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Li C, Zhou H, Gou H, Fan Z, Zhang Y, Tang P, Huang J, Xu Y, Li L. Autoinducer-2 produced by oral microbial flora and alveolar bone loss in periodontitis. J Periodontal Res 2024; 59:576-588. [PMID: 38411269 DOI: 10.1111/jre.13247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 12/21/2023] [Accepted: 02/06/2024] [Indexed: 02/28/2024]
Abstract
OBJECTIVE The aim of this study was to investigate the association between autoinducer-2 (AI-2) of oral microbial flora and the alveolar bone destruction in periodontitis to determine if AI-2 may have the potential that monitor periodontitis and predict bone loss. BACKGROUND Plaque biofilm was the initiating factor of periodontitis and the essential factor of periodontal tissue destruction. The formation of biofilms depended on the complex regulation of the quorum sensing (QS) system, in which bacteria could sense changes in surrounding bacterial density by secreting the autoinducer (AI) to regulate the corresponding physiological function. Most oral bacteria also communicated with each other to form biofilms administrating the QS system, which implied that the QS system of periodontal pathogens was related to periodontitis, but the specific relationship was unknown. METHOD We collected the gingival crevicular fluid (GCF) samples and measured the concentration of AI-2 in samples using the Vibrio harveyi BB180 bioluminescent-reporter system. To explore the interaction between AI-2 and bone metabolism, we utilized AI-2 purified from Fusobacterium nucleatum to investigate the impact of F. nucleatum AI-2 on osteoclast differentiation. Moreover, we constructed murine periodontitis models and multi-species biofilm models to study the association between AI-2 and periodontal disease progression. RESULTS The AI-2 concentration in GCF samples increased along with periodontal disease progression (p < .0001). F. nucleatum AI-2 promoted osteoclast differentiation in a dose-dependent manner. In the periodontitis mice model, the CEJ-ABC distance in the F. nucleatum AI-2 treatment group was higher than that in the simple ligation group (p < .01), and the maxilla of the mice in the group exhibited significantly lower BMD and BV/TV values (p < .05). CONCLUSIONS We demonstrated that the AI-2 concentration varied with the alveolar bone destruction in periodontitis, and it may have the potential for screening periodontitis. F. nucleatum AI-2 promoted osteoclast differentiation in a dose-dependent manner and aggravated bone loss.
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Affiliation(s)
- Cheng Li
- Department of Periodontics, Affiliated Stomatological Hospital of Nanjing Medical University, Nanjing, China
- Jiangsu Key Laboratory of Oral Disease, Nanjing Medical University, Nanjing, China
- Jiangsu Province Engineering Research Center of Stomatological Translational Medicine, Nanjing, China
| | - Hancheng Zhou
- Department of Periodontics, Affiliated Stomatological Hospital of Nanjing Medical University, Nanjing, China
- Jiangsu Key Laboratory of Oral Disease, Nanjing Medical University, Nanjing, China
- Jiangsu Province Engineering Research Center of Stomatological Translational Medicine, Nanjing, China
| | - Huiqing Gou
- Department of Periodontics, Affiliated Stomatological Hospital of Nanjing Medical University, Nanjing, China
- Jiangsu Key Laboratory of Oral Disease, Nanjing Medical University, Nanjing, China
- Jiangsu Province Engineering Research Center of Stomatological Translational Medicine, Nanjing, China
| | - Zixin Fan
- Department of Periodontics, Affiliated Stomatological Hospital of Nanjing Medical University, Nanjing, China
- Jiangsu Key Laboratory of Oral Disease, Nanjing Medical University, Nanjing, China
- Jiangsu Province Engineering Research Center of Stomatological Translational Medicine, Nanjing, China
| | - Yifei Zhang
- Department of Periodontics, Affiliated Stomatological Hospital of Nanjing Medical University, Nanjing, China
- Jiangsu Key Laboratory of Oral Disease, Nanjing Medical University, Nanjing, China
- Jiangsu Province Engineering Research Center of Stomatological Translational Medicine, Nanjing, China
| | - Pengzhou Tang
- Department of Periodontics, Affiliated Stomatological Hospital of Nanjing Medical University, Nanjing, China
- Jiangsu Key Laboratory of Oral Disease, Nanjing Medical University, Nanjing, China
- Jiangsu Province Engineering Research Center of Stomatological Translational Medicine, Nanjing, China
| | - Jiaxin Huang
- Department of Periodontics, Affiliated Stomatological Hospital of Nanjing Medical University, Nanjing, China
- Jiangsu Key Laboratory of Oral Disease, Nanjing Medical University, Nanjing, China
- Jiangsu Province Engineering Research Center of Stomatological Translational Medicine, Nanjing, China
| | - Yan Xu
- Department of Periodontics, Affiliated Stomatological Hospital of Nanjing Medical University, Nanjing, China
- Jiangsu Key Laboratory of Oral Disease, Nanjing Medical University, Nanjing, China
- Jiangsu Province Engineering Research Center of Stomatological Translational Medicine, Nanjing, China
| | - Lu Li
- Department of Periodontics, Affiliated Stomatological Hospital of Nanjing Medical University, Nanjing, China
- Jiangsu Key Laboratory of Oral Disease, Nanjing Medical University, Nanjing, China
- Jiangsu Province Engineering Research Center of Stomatological Translational Medicine, Nanjing, China
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Sikdar R, Beauclaire MV, Lima BP, Herzberg MC, Elias MH. N-acyl homoserine lactone signaling modulates bacterial community associated with human dental plaque. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.15.585217. [PMID: 38559107 PMCID: PMC10980036 DOI: 10.1101/2024.03.15.585217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
N-acyl homoserine lactones (AHLs) are small diffusible signaling molecules that mediate a cell density-dependent bacterial communication system known as quorum sensing (QS). AHL-mediated QS regulates gene expression to control many critical bacterial behaviors including biofilm formation, pathogenicity, and antimicrobial resistance. Dental plaque is a complex multispecies oral biofilm formed by successive colonization of the tooth surface by groups of commensal, symbiotic, and pathogenic bacteria, which can contribute to tooth decay and periodontal diseases. While the existence and roles of AHL-mediated QS in oral microbiota have been debated, recent evidence indicates that AHLs play significant roles in oral biofilm development and community dysbiosis. The underlying mechanisms, however, remain poorly characterized. To better understand the importance of AHL signaling in dental plaque formation, we manipulated AHL signaling by adding AHL lactonases or exogenous AHL signaling molecules. We find that AHLs can be detected in dental plaque grown under 5% CO2 conditions, but not when grown under anaerobic conditions, and yet anaerobic cultures are still responsive to AHLs. QS signal disruption using lactonases leads to changes in microbial population structures in both planktonic and biofilm states, changes that are dependent on the substrate preference of the used lactonase but mainly result in the increase in the abundance of commensal and pioneer colonizer species. Remarkably, the opposite manipulation, that is the addition of exogenous AHLs increases the abundance of late colonizer bacterial species. Hence, this work highlights the importance of AHL-mediated QS in dental plaque communities, its potential different roles in anaerobic and aerobic parts of dental plaque, and underscores the potential of QS interference in the control of periodontal diseases.
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Affiliation(s)
- Rakesh Sikdar
- Biotechnology Institute, University of Minnesota, Saint Paul, MN 55108, USA
| | - Mai V. Beauclaire
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Saint Paul, MN 55108, USA
| | - Bruno P. Lima
- Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Mark C. Herzberg
- Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Mikael H. Elias
- Biotechnology Institute, University of Minnesota, Saint Paul, MN 55108, USA
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Saint Paul, MN 55108, USA
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Lamont RJ, Hajishengallis G, Koo H. Social networking at the microbiome-host interface. Infect Immun 2023; 91:e0012423. [PMID: 37594277 PMCID: PMC10501221 DOI: 10.1128/iai.00124-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/19/2023] Open
Abstract
Microbial species colonizing host ecosystems in health or disease rarely do so alone. Organisms conglomerate into dynamic heterotypic communities or biofilms in which interspecies and interkingdom interactions drive functional specialization of constituent species and shape community properties, including nososymbiocity or pathogenic potential. Cell-to-cell binding, exchange of signaling molecules, and nutritional codependencies can all contribute to the emergent properties of these communities. Spatial constraints defined by community architecture also determine overall community function. Multilayered interactions thus occur between individual pairs of organisms, and the relative impact can be determined by contextual cues. Host responses to heterotypic communities and impact on host surfaces are also driven by the collective action of the community. Additionally, the range of interspecies interactions can be extended by bacteria utilizing host cells or host diet to indirectly or directly influence the properties of other organisms and the community microenvironment. In contexts where communities transition to a dysbiotic state, their quasi-organismal nature imparts adaptability to nutritional availability and facilitates resistance to immune effectors and, moreover, exploits inflammatory and acidic microenvironments for their persistence.
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Affiliation(s)
- Richard J. Lamont
- Department of Oral Immunology and Infectious Diseases, School of Dentistry, University of Louisville, Louisville, Kentucky, USA
| | - George Hajishengallis
- Department of Basic and Translational Sciences, Laboratory of Innate Immunity and Inflammation, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Hyun Koo
- Department of Orthodontics and Divisions of Pediatric Dentistry and Community Oral Health, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Biofilm Research Laboratories, Center for Innovation & Precision Dentistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Alothaim AS, Alhoqail WA, Menakha M, Vijayakumar R. Combining molecular modelling and experimental approaches to gain mechanistic insights into the LuxP drug target in Streptococcus pyogens. J Biomol Struct Dyn 2023:1-11. [PMID: 37642991 DOI: 10.1080/07391102.2023.2252079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 08/20/2023] [Indexed: 08/31/2023]
Abstract
Autoinducer-2 can mediate inter- and intra-species communication signal between bacteria and these signals from AI-2 is noted from limited species of bacteria. In humans, S. pyogenes is a pathogen that causes a wide range of illnesses and can survive in the host system and transmit infection. The process by which S. pyogenes acquires the competence to live and disseminate infection remains unknown. We hypothesized that AI-2 and their receptors would play a significant role during infection, and for that present investigation provides the experimental and molecular insights. In the absence of details about the receptor LuxP and LuxQ, the screening approach provides supporting insights. The evolutionary relationship and similarities of the PBP domain (Spy 1535) and the signal transmission PDZ domain (Spy 1536) were studied in relation to their counterparts in other bacteria. Molecular docking and modeling confirmed the domain-enhanced specificity for AI-2 binding. In vitro studies showed that AI-2, which is present in the cell-free supernatant of S. pyogenes, regulates luminescence in P. luminous and biofilm development in E. coli using the LuxS reporter genes. Examination of S. pyogenes gene expression revealed modulation of virulence genes when the pathogen was exposed to V. harveyi HSL and AI-2. Therefore, S. pyogenes pathogenicity is sequentially regulated by AI-2 it acquires from other commensal bacteria. Overall, this study lays the groundwork for understanding the signalling mechanism from AI-2, which are critical to the pathogenic mechanism of S. pyogenes.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Abdulaziz S Alothaim
- Department of Biology, College of Science, Majmaah University, Al-Majmaah, Saudi Arabia
| | - Wardah A Alhoqail
- Department of Biology, College of Education, Majmaah University, Al-Majmaah, Saudi Arabia
| | - Muniraj Menakha
- Department of Bio-informatics, School of Life Sciences, Bharathidasan University, Tiruchirappalli, Tamil Nadu, India
| | - Rajendran Vijayakumar
- Department of Biology, College of Science, Majmaah University, Al-Majmaah, Saudi Arabia
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Zhang Y, Ma N, Tan P, Ma X. Quorum sensing mediates gut bacterial communication and host-microbiota interaction. Crit Rev Food Sci Nutr 2022; 64:3751-3763. [PMID: 36239296 DOI: 10.1080/10408398.2022.2134981] [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: 11/03/2022]
Abstract
Gut bacteria employ quorum sensing (QS) to coordinate their activities and communicate with one another, this process relies on the production, detection, and response to autoinducers, which are extracellular signaling molecules. In addition to synchronizing behavioral activities within the species, QS plays a crucial role in the gut host-microbiota interaction. In this review, an overview of classical QS systems is presented as well as the interspecies communication mediated by QS, and recent advances in the host-microbiota interaction mediated by QS. A greater knowledge of the communication network of gut microbiota is not only an opportunity and a challenge for developing nutritional and therapeutic strategies against bacterial illnesses, but also a means for improving gut health.
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Affiliation(s)
- Yucheng Zhang
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Ning Ma
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Peng Tan
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Xi Ma
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, China
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Candidate Phyla Radiation, an Underappreciated Division of the Human Microbiome, and Its Impact on Health and Disease. Clin Microbiol Rev 2022; 35:e0014021. [PMID: 35658516 DOI: 10.1128/cmr.00140-21] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Candidate phyla radiation (CPR) is an emerging division of the bacterial domain within the human microbiota. Still poorly known, these microorganisms were first described in the environment in 1981 as "ultramicrobacteria" with a cell volume under 0.1 μm3 and were first associated with the human oral microbiota in 2007. The evolution of technology has been paramount for the study of CPR within the human microbiota. In fact, since these ultramicrobacteria have yet to be axenically cultured despite ongoing efforts, progress in imaging technology has allowed their observation and morphological description. Although their genomic abilities and taxonomy are still being studied, great strides have been made regarding their taxonomic classification, as well as their lifestyle. In addition, advancements in next-generation sequencing and the continued development of bioinformatics tools have allowed their detection as commensals in different human habitats, including the oral cavity and gastrointestinal and genital tracts, thus highlighting CPR as a nonnegligible part of the human microbiota with an impact on physiological settings. Conversely, several pathologies present dysbiosis affecting CPR levels, including inflammatory, mucosal, and infectious diseases. In this exhaustive review of the literature, we provide a historical perspective on the study of CPR, an overview of the methods available to study these organisms and a description of their taxonomy and lifestyle. In addition, their distribution in the human microbiome is presented in both homeostatic and dysbiotic settings. Future efforts should focus on developing cocultures and, if possible, axenic cultures to obtain isolates and therefore genomes that would provide a better understanding of these ultramicrobacteria, the importance of which in the human microbiome is undeniable.
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Laveilhé A, Fochesato S, Lalaouna D, Heulin T, Achouak W. Phytobeneficial traits of rhizobacteria under the control of multiple molecular dialogues. Microb Biotechnol 2022; 15:2083-2096. [PMID: 35502577 PMCID: PMC9249325 DOI: 10.1111/1751-7915.14023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 02/14/2022] [Accepted: 02/14/2022] [Indexed: 11/29/2022] Open
Abstract
Pseudomonads play crucial roles in plant growth promotion and control of plant diseases. However, under natural conditions, other microorganisms competing for the same nutrient resources in the rhizosphere may exert negative control over their phytobeneficial characteristics. We assessed the expression of phytobeneficial genes involved in biocontrol, biostimulation and iron regulation such as, phlD, hcnA, acdS, and iron‐small regulatory RNAs prrF1 and prrF2 in Pseudomonas brassicacearum co‐cultivated with three phytopathogenic fungi, and two rhizobacteria in the presence or absence of Brassica napus, and in relation to iron availability. We found that the antifungal activity of P. brassicacearum depends mostly on the production of DAPG and not on HCN whose production is suppressed by fungi. We have also shown that the two‐competing bacterial strains modulate the plant growth promotion activity of P. brassicacearum by modifying the expression of phlD, hcnA and acdS according to iron availability. Overall, it allows us to better understand the complexity of the multiple molecular dialogues that take place underground between microorganisms and between plants and its rhizosphere microbiota and to show that synergy in favour of phytobeneficial gene expression may exist between different bacterial species. We assessed the expression of phytobeneficial genes, phlD, hcnA and acdS, and iron‐small regulatory RNAs prrF1 and prrF2 in Pseudomonas brassicacearum co‐cultivated with three phytopathogenic fungi, and two rhizobacteria in the presence or absence of Brassica napus, and in relation to iron availability. Our study illustrates that interkingdom and interspecies interactions in addition to external factors may affect the success of introduced beneficial microorganisms by modulating the expression of phytobeneficial genes.
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Affiliation(s)
- Arnaud Laveilhé
- Lab Microbial Ecology of the Rhizosphere (LEMiRE), CEA, CNRS, BIAM, Aix Marseille Univ, Saint-Paul-Lez-Durance, F-13108, France
| | - Sylvain Fochesato
- Lab Microbial Ecology of the Rhizosphere (LEMiRE), CEA, CNRS, BIAM, Aix Marseille Univ, Saint-Paul-Lez-Durance, F-13108, France
| | - David Lalaouna
- ARN UPR 9002, Université de Strasbourg, CNRS, Strasbourg, F-67000, France
| | - Thierry Heulin
- Lab Microbial Ecology of the Rhizosphere (LEMiRE), CEA, CNRS, BIAM, Aix Marseille Univ, Saint-Paul-Lez-Durance, F-13108, France
| | - Wafa Achouak
- Lab Microbial Ecology of the Rhizosphere (LEMiRE), CEA, CNRS, BIAM, Aix Marseille Univ, Saint-Paul-Lez-Durance, F-13108, France
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Niazy AA. LuxS quorum sensing system and biofilm formation of oral microflora: A short review article. Saudi Dent J 2021; 33:116-123. [PMID: 33679103 PMCID: PMC7910685 DOI: 10.1016/j.sdentj.2020.12.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 12/21/2020] [Accepted: 12/22/2020] [Indexed: 02/07/2023] Open
Abstract
The LuxS quorum sensing system is considered as the main system that most of the oral bacteria use to communicate in order to create biofilms. Here we identified 11 of the most important biofilm formers that utilize the LuxS system and presented current and recent information regarding this system. Though different bacterial species are able to communicate thorough the LuxS system, it was also found that cross kingdom communication can occur between bacteria and fungi and bacteria and epithelial cells. Immune response also plays and important role in mitigating the effects of biofilms. Here we identified 6 of the most important molecules that are involved in the immune response to biofilms. These immune molecules maintain the stability in the oral cavity by preventing bacteria from overwhelming the space and simultaneously minimizing the immune response in order not to cause tissue damage. Here we also discuss current research being done in order to maintain the balance in the oral cavity via inhibiting biofilm formation without eradicating oral bacteria in order to prevent the overgrowth of other organisms such as Candida albicans. One approach being used is inhibiting AI-2 intermediates which leads to lack of quorum sensing communication between bacteria through the use of intermediate analogues. Another approach that found success is the utilization of D forms of sugars where D-ribose and D-galactose have been proven to inhibit the LuxS system and subsequently preventing the process of quorum sensing leading to the reduction in biofilm formation.
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Affiliation(s)
- Abdurahman A. Niazy
- Address: Molecular and Cell Biology Laboratory, Prince Naif bin AbdulAziz Health Research Center, College of Dentistry, King Saud University Medical City, King Saud University, Riyadh 11545, Saudi Arabia.
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Baek DH, Lee SH. Characteristics of Treponema denticola lipooligosaccharide in presence of hemin and quorum-sensing molecule. Arch Oral Biol 2021; 124:105062. [PMID: 33524879 DOI: 10.1016/j.archoralbio.2021.105062] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 12/22/2020] [Accepted: 01/15/2021] [Indexed: 10/22/2022]
Abstract
OBJECTIVES The study aimed to examine the diverse bioactivity of lipooligosaccharide extracted from T. denticola cultured in the presence of hemin and quorum-sensing inhibitor. DESIGN T. denticola was cultured in the presence or absence hemin or 2(5 H)-furanone, and lipooligosaccharide from T. denticola cultured in various conditions was extracted using an extraction kit. To investigate bioactivity of the lipooligosaccharide, human gingival fibroblasts (HGFs) were treated with the extracted lipooligosaccharide in the presence or absence of Tannerella forsythia lipopolysaccharide. The induction of cytokine expressions was investigated by real-time RT-PCR and ELISA, and the signaling pathway was examined by immunoblotting. To investigate antagonistic mechanisms of the lipooligosaccharide, HGFs were cotreated with fluorescence-labeled T. forsythia lipopolysaccharide and the extracted lipooligosaccharide. Binding of T. forsythia lipopolysaccharide to the cell was analyzed by a flow cytometer. RESULTS Lipooligosaccharide induced a low level of cytokine expression at high concentration of hemin or 2(5 H)-furanone. Lipooligosaccharide extracted from T. denticola cultured in higher concentration of hemin and 2(5 H)-furanone had a greater inhibitory effect on induction of cytokine expression by T. forsythia lipopolysaccharide. Further, lipooligosaccharide inhibited the activation of NF-κB and mitogen-activated protein kinase signaling pathways by T. forsythia lipopolysaccharide. Lipooligosaccharide inhibited the binding of T. forsythia lipopolysaccharide to HGFs in the presence of CD14 and LBP. CONCLUSIONS The characteristics of T. denticola lipooligosaccharide may be altered by bacterial communication and host factors.
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Affiliation(s)
- Dong-Heon Baek
- Department of Oral Microbiology and Immunology, College of Dentistry, Dankook University, Cheonan, Republic of Korea
| | - Sung-Hoon Lee
- Department of Oral Microbiology and Immunology, College of Dentistry, Dankook University, Cheonan, Republic of Korea.
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The Role of luxS in Histophilus somni Virulence and Biofilm Formation. Infect Immun 2021; 89:IAI.00567-20. [PMID: 33139386 DOI: 10.1128/iai.00567-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 10/29/2020] [Indexed: 01/09/2023] Open
Abstract
S-Ribosylhomocysteinase (LuxS) is required for the synthesis of the autoinducer-2 (AI-2) quorum-sensing signaling molecule in many Gram-negative bacteria. The bovine (and ovine) opportunistic pathogen Histophilus somni contains luxS and forms a biofilm containing an exopolysaccharide (EPS) in the matrix. Since biofilm formation is regulated by quorum sensing in many bacteria, the roles of luxS in H. somni virulence and biofilm formation were investigated. Although culture supernatants from H. somni were ineffective at inducing bioluminescence in the Vibrio harveyi reporter strain BB170, H. somni luxS complemented the biosynthesis of AI-2 in the luxS-deficient Escherichia coli strain DH5α. H. somni strain 2336 luxS was inactivated by transposon mutagenesis. RNA expression profiles revealed that many genes were significantly differentially expressed in the luxS mutant compared to that in the wild-type, whether the bacteria were grown planktonically or in a biofilm. Furthermore, the luxS mutant had a truncated and asialylated lipooligosaccharide (LOS) and was substantially more serum sensitive than the wild-type. Not surprisingly, the luxS mutant was attenuated in a mouse model for H. somni virulence, and some of the altered phenotypes were partially restored after the mutation was complemented with a functional luxS However, no major differences were observed between the wild-type and the luxS mutant in regard to outer membrane protein profiles, biofilm formation, EPS production, or intracellular survival. These results indicate that luxS plays a role in H. somni virulence in the context of LOS biosynthesis but not biofilm formation or other phenotypic properties examined.
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Bachtiar EW, Bachtiar BM. Effect of cell-free spent media prepared from Aggregatibacter actinomycetemcomitans on the growth of Candida albicans and Streptococcus mutans in co-species biofilms. Eur J Oral Sci 2020; 128:395-404. [PMID: 32808302 DOI: 10.1111/eos.12725] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/29/2020] [Indexed: 12/22/2022]
Abstract
This study explored the influence of cell-free spent media prepared from Aggregatibacter actinomycetemcomitans LuxS mutant (Aa-LuxS), its wild type strain (Aa-WT), and the laboratory strain (Aa-Y4), on the interaction between Candida albicans and Streptococcus mutans while growing in co-species biofilm for 48 h. By analyzing the results of crystal violet staining, [3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide] (MTT) assays, and quantitative real-time polymerase chain reaction (qPCR), we found that the presence of Aa-LuxS in treated biofilms did not affect biofilm development, while added Aa-WT or Aa-Y4 resulted in a significant decrease in both biofilm mass and the number of cells. The inhibitory effect of Aa-WT or Aa-Y4 was not dependent on the protein concentration in the spent media tested (1 and 10%). Gene transcription analyses indicated that Aa-WT/Aa-Y4 exhibits comparable inhibitory effects on the expression of hyphal-associated genes (ALS3 and HWP1), but not on the expression of YWP1, which encodes a yeast form of C. albicans. In contrast, except for gtfD, the expression of S. mutans gtfB/C genes encoding glucosyltransferase was not affected in Aa-WT and Aa-Y4 treated biofilms compared to the levels found in Aa-LuxS treated biofilms. Our results indicate that AI-2-containing spent media derived from Aa can reduce biofilm biomass without significantly inhibiting the survival rate of S. mutans.
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Affiliation(s)
- Endang W Bachtiar
- Department of Oral Biology and Oral Science Research Center, Faculty of Dentistry, Universitas Indonesia, Jakarta, Indonesia
| | - Boy M Bachtiar
- Department of Oral Biology and Oral Science Research Center, Faculty of Dentistry, Universitas Indonesia, Jakarta, Indonesia
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Chen C, Feng P, Slots J. Herpesvirus-bacteria synergistic interaction in periodontitis. Periodontol 2000 2020; 82:42-64. [PMID: 31850623 DOI: 10.1111/prd.12311] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The etiopathogenesis of severe periodontitis includes herpesvirus-bacteria coinfection. This article evaluates the pathogenicity of herpesviruses (cytomegalovirus and Epstein-Barr virus) and periodontopathic bacteria (Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis) and coinfection of these infectious agents in the initiation and progression of periodontitis. Cytomegalovirus and A. actinomycetemcomitans/P. gingivalis exercise synergistic pathogenicity in the development of localized ("aggressive") juvenile periodontitis. Cytomegalovirus and Epstein-Barr virus are associated with P. gingivalis in adult types of periodontitis. Periodontal herpesviruses that enter the general circulation may also contribute to disease development in various organ systems. A 2-way interaction is likely to occur between periodontal herpesviruses and periodontopathic bacteria, with herpesviruses promoting bacterial upgrowth, and bacterial factors reactivating latent herpesviruses. Bacterial-induced gingivitis may facilitate herpesvirus colonization of the periodontium, and herpesvirus infections may impede the antibacterial host defense and alter periodontal cells to predispose for bacterial adherence and invasion. Herpesvirus-bacteria synergistic interactions, are likely to comprise an important pathogenic determinant of aggressive periodontitis. However, mechanistic investigations into the molecular and cellular interaction between periodontal herpesviruses and bacteria are still scarce. Herpesvirus-bacteria coinfection studies may yield significant new discoveries of pathogenic determinants, and drug and vaccine targets to minimize or prevent periodontitis and periodontitis-related systemic diseases.
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Affiliation(s)
- Casey Chen
- Division of Periodontology, Diagnostic Sciences & Dental Hygiene, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, California, USA
| | - Pinghui Feng
- Section of Infection and Immunity, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, California, USA
| | - Jørgen Slots
- Division of Periodontology, Diagnostic Sciences & Dental Hygiene, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, California, USA
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Short-Chain N-Acylhomoserine Lactone Quorum-Sensing Molecules Promote Periodontal Pathogens in In Vitro Oral Biofilms. Appl Environ Microbiol 2020; 86:AEM.01941-19. [PMID: 31757829 DOI: 10.1128/aem.01941-19] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 11/11/2019] [Indexed: 12/14/2022] Open
Abstract
Acylhomoserine lactones (AHLs), the quorum-sensing (QS) signals produced by a range of Gram-negative bacteria, are involved in biofilm formation in many pathogenic and environmental bacteria. Nevertheless, the current paradigm excludes a role of AHLs in dental plaque formation, while other QS signals, such as AI-2 and autoinducer peptides, have been demonstrated to play an important role in biofilm formation and virulence-related gene expression in oral pathogens. In the present work, we have explored the effect of externally added AHLs on in vitro oral biofilm models for commensal, cariogenic, and periodontal dental plaque. While little effect on bacterial growth was observed, some AHLs specifically affected the lactic acid production and protease activity of the biofilms. Most importantly, the analysis of bacterial diversity in the biofilms showed that the addition of C6-homoserine lactone (C6-HSL) results in a shift toward a periodontal bacterial composition profile by increasing the relative presence of the orange-complex bacteria Peptostreptococcus and Prevotella These results point to a relevant role of AHL-mediated QS in dental plaque formation and might be involved in the development of dysbiosis, the mechanism of which should be further investigated. This finding potentially opens new opportunities for the prevention or treatment of the periodontal disease.IMPORTANCE Dental plaque is omnipresent in healthy oral cavities and part of our commensal microbial colonization. At the same time, dental plaque is the cause of the most common human diseases, caries and gum disease. Dental plaque consists of billions of microbes attached to the surface of your teeth. Communication among these microbes is pivotal for development of these complex communities yet poorly studied in dental plaque. In the present study, we show that a specific communication molecule induces changes within the community related to the development of gum disease. This finding suggests that interfering with microbial communication may represent an interesting novel strategy to prevent gum disease that should be further investigated.
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14
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Zhang B, Ku X, Zhang X, Zhang Y, Chen G, Chen F, Zeng W, Li J, Zhu L, He Q. The AI-2/ luxS Quorum Sensing System Affects the Growth Characteristics, Biofilm Formation, and Virulence of Haemophilus parasuis. Front Cell Infect Microbiol 2019; 9:62. [PMID: 30941317 PMCID: PMC6434701 DOI: 10.3389/fcimb.2019.00062] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 02/28/2019] [Indexed: 12/12/2022] Open
Abstract
Haemophilus parasuis (H. parasuis) is a kind of opportunistic pathogen of the upper respiratory tract of piglets. Under certain circumstances, virulent strains can breach the mucosal barrier and enter the bloodstream, causing severe Glässer's disease. Many virulence factors are found to be related to the pathogenicity of H. parasuis strain, but the pathogenic mechanism remains unclear. LuxS/AI-2, as a kind of very important quorum sensing system, affects the growth characteristics, biofilm formation, antibiotic production, virulence, and metabolism of different strains. In order to investigate the effect of luxS/AI-2 quorum sensing system on the virulence of H. parasuis, a deletion mutant strain (ΔluxS) and complemented strain (C-luxS) were constructed and characterized. The results showed that the luxS gene participated in regulating and controlling stress resistance, biofilm formation and virulence. Compared with wild-type strain, ΔluxS strain decreased the production of AI-2 molecules and the tolerance toward oxidative stress and heat shock, and it reduced the abilities of autoagglutination, hemagglutination, and adherence, whereas it increased the abilities to form biofilm in vitro. In vivo experiments showed that ΔluxS strain attenuated its virulence about 10-folds and significantly decreased its tissue burden of bacteria in mice, compared with the wild-type strain. Taken together, the luxS/AI-2 quorum sensing system in H. parasuis not only plays an important role in growth and biofilm formation, but also affects the pathogenicity of H. parasuis.
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Affiliation(s)
- Bingzhou Zhang
- State Key Laboratory of Agricultural Microbiology, Division of Animal Infectious Diseases, College of Animal Sciences and Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Xugang Ku
- State Key Laboratory of Agricultural Microbiology, Division of Animal Infectious Diseases, College of Animal Sciences and Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Xiaoqian Zhang
- State Key Laboratory of Agricultural Microbiology, Division of Animal Infectious Diseases, College of Animal Sciences and Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Yan Zhang
- College of Animal Sciences and Veterinary Medicine, Xinjiang Agricultural University, Urumqi, China
| | - Guo Chen
- State Key Laboratory of Agricultural Microbiology, Division of Animal Infectious Diseases, College of Animal Sciences and Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Fangzhou Chen
- State Key Laboratory of Agricultural Microbiology, Division of Animal Infectious Diseases, College of Animal Sciences and Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Wei Zeng
- State Key Laboratory of Agricultural Microbiology, Division of Animal Infectious Diseases, College of Animal Sciences and Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Jing Li
- State Key Laboratory of Agricultural Microbiology, Division of Animal Infectious Diseases, College of Animal Sciences and Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Ling Zhu
- State Key Laboratory of Agricultural Microbiology, Division of Animal Infectious Diseases, College of Animal Sciences and Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Qigai He
- State Key Laboratory of Agricultural Microbiology, Division of Animal Infectious Diseases, College of Animal Sciences and Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
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15
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du Teil Espina M, Gabarrini G, Harmsen HJM, Westra J, van Winkelhoff AJ, van Dijl JM. Talk to your gut: the oral-gut microbiome axis and its immunomodulatory role in the etiology of rheumatoid arthritis. FEMS Microbiol Rev 2019; 43:1-18. [PMID: 30219863 DOI: 10.1093/femsre/fuy035] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 09/13/2018] [Indexed: 02/07/2023] Open
Abstract
Microbial communities inhabiting the human body, collectively called the microbiome, are critical modulators of immunity. This notion is underpinned by associations between changes in the microbiome and particular autoimmune disorders. Specifically, in rheumatoid arthritis, one of the most frequently occurring autoimmune disorders worldwide, changes in the oral and gut microbiomes have been implicated in the loss of tolerance against self-antigens and in increased inflammatory events promoting the damage of joints. In the present review, we highlight recently gained insights in the roles of microbes in the etiology of rheumatoid arthritis. In addition, we address important immunomodulatory processes, including biofilm formation and neutrophil function, which have been implicated in host-microbe interactions relevant for rheumatoid arthritis. Lastly, we present recent advances in the development and evaluation of emerging microbiome-based therapeutic approaches. Altogether, we conclude that the key to uncovering the etiopathogenesis of rheumatoid arthritis will lie in the immunomodulatory functions of the oral and gut microbiomes.
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Affiliation(s)
- Marines du Teil Espina
- University of Groningen, University Medical Center Groningen, Department of Medical Microbiology, Hanzeplein 1, 9700 RB Groningen, the Netherlands
| | - Giorgio Gabarrini
- University of Groningen, University Medical Center Groningen, Department of Medical Microbiology, Hanzeplein 1, 9700 RB Groningen, the Netherlands.,University of Groningen, University Medical Center Groningen, Center for Dentistry and Oral Hygiene, Antonius Deusinglaan 1, 9713 AV Groningen, the Netherlands
| | - Hermie J M Harmsen
- University of Groningen, University Medical Center Groningen, Department of Medical Microbiology, Hanzeplein 1, 9700 RB Groningen, the Netherlands
| | - Johanna Westra
- University of Groningen, University Medical Center Groningen, Department of Rheumatology and Clinical Immunology, Hanzeplein 1, 9700 RB Groningen, the Netherlands
| | - Arie Jan van Winkelhoff
- University of Groningen, University Medical Center Groningen, Department of Medical Microbiology, Hanzeplein 1, 9700 RB Groningen, the Netherlands.,University of Groningen, University Medical Center Groningen, Center for Dentistry and Oral Hygiene, Antonius Deusinglaan 1, 9713 AV Groningen, the Netherlands
| | - Jan Maarten van Dijl
- University of Groningen, University Medical Center Groningen, Department of Medical Microbiology, Hanzeplein 1, 9700 RB Groningen, the Netherlands
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16
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Bedree JK, Bor B, Cen L, Edlund A, Lux R, McLean JS, Shi W, He X. Quorum Sensing Modulates the Epibiotic-Parasitic Relationship Between Actinomyces odontolyticus and Its Saccharibacteria epibiont, a Nanosynbacter lyticus Strain, TM7x. Front Microbiol 2018; 9:2049. [PMID: 30319555 PMCID: PMC6166536 DOI: 10.3389/fmicb.2018.02049] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 08/13/2018] [Indexed: 11/13/2022] Open
Abstract
The ultra-small, obligate parasitic epibiont, TM7x, the first and only current member of the long-elusive Saccharibacteria (formerly the TM7 phylum) phylum to be cultivated, was isolated in co-culture with its bacterial host, Actinomyces odontolyticus subspecies actinosynbacter, XH001. Initial phenotypic characterization of the TM7x-associated XH001 co-culture revealed enhanced biofilm formation in the presence of TM7x compared to XH001 as monoculture. Genomic analysis and previously published transcriptomic profiling of XH001 also revealed the presence of a putative AI-2 quorum sensing (QS) operon, which was highly upregulated upon association of TM7x with XH001. This analysis revealed that the most highly induced gene in XH001 was an lsrB ortholog, which encodes a putative periplasmic binding protein for the auto inducer (AI)-2 QS signaling molecule. Further genomic analyses suggested the lsrB operon in XH001 is a putative hybrid AI-2/ribose transport operon as well as the existence of a luxS ortholog, which encodes the AI-2 synthase. In this study, the potential role of AI-2 QS in the epibiotic-parasitic relationship between XH001 and TM7x in the context of biofilm formation was investigated. A genetic system for XH001 was developed to generate lsrB and luxS gene deletion mutants in XH001. Phenotypic characterization demonstrated that deletion mutations in either lsrB or luxS did not affect XH001's growth dynamic, mono-species biofilm formation capability, nor its ability to associate with TM7x. TM7x association with XH001 induced lsrB gene expression in a luxS-dependent manner. Intriguingly, unlike wild type XH001, which displayed significantly increased biofilm formation upon establishing the epibiotic-parasitic relationship with TM7x, XH001ΔlsrB, and XH001ΔluxS mutants failed to achieve enhanced biofilm formation when associated with TM7x. In conclusion, we demonstrated a significant role for AI-2 QS in modulating dual-species biofilm formation when XH001 and TM7x establish their epibiotic-parasitic relationship.
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Affiliation(s)
- Joseph K Bedree
- Section of Oral Biology, Division of Oral Biology and Medicine, School of Dentistry, University of California, Los Angeles, Los Angeles, CA, United States.,Department of Microbiology, The Forsyth Institute, Cambridge, MA, United States
| | - Batbileg Bor
- Department of Microbiology, The Forsyth Institute, Cambridge, MA, United States
| | - Lujia Cen
- Department of Microbiology, The Forsyth Institute, Cambridge, MA, United States
| | - Anna Edlund
- Department of Genomic Medicine, J. Craig Venter Institute, La Jolla, CA, United States
| | - Renate Lux
- Section of Periodontics, Division of Constitutive and Regenerative Sciences, School of Dentistry, University of California, Los Angeles, Los Angeles, CA, United States
| | - Jeffrey S McLean
- Department of Periodontics, School of Dentistry, University of Washington, Seattle, WA, United States
| | - Wenyuan Shi
- Department of Microbiology, The Forsyth Institute, Cambridge, MA, United States
| | - Xuesong He
- Department of Microbiology, The Forsyth Institute, Cambridge, MA, United States
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17
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Ben Amara H, Song HY, Ryu E, Park JS, Schwarz F, Kim BM, Choi BK, Koo KT. Effects of quorum-sensing inhibition on experimental periodontitis induced by mixed infection in mice. Eur J Oral Sci 2018; 126:449-457. [PMID: 30230039 DOI: 10.1111/eos.12570] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/10/2018] [Indexed: 02/06/2023]
Abstract
This study aimed to verify, in in vivo settings, whether quorum-sensing inhibition molecules could attenuate alveolar bone loss induced by Porphyromonas gingivalis/Fusobacterium nucleatum co-infection and reduce the bacterial colonization of periodontal tissues. In BALB/c mice, periodontitis was induced through oral inoculation with P. gingivalis and F. nucleatum six times during a 42-d period. Quorum sensing inhibitors (a furanone compound and D-ribose) were administered simultaneously with bacterial infection. Linear and volumetric modifications of interproximal alveolar bone levels were compared between groups using micro-computed tomography. Total bacteria, and P. gingivalis and F. nucleatum DNA in periodontal tissues, were quantified using real-time PCR. Radiographic linear measurements demonstrated a significant reduction of alveolar bone loss, of approximately 40%, in mice treated with quorum sensing inhibitors when compared with the co-infection group. This was confirmed by a significant increase of residual bone volume in the test group. While total bacterial genes in the treatment group significantly decreased by 93% in periodontal tissue samples when quorum sensing inhibitors were administered, no significant differences of P. gingivalis DNA were found. Quorum sensing inhibitors reduced periodontal breakdown and bacterial infection in periodontal tissues after co-infection with P. gingivalis and F. nucleatum.
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Affiliation(s)
- Heithem Ben Amara
- Department of Periodontology and Dental Research Institute, Translational Research Laboratory for Tissue Engineering (TTE), School of Dentistry, Seoul National University, Seoul, Korea
| | - Hyun Y Song
- Department of Periodontology and Dental Research Institute, Translational Research Laboratory for Tissue Engineering (TTE), School of Dentistry, Seoul National University, Seoul, Korea
| | - Eunju Ryu
- Department of Oral Microbiology and Immunology, School of Dentistry, Seoul National University, Seoul, Korea
| | - Ji S Park
- Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul, Korea
| | - Frank Schwarz
- Department of Oral Surgery, Universitätsklinikum Düsseldorf, Düsseldorf, Germany
| | - Byeong M Kim
- Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul, Korea
| | - Bong-Kyu Choi
- Department of Oral Microbiology and Immunology, School of Dentistry, Seoul National University, Seoul, Korea
| | - Ki-Tae Koo
- Department of Periodontology and Dental Research Institute, Translational Research Laboratory for Tissue Engineering (TTE), School of Dentistry, Seoul National University, Seoul, Korea
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18
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Oral pathogenesis of Aggregatibacter actinomycetemcomitans. Microb Pathog 2017; 113:303-311. [DOI: 10.1016/j.micpath.2017.11.001] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2017] [Revised: 10/31/2017] [Accepted: 11/02/2017] [Indexed: 12/30/2022]
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19
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Wang X, Li X, Ling J. Streptococcus gordonii LuxS/autoinducer-2 quorum-sensing system modulates the dual-species biofilm formation with Streptococcus mutans. J Basic Microbiol 2017; 57:605-616. [PMID: 28485524 DOI: 10.1002/jobm.201700010] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 04/04/2017] [Accepted: 04/21/2017] [Indexed: 01/26/2023]
Abstract
Dental plaques are mixed-species biofilms that are related to the development of dental caries. Streptococcus mutans (S. mutans) is an important cariogenic bacterium that forms mixed-species biofilms with Streptococcus gordonii (S. gordonii), an early colonizer of the tooth surface. The LuxS/autoinducer-2(AI-2) quorum sensing system is involved in the regulation of mixed-species biofilms, and AI-2 is proposed as a universal signal for the interaction between bacterial species. In this work, a S. gordonii luxS deficient strain was constructed to investigate the effect of the S. gordonii luxS gene on dual-species biofilm formed by S. mutans and S. gordonii. In addition, AI-2 was synthesized in vitro by incubating recombinant LuxS and Pfs enzymes of S. gordonii together. The effect of AI-2 on S. mutans single-species biofilm formation and cariogenic virulence gene expression were also assessed. The results showed that luxS disruption in S. gordonii altered dual-species biofilm formation, architecture, and composition, as well as the susceptibility to chlorhexidine. And the in vitro synthesized AI-2 had a concentration-dependent effect on S. mutans biofilm formation and virulence gene expression. These findings indicate that LuxS/AI-2 quorum-sensing system of S. gordonii plays a role in regulating the dual-species biofilm formation with S. mutans.
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Affiliation(s)
- Xiao Wang
- Department of Operative Dentistry and Endodontics, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-Sen University, Guangzhou, China.,Guangdong Province Key Laboratory of Stomatology, Sun Yat-Sen University, Guangzhou, China
| | - Xiaolan Li
- Department of Operative Dentistry and Endodontics, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-Sen University, Guangzhou, China.,Guangdong Province Key Laboratory of Stomatology, Sun Yat-Sen University, Guangzhou, China
| | - Junqi Ling
- Department of Operative Dentistry and Endodontics, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-Sen University, Guangzhou, China.,Guangdong Province Key Laboratory of Stomatology, Sun Yat-Sen University, Guangzhou, China
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20
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Gerits E, Verstraeten N, Michiels J. New approaches to combat Porphyromonas gingivalis biofilms. J Oral Microbiol 2017; 9:1300366. [PMID: 28473880 PMCID: PMC5405727 DOI: 10.1080/20002297.2017.1300366] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Revised: 03/01/2017] [Accepted: 02/22/2017] [Indexed: 12/14/2022] Open
Abstract
In nature, bacteria predominantly reside in structured, surface-attached communities embedded in a self-produced, extracellular matrix. These so-called biofilms play an important role in the development and pathogenesis of many infections, as they are difficult to eradicate due to their resistance to antimicrobials and host defense mechanisms. This review focusses on the biofilm-forming periodontal bacterium Porphyromonas gingivalis. Current knowledge on the virulence mechanisms underlying P. gingivalis biofilm formation is presented. In addition, oral infectious diseases in which P. gingivalis plays a key role are described, and an overview of conventional and new therapies for combating P. gingivalis biofilms is given. More insight into this intriguing pathogen might direct the development of better strategies to combat oral infections.
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Affiliation(s)
- Evelien Gerits
- Department of Microbial and Molecular Systems, KU Leuven, Centre of Microbial and Plant Genetics, Leuven, Belgium
| | - Natalie Verstraeten
- Department of Microbial and Molecular Systems, KU Leuven, Centre of Microbial and Plant Genetics, Leuven, Belgium
| | - Jan Michiels
- Department of Microbial and Molecular Systems, KU Leuven, Centre of Microbial and Plant Genetics, Leuven, Belgium
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21
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Talagrand-Reboul E, Jumas-Bilak E, Lamy B. The Social Life of Aeromonas through Biofilm and Quorum Sensing Systems. Front Microbiol 2017; 8:37. [PMID: 28163702 PMCID: PMC5247445 DOI: 10.3389/fmicb.2017.00037] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 01/06/2017] [Indexed: 01/25/2023] Open
Abstract
Bacteria of the genus Aeromonas display multicellular behaviors herein referred to as “social life”. Since the 1990s, interest has grown in cell-to-cell communication through quorum sensing signals and biofilm formation. As they are interconnected, these two self-organizing systems deserve to be considered together for a fresh perspective on the natural history and lifestyles of aeromonads. In this review, we focus on the multicellular behaviors of Aeromonas, i.e., its social life. First, we review and discuss the available knowledge at the molecular and cellular levels for biofilm and quorum sensing. We then discuss the complex, subtle, and nested interconnections between the two systems. Finally, we focus on the aeromonad multicellular coordinated behaviors involved in heterotrophy and virulence that represent technological opportunities and applied research challenges.
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Affiliation(s)
- Emilie Talagrand-Reboul
- Équipe Pathogènes Hydriques Santé Environnements, UMR 5569 HSM, Université de MontpellierMontpellier, France; Département d'Hygiène Hospitalière, Centre Hospitalier Régional Universitaire (CHRU) de MontpellierMontpellier, France
| | - Estelle Jumas-Bilak
- Équipe Pathogènes Hydriques Santé Environnements, UMR 5569 HSM, Université de MontpellierMontpellier, France; Département d'Hygiène Hospitalière, Centre Hospitalier Régional Universitaire (CHRU) de MontpellierMontpellier, France
| | - Brigitte Lamy
- Équipe Pathogènes Hydriques Santé Environnements, UMR 5569 HSM, Université de MontpellierMontpellier, France; Département de Bactériologie, Centre Hospitalier Universitaire (CHU) de NiceNice, France
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22
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A diketopiperazine factor from Rheinheimera aquimaris QSI02 exhibits anti-quorum sensing activity. Sci Rep 2016; 6:39637. [PMID: 28000767 PMCID: PMC5175134 DOI: 10.1038/srep39637] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 11/24/2016] [Indexed: 02/03/2023] Open
Abstract
An ethyl acetate (EtOAc) extract isolated from the marine bacterium, Rheinheimera aquimaris QSI02, was found to exhibit anti-quorum sensing (anti-QS) activity. A subsequent bioassay-guided isolation protocol led to the detection of an active diketopiperazine factor, cyclo(Trp-Ser). Biosensor assay data showed that the minimum inhibitory concentration (MIC) of cyclo(Trp-Ser) ranged from 3.2 mg/ml to 6.4 mg/m for several microorganisms, including Escherichia coli, Chromobacterium violaceum CV026, Pseudomonas aeruginosa PA01, Staphylococcus aureus, and Candida albicans. Additionally, sub-MICs of cyclo(Trp-Ser) decreased the QS-regulated violacein production in C. violaceum CV026 by 67%. Furthermore, cyclo(Trp-Ser) can decrease QS-regulated pyocyanin production, elastase activity and biofilm formation in P. aeruginosa PA01 by 65%, 40% and 59.9%, respectively. Molecular docking results revealed that cyclo(Trp-Ser) binds to CviR receptor more rigidly than C6HSL with lower docking energy −8.68 kcal/mol, while with higher binding energy of −8.40 kcal/mol than 3-oxo-C12HSL in LasR receptor. Molecular dynamics simulation suggested that cyclo(Trp-Ser) is more easy to bind to CviR receptor than natural signaling molecule, but opposite in LasR receptor. These results suggest that cyclo(Trp-Ser) can be used as a potential inhibitor to control QS systems of C. violaceum and P. aeruginosa and provide increased the understanding of molecular mechanism that influences QS-regulated behaviors.
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23
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Scheie AA, Petersen FC. The Biofilm Concept: Consequences for Future Prophylaxis of Oral Diseases? ACTA ACUST UNITED AC 2016; 15:4-12. [PMID: 14761896 DOI: 10.1177/154411130401500102] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Biofilm control is fundamental to oral health. Existing oral prophylactic measures, however, are insufficient. The main reason is probably because the micro-organisms involved organize into complex biofilm communities with features that differ from those of planktonic cells. Micro-organisms have traditionally been studied in the planktonic state. Conclusions drawn from many of these studies, therefore, need to be revalidated. Recent global approaches to the study of microbial gene expression and regulation in non-oral micro-organisms have shed light on two-component and quorum-sensing systems for the transduction of stimuli that allow for coordinated gene expression. We suggest interference with two-component and quorum-sensing systems as potential novel strategies for the prevention of oral diseases through control of oral biofilms. Information is still lacking, however, on the genetic regulation of oral biofilm formation. A better understanding of these processes is of considerable importance.
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Affiliation(s)
- Anne Aamdal Scheie
- Dept. of Oral Biology, Faculty of Dentistry, University of Oslo, PB 1052 Blindern, 0316 Oslo, Norway
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24
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Rudney JD, Chen R, Sedgewick GJ. Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Tannerella forsythensis are Components of a Polymicrobial Intracellular Flora within Human Buccal Cells. J Dent Res 2016; 84:59-63. [PMID: 15615877 DOI: 10.1177/154405910508400110] [Citation(s) in RCA: 127] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Previously, we used in situ hybridization and confocal microscopy to detect the periodontal pathogens Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Tannerella forsythensis within buccal epithelial cells taken directly from the mouth. This study tested the hypothesis that the intracellular flora of buccal cells is polymicrobial. Mixtures containing a red fluorescent universal probe paired with green fluorescent versions of either A. actinomycetemcomitans-, P. gingivalis-, or T. forsythensis-specific probes were hybridized with buccal cells collected from each of 38 healthy humans. We verified co-localization of probe pairs within cells by generating three-dimensional reconstructions. Intracellular bacteria were detected in every subject. Each cell that was labeled with a species-specific probe also contained bacteria recognized only by the universal probe. Bacteria labeled with specific probes often occupied smaller regions within larger masses of bacteria. Those findings suggest that future studies of invasion by oral bacteria may need to include microbial consortia.
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Affiliation(s)
- J D Rudney
- Department of Oral Science, School of Dentistry, University of Minnesota, Minneapolis, 55455, USA.
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25
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Abstract
The term 'quorum sensing' describes intercellular bacterial communication which regulates bacterial gene expression according to population cell density. Bacteria produce and secrete small molecules, named autoinducers, into the intercellular space. The concentration of these molecules increases as a function of population cell density. Once the concentration of the stimulatory threshold is reached, alteration in gene expression occurs. Gram-positive and Gram-negative bacteria possess different types of quorum sensing systems. Canonical LuxI/R-type/acyl homoserine lactone mediated quorum sensing system is the best studied quorum sensing circuit and is described in Gram-negative bacteria which employ it for inter-species communication mostly. Gram-positive bacteria possess a peptide-mediated quorum sensing system. Bacteria can communicate within their own species (intra-species) but also between species (inter-species), for which they employ an autoinducer-2 quorum sensing system which is called the universal language of the bacteria. Periodontal pathogenic bacteria possess AI-2 quorum sensing systems. It is known that they use it for regulation of biofilm formation, iron uptake, stress response and virulence factor expression. A better understanding of bacterial communication mechanisms will allow the targeting of quorum sensing with quorum sensing inhibitors to prevent and control disease.
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Affiliation(s)
- Darije Plančak
- Department of Periodontology, School of Dental Medicine, Zagreb, Croatia
| | - Larisa Musić
- Dental practice, Community Healthcare Center Čakovec, Čakovec, Croatia
| | - Ivan Puhar
- Department of Periodontology, School of Dental Medicine, Zagreb, Croatia
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26
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Wang X, Li S, Lu X, Hu P, Chen H, Li Z, Bu Z, Lang X, Wang X. Rapid method of luxS and pfs gene inactivation in enterotoxigenic Escherichia coli and the effect on biofilm formation. Mol Med Rep 2015; 13:257-64. [PMID: 26549009 DOI: 10.3892/mmr.2015.4532] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 08/24/2015] [Indexed: 11/06/2022] Open
Abstract
Rapid and efficient inactivation of a target gene in Escherichia coli chromosomes is required to investigate metabolic engineering. In the present study, a multiple gene inactivation approach was demonstrated in four strains of enterotoxigenic E. coli (ETEC), which are the predominant pathogenic bacteria causing piglet diarrhea, mediated by λ Red and Xer recombination. The chromosomal genes, luxS and pfs were inactivated using the multiple gene inactivation approach in the wild‑type strains of E. coli, K88, K99, 987P and F41. This indicated that dif sites may be reused to inactivate multiple chromosomal genes when no antibiotic‑resistant selectable markers remain. Following inactivation of luxS and pfs, the ability of ETEC to produce the quorum sensing signal, and induce auto‑inducer 2 activity and biofilm formation were significantly reduced. Furthermore, the multiple gene inactivation approach also exhibits a high recombination efficiency and follows a simple process.
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Affiliation(s)
- Xiaoxu Wang
- Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Institute of Military Veterinary Medicine, Academy of Military Medical Sciences, Changchun, Jilin 130122, P.R. China
| | - Shiyu Li
- Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Institute of Military Veterinary Medicine, Academy of Military Medical Sciences, Changchun, Jilin 130122, P.R. China
| | - Xiaoran Lu
- Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Institute of Military Veterinary Medicine, Academy of Military Medical Sciences, Changchun, Jilin 130122, P.R. China
| | - Pan Hu
- Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, College of Veterinary Medicine, Jilin University, Changchun, Jilin 130062, P.R. China
| | - Haiyan Chen
- Changchun University of Science and Technology, Changchun, Jilin 130022, P.R. China
| | - Zheng Li
- Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Institute of Military Veterinary Medicine, Academy of Military Medical Sciences, Changchun, Jilin 130122, P.R. China
| | - Zhaoyang Bu
- Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Institute of Military Veterinary Medicine, Academy of Military Medical Sciences, Changchun, Jilin 130122, P.R. China
| | - Xulong Lang
- Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Institute of Military Veterinary Medicine, Academy of Military Medical Sciences, Changchun, Jilin 130122, P.R. China
| | - Xinglong Wang
- Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Institute of Military Veterinary Medicine, Academy of Military Medical Sciences, Changchun, Jilin 130122, P.R. China
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Marchesan J, Morelli T, Moss K, Barros S, Ward M, Jenkins W, Aspiras M, Offenbacher S. Association of Synergistetes and Cyclodipeptides with Periodontitis. J Dent Res 2015. [DOI: 10.1177/0022034515594779] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The purpose of this study was to evaluate the microbial community (MC) composition as it relates to salivary metabolites and periodontal clinical parameters in a 21-d biofilm-overgrowth model. Subjects ( N = 168) were enrolled equally into 5 categories of periodontal status per the biofilm-gingival interface classification. Microbial species within subgingival plaque samples were identified by human microbiome identification microarray. Whole saliva was analyzed by liquid chromatography–mass spectrometry and gas chromatography–mass spectrometry for metabolite identification. Phylum was grouped into MCs according to principal component analysis. Generalized linear and regression models were used to examine the association among MC, species, periodontal clinical parameters, and salivary metabolome. Multiple comparisons were adjusted with the false discovery rate. The study population was distributed into 8 distinct MC profiles, designated MC-1 to MC-8. MC-2 explained 14% of the variance and was dominated by Synergistetes and Spirochaetes. It was the only community structure significantly associated with high probing depth ( P = 0.02) and high bleeding on probing ( P = 0.008). MC-2 was correlated with traditional periodontal pathogens and several newly identified putative periodontal pathogens: Fretibacterium fastidiosum, Fretibacterium sp. OT360/OT362, Filifactor alocis, Treponema lecithinolyticum, Eubacterium saphenum, Desulfobulbus sp. /OT041, and Mogibacterium timidum. Synergistetes phylum was strongly associated with 2 novel metabolites—cyclo (-leu-pro) and cyclo (-phe-pro)—at 21 d of biofilm overgrowth ( P = 0.02). In subjects with severe periodontitis (P2 and P3), cyclo (-leu-pro) and cyclo (-phe-pro) were significantly associated with increased changes in probing depth at 21 d of biofilm overgrowth ( P ≤ 0.05). The analysis identified a MC dominated by Synergistetes, with classic and putative newly identified pathogens/pathobionts associated with clinical disease. The metabolomic discovery of 2 novel cyclodipeptides that have been reported to serve as quorum-sensing and/or bacteriocidal/bacteriostatic molecules, in association with Synergistetes, suggests a potential role in periodontal biofilm dysbiosis and periodontal disease that warrants further investigation.
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Affiliation(s)
- J.T. Marchesan
- Center for Oral and Systemic Diseases, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Periodontology, School of Dentistry, University of North Carolina at Chapel hill, Chapel Hill, NC, USA
| | - T. Morelli
- Center for Oral and Systemic Diseases, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Periodontology, School of Dentistry, University of North Carolina at Chapel hill, Chapel Hill, NC, USA
| | - K. Moss
- Department of Dental Ecology, School of Dentistry, University of North Carolina at Chapel hill, Chapel Hill, NC, USA
| | - S.P. Barros
- Center for Oral and Systemic Diseases, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Periodontology, School of Dentistry, University of North Carolina at Chapel hill, Chapel Hill, NC, USA
| | - M. Ward
- Philips Oral Healthcare, Dental & Scientific Affairs, Bothell, WA, USA
| | - W. Jenkins
- Philips Oral Healthcare, Dental & Scientific Affairs, Bothell, WA, USA
| | | | - S. Offenbacher
- Center for Oral and Systemic Diseases, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Periodontology, School of Dentistry, University of North Carolina at Chapel hill, Chapel Hill, NC, USA
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Weigel WA, Demuth DR, Torres-Escobar A, Juárez-Rodríguez MD. Aggregatibacter actinomycetemcomitans QseBC is activated by catecholamines and iron and regulates genes encoding proteins associated with anaerobic respiration and metabolism. Mol Oral Microbiol 2015; 30:384-98. [PMID: 25923132 PMCID: PMC4660874 DOI: 10.1111/omi.12101] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/21/2015] [Indexed: 01/09/2023]
Abstract
Aggregatibacter actinomycetemcomitans QseBC regulates its own expression and is essential for biofilm growth and virulence. However, the signal that activates the QseC sensor has not been identified and the qseBC regulon has not been defined. In this study, we show that QseC is activated by catecholamine hormones and iron but not by either component alone. Activation of QseC requires an EYRDD motif in the periplasmic domain of the sensor and site-specific mutations in EYRDD or the deletion of the periplasmic domain inhibits catecholamine/iron-dependent induction of the ygiW-qseBC operon. Catecholamine/iron-dependent induction of transcription also requires interaction of the QseB response regulator with its binding site in the ygiW-qseBC promoter. Whole genome microarrays were used to compare gene expression profiles of A. actinomycetemcomitans grown in a chemically defined medium with and without catecholamine and iron supplementation. Approximately 11.5% of the A. actinomycetemcomitans genome was differentially expressed by at least two-fold upon exposure to catecholamines and iron. The expression of ferritin was strongly induced, suggesting that intracellular iron storage capacity is increased upon QseBC activation. Consistent with this, genes encoding iron binding and transport proteins were down-regulated by QseBC. Strikingly, 57% of the QseBC up-regulated genes (56/99) encode proteins associated with anaerobic metabolism and respiration. Most of these up-regulated genes were recently reported to be induced during in vivo growth of A. actinomycetemcomitans. These results suggest that detection of catecholamines and iron by QseBC may alter the cellular metabolism of A. actinomycetemcomitans for increased fitness and growth in an anaerobic host environment.
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Affiliation(s)
- W A Weigel
- Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry, Louisville, KY, USA.,Department of Microbiology and Immunology, University of Louisville School of Medicine, Louisville, KY, USA
| | - D R Demuth
- Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry, Louisville, KY, USA
| | - A Torres-Escobar
- Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry, Louisville, KY, USA
| | - M D Juárez-Rodríguez
- Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry, Louisville, KY, USA
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Parashar A, Parashar S, Zingade A, Gupta S, Sanikop S. Interspecies communication in oral biofilm: An ocean of information. ACTA ACUST UNITED AC 2015. [DOI: 10.1016/s1348-8643(15)00016-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Abstract
UNLABELLED Clostridium difficile infection (CDI) is dramatically increasing as a cause of antibiotic- and hospital-associated diarrhea worldwide. C. difficile, a multidrug-resistant pathogen, flourishes in the colon after the gut microbiota has been altered by antibiotic therapy. Consequently, it produces toxins A and B that directly cause disease. Despite the enormous public health problem posed by this pathogen, the molecular mechanisms that regulate production of the toxins, which are directly responsible for disease, remained largely unknown until now. Here, we show that C. difficile toxin synthesis is regulated by an accessory gene regulator quorum-signaling system, which is mediated through a small (<1,000-Da) thiolactone that can be detected directly in stools of CDI patients. These findings provide direct evidence of the mechanism of regulation of C. difficile toxin synthesis and offer exciting new avenues both for rapid detection of C. difficile infection and development of quorum-signaling-based non-antibiotic therapies to combat this life-threatening emerging pathogen. IMPORTANCE Clostridium difficile infection (CDI) is the most common definable cause of hospital-acquired and antibiotic-associated diarrhea in the United States, with the total cost of treatment estimated between 1 and 4.8 billion U.S. dollars annually. C. difficile, a Gram-positive, spore-forming anaerobe, flourishes in the colon after the gut microbiota has been altered by antibiotic therapy. As a result, there is an urgent need for non-antibiotic CDI treatments that preserve the colonic microbiota. C. difficile produces toxins A and B, which are directly responsible for disease. Here, we report that C. difficile regulates its toxin synthesis by quorum signaling, in which a novel signaling peptide activates transcription of the disease-causing toxin genes. This finding provides new therapeutic targets to be harnessed for novel nonantibiotic therapy for C. difficile infections.
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Scheres N, Lamont RJ, Crielaard W, Krom BP. LuxS signaling in Porphyromonas gingivalis-host interactions. Anaerobe 2014; 35:3-9. [PMID: 25434960 DOI: 10.1016/j.anaerobe.2014.11.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 11/16/2014] [Accepted: 11/17/2014] [Indexed: 12/27/2022]
Abstract
Dental plaque is a multispecies biofilm in the oral cavity that significantly influences oral health. The presence of the oral anaerobic pathogen Porphyromonas gingivalis is an important determinant in the development of periodontitis. Direct and indirect interactions between P. gingivalis and the host play a major role in disease development. Transcriptome analysis recently revealed that P. gingivalis gene-expression is regulated by LuxS in both an AI-2-dependent and an AI-2 independent manner. However, little is known about the role of LuxS-signaling in P. gingivalis-host interactions. Here, we investigated the effect of a luxS mutation on the ability of P. gingivalis to induce an inflammatory response in human oral cells in vitro. Primary periodontal ligament (PDL) fibroblasts were challenged with P. gingivalis ΔluxS or the wild-type parental strain and gene-expression of pro-inflammatory mediators IL-1β, IL-6 and MCP-1 was determined by real-time PCR. The ability of P. gingivalis ΔluxS to induce an inflammatory response was severely impaired in PDL-fibroblasts. This phenotype could be restored by providing of LuxS in trans, but not by addition of the AI-2 precursor DPD. A similar phenomenon was observed in a previous transcriptome study showing that expression of PGN_0482 was reduced in the luxS mutant independently of AI-2. We therefore also analyzed the effect of a mutation in PGN_0482, which encodes an immuno-reactive, putative outer-membrane protein. Similar to P. gingivalis ΔluxS, the P. gingivalis Δ0482 mutant had an impaired ability to induce an inflammatory response in PDL fibroblasts. LuxS thus appears to influence the pro-inflammatory responses of host cells to P. gingivalis, likely through regulation of PGN_0482.
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Affiliation(s)
- Nina Scheres
- Department of Preventive Dentistry, Academic Centre for Dentistry Amsterdam (ACTA), VU Free University and the University of Amsterdam, Gustav Mahlerlaan 3004, 1081 BT Amsterdam, The Netherlands.
| | - Richard J Lamont
- Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry, Louisville, KY 40202, United States
| | - Wim Crielaard
- Department of Preventive Dentistry, Academic Centre for Dentistry Amsterdam (ACTA), VU Free University and the University of Amsterdam, Gustav Mahlerlaan 3004, 1081 BT Amsterdam, The Netherlands
| | - Bastiaan P Krom
- Department of Preventive Dentistry, Academic Centre for Dentistry Amsterdam (ACTA), VU Free University and the University of Amsterdam, Gustav Mahlerlaan 3004, 1081 BT Amsterdam, The Netherlands.
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Juárez-Rodríguez MD, Torres-Escobar A, Demuth DR. Transcriptional regulation of the Aggregatibacter actinomycetemcomitans ygiW-qseBC operon by QseB and integration host factor proteins. MICROBIOLOGY-SGM 2014; 160:2583-2594. [PMID: 25223341 DOI: 10.1099/mic.0.083501-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The QseBC two-component system plays a pivotal role in regulating virulence and biofilm growth of the oral pathogen Aggregatibacter actinomycetemcomitans. We previously showed that QseBC autoregulates the ygiW-qseBC operon. In this study, we characterized the promoter that drives ygiW-qseBC expression. Using lacZ transcriptional fusion constructs and 5'-rapid amplification of cDNA ends, we showed that ygiW-qseBC expression is driven by a promoter that initiates transcription 53 bases upstream of ygiW and identified putative cis-acting promoter elements, whose function was confirmed using site-specific mutagenesis. Using electrophoretic mobility shift assays, two trans-acting proteins were shown to interact with the ygiW-qseBC promoter. The QseB response regulator bound to probes containing the direct repeat sequence CTTAA-N6-CTTAA, where the CTTAA repeats flank the -35 element of the promoter. The ygiW-qseBC expression could not be detected in A. actinomycetemcomitans ΔqseB or ΔqseBC strains, but was restored to WT levels in the ΔqseBC mutant when complemented by single copy chromosomal insertion of qseBC. Interestingly, qseB partially complemented the ΔqseBC strain, suggesting that QseB could be activated in the absence of QseC. QseB activation required its phosphorylation since complementation did not occur using qseB(pho-), encoding a protein with the active site aspartate substituted with alanine. These results suggest that QseB is a strong positive regulator of ygiW-qseBC expression. In addition, integration host factor (IHF) bound to two sites in the promoter region and an additional site near the 5' end of the ygiW ORF. The expression of ygiW-qseBC was increased by twofold in ΔihfA and ΔihfB strains of A. actinomycetemcomitans, suggesting that IHF is a negative regulator of the ygiW-qseBC operon.
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Affiliation(s)
- María Dolores Juárez-Rodríguez
- Research Group in Oral Health and Systemic Disease, University of Louisville School of Dentistry, 501 S. Preston Street, Louisville, KY 40202, USA
| | - Ascención Torres-Escobar
- Research Group in Oral Health and Systemic Disease, University of Louisville School of Dentistry, 501 S. Preston Street, Louisville, KY 40202, USA
| | - Donald R Demuth
- Research Group in Oral Health and Systemic Disease, University of Louisville School of Dentistry, 501 S. Preston Street, Louisville, KY 40202, USA
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Bachtiar EW, Bachtiar BM, Jarosz LM, Amir LR, Sunarto H, Ganin H, Meijler MM, Krom BP. AI-2 of Aggregatibacter actinomycetemcomitans inhibits Candida albicans biofilm formation. Front Cell Infect Microbiol 2014; 4:94. [PMID: 25101248 PMCID: PMC4104835 DOI: 10.3389/fcimb.2014.00094] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 06/26/2014] [Indexed: 12/14/2022] Open
Abstract
Aggregatibacter actinomycetemcomitans, a Gram-negative bacterium, and Candida albicans, a polymorphic fungus, are both commensals of the oral cavity but both are opportunistic pathogens that can cause oral diseases. A. actinomycetemcomitans produces a quorum-sensing molecule called autoinducer-2 (AI-2), synthesized by LuxS, that plays an important role in expression of virulence factors, in intra- but also in interspecies communication. The aim of this study was to investigate the role of AI-2 based signaling in the interactions between C. albicans and A. actinomycetemcomitans. A. actinomycetemcomitans adhered to C. albicans and inhibited biofilm formation by means of a molecule that was secreted during growth. C. albicans biofilm formation increased significantly when co-cultured with A. actinomycetemcomitans luxS, lacking AI-2 production. Addition of wild-type-derived spent medium or synthetic AI-2 to spent medium of the luxS strain, restored inhibition of C. albicans biofilm formation to wild-type levels. Addition of synthetic AI-2 significantly inhibited hypha formation of C. albicans possibly explaining the inhibition of biofilm formation. AI-2 of A. actinomycetemcomitans is synthesized by LuxS, accumulates during growth and inhibits C. albicans hypha- and biofilm formation. Identifying the molecular mechanisms underlying the interaction between bacteria and fungi may provide important insight into the balance within complex oral microbial communities.
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Affiliation(s)
- Endang W Bachtiar
- Department of Oral Biology, Faculty of Dentistry, Universitas Indonesia Jakarta, Indonesia
| | - Boy M Bachtiar
- Department of Oral Biology, Faculty of Dentistry, Universitas Indonesia Jakarta, Indonesia
| | - Lucja M Jarosz
- Department of Biomedical Engineering, The W.J. Kolff Institute, University Medical Center Groningen and University of Groningen Groningen, Netherlands
| | - Lisa R Amir
- Department of Oral Biology, Faculty of Dentistry, Universitas Indonesia Jakarta, Indonesia
| | - Hari Sunarto
- Department of Periodontology, Faculty of Dentistry, Universitas Indonesia Jakarta, Indonesia
| | - Hadas Ganin
- Department of Chemistry, Ben-Gurion University of the Negev Be'er-Sheva, Israel
| | - Michael M Meijler
- Department of Chemistry, Ben-Gurion University of the Negev Be'er-Sheva, Israel
| | - Bastiaan P Krom
- Department of Preventive Dentistry, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Free University Amsterdam Amsterdam, Netherlands
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Guo L, He X, Shi W. Intercellular communications in multispecies oral microbial communities. Front Microbiol 2014; 5:328. [PMID: 25071741 PMCID: PMC4076886 DOI: 10.3389/fmicb.2014.00328] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2014] [Accepted: 06/14/2014] [Indexed: 01/22/2023] Open
Abstract
The oral cavity contains more than 700 microbial species that are engaged in extensive cell–cell interactions. These interactions contribute to the formation of highly structured multispecies communities, allow them to perform physiological functions, and induce synergistic pathogenesis. Co-adhesion between oral microbial species influences their colonization of oral cavity and effectuates, to a large extent, the temporal and spatial formation of highly organized polymicrobial community architecture. Individual species also compete and collaborate with other neighboring species through metabolic interactions, which not only modify the local microenvironment such as pH and the amount of oxygen, making it more suitable for the growth of other species, but also provide a metabolic framework for the participating microorganisms by maximizing their potential to extract energy from limited substrates. Direct physical contact of bacterial species with its neighboring co-habitants within microbial community could initiate signaling cascade and achieve modulation of gene expression in accordance with different species it is in contact with. In addition to communication through cell–cell contact, quorum sensing (QS) mediated by small signaling molecules such as competence-stimulating peptides (CSPs) and autoinducer-2 (AI-2), plays essential roles in bacterial physiology and ecology. This review will summarize the evidence that oral microbes participate in intercellular communications with co-inhabitants through cell contact-dependent physical interactions, metabolic interdependencies, as well as coordinative signaling systems to establish and maintain balanced microbial communities.
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Affiliation(s)
- Lihong Guo
- School of Dentistry, University of California-Los Angeles, Los Angeles CA, USA
| | - Xuesong He
- School of Dentistry, University of California-Los Angeles, Los Angeles CA, USA
| | - Wenyuan Shi
- School of Dentistry, University of California-Los Angeles, Los Angeles CA, USA
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Reiland HA, Omolo MA, Johnson TJ, Baumler DJ. A Survey of <i>Escherichia coli</i> O157:H7 Virulence Factors: The First 25 Years and 13 Genomes. ACTA ACUST UNITED AC 2014. [DOI: 10.4236/aim.2014.47046] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Interspecies communication and periodontal disease. ScientificWorldJournal 2013; 2013:765434. [PMID: 24396307 PMCID: PMC3874309 DOI: 10.1155/2013/765434] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Accepted: 09/11/2013] [Indexed: 11/18/2022] Open
Abstract
More than 500 bacterial strains may be found in dental plaque. In the beginning, the emphasis was laid on the isolation of bacteria in pure culture to define their properties. However, now, it has been well established that in nature the bacteria exist as a member of polymicrobial community or consortium of interacting species. Interactions among human oral bacteria are integral to the development and maturation of the plaque. These interactions occur at several levels including physical contact, metabolic exchange, small-signal molecule-mediated communication, and exchange of genetic material. This high level of interspecies interaction benefits the microorganism by providing a broader habitat range, effective metabolism, increasing the resistance to host defence, and enhancing their virulence. This generally has a detrimental effect on the host and is attributed to many chronic infections which poses a therapeutic challenge.
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Zhou M, Guo Z, Yang Y, Duan Q, Zhang Q, Yao F, Zhu J, Zhang X, Hardwidge PR, Zhu G. Flagellin and F4 fimbriae have opposite effects on biofilm formation and quorum sensing in F4ac+ enterotoxigenic Escherichia coli. Vet Microbiol 2013; 168:148-53. [PMID: 24238669 DOI: 10.1016/j.vetmic.2013.10.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Revised: 09/30/2013] [Accepted: 10/16/2013] [Indexed: 12/17/2022]
Abstract
Bacteria that form biofilms are often highly resistant to antibiotics and are capable of evading the host immune system. To evaluate the role of flagellin and F4 fimbriae on biofilm formation by enterotoxigenic Escherichia coli (ETEC), we deleted the fliC (encoding the major flagellin protein) and/or the faeG (encoding the major subunit of F4 fimbriae) genes from ETEC C83902. Biofilm formation was reduced in the fliC mutant but increased in the faeG mutant, as compared with the wild-type strain. The expression of AI-2 quorum sensing associated genes was regulated in the fliC and faeG mutants, consistent with the biofilm formation of these strains. But, deleting fliC and/or faeG also inhibited AI-2 quorum sensing activity.
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Affiliation(s)
- Mingxu Zhou
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-Innovation Center for Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China.
| | - Zhiyan Guo
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-Innovation Center for Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China.
| | - Yang Yang
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-Innovation Center for Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China.
| | - Qiangde Duan
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Agriculture College, Weinan Vocational and Technical College, Weinan 714000, China.
| | - Qi Zhang
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-Innovation Center for Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China.
| | - Fenghua Yao
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-Innovation Center for Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China.
| | - Jun Zhu
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-Innovation Center for Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China.
| | - Xinjun Zhang
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-Innovation Center for Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China.
| | - Philip R Hardwidge
- College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA.
| | - Guoqiang Zhu
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-Innovation Center for Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China.
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Jang YJ, Sim J, Jun HK, Choi BK. Differential effect of autoinducer 2 of Fusobacterium nucleatum on oral streptococci. Arch Oral Biol 2013; 58:1594-602. [PMID: 24112724 DOI: 10.1016/j.archoralbio.2013.08.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Revised: 08/06/2013] [Accepted: 08/11/2013] [Indexed: 11/18/2022]
Abstract
Autoinducer 2 (AI-2) is a quorum sensing molecule and plays an important role in dental biofilm formation, mediating interspecies communication and virulence expression of oral bacteria. Fusobacterium nucleatum connects early colonizing commensals and late colonizing periodontopathogens. F. nucleatum AI-2 and quorum sensing inhibitors (QSIs) can manipulate dental biofilm formation. In this study, we evaluated the effect of F. nucleatum AI-2 and QSIs on biofilm formation of Streptococcus gordonii and Streptococcus oralis, which are initial colonizers in dental biofilm. F. nucleatum AI-2 significantly enhanced biofilm growth of S. gordonii and attachment of F. nucleatum to preformed S. gordonii biofilms. By contrast, F. nucleatum AI-2 reduced biofilm growth of S. oralis and attachment of F. nucleatum to preformed S. oralis biofilms. The QSIs, (5Z)-4-bromo-5-(bromomethylene)-2(5H)-furanone and d-ribose, reversed the stimulatory and inhibitory effects of AI-2 on S. gordonii and S. oralis, respectively. In addition, co-culture using a two-compartment system showed that secreted molecules of F. nucleatum had the same effect on biofilm growth of the streptococci as AI-2. Our results demonstrate that early colonizing bacteria can influence the accretion of F. nucleatum, a secondary colonizer, which ultimately influences the binding of periodontopathogens.
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Affiliation(s)
- Yun-Ji Jang
- Department of Oral Microbiology and Immunology, School of Dentistry, Seoul National University, Seoul, Republic of Korea
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Longo PL, Nunes ACR, Umeda JE, Mayer MPA. Gene expression and phenotypic traits of Aggregatibacter actinomycetemcomitans
in response to environmental changes. J Periodontal Res 2013; 48:766-72. [DOI: 10.1111/jre.12067] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/30/2013] [Indexed: 11/30/2022]
Affiliation(s)
- P. L. Longo
- Department of Microbiology; Institute of Biomedical Sciences; University of São Paulo; São Paulo Brazil
| | - A. C. R. Nunes
- Department of Microbiology; Institute of Biomedical Sciences; University of São Paulo; São Paulo Brazil
| | - J. E. Umeda
- Department of Microbiology; Institute of Biomedical Sciences; University of São Paulo; São Paulo Brazil
| | - M. P. A. Mayer
- Department of Microbiology; Institute of Biomedical Sciences; University of São Paulo; São Paulo Brazil
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Juárez-Rodríguez MD, Torres-Escobar A, Demuth DR. ygiW and qseBC are co-expressed in Aggregatibacter actinomycetemcomitans and regulate biofilm growth. MICROBIOLOGY-SGM 2013; 159:989-1001. [PMID: 23519160 DOI: 10.1099/mic.0.066183-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The quorum-sensing Escherichia coli regulators B and C (QseBC) two-component system were previously shown to regulate biofilm growth of the oral pathogen Aggregatibacter actinomycetemcomitans and to be essential for virulence. In this study, we use RT-PCR to show that an open reading frame, ygiW, residing upstream of qseBC and encoding a hypothetical protein is co-expressed with qseBC. In addition, using a series of lacZ transcriptional fusion constructs and 5'-rapid amplification of cDNA Ends (RACE), the promoter that drives expression of the ygiW-qseBC operon and the transcriptional start site was mapped to the 372 bp intergenic region upstream from ygiW. No internal promoters drive qseBC expression independently from ygiW. However, qseBC expression is attenuated by approximately ninefold by a putative attenuator stem-loop (ΔG = -77.0 KJ/mol) that resides in the 137 bp intergenic region between ygiW and qseB. The QseB response regulator activates expression of the ygiW-qseBC operon and transcription from the ygiW promoter is drastically reduced in ΔqseB and ΔqseBC mutants of A. actinomycetemcomitans. In addition, transcriptional activity of the ygiW promoter is significantly reduced in a mutant expressing an in-frame deletion of qseC that lacks the sensor domain of QseC, suggesting that a periplasmic signal is required for QseB activation. Finally, a non-polar in-frame deletion in ygiW had little effect on biofilm depth but caused a significant increase in surface coverage relative to wild-type. Complementation of the mutant with a plasmid-borne copy of ygiW reduced surface coverage back to wild-type levels. Interestingly, deletion of the sensor domain of QseC or of the entire qseC open reading frame resulted in significant reductions in biofilm depth, biomass and surface coverage, indicating that the sensor domain is essential for optimal biofilm formation by A. actinomycetemcomitans. Thus, although ygiW and qseBC are co-expressed, they regulate biofilm growth by distinct mechanisms.
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Affiliation(s)
- María Dolores Juárez-Rodríguez
- Research Group in Oral Health and Systemic Disease, University of Louisville School of Dentistry, 501 S. Preston Street, Louisville, KY 40202, USA
| | - Ascención Torres-Escobar
- Research Group in Oral Health and Systemic Disease, University of Louisville School of Dentistry, 501 S. Preston Street, Louisville, KY 40202, USA
| | - Donald R Demuth
- Research Group in Oral Health and Systemic Disease, University of Louisville School of Dentistry, 501 S. Preston Street, Louisville, KY 40202, USA
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Mlc is a transcriptional activator with a key role in integrating cyclic AMP receptor protein and integration host factor regulation of leukotoxin RNA synthesis in Aggregatibacter actinomycetemcomitans. J Bacteriol 2013; 195:2284-97. [PMID: 23475968 DOI: 10.1128/jb.02144-12] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aggregatibacter actinomycetemcomitans, a periodontal pathogen, synthesizes leukotoxin (LtxA), a protein that helps the bacterium evade the host immune response. Transcription of the ltxA operon is induced during anaerobic growth. The cyclic AMP (cAMP) receptor protein (CRP) indirectly increases ltxA expression, but the intermediary regulator is unknown. Integration host factor (IHF) binds to and represses the leukotoxin promoter, but neither CRP nor IHF is responsible for the anaerobic induction of ltxA RNA synthesis. Thus, we have undertaken studies to identify other regulators of leukotoxin transcription and to demonstrate how these proteins work together to modulate leukotoxin synthesis. First, analyses of ltxA RNA expression from defined leukotoxin promoter mutations in the chromosome identify positions -69 to -35 as the key control region and indicate that an activator protein modulates leukotoxin transcription. We show that Mlc, which is a repressor in Escherichia coli, functions as a direct transcriptional activator in A. actinomycetemcomitans; an mlc deletion mutant reduces leukotoxin RNA synthesis, and recombinant Mlc protein binds specifically at the -68 to -40 region of the leukotoxin promoter. Furthermore, we show that CRP activates ltxA expression indirectly by increasing the levels of Mlc. Analyses of Δmlc, Δihf, and Δihf Δmlc strains demonstrate that Mlc can increase RNA polymerase (RNAP) activity directly and that IHF represses ltxA RNA synthesis mainly by blocking Mlc binding. Finally, a Δihf Δmlc mutant still induces ltxA during anaerobic growth, indicating that there are additional factors involved in leukotoxin transcriptional regulation. A model for the coordinated regulation of leukotoxin transcription is presented.
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Mishra V, Ronning DR. Crystal structures of the Helicobacter pylori MTAN enzyme reveal specific interactions between S-adenosylhomocysteine and the 5'-alkylthio binding subsite. Biochemistry 2012; 51:9763-72. [PMID: 23148563 DOI: 10.1021/bi301221k] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The bacterial 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTAN) enzyme is a multifunctional enzyme that catalyzes the hydrolysis of the N-ribosidic bond of at least four different adenosine-based metabolites: S-adenosylhomocysteine (SAH), 5'-methylthioadenosine (MTA), 5'-deoxyadenosine (5'-DOA), and 6-amino-6-deoxyfutalosine. These activities place the enzyme at the hub of seven fundamental bacterial metabolic pathways: S-adenosylmethionine (SAM) utilization, polyamine biosynthesis, the purine salvage pathway, the methionine salvage pathway, the SAM radical pathways, autoinducer-2 biosynthesis, and menaquinone biosynthesis. The last pathway makes MTAN essential for Helicobacter pylori viability. Although structures of various bacterial and plant MTANs have been described, the interactions between the homocysteine moiety of SAH and the 5'-alkylthiol binding site of MTAN have never been resolved. We have determined crystal structures of an inactive mutant form of H. pylori MTAN bound to MTA and SAH to 1.63 and 1.20 Å, respectively. The active form of MTAN was also crystallized in the presence of SAH, allowing the determination of the structure of a ternary enzyme-product complex resolved at 1.50 Å. These structures identify interactions between the homocysteine moiety and the 5'-alkylthiol binding site of the enzyme. This information can be leveraged for the development of species-specific MTAN inhibitors that prevent the growth of H. pylori.
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Affiliation(s)
- Vidhi Mishra
- Department of Chemistry, University of Toledo, Toledo, OH 43606, USA
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Transcriptional regulation of Aggregatibacter actinomycetemcomitans lsrACDBFG and lsrRK operons and their role in biofilm formation. J Bacteriol 2012; 195:56-65. [PMID: 23104800 DOI: 10.1128/jb.01476-12] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Autoinducer-2 (AI-2) is required for biofilm formation and virulence of the oral pathogen Aggregatibacter actinomycetemcomitans, and we previously showed that lsrB codes for a receptor for AI-2. The lsrB gene is expressed as part of the lsrACDBFG operon, which is divergently transcribed from an adjacent lsrRK operon. In Escherichia coli, lsrRK encodes a repressor and AI-2 kinase that function to regulate lsrACDBFG. To determine if lsrRK controls lsrACDBFG expression and influences biofilm growth of A. actinomycetemcomitans, we first defined the promoters for each operon. Transcriptional reporter plasmids containing the 255-bp lsrACDBFG-lsrRK intergenic region (IGR) fused to lacZ showed that essential elements of lsrR promoter reside 89 to 255 bp upstream from the lsrR start codon. Two inverted repeat sequences that represent potential binding sites for LsrR and two sequences resembling the consensus cyclic AMP receptor protein (CRP) binding site were identified in this region. Using electrophoretic mobility shift assay (EMSA), purified LsrR and CRP proteins were shown to bind probes containing these sequences. Surprisingly, the 255-bp IGR did not contain the lsrA promoter. Instead, a fragment encompassing nucleotides +1 to +159 of lsrA together with the 255-bp IGR was required to promote lsrA transcription. This suggests that a region within the lsrA coding sequence influences transcription, or alternatively that the start codon of A. actinomycetemcomitans lsrA has been incorrectly annotated. Transformation of ΔlsrR, ΔlsrK, ΔlsrRK, and Δcrp deletion mutants with lacZ reporters containing the lsrA or lsrR promoter showed that LsrR negatively regulates and CRP positively regulates both lsrACDBFG and lsrRK. However, in contrast to what occurs in E. coli, deletion of lsrK had no effect on the transcriptional activity of the lsrA or lsrR promoters, suggesting that another kinase may be capable of phosphorylating AI-2 in A. actinomycetemcomitans. Finally, biofilm formation of the ΔlsrR, ΔlsrRK, and Δcrp mutants was significantly reduced relative to that of the wild type, indicating that proper regulation of the lsr locus is required for optimal biofilm growth by A. actinomycetemcomitans.
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Yin WF, Purmal K, Chin S, Chan XY, Chan KG. Long chain N-acyl homoserine lactone production by Enterobacter sp. isolated from human tongue surfaces. SENSORS 2012. [PMID: 23202161 PMCID: PMC3522914 DOI: 10.3390/s121114307] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We report the isolation of N-acyl homoserine lactone-producing Enterobacter sp. isolate T1-1 from the posterior dorsal surfaces of the tongue of a healthy individual. Spent supernatants extract from Enterobacter sp. isolate T1-1 activated the biosensor Agrobacterium tumefaciens NTL4(pZLR4), suggesting production of long chain AHLs by these isolates. High resolution mass spectrometry analysis of these extracts confirmed that Enterobacter sp. isolate T1-1 produced a long chain N-acyl homoserine lactone, namely N-dodecanoyl-homoserine lactone (C12-HSL). To the best of our knowledge, this is the first isolation of Enterobacter sp., strain T1-1 from the posterior dorsal surface of the human tongue and N-acyl homoserine lactones production by this bacterium.
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Affiliation(s)
- Wai-Fong Yin
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia; E-Mails: (W.-F.Y.); (S.C.); (X.-Y.C.)
| | - Kathiravan Purmal
- Department of General Dental Practice and Oral and Maxillofacial Imaging, Faculty of Dentistry, Universiti Sains Malaysia, 50603 Kuala Lumpur, Malaysia; E-Mail:
| | - Shenyang Chin
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia; E-Mails: (W.-F.Y.); (S.C.); (X.-Y.C.)
| | - Xin-Yue Chan
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia; E-Mails: (W.-F.Y.); (S.C.); (X.-Y.C.)
| | - Kok-Gan Chan
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia; E-Mails: (W.-F.Y.); (S.C.); (X.-Y.C.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +603-7967-5162; Fax: +603-7967-4509
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Mirza BS, Rodrigues JLM. Development of a direct isolation procedure for free-living diazotrophs under controlled hypoxic conditions. Appl Environ Microbiol 2012; 78:5542-9. [PMID: 22660701 PMCID: PMC3406155 DOI: 10.1128/aem.00714-12] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 05/22/2012] [Indexed: 11/20/2022] Open
Abstract
Free-living diazotrophs are diverse and ubiquitous in soil, contributing the nitrogen pool in natural ecosystems. The isolation of nitrogen-fixing microorganisms has relied on semisolid nitrogen-free medium enrichment, followed by multiple subculturing steps. These procedures limit the diversity of recovered isolates. In the current study, we investigated three different isolation strategies for free-living diazotrophs using a soil sample from the Amazon forest. The methods were (i) direct plating on solid nitrogen-free medium under a 2% O(2) concentration, (ii) enrichment in semisolid nitrogen-free medium before plating on solid nitrogen-free medium under 2% O(2), and (iii) enrichment followed by subculturing in the semisolid nitrogen-free medium before plating on nitrogen containing medium under a 21% O(2) concentration. A total of 794 isolates were differentiated by their genomic fingerprinting patterns, and strains with unique profiles were identified on the basis of sequencing of their 16S rRNA gene. Isolates belonged to four bacterial phyla: Proteobacteria, Firmicutes, Actinobacteria, and Bacteriodetes. The novel strategy of combining a solid N-free medium and hypoxic conditions showed an increase of 62.6% in the diversity of diazotrophs in comparison to that obtained by the conventional semisolid medium-based methods. All isolates grew on the nitrogen-free medium under a 2% O(2) concentration, 78% of them showed the presence of the nifH gene, and 39% tested positive for acetylene reduction activity. Our results suggest that direct plating of soil dilutions on nitrogen-free solid medium under a 2% O(2) concentration is a useful strategy for the isolation of the diverse diazotrophic communities.
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Affiliation(s)
- Babur S Mirza
- Department of Biology, University of Texas, Arlington, Texas, USA
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Pereira CS, Thompson JA, Xavier KB. AI-2-mediated signalling in bacteria. FEMS Microbiol Rev 2012; 37:156-81. [PMID: 22712853 DOI: 10.1111/j.1574-6976.2012.00345.x] [Citation(s) in RCA: 348] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 06/06/2012] [Accepted: 06/08/2012] [Indexed: 02/06/2023] Open
Abstract
Success in nature depends upon an ability to perceive and adapt to the surrounding environment. Bacteria are not an exception; they recognize and constantly adjust to changing situations by sensing environmental and self-produced signals, altering gene expression accordingly. Autoinducer-2 (AI-2) is a signal molecule produced by LuxS, an enzyme found in many bacterial species and thus proposed to enable interspecies communication. Two classes of AI-2 receptors and many layers and interactions involved in downstream signalling have been identified so far. Although AI-2 has been implicated in the regulation of numerous niche-specific behaviours across the bacterial kingdom, interpretation of these results is complicated by the dual role of LuxS in signalling and the activated methyl cycle, a crucial central metabolic pathway. In this article, we present a comprehensive review of the discovery and early characterization of AI-2, current developments in signal detection, transduction and regulation, and the major studies investigating the phenotypes regulated by this molecule. The development of novel tools should help to resolve many of the remaining questions in the field; we highlight how these advances might be exploited in AI-2 quorum quenching, treatment of diseases, and the manipulation of beneficial behaviours caused by polyspecies communities.
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Arirachakaran P, Apinhasmit W, Paungmalit P, Jeramethakul P, Rerkyen P, Mahanonda R. Infection of human gingival fibroblasts with Aggregatibacter actinomycetemcomitans: An in vitro study. Arch Oral Biol 2012; 57:964-72. [DOI: 10.1016/j.archoralbio.2012.01.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 01/24/2012] [Accepted: 01/29/2012] [Indexed: 10/28/2022]
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Lönn-Stensrud J, Naemi AO, Benneche T, Petersen FC, Scheie AA. Thiophenones inhibitStaphylococcus epidermidisbiofilm formation at nontoxic concentrations. ACTA ACUST UNITED AC 2012; 65:326-34. [DOI: 10.1111/j.1574-695x.2012.00964.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 02/03/2012] [Accepted: 03/12/2012] [Indexed: 12/26/2022]
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Jang YJ, Choi YJ, Lee SH, Jun HK, Choi BK. Autoinducer 2 of Fusobacterium nucleatum as a target molecule to inhibit biofilm formation of periodontopathogens. Arch Oral Biol 2012; 58:17-27. [PMID: 22633049 DOI: 10.1016/j.archoralbio.2012.04.016] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Revised: 03/27/2012] [Accepted: 04/24/2012] [Indexed: 01/21/2023]
Abstract
Periodontitis is initiated by bacteria in subgingival biofilms, which are composed mostly of Gram-negative anaerobes. Autoinducer 2 (AI-2) is a universal quorum sensing (QS) molecule that mediates intergeneric signalling in multispecies bacterial communities and may induce biofilm formation. As Fusobacterium nucleatum is the major coaggregation bridge organism that links early colonising commensals and late pathogenic colonisers in dental biofilms via the accretion of periodontopathogens, we hypothesised that AI-2 of F. nucleatum contributes to this interspecies interaction, and interruption of this signalling could result in the inhibition of biofilm formation of periodontopathogens. To test this hypothesis, we evaluated the effect of partially purified F. nucleatum AI-2 on monospecies biofilm as well as mutualistic interactions between F. nucleatum and the so-called 'red complex' (Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia). Then we tested the effect of two QS inhibitors (QSIs), (5Z)-4-bromo-5-(bromomethylene)-2(5H)-furanone (furanone compound) and d-ribose, on AI-2-induced biofilm formation and coaggregation. F. nucleatum AI-2 remarkably induced biofilm growth of single and dual species and coaggregation between F. nucleatum and each species of the 'red complex', all of which were inhibited by the QSIs. F. nucleatum AI-2 induced the expression of the representative adhesion molecules of the periodontopathogens, which were inhibited by the QSIs. Our results demonstrate that F. nucleatum AI-2 plays an important role in inter- and intraspecies interactions between periodontopathogens via enhanced expression of adhesion molecules and may be a target for the inhibition of pathogenic dental biofilm formation.
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Affiliation(s)
- Yun-Ji Jang
- Department of Oral Microbiology and Immunology, School of Dentistry, Seoul National University, Seoul, Republic of Korea
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