Host-Microbe Interactomics, Animal Sciences, Wageningen University Wageningen, Netherlands
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12
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Effects of Carbohydrate Source on Genetic Competence in Streptococcus mutans. Appl Environ Microbiol 2016; 82:4821-4834. [PMID: 27260355 DOI: 10.1128/aem.01205-16] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 05/25/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The capacity to internalize and catabolize carbohydrates is essential for dental caries pathogens to persist and cause disease. The expression of many virulence-related attributes by Streptococcus mutans, an organism strongly associated with human dental caries, is influenced by the peptide signaling pathways that control genetic competence. Here, we demonstrate a relationship between the efficiency of competence signaling and carbohydrate source. A significant increase in the activity of the promoters for comX, comS, and comYA after exposure to competence-stimulating peptide (CSP) was observed in cells growing on fructose, maltose, sucrose, or trehalose as the primary carbohydrate source, compared to cells growing on glucose. However, only cells grown in the presence of trehalose or sucrose displayed a significant increase in transformation frequency. Notably, even low concentrations of these carbohydrates in the presence of excess glucose could enhance the expression of comX, encoding a sigma factor needed for competence, and the effects on competence were dependent on the cognate sugar:phosphotransferase permease for each carbohydrate. Using green fluorescent protein (GFP) reporter fusions, we observed that growth in fructose or trehalose resulted in a greater proportion of the population activating expression of comX and comS, encoding the precursor of comX-inducing peptide (XIP), after addition of CSP, than growth in glucose. Thus, the source of carbohydrate significantly impacts the stochastic behaviors that regulate subpopulation responses to CSP, which can induce competence in S. mutans IMPORTANCE The signaling pathways that regulate development of genetic competence in Streptococcus mutans are intimately intertwined with the pathogenic potential of the organism, impacting biofilm formation, stress tolerance, and expression of known virulence determinants. Induction of the gene for the master regulator of competence, ComX, by competence-stimulating peptide (CSP) occurs in a subpopulation of cells. Here, we show that certain carbohydrates that are common in the human diet enhance the ability of CSP to activate transcription of comX and that a subset of these carbohydrates stimulates progression to the competent state. The cognate sugar:phosphotransferase permeases for each sugar are needed for these effects. Interestingly, single-cell analysis shows that the carbohydrates that increase com gene expression do so by enhancing the proportion of cells that respond to CSP. A mathematical model is developed to explain how carbohydrates modulate bistable behavior in the system via the ComRS pathway and ComX stability.
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13
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Dufour D, Villemin C, Perry JA, Lévesque CM. Escape from the competence state in Streptococcus mutans is governed by the bacterial population density. Mol Oral Microbiol 2015; 31:501-514. [PMID: 26513533 DOI: 10.1111/omi.12145] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/26/2015] [Indexed: 12/25/2022]
Abstract
Horizontal gene transfer through natural DNA transformation is an important evolutionary mechanism among bacteria. Transformation requires that the bacteria are physiologically competent to take and incorporate free DNA directly from the environment. Although natural genetic transformation is a remarkable feature of many naturally competent bacteria, the process is energetically expensive for the cells. Consequently, a tight control of the competence state is necessary. The objective of the present work was to help decipher the molecular mechanisms regulating the escape from the competence state in Streptococcus mutans, the principal etiological agent responsible for tooth decay in humans. Our results showed that the cessation of competence in S. mutans was abrupt, and did not involve the accumulation of a competence inhibitor nor the depletion of a competence activator in the extracellular environment. The competence state was repressed at high cell population density via concomitant repression of sigX gene encoding the master regulator of the competence regulon. Co-culture experiments performed with oral and non-oral bacteria showed that S. mutans assesses its own population density and also the microbial density of its surroundings to regulate its competence escape. Interestingly, neither the intra-species and extra-species quorum-sensing systems nor the other 13 two-component regulatory systems identified in S. mutans were involved in the cell-density-dependent escape of the competence state. Altogether, our results suggest a complex mechanism regulating the competence shut-off involving cell-density-dependent repression of sigX through an as yet undefined system, and possibly SigX protein stability.
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Affiliation(s)
- D Dufour
- Dental Research Institute, Faculty of Dentistry, University of Toronto, Toronto, ON, Canada
| | - C Villemin
- Dental Research Institute, Faculty of Dentistry, University of Toronto, Toronto, ON, Canada
| | - J A Perry
- Dental Research Institute, Faculty of Dentistry, University of Toronto, Toronto, ON, Canada
| | - C M Lévesque
- Dental Research Institute, Faculty of Dentistry, University of Toronto, Toronto, ON, Canada.
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14
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Son M, Shields RC, Ahn SJ, Burne RA, Hagen SJ. Bidirectional signaling in the competence regulatory pathway of Streptococcus mutans. FEMS Microbiol Lett 2015; 362:fnv159. [PMID: 26363019 DOI: 10.1093/femsle/fnv159] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/04/2015] [Indexed: 11/14/2022] Open
Abstract
Streptococcus mutans expresses comX (also known as sigX), which encodes a sigma factor that is required for development of genetic competence, in response to the peptide signals XIP and CSP and environmental factors. XIP (sigX inducing peptide) is derived from ComS and activates comX unimodally in chemically defined media via the ComRS system. CSP (competence stimulating peptide) activates comX bimodally in peptide-rich media through the ComDE two-component system. However, CSP-ComDE activation of comX is indirect and involves ComRS. Therefore, the bimodality of CSP-dependent activation of comX may arise from either ComRS or ComDE. Here we study, at the single-cell level, how genes in the CSP signaling pathway respond to CSP, XIP and media. Our data indicate that activation of comX stimulates expression of comE. In addition, activation of comE requires intact comR and comS genes. Therefore, not only does CSP-ComDE stimulate the ComRS pathway to activate comX expression, but ComRS activation of comX also stimulates expression of the CSP-ComDE pathway and its regulon. The results demonstrate the mutual interconnection of the signaling pathways that control bacteriocin expression (ComDE) and genetic competence (ComRS), both of which are linked to lytic and virulence behaviors.
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Affiliation(s)
- Minjun Son
- Department of Physics, University of Florida, Gainesville FL 32611, USA
| | - Robert C Shields
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, Florida 32610, USA
| | - Sang-Joon Ahn
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, Florida 32610, USA
| | - Robert A Burne
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, Florida 32610, USA
| | - Stephen J Hagen
- Department of Physics, University of Florida, Gainesville FL 32611, USA
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15
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Fontaine L, Wahl A, Fléchard M, Mignolet J, Hols P. Regulation of competence for natural transformation in streptococci. INFECTION GENETICS AND EVOLUTION 2015; 33:343-60. [DOI: 10.1016/j.meegid.2014.09.010] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Revised: 08/28/2014] [Accepted: 09/07/2014] [Indexed: 02/02/2023]
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16
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The copYAZ Operon Functions in Copper Efflux, Biofilm Formation, Genetic Transformation, and Stress Tolerance in Streptococcus mutans. J Bacteriol 2015; 197:2545-57. [PMID: 26013484 DOI: 10.1128/jb.02433-14] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 05/12/2015] [Indexed: 12/18/2022] Open
Abstract
UNLABELLED In bacteria, copper homeostasis is closely monitored to ensure proper cellular functions while avoiding cell damage. Most Gram-positive bacteria utilize the copYABZ operon for copper homeostasis, where copA and copB encode copper-transporting P-type ATPases, whereas copY and copZ regulate the expression of the cop operon. Streptococcus mutans is a biofilm-forming oral pathogen that harbors a putative copper-transporting copYAZ operon. Here, we characterized the role of copYAZ operon in the physiology of S. mutans and delineated the mechanisms of copper-induced toxicity in this bacterium. We observed that copper induced toxicity in S. mutans cells by generating oxidative stress and disrupting their membrane potential. Deletion of the copYAZ operon in S. mutans strain UA159 resulted in reduced cell viability under copper, acid, and oxidative stress relative to the viability of the wild type under these conditions. Furthermore, the ability of S. mutans to form biofilms and develop genetic competence was impaired under copper stress. Briefly, copper stress significantly reduced cell adherence and total biofilm biomass, concomitantly repressing the transcription of the gtfB, gtfC, gtfD, gbpB, and gbpC genes, whose products have roles in maintaining the structural and/or functional integrity of the S. mutans biofilm. Furthermore, supplementation with copper or loss of copYAZ resulted in significant reductions in transformability and in the transcription of competence-associated genes. Copper transport assays revealed that the ΔcopYAZ strain accrued significantly large amounts of intracellular copper compared with the amount of copper accumulation in the wild-type strain, thereby demonstrating a role for CopYAZ in the copper efflux of S. mutans. The complementation of the CopYAZ system restored copper expulsion, membrane potential, and stress tolerance in the copYAZ-null mutant. Taking these results collectively, we have established the function of the S. mutans CopYAZ system in copper export and have further expanded knowledge on the importance of copper homeostasis and the CopYAZ system in modulating streptococcal physiology, including stress tolerance, membrane potential, genetic competence, and biofilm formation. IMPORTANCE S. mutans is best known for its role in the initiation and progression of human dental caries, one of the most common chronic diseases worldwide. S. mutans is also implicated in bacterial endocarditis, a life-threatening inflammation of the heart valve. The core virulence factors of S. mutans include its ability to produce and sustain acidic conditions and to form a polysaccharide-encased biofilm that provides protection against environmental insults. Here, we demonstrate that the addition of copper and/or deletion of copYAZ (the copper homeostasis system) have serious implications in modulating biofilm formation, stress tolerance, and genetic transformation in S. mutans. Manipulating the pathways affected by copper and the copYAZ system may help to develop potential therapeutics to prevent S. mutans infection in and beyond the oral cavity.
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Conrads G, de Soet JJ, Song L, Henne K, Sztajer H, Wagner-Döbler I, Zeng AP. Comparing the cariogenic species Streptococcus sobrinus and S. mutans on whole genome level. J Oral Microbiol 2014; 6:26189. [PMID: 25475081 PMCID: PMC4256546 DOI: 10.3402/jom.v6.26189] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 11/10/2014] [Accepted: 11/10/2014] [Indexed: 02/03/2023] Open
Abstract
Background Two closely related species of mutans streptococci, namely Streptococcus mutans and Streptococcus sobrinus, are associated with dental caries in humans. Their acidogenic and aciduric capacity is directly associated with the cariogenic potential of these bacteria. To survive acidic and temporarily harsh conditions in the human oral cavity with hundreds of other microbial co-colonizers as competitors, both species have developed numerous mechanisms for adaptation. Objectives The recently published novel genome information for both species is used to elucidate genetic similarities but especially differences and to discuss the impact on cariogenicity of the corresponding phenotypic properties including adhesion, carbohydrate uptake and fermentation, acid tolerance, signaling by two component systems, competence, and oxidative stress resistance. Conclusions S. sobrinus can down-regulate the SpaA-mediated adherence to the pellicle. It has a smaller number of two-component signaling systems and bacteriocin-related genes than S. mutans, but all or even more immunity proteins. It lacks the central competence genes comC, comS, and comR. There are more genes coding for glucosyltransferases and a novel energy production pathway formed by lactate oxidase, which is not found in S. mutans. Both species show considerable differences in the regulation of fructan catabolism. However, both S. mutans and S. sobrinus share most of these traits and should therefore be considered as equally virulent with regard to dental caries.
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Affiliation(s)
- Georg Conrads
- Division of Oral Microbiology and Immunology, Department of Operative and Preventive Dentistry & Periodontology, RWTH Aachen University Hospital, Aachen, Germany;
| | - Johannes J de Soet
- Department of Preventive Dentistry, Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam, The Netherlands
| | - Lifu Song
- Institute of Bioprocess and Biosystems, Technical University Hamburg, Harburg, Germany
| | - Karsten Henne
- Division of Oral Microbiology and Immunology, Department of Operative and Preventive Dentistry & Periodontology, RWTH Aachen University Hospital, Aachen, Germany
| | - Helena Sztajer
- Helmholtz-Centre for Infection Research, Group Microbial Communication, Division of Microbial Pathogenesis, Braunschweig, Germany
| | - Irene Wagner-Döbler
- Helmholtz-Centre for Infection Research, Group Microbial Communication, Division of Microbial Pathogenesis, Braunschweig, Germany
| | - An-Ping Zeng
- Institute of Bioprocess and Biosystems, Technical University Hamburg, Harburg, Germany
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18
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Sztajer H, Szafranski SP, Tomasch J, Reck M, Nimtz M, Rohde M, Wagner-Döbler I. Cross-feeding and interkingdom communication in dual-species biofilms of Streptococcus mutans and Candida albicans. THE ISME JOURNAL 2014; 8:2256-71. [PMID: 24824668 PMCID: PMC4992082 DOI: 10.1038/ismej.2014.73] [Citation(s) in RCA: 162] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 03/27/2014] [Accepted: 03/28/2014] [Indexed: 01/30/2023]
Abstract
Polymicrobial biofilms are of large medical importance, but relatively little is known about the role of interspecies interactions for their physiology and virulence. Here, we studied two human pathogens co-occuring in the oral cavity, the opportunistic fungus Candida albicans and the caries-promoting bacterium Streptococcus mutans. Dual-species biofilms reached higher biomass and cell numbers than mono-species biofilms, and the production of extracellular polymeric substances (EPSs) by S. mutans was strongly suppressed, which was confirmed by scanning electron microscopy, gas chromatography-mass spectrometry and transcriptome analysis. To detect interkingdom communication, C. albicans was co-cultivated with a strain of S. mutans carrying a transcriptional fusion between a green fluorescent protein-encoding gene and the promoter for sigX, the alternative sigma factor of S. mutans, which is induced by quorum sensing signals. Strong induction of sigX was observed in dual-species biofilms, but not in single-species biofilms. Conditioned media from mixed biofilms but not from C. albicans or S. mutans cultivated alone activated sigX in the reporter strain. Deletion of comS encoding the synthesis of the sigX-inducing peptide precursor abolished this activity, whereas deletion of comC encoding the competence-stimulating peptide precursor had no effect. Transcriptome analysis of S. mutans confirmed induction of comS, sigX, bacteriocins and the downstream late competence genes, including fratricins, in dual-species biofilms. We show here for the first time the stimulation of the complete quorum sensing system of S. mutans by a species from another kingdom, namely the fungus C. albicans, resulting in fundamentally changed virulence properties of the caries pathogen.
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Affiliation(s)
- Helena Sztajer
- Research Group Microbial Communication, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Szymon P Szafranski
- Research Group Microbial Communication, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Jürgen Tomasch
- Research Group Microbial Communication, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Michael Reck
- Research Group Microbial Communication, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Manfred Nimtz
- Research Group Proteomics, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Manfred Rohde
- Central Facility for Microscopy, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Irene Wagner-Döbler
- Research Group Microbial Communication, Helmholtz Centre for Infection Research, Braunschweig, Germany
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19
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Dong G, Tian XL, Gomez ZA, Li YH. Regulated proteolysis of the alternative sigma factor SigX in Streptococcus mutans: implication in the escape from competence. BMC Microbiol 2014; 14:183. [PMID: 25005884 PMCID: PMC4109385 DOI: 10.1186/1471-2180-14-183] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 07/03/2014] [Indexed: 03/01/2023] Open
Abstract
BACKGROUND SigX (σX), the alternative sigma factor of Streptococcus mutans, is the key regulator for transcriptional activation of late competence genes essential for taking up exogenous DNA. Recent studies reveal that adaptor protein MecA and the protease ClpC act as negative regulators of competence by a mechanism that involves MecA-mediated proteolysis of SigX by the ClpC in S. mutans. However, the molecular detail how MecA and ClpC negatively regulate competence in this species remains to be determined. Here, we provide evidence that adaptor protein MecA targets SigX for degradation by the protease complex ClpC/ClpP when S. mutans is grown in a complex medium. RESULTS By analyzing the cellular levels of SigX, we demonstrate that the synthesis of SigX is transiently induced by competence-stimulating peptide (CSP), but the SigX is rapidly degraded during the escape from competence. A deletion of MecA, ClpC or ClpP results in the cellular accumulation of SigX and a prolonged competence state, while an overexpression of MecA enhances proteolysis of SigX and accelerates the escape from competence. In vitro protein-protein interaction assays confirm that MecA interacts with SigX via its N-terminal domain (NTD1-82) and with ClpC via its C-terminal domain (CTD123-240). Such an interaction mediates the formation of a ternary SigX-MecA-ClpC complex, triggering the ATP-dependent degradation of SigX in the presence of ClpP. A deletion of the N-terminal or C-terminal domain of MecA abolishes its binding to SigX or ClpC. We have also found that MecA-regulated proteolysis of SigX appears to be ineffective when S. mutans is grown in a chemically defined medium (CDM), suggesting the possibility that an unknown mechanism may be involved in negative regulation of MecA-mediated proteolysis of SigX under this condition. CONCLUSION Adaptor protein MecA in S. mutans plays a crucial role in recognizing and targeting SigX for degradation by the protease ClpC/ClpP. Thus, MecA actually acts as an anti-sigma factor to regulate the stability of SigX during competence development.
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Affiliation(s)
- Gaofeng Dong
- Department of Applied Oral Sciences, Faculty of Dentistry, Dalhousie University, 5981 University Avenue, Halifax, Nova Scotia B3H 1 W2, Canada
| | - Xiao-Lin Tian
- Department of Applied Oral Sciences, Faculty of Dentistry, Dalhousie University, 5981 University Avenue, Halifax, Nova Scotia B3H 1 W2, Canada
| | - Zubelda A Gomez
- Department of Microbiology and Immunology, Faculty of Medicine, Dalhousie University, 5850 College Street, Halifax, Nova Scotia B3H 4R2, Canada
| | - Yung-Hua Li
- Department of Applied Oral Sciences, Faculty of Dentistry, Dalhousie University, 5981 University Avenue, Halifax, Nova Scotia B3H 1 W2, Canada
- Department of Microbiology and Immunology, Faculty of Medicine, Dalhousie University, 5850 College Street, Halifax, Nova Scotia B3H 4R2, Canada
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20
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Sudhakar P, Reck M, Wang W, He FQ, Wagner-Döbler I, Dobler IW, Zeng AP. Construction and verification of the transcriptional regulatory response network of Streptococcus mutans upon treatment with the biofilm inhibitor carolacton. BMC Genomics 2014; 15:362. [PMID: 24884510 PMCID: PMC4048456 DOI: 10.1186/1471-2164-15-362] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 04/17/2014] [Indexed: 11/26/2022] Open
Abstract
Background Carolacton is a newly identified secondary metabolite causing altered cell morphology and death of Streptococcus mutans biofilm cells. To unravel key regulators mediating these effects, the transcriptional regulatory response network of S. mutans biofilms upon carolacton treatment was constructed and analyzed. A systems biological approach integrating time-resolved transcriptomic data, reverse engineering, transcription factor binding sites, and experimental validation was carried out. Results The co-expression response network constructed from transcriptomic data using the reverse engineering algorithm called the Trend Correlation method consisted of 8284 gene pairs. The regulatory response network inferred by superimposing transcription factor binding site information into the co-expression network comprised 329 putative transcriptional regulatory interactions and could be classified into 27 sub-networks each co-regulated by a transcription factor. These sub-networks were significantly enriched with genes sharing common functions. The regulatory response network displayed global hierarchy and network motifs as observed in model organisms. The sub-networks modulated by the pyrimidine biosynthesis regulator PyrR, the glutamine synthetase repressor GlnR, the cysteine metabolism regulator CysR, global regulators CcpA and CodY and the two component system response regulators VicR and MbrC among others could putatively be related to the physiological effect of carolacton. The predicted interactions from the regulatory network between MbrC, known to be involved in cell envelope stress response, and the murMN-SMU_718c genes encoding peptidoglycan biosynthetic enzymes were experimentally confirmed using Electro Mobility Shift Assays. Furthermore, gene deletion mutants of five predicted key regulators from the response networks were constructed and their sensitivities towards carolacton were investigated. Deletion of cysR, the node having the highest connectivity among the regulators chosen from the regulatory network, resulted in a mutant which was insensitive to carolacton thus demonstrating not only the essentiality of cysR for the response of S. mutans biofilms to carolacton but also the relevance of the predicted network. Conclusion The network approach used in this study revealed important regulators and interactions as part of the response mechanisms of S. mutans biofilm cells to carolacton. It also opens a door for further studies into novel drug targets against streptococci. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-362) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | | | | | - Irene W Dobler
- Institute of Bioprocess and Biosystems Engineering, Hamburg University of Technology, 21073 Hamburg, Germany.
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Johnston C, Martin B, Fichant G, Polard P, Claverys JP. Bacterial transformation: distribution, shared mechanisms and divergent control. Nat Rev Microbiol 2014; 12:181-96. [DOI: 10.1038/nrmicro3199] [Citation(s) in RCA: 402] [Impact Index Per Article: 40.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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22
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Cook LC, Federle MJ. Peptide pheromone signaling in Streptococcus and Enterococcus. FEMS Microbiol Rev 2013; 38:473-92. [PMID: 24118108 DOI: 10.1111/1574-6976.12046] [Citation(s) in RCA: 122] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 09/06/2013] [Accepted: 09/09/2013] [Indexed: 01/08/2023] Open
Abstract
Intercellular chemical signaling in bacteria, commonly referred to as quorum sensing (QS), relies on the production and detection of compounds known as pheromones to elicit coordinated responses among members of a community. Pheromones produced by Gram-positive bacteria are comprised of small peptides. Based on both peptide structure and sensory system architectures, Gram-positive bacterial signaling pathways may be classified into one of four groups with a defining hallmark: cyclical peptides of the Agr type, peptides that contain Gly-Gly processing motifs, sensory systems of the RNPP family, or the recently characterized Rgg-like regulatory family. The recent discovery that Rgg family members respond to peptide pheromones increases substantially the number of species in which QS is likely a key regulatory component. These pathways control a variety of fundamental behaviors including conjugation, natural competence for transformation, biofilm development, and virulence factor regulation. Overlapping QS pathways found in multiple species and pathways that utilize conserved peptide pheromones provide opportunities for interspecies communication. Here we review pheromone signaling identified in the genera Enterococcus and Streptococcus, providing examples of all four types of pathways.
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Affiliation(s)
- Laura C Cook
- Department of Medicinal Chemistry and Pharmacognosy, Center for Pharmaceutical Biotechnology, University of Illinois at Chicago, Chicago, IL, USA
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23
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MecA protein acts as a negative regulator of genetic competence in Streptococcus mutans. J Bacteriol 2013; 195:5196-206. [PMID: 24039267 DOI: 10.1128/jb.00821-13] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Streptococcus mutans develops competence for genetic transformation through a complex network that receives inputs from at least two signaling peptides, competence-stimulating peptide (CSP) and sigX-inducing peptide (XIP). The key step of competence induction is the transcriptional activation of comX, which encodes an alternative sigma factor, SigX (σ(X)), controlling the expression of late competence genes essential for DNA uptake and recombination. In this study, we provide evidence that MecA acts as a negative regulator in the posttranslational regulation of SigX in S. mutans. Using luxAB transcriptional reporter strains, we demonstrate that MecA represses the expression of late competence genes in S. mutans grown in a complex medium that is subpermissive for competence induction by CSP. The negative regulation of competence by MecA requires the presence of a functional SigX. Accordingly, inactivation of MecA results in a prolonged competence state of S. mutans under this condition. We have also found that the AAA+ protease ClpC displays a similar repressing effect on late competence genes, suggesting that both MecA and ClpC function coordinately to regulate competence in the same regulatory circuit in S. mutans. This suggestion is strongly supported by the results of bacterial two-hybrid assays, which demonstrate that MecA interacts with both SigX and ClpC, forming a ternary SigX-MecA-ClpC complex. Western blot analysis also confirms that inactivation of MecA or ClpC results in the intracellular accumulation of the SigX in S. mutans. Together, our data support the notion that MecA mediates the formation of a ternary SigX-MecA-ClpC complex that sequesters SigX and thereby negatively regulates genetic competence in S. mutans.
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Palmer SR, Miller JH, Abranches J, Zeng L, Lefebure T, Richards VP, Lemos JA, Stanhope MJ, Burne RA. Phenotypic heterogeneity of genomically-diverse isolates of Streptococcus mutans. PLoS One 2013; 8:e61358. [PMID: 23613838 PMCID: PMC3628994 DOI: 10.1371/journal.pone.0061358] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 03/07/2013] [Indexed: 11/18/2022] Open
Abstract
High coverage, whole genome shotgun (WGS) sequencing of 57 geographically- and genetically-diverse isolates of Streptococcus mutans from individuals of known dental caries status was recently completed. Of the 57 sequenced strains, fifteen isolates, were selected based primarily on differences in gene content and phenotypic characteristics known to affect virulence and compared with the reference strain UA159. A high degree of variability in these properties was observed between strains, with a broad spectrum of sensitivities to low pH, oxidative stress (air and paraquat) and exposure to competence stimulating peptide (CSP). Significant differences in autolytic behavior and in biofilm development in glucose or sucrose were also observed. Natural genetic competence varied among isolates, and this was correlated to the presence or absence of competence genes, comCDE and comX, and to bacteriocins. In general strains that lacked the ability to become competent possessed fewer genes for bacteriocins and immunity proteins or contained polymorphic variants of these genes. WGS sequence analysis of the pan-genome revealed, for the first time, components of a Type VII secretion system in several S. mutans strains, as well as two putative ORFs that encode possible collagen binding proteins located upstream of the cnm gene, which is associated with host cell invasiveness. The virulence of these particular strains was assessed in a wax-worm model. This is the first study to combine a comprehensive analysis of key virulence-related phenotypes with extensive genomic analysis of a pathogen that evolved closely with humans. Our analysis highlights the phenotypic diversity of S. mutans isolates and indicates that the species has evolved a variety of adaptive strategies to persist in the human oral cavity and, when conditions are favorable, to initiate disease.
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Affiliation(s)
- Sara R. Palmer
- Department of Oral Biology, University of Florida, Gainesville, Florida, United States of America
| | - James H. Miller
- Center for Oral Biology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Jacqueline Abranches
- Center for Oral Biology, University of Rochester Medical Center, Rochester, New York, United States of America
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Lin Zeng
- Department of Oral Biology, University of Florida, Gainesville, Florida, United States of America
| | - Tristan Lefebure
- Université de Lyon, CNRS, Ecologie des Hydrosystèmes Naturels et Anthropisés; Université Lyon, Villeurbanne, France
- Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America
| | - Vincent P. Richards
- Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America
| | - José A. Lemos
- Center for Oral Biology, University of Rochester Medical Center, Rochester, New York, United States of America
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Michael J. Stanhope
- Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America
| | - Robert A. Burne
- Department of Oral Biology, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
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25
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Competence for natural genetic transformation in the Streptococcus bovis group streptococci S. infantarius and S. macedonicus. J Bacteriol 2013; 195:2612-20. [PMID: 23543718 DOI: 10.1128/jb.00230-13] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Natural genetic transformation is common among many species of the genus Streptococcus, but it has never, or rarely, been reported for the Streptococcus pyogenes and S. bovis groups of species, even though many streptococcal competence genes and the competence regulators SigX, ComR, and ComS are well conserved in both groups. To explore the incidence of competence in the S. bovis group, 25 isolates of S. infantarius and S. macedonicus were surveyed by employing culture in chemically defined media devoid of peptide nutrients and treatment with synthetic candidate pheromone peptides predicted from the sequence of the gene comS. Approximately half of strains examined were transformable, many transforming at high rates comparable to those for the well-characterized streptococcal natural transformation systems. In S. infantarius, nanomolar amounts of the synthetic pheromone LTAWWGL induced robust but transient competence in high-density cultures, but mutation of the ComRS locus abolished transformation. We conclude that at least these two species of the S. bovis group retain a robust system of natural transformation regulated by a ComRS pheromone circuit and the alternative sigma factor SigX and infer that transformation is even more common among the streptococci than has been recognized. The tools presented here will facilitate targeted genetic manipulation in this group of streptococci.
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