1
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Treerat P, de Mattos C, Burnside M, Zhang H, Zhu Y, Zou Z, Anderson D, Wu H, Merritt J, Kreth J. Ribosomal-processing cysteine protease homolog modulates Streptococcus mutans glucan production and interkingdom interactions. J Bacteriol 2024; 206:e0010424. [PMID: 38899897 PMCID: PMC11270869 DOI: 10.1128/jb.00104-24] [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: 03/25/2024] [Accepted: 06/02/2024] [Indexed: 06/21/2024] Open
Abstract
Glucan-dependent biofilm formation is a crucial process in the establishment of Streptococcus mutans as a cariogenic oral microbe. The process of glucan formation has been investigated in great detail, with glycosyltransferases GtfB, GtfC, and GtfD shown to be indispensable for the synthesis of glucans from sucrose. Glucan production can be visualized during biofilm formation through fluorescent labeling, and its abundance, as well as the effect of glucans on general biofilm architecture, is a common phenotype to study S. mutans virulence regulation. Here, we describe an entirely new phenotype associated with glucan production, caused by a mutation in the open reading frame SMU_848, which is located in an operon encoding ribosome-associated proteins. This mutation led to the excess production and accumulation of glucan-containing droplets on the surface of biofilms formed on agar plates after prolonged incubation. While not characterized in S. mutans, SMU_848 shows homology to the phage-related ribosomal protease Prp, essential in cleaving off the N-terminal extension of ribosomal protein L27 for functional ribosome assembly in Staphylococcus aureus. We present a further characterization of SMU_848/Prp, demonstrating that the deletion of this gene leads to significant changes in S. mutans gtfBC expression. Surprisingly, it also profoundly impacts the interkingdom interaction between S. mutans and Candida albicans, a relevant dual-species interaction implicated in severe early childhood caries. The presented data support a potential broader role for SMU_848/Prp, possibly extending its functionality beyond the ribosomal network to influence important ecological processes. IMPORTANCE Streptococcus mutans is an important member of the oral biofilm and is implicated in the initiation of caries. One of the main virulence mechanisms is the glucan-dependent formation of biofilms. We identified a new player in the regulation of glucan production, SMU_848, which is part of an operon that also encodes for ribosomal proteins L27 and L21. A mutation in SMU_848, which encodes a phage-related ribosomal protease Prp, leads to a significant accumulation of glucan-containing droplets on S. mutans biofilms, a previously unknown phenotype. Further investigations expanded our knowledge about the role of SMU_848 beyond its role in glucan production, including significant involvement in interkingdom interactions, thus potentially playing a global role in the virulence regulation of S. mutans.
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Affiliation(s)
- Puthayalai Treerat
- Biomaterial and Biomedical Sciences, School of Dentistry, Oregon Health & Science University (OHSU), Portland, Oregon, USA
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, Virginia, USA
| | - Camilla de Mattos
- Biomaterial and Biomedical Sciences, School of Dentistry, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Molly Burnside
- Biomaterial and Biomedical Sciences, School of Dentistry, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Hua Zhang
- Biomaterial and Biomedical Sciences, School of Dentistry, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Yanting Zhu
- Biomaterial and Biomedical Sciences, School of Dentistry, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Zhengzhong Zou
- Biomaterial and Biomedical Sciences, School of Dentistry, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - David Anderson
- Biomaterial and Biomedical Sciences, School of Dentistry, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Hui Wu
- Biomaterial and Biomedical Sciences, School of Dentistry, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Justin Merritt
- Biomaterial and Biomedical Sciences, School of Dentistry, Oregon Health & Science University (OHSU), Portland, Oregon, USA
- Department of Molecular Microbiology and Immunology, School of Medicine, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Jens Kreth
- Biomaterial and Biomedical Sciences, School of Dentistry, Oregon Health & Science University (OHSU), Portland, Oregon, USA
- Department of Molecular Microbiology and Immunology, School of Medicine, Oregon Health & Science University (OHSU), Portland, Oregon, USA
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2
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Li J, Ma Q, Huang J, Liu Y, Zhou J, Yu S, Zhang Q, Lin Y, Wang L, Zou J, Li Y. Small RNA SmsR1 modulates acidogenicity and cariogenic virulence by affecting protein acetylation in Streptococcus mutans. PLoS Pathog 2024; 20:e1012147. [PMID: 38620039 PMCID: PMC11045139 DOI: 10.1371/journal.ppat.1012147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 04/25/2024] [Accepted: 03/25/2024] [Indexed: 04/17/2024] Open
Abstract
Post-transcriptional regulation by small RNAs and post-translational modifications (PTM) such as lysine acetylation play fundamental roles in physiological circuits, offering rapid responses to environmental signals with low energy consumption. Yet, the interplay between these regulatory systems remains underexplored. Here, we unveil the cross-talk between sRNAs and lysine acetylation in Streptococcus mutans, a primary cariogenic pathogen known for its potent acidogenic virulence. Through systematic overexpression of sRNAs in S. mutans, we identified sRNA SmsR1 as a critical player in modulating acidogenicity, a key cariogenic virulence feature in S. mutans. Furthermore, combined with the analysis of predicted target mRNA and transcriptome results, potential target genes were identified and experimentally verified. A direct interaction between SmsR1 and 5'-UTR region of pdhC gene was determined by in vitro binding assays. Importantly, we found that overexpression of SmsR1 reduced the expression of pdhC mRNA and increased the intracellular concentration of acetyl-CoA, resulting in global changes in protein acetylation levels. This was verified by acetyl-proteomics in S. mutans, along with an increase in acetylation level and decreased activity of LDH. Our study unravels a novel regulatory paradigm where sRNA bridges post-transcriptional regulation with post-translational modification, underscoring bacterial adeptness in fine-tuning responses to environmental stress.
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Affiliation(s)
- Jing Li
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Qizhao Ma
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jun Huang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yaqi Liu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jing Zhou
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Shuxing Yu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Qiong Zhang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yongwang Lin
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Lingyun Wang
- Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Jing Zou
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yuqing Li
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
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3
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Rued BE, Federle MJ. The ComRS-SigX Pathway Regulates Natural Transformation in Streptococcus ferus. J Bacteriol 2023; 205:e0008923. [PMID: 37195233 PMCID: PMC10294618 DOI: 10.1128/jb.00089-23] [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] [Received: 03/03/2023] [Accepted: 04/27/2023] [Indexed: 05/18/2023] Open
Abstract
The ability to take up and incorporate foreign DNA via natural transformation is a well-known characteristic of some species of Streptococcus, and is a mechanism that rapidly allows for the acquisition of antibacterial resistance. Here, we describe that the understudied species Streptococcus ferus is also capable of natural transformation and uses a system analogous to that identified in Streptococcus mutans. S. mutans natural transformation is under the control of the alternative sigma factor sigX (also known as comX), whose expression is induced by two types of peptide signals: CSP (competence stimulating peptide, encoded by comC) and XIP (sigX-inducing peptide, encoded by comS). These systems induce competence via either the two-component signal-transduction system ComDE or the RRNPP transcriptional regulator ComR, respectively. Protein and nucleotide homology searches identified putative orthologs of comRS and sigX in S. ferus, but not homologs of S. mutans blpRH (also known as comDE). We demonstrate that natural transformation in S. ferus is induced by a small, double-tryptophan containing sigX-inducing peptide (XIP), akin to that of S. mutans, and requires the presence of the comR and sigX orthologs for efficient transformation. Additionally, we find that natural transformation is induced in S. ferus by both the native XIP and the XIP variant of S. mutans, implying that cross talk between the two species is possible. This process has been harnessed to construct gene deletions in S. ferus and provides a method to genetically manipulate this understudied species. IMPORTANCE Natural transformation is the process by which bacteria take up DNA and allows for acquisition of new genetic traits, including those involved in antibiotic resistance. This study demonstrates that the understudied species Streptococcus ferus is capable of natural transformation using a peptide-pheromone system like that previously identified in Streptococcus mutans and provides a framework for future studies concerning this organism.
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Affiliation(s)
- Britta E. Rued
- Department of Pharmaceutical Sciences, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Michael J. Federle
- Department of Pharmaceutical Sciences, University of Illinois at Chicago, Chicago, Illinois, USA
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4
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Rued BE, Federle MJ. The ComRS-SigX pathway regulates natural transformation in Streptococcus ferus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.06.531454. [PMID: 36945404 PMCID: PMC10028898 DOI: 10.1101/2023.03.06.531454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
Abstract
The ability to take up and incorporate foreign DNA via natural transformation is a well-known characteristic of some species of Streptococcus, and is a mechanism that rapidly allows for the acquisition of antibacterial resistance. Here, we describe that the understudied species Streptococcus ferus is also capable of natural transformation and uses a system analogous to that identified in Streptococcus mutans . S. mutans natural transformation is under the control of the alternative sigma factor sigX (also known as comX ), whose expression is induced by two types of peptide signals: CSP ( c ompetence s timulating p eptide, encoded by comC ) and XIP ( sig X -inducing p eptide, encoded by comS ). These systems induce competence via either the two-component signal-transduction system ComDE or the RRNPP transcriptional regulator ComR, respectively. Protein and nucleotide homology searches identified putative orthologs of comRS and sigX in S. ferus , but not homologs of S. mutans blpRH (also known as comDE ). We demonstrate that natural transformation in S. ferus is induced by a small, double-tryptophan containing competence-inducing peptide (XIP), akin to that of S. mutans , and requires the presence of the comR and sigX orthologs for efficient transformation. Additionally, we find that natural transformation is induced in S. ferus by both the native XIP and the XIP variant of S. mutans , implying that crosstalk between the two species is possible. This process has been harnessed to construct gene deletions in S. ferus and provides a method to genetically manipulate this understudied species. IMPORTANCE Natural transformation is the process by which bacteria take up DNA and allows for acquisition of new genetic traits, including those involved in antibiotic resistance. This study demonstrates that the understudied species Streptococcus ferus is capable of natural transformation using a peptide-pheromone system like that previously identified in Streptococcus mutans and provides a framework for future studies concerning this organism.
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5
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Polizzi A, Donzella M, Nicolosi G, Santonocito S, Pesce P, Isola G. Drugs for the Quorum Sensing Inhibition of Oral Biofilm: New Frontiers and Insights in the Treatment of Periodontitis. Pharmaceutics 2022; 14:2740. [PMID: 36559234 PMCID: PMC9781207 DOI: 10.3390/pharmaceutics14122740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 12/01/2022] [Accepted: 12/06/2022] [Indexed: 12/13/2022] Open
Abstract
Chemical molecules are used by microorganisms to communicate with each other. Quorum sensing is the mechanism through which microorganisms regulate their population density and activity with chemical signaling. The inhibition of quorum sensing, called quorum quenching, may disrupt oral biofilm formation, which is the main etiological factor of oral diseases, including periodontitis. Periodontitis is a chronic inflammatory disorder of infectious etiology involving the hard and soft periodontal tissues and which is related to various systemic disorders, including cardiovascular diseases, diabetes and obesity. The employment of adjuvant therapies to traditional scaling and root planing is currently being studied to further reduce the impact of periodontitis. In this sense, using antibiotics and antiseptics involves non-negligible risks, such as antibiotic resistance phenomena and hinders the re-establishment of eubiosis. Different quorum sensing signal molecules have been identified in periodontal pathogenic oral bacteria. In this regard, quorum sensing inhibitors are emerging as some interesting solutions for the management of periodontitis. Therefore, the aim of this review is to summarize the current state of knowledge on the mechanisms of quorum sensing signal molecules produced by oral biofilm and to analyze the potential of quorum sensing inhibitors for the management of periodontitis.
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Affiliation(s)
- Alessandro Polizzi
- Department of General Surgery and Surgical-Medical Specialties, School of Dentistry, University of Catania, Via Sofia 78, 95125 Catania, Italy
- Department of Surgical Sciences (DISC), University of Genova, 16132 Genoa, Italy
| | - Martina Donzella
- Department of General Surgery and Surgical-Medical Specialties, School of Dentistry, University of Catania, Via Sofia 78, 95125 Catania, Italy
| | - Giada Nicolosi
- Department of General Surgery and Surgical-Medical Specialties, School of Dentistry, University of Catania, Via Sofia 78, 95125 Catania, Italy
| | - Simona Santonocito
- Department of General Surgery and Surgical-Medical Specialties, School of Dentistry, University of Catania, Via Sofia 78, 95125 Catania, Italy
| | - Paolo Pesce
- Department of Surgical Sciences (DISC), University of Genova, 16132 Genoa, Italy
| | - Gaetano Isola
- Department of General Surgery and Surgical-Medical Specialties, School of Dentistry, University of Catania, Via Sofia 78, 95125 Catania, Italy
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6
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Quorum Sensing and Quorum Quenching with a Focus on Cariogenic and Periodontopathic Oral Biofilms. Microorganisms 2022; 10:microorganisms10091783. [PMID: 36144385 PMCID: PMC9503171 DOI: 10.3390/microorganisms10091783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 08/31/2022] [Accepted: 09/01/2022] [Indexed: 11/17/2022] Open
Abstract
Numerous in vitro studies highlight the role of quorum sensing in the pathogenicity and virulence of biofilms. This narrative review discusses general principles in quorum sensing, including Gram-positive and Gram-negative models and the influence of flow, before focusing on quorum sensing and quorum quenching in cariogenic and periodontopathic biofilms. In cariology, quorum sensing centres on the role of Streptococcus mutans, and to a lesser extent Candida albicans, while Fusobacterium nucleatum and the red complex pathogens form the basis of the majority of the quorum sensing research on periodontopathic biofilms. Recent research highlights developments in quorum quenching, also known as quorum sensing inhibition, as a potential antimicrobial tool to attenuate the pathogenicity of oral biofilms by the inhibition of bacterial signalling networks. Quorum quenchers may be synthetic or derived from plant or bacterial products, or human saliva. Furthermore, biofilm inhibition by coating quorum sensing inhibitors on dental implant surfaces provides another potential application of quorum quenching technologies in dentistry. While the body of predominantly in vitro research presented here is steadily growing, the clinical value of quorum sensing inhibitors against in vivo oral polymicrobial biofilms needs to be ascertained.
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7
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Brennan AA, Mehrani M, Tal-Gan Y. Modulating streptococcal phenotypes using signal peptide analogues. Open Biol 2022; 12:220143. [PMID: 35920042 PMCID: PMC9346555 DOI: 10.1098/rsob.220143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Understanding bacterial communication mechanisms is imperative to improve our current understanding of bacterial infectivity and find alternatives to current modes of antibacterial therapeutics. Both Gram-positive and Gram-negative bacteria use quorum sensing (QS) to regulate group behaviours and associated phenotypes in a cell-density-dependent manner. Group behaviours, phenotypic expression and resultant infection and disease can largely be attributed to efficient bacterial communication. Of particular interest are the communication mechanisms of Gram-positive bacteria known as streptococci. This group has demonstrated marked resistance to traditional antibiotic treatment, resulting in increased morbidity and mortality of infected hosts and an ever-increasing burden on the healthcare system. Modulating circuits and mechanisms involved in streptococcal communication has proven to be a promising anti-virulence therapeutic approach that allows managing bacterial phenotypic response but does not affect bacterial viability. Targeting the chemical signals bacteria use for communication is a promising starting point, as manipulation of these signals can dramatically affect resultant bacterial phenotypes, minimizing associated morbidity and mortality. This review will focus on the use of modified peptide signals in modulating the development of proliferative phenotypes in different streptococcal species, specifically regarding how such modification can attenuate bacterial infectivity and aid in developing future alternative therapeutic agents.
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Affiliation(s)
- Alec A Brennan
- Department of Chemistry, University of Nevada, Reno, 1664 N. Virginia St., Reno, NV 89557, USA
| | - Mona Mehrani
- Department of Chemistry, University of Nevada, Reno, 1664 N. Virginia St., Reno, NV 89557, USA
| | - Yftah Tal-Gan
- Department of Chemistry, University of Nevada, Reno, 1664 N. Virginia St., Reno, NV 89557, USA
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8
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O'Connell LM, Kelleher P, van Rijswijck IMH, de Waal P, van Peij NNME, Mahony J, van Sinderen D. Natural Transformation in Gram-Positive Bacteria and Its Biotechnological Relevance to Lactic Acid Bacteria. Annu Rev Food Sci Technol 2022; 13:409-431. [PMID: 35333592 DOI: 10.1146/annurev-food-052720-011445] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Competence refers to the specialized physiological state in which bacteria undergo transformation through the internalization of exogenous DNA in a controlled and genetically encoded process that leads to genotypic and, in many cases, phenotypic changes. Natural transformation was first described in Streptococcus pneumoniae and has since been demonstrated in numerous species, including Bacillus subtilis and Neisseria gonorrhoeae. Homologs of the genes encoding the DNA uptake machinery for natural transformation have been reported to be present in several lactic acid bacteria, including Lactobacillus spp., Streptococcus thermophilus, and Lactococcus spp. In this review, we collate current knowledge of the phenomenon of natural transformation in Gram-positive bacteria. Furthermore, we describe the mechanism of competence development and its regulation in model bacterial species. We highlight the importance and opportunities for the application of these findings in the context of bacterial starter cultures associated with food fermentations as well as current limitations in this area of research.
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Affiliation(s)
- Laura M O'Connell
- APC Microbiome Ireland and School of Microbiology, University College Cork, Cork, Ireland;
| | - Philip Kelleher
- APC Microbiome Ireland and School of Microbiology, University College Cork, Cork, Ireland;
| | | | - Paul de Waal
- DSM Biotechnology Center, Delft, The Netherlands
| | | | - Jennifer Mahony
- APC Microbiome Ireland and School of Microbiology, University College Cork, Cork, Ireland;
| | - Douwe van Sinderen
- APC Microbiome Ireland and School of Microbiology, University College Cork, Cork, Ireland;
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9
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Kang J, Zhou X, Zhang W, Pei F, Ge J. Transcriptomic analysis of bacteriocin synthesis and stress response in Lactobacillus paracasei HD1.7 under acetic acid stress. Lebensm Wiss Technol 2022. [DOI: 10.1016/j.lwt.2021.112897] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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10
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Rebuffat S. Ribosomally synthesized peptides, foreground players in microbial interactions: recent developments and unanswered questions. Nat Prod Rep 2021; 39:273-310. [PMID: 34755755 DOI: 10.1039/d1np00052g] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
It is currently well established that multicellular organisms live in tight association with complex communities of microorganisms including a large number of bacteria. These are immersed in complex interaction networks reflecting the relationships established between them and with host organisms; yet, little is known about the molecules and mechanisms involved in these mutual interactions. Ribosomally synthesized peptides, among which bacterial antimicrobial peptides called bacteriocins and microcins have been identified as contributing to host-microbe interplays, are either unmodified or post-translationally modified peptides. This review will unveil current knowledge on these ribosomal peptide-based natural products, their interplay with the host immune system, and their roles in microbial interactions and symbioses. It will include their major structural characteristics and post-translational modifications, the main rules of their maturation pathways, and the principal ecological functions they ensure (communication, signalization, competition), especially in symbiosis, taking select examples in various organisms. Finally, we address unanswered questions and provide a framework for deciphering big issues inspiring future directions in the field.
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Affiliation(s)
- Sylvie Rebuffat
- Laboratory Molecules of Communication and Adaptation of Microorganisms (MCAM, UMR 7245 CNRS-MNHN), National Museum of Natural History (MNHN), National Centre of Scientific Research (CNRS), CP 54, 57 rue Cuvier 75005, Paris, France.
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11
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The transcription regulator BrsR serves as a network hub of natural competence protein-protein interactions in Streptococcus mutans. Proc Natl Acad Sci U S A 2021; 118:2106048118. [PMID: 34544866 DOI: 10.1073/pnas.2106048118] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/13/2021] [Indexed: 11/18/2022] Open
Abstract
Genome evolution is an essential and stringently regulated aspect of biological fitness. For bacteria, natural competence is one of the principal mechanisms of genome evolution and is frequently subject to multiple layers of regulation derived from a plethora of environmental and physiological stimuli. Here, we present a regulatory mechanism that illustrates how such disparate stimuli can be integrated into the Streptococcus mutans natural competence phenotype. S. mutans possesses an intriguing, but poorly understood ability to coordinately control its independently regulated natural competence and bacteriocin genetic pathways as a means to acquire DNA released from closely related, bacteriocin-susceptible streptococci. Our results reveal how the bacteriocin-specific transcription activator BrsR directly mediates this coordination by serving as an anti-adaptor protein responsible for antagonizing the proteolysis of the inherently unstable, natural competence-specific alternative sigma factor ComX. This BrsR ability functions entirely independent of its transcription regulator function and directly modulates the timing and severity of the natural competence phenotype. Additionally, many of the DNA uptake proteins produced by the competence system were surprisingly found to possess adaptor abilities, which are employed to terminate the BrsR regulatory circuit via negative feedback. BrsR-competence protein heteromeric complexes directly inhibit nascent brsR transcription as well as stimulate the Clp-dependent proteolysis of extant BrsR proteins. This study illustrates how critical genetic regulatory abilities can evolve in a potentially limitless variety of proteins without disrupting their conserved ancestral functions. These unrecognized regulatory abilities are likely fundamental for transducing information through complex genetic networks.
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12
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Kaspar JR, Lee K, Richard B, Walker AR, Burne RA. Direct interactions with commensal streptococci modify intercellular communication behaviors of Streptococcus mutans. THE ISME JOURNAL 2021; 15:473-488. [PMID: 32999420 PMCID: PMC8027600 DOI: 10.1038/s41396-020-00789-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 09/10/2020] [Accepted: 09/18/2020] [Indexed: 02/07/2023]
Abstract
The formation of dental caries is a complex process that ultimately leads to damage of the tooth enamel from acids produced by microbes in attached biofilms. The bacterial interactions occurring within these biofilms between cariogenic bacteria, such as the mutans streptococci, and health-associated commensal streptococci, are thought to be critical determinants of health and disease. To better understand these interactions, a Streptococcus mutans reporter strain that actively monitors cell-cell communication via peptide signaling was cocultured with different commensal streptococci. Signaling by S. mutans, normally highly active in monoculture, was completely inhibited by several species of commensals, but only when the bacteria were in direct contact with S. mutans. We identified a novel gene expression pattern that occurred in S. mutans when cultured directly with these commensals. Finally, mutant derivatives of commensals lacking previously shown antagonistic gene products displayed wild-type levels of signal inhibition in cocultures. Collectively, these results reveal a novel pathway(s) in multiple health-associated commensal streptococci that blocks peptide signaling and induces a common contact-dependent pattern of differential gene expression in S. mutans. Understanding the molecular basis for this inhibition will assist in the rational design of new risk assessments, diagnostics, and treatments for the most pervasive oral infectious diseases.
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Affiliation(s)
- Justin R Kaspar
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA.
- Division of Biosciences, College of Dentistry, Ohio State University, Columbus, OH, USA.
| | - Kyulim Lee
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
| | - Brook Richard
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
| | - Alejandro R Walker
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
| | - Robert A Burne
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
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13
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García-Curiel L, Del Rocío López-Cuellar M, Rodríguez-Hernández AI, Chavarría-Hernández N. Toward understanding the signals of bacteriocin production by Streptococcus spp. and their importance in current applications. World J Microbiol Biotechnol 2021; 37:15. [PMID: 33394178 DOI: 10.1007/s11274-020-02973-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Accepted: 12/01/2020] [Indexed: 12/25/2022]
Abstract
Microorganisms have developed quorum sensing (QS) systems to detect small signaling molecules that help to control access to additional nutrients and space in highly competitive polymicrobial niches. Many bacterial processes are QS-regulated; two examples are the highly related traits of the natural genetic competence state and the production of antimicrobial peptides such as bacteriocins. The Streptococcus genus is widely studied for its competence and for its ability to produce bacteriocins, as these antimicrobial peptides have significant potential in the treatment of infections caused by multiple-resistant pathogens, a severe public health issue. The transduction of a two-component system controls competence in streptococci: (1) ComD/E, which controls the competence in the Mitis and Anginosus groups, and (2) ComR/S, which performs the same function in the Bovis, Mutans, Salivarius, and Pyogenic groups. The cell-to-cell communication required for bacteriocin production in the Streptococcus groups is controlled mainly by a paralog of the ComD/E system. The relationships between pheromone signals and induction pathways are related to the bacteriocin production systems. In this review, we discuss the recent advances in the understanding of signaling and the induction of bacteriocin biosynthesis by QS regulation in streptococci. This information could aid in the design of better methods for the development and production of these antimicrobial peptides. It could also contribute to the analysis and emerging applications of bacteriocins in terms of their safety, quality, and human health benefits.
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Affiliation(s)
- Laura García-Curiel
- Cuerpo Académico de Biotecnología Agroalimentaria, Instituto de Ciencias Agropecuarias-Universidad Autónoma del Estado de Hidalgo, Tulancingo de Bravo, México
| | - Ma Del Rocío López-Cuellar
- Cuerpo Académico de Biotecnología Agroalimentaria, Instituto de Ciencias Agropecuarias-Universidad Autónoma del Estado de Hidalgo, Tulancingo de Bravo, México.
| | - Adriana Inés Rodríguez-Hernández
- Cuerpo Académico de Biotecnología Agroalimentaria, Instituto de Ciencias Agropecuarias-Universidad Autónoma del Estado de Hidalgo, Tulancingo de Bravo, México
| | - Norberto Chavarría-Hernández
- Cuerpo Académico de Biotecnología Agroalimentaria, Instituto de Ciencias Agropecuarias-Universidad Autónoma del Estado de Hidalgo, Tulancingo de Bravo, México
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Bikash CR, Tal-Gan Y. Structure Activity Relationship Study of the XIP Quorum Sensing Pheromone in Streptococcus mutans Reveal Inhibitors of the Competence Regulon. ACS Chem Biol 2020; 15:2833-2841. [PMID: 32946208 DOI: 10.1021/acschembio.0c00650] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The dental cariogenic pathogen Streptococcus mutans coordinates competence for genetic transformation via two peptide pheromones, competence stimulating peptide (CSP) and comX-inducing peptide (XIP). CSP is sensed by the comCDE system and induces competence indirectly, whereas XIP is sensed by the comRS system and induces competence directly. In chemically defined media (CDM), after uptake by oligopeptide permease, XIP interacts with the cytosolic receptor ComR to form the XIP::ComR complex that activates the expression of comX, an alternative sigma factor that initiates the transcription of late-competence genes. In this study, we set out to determine the molecular mechanism of XIP::ComR interaction. To this end, we performed systematic replacement of the amino acid residues in the XIP pheromone and assessed the ability of the mutated analogs to modulate the competence regulon in CDM. We were able to identify structural features that are important to ComR binding and activation. Our structure-activity relationship insights led us to construct multiple XIP-based inhibitors of the comRS pathway. Furthermore, when comCDE and comRS were both stimulated with CSP and XIP, respectively, a lead XIP-based inhibitor was able to maintain the inhibitory activity. Last, phenotypic assays were used to highlight the potential of XIP-based inhibitors to attenuate pathogenicity in S. mutans and to validate the specificity of these compounds to the comRS pathway within the competence regulon. The XIP-based inhibitors developed in this study can be used as lead scaffolds for the design and development of potential therapeutics against S. mutans infections.
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Affiliation(s)
- Chowdhury Raihan Bikash
- Department of Chemistry, University of Nevada, Reno, 1664 North Virginia Street, Reno, Nevada 89557, United States
| | - Yftah Tal-Gan
- Department of Chemistry, University of Nevada, Reno, 1664 North Virginia Street, Reno, Nevada 89557, United States
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Ricomini Filho AP, Khan R, Åmdal HA, Petersen FC. Conserved Pheromone Production, Response and Degradation by Streptococcus mutans. Front Microbiol 2019; 10:2140. [PMID: 31572344 PMCID: PMC6753979 DOI: 10.3389/fmicb.2019.02140] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 08/30/2019] [Indexed: 01/27/2023] Open
Abstract
Streptococcus mutans, a bacterium with high cariogenic potential, coordinates competence for natural transformation and bacteriocin production via the XIP and CSP pheromones. CSP is effective in inducing bacteriocin responses but not competence in chemically defined media (CDM). This is in contrast to XIP, which is a strong inducer of competence in CDM but can also stimulate bacteriocin genes as a late response. Interconnections between the pathways activated by the two pheromones have been characterized in certain detail in S. mutans UA159, but it is mostly unknown whether such findings are representative for the species. In this study, we used bioassays based on luciferase reporters for the bacteriocin gene cipB and the alternative sigma factor sigX to investigate various S. mutans isolates for production and response to CSP and XIP pheromones in CDM. Similar to S. mutans UA159, endogenous CSP was undetectable in the culture supernatants of all tested strains. During optimization of the bioassay using the cipB reporter, we discovered that the activity of exogenous CSP used as a standard was reduced over time during S. mutans growth. Using a FRET-CSP reporter peptide, we found that S. mutans UA159 was able to degrade CSP, and that such activity was not significantly different in isogenic mutants with deletion of the protease gene htrA or the competence genes sigX, oppD, and comR. CSP cleavage was also detected in all the wild type strains, indicating that this is a conserved feature in S. mutans. For the XIP pheromone, endogenous production was observed in the supernatants of all 34 tested strains at peak concentrations in culture supernatants that varied between 200 and 26000 nM. Transformation in the presence of exogenous XIP was detected in all but one of the isolates. The efficiency of transformation varied, however, among the different strains, and for those with the highest transformation rates, endogenous XIP peak concentrations in the supernatants were above 2000 nM XIP. We conclude that XIP production and inducing effect on transformation, as well as the ability to degrade CSP, are conserved functions among different S. mutans isolates. Understanding the functionality and conservation of pheromone systems in S. mutans may lead to novel strategies to prevent or treat unbalances in oral microbiomes that may favor diseases.
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Affiliation(s)
| | - Rabia Khan
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - Heidi Aarø Åmdal
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - Fernanda C. Petersen
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
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