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Liu C, Zhang H, Peng X, Blackledge MS, Furlani RE, Li H, Su Z, Melander RJ, Melander C, Michalek S, Wu H. Small Molecule Attenuates Bacterial Virulence by Targeting Conserved Response Regulator. mBio 2023; 14:e0013723. [PMID: 37074183 PMCID: PMC10294662 DOI: 10.1128/mbio.00137-23] [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: 01/19/2023] [Accepted: 01/23/2023] [Indexed: 04/20/2023] Open
Abstract
Antibiotic tolerance within a biofilm community presents a serious public health challenge. Here, we report the identification of a 2-aminoimidazole derivative that inhibits biofilm formation by two pathogenic Gram-positive bacteria, Streptococcus mutans and Staphylococcus aureus. In S. mutans, the compound binds to VicR, a key response regulator, at the N-terminal receiver domain, and concurrently inhibits expression of vicR and VicR-regulated genes, including the genes that encode the key biofilm matrix producing enzymes, Gtfs. The compound inhibits S. aureus biofilm formation via binding to a Staphylococcal VicR homolog. In addition, the inhibitor effectively attenuates S. mutans virulence in a rat model of dental caries. As the compound targets bacterial biofilms and virulence through a conserved transcriptional factor, it represents a promising new class of anti-infective agents that can be explored to prevent or treat a host of bacterial infections. IMPORTANCE Antibiotic resistance is a major public health issue due to the growing lack of effective anti-infective therapeutics. New alternatives to treat and prevent biofilm-driven microbial infections, which exhibit high tolerance to clinically available antibiotics, are urgently needed. We report the identification of a small molecule that inhibits biofilm formation by two important pathogenic Gram-positive bacteria, Streptococcus mutans and Staphylococcus aureus. The small molecule selectively targets a transcriptional regulator leading to attenuation of a biofilm regulatory cascade and concurrent reduction of bacterial virulence in vivo. As the regulator is highly conserved, the finding has broad implication for the development of antivirulence therapeutics that selectively target biofilms.
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Affiliation(s)
- Chang Liu
- Department of Pediatric Dentistry, University of Alabama at Birmingham Schools of Dentistry and Medicine, Birmingham, Alabama, USA
- Department of Microbiology, University of Alabama at Birmingham Schools of Dentistry and Medicine, Birmingham, Alabama, USA
| | - Hua Zhang
- Department of Pediatric Dentistry, University of Alabama at Birmingham Schools of Dentistry and Medicine, Birmingham, Alabama, USA
- Department of Integrative Biomedical & Diagnostic Sciences, Oregon Health & Science University School of Dentistry, Portland, Oregon, USA
- Department of Microbiology, University of Alabama at Birmingham Schools of Dentistry and Medicine, Birmingham, Alabama, USA
| | - Xian Peng
- Department of Pediatric Dentistry, University of Alabama at Birmingham Schools of Dentistry and Medicine, Birmingham, Alabama, USA
- Department of Microbiology, University of Alabama at Birmingham Schools of Dentistry and Medicine, Birmingham, Alabama, USA
| | - Meghan S. Blackledge
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Robert E. Furlani
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Haoting Li
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Zhaoming Su
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Roberta J. Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Christian Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Suzanne Michalek
- Department of Integrative Biomedical & Diagnostic Sciences, Oregon Health & Science University School of Dentistry, Portland, Oregon, USA
| | - Hui Wu
- Department of Pediatric Dentistry, University of Alabama at Birmingham Schools of Dentistry and Medicine, Birmingham, Alabama, USA
- Department of Integrative Biomedical & Diagnostic Sciences, Oregon Health & Science University School of Dentistry, Portland, Oregon, USA
- Department of Microbiology, University of Alabama at Birmingham Schools of Dentistry and Medicine, Birmingham, Alabama, USA
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2
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Li H, Miao MX, Jia CL, Cao YB, Yan TH, Jiang YY, Yang F. Interactions between Candida albicans and the resident microbiota. Front Microbiol 2022; 13:930495. [PMID: 36204612 PMCID: PMC9531752 DOI: 10.3389/fmicb.2022.930495] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 08/31/2022] [Indexed: 01/09/2023] Open
Abstract
Candida albicans is a prevalent, opportunistic human fungal pathogen. It usually dwells in the human body as a commensal, however, once in its pathogenic state, it causes diseases ranging from debilitating superficial to life-threatening systemic infections. The switch from harmless colonizer to virulent pathogen is, in most cases, due to perturbation of the fungus-host-microbiota interplay. In this review, we focused on the interactions between C. albicans and the host microbiota in the mouth, gut, blood, and vagina. We also highlighted important future research directions. We expect that the evaluation of these interplays will help better our understanding of the etiology of fungal infections and shed new light on the therapeutic approaches.
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Affiliation(s)
- Hao Li
- Department of Pharmacy, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, China,Department of Physiology and Pharmacology, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Ming-xing Miao
- Department of Physiology and Pharmacology, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Cheng-lin Jia
- Institute of Vascular Disease, Shanghai TCM-Integrated Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Yong-bing Cao
- Institute of Vascular Disease, Shanghai TCM-Integrated Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Tian-hua Yan
- Department of Physiology and Pharmacology, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China,*Correspondence: Tian-hua Yan,
| | - Yuan-ying Jiang
- Department of Pharmacy, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, China,Yuan-ying Jiang,
| | - Feng Yang
- Department of Pharmacy, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, China,Feng Yang,
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The Role of Glycoside Hydrolases in S. gordonii and C. albicans Interactions. Appl Environ Microbiol 2022; 88:e0011622. [PMID: 35506689 DOI: 10.1128/aem.00116-22] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Candida albicans can coaggregate with Streptococcus gordonii and cocolonize in the oral cavity. Saliva provides a vital microenvironment for close interactions of oral microorganisms. However, the level of fermentable carbohydrates in saliva is not sufficient to support the growth of multiple species. Glycoside hydrolases (GHs) that hydrolyze glycoproteins are critical for S. gordonii growth in low-fermentable-carbohydrate environments such as saliva. However, whether GHs are involved in the cross-kingdom interactions between C. albicans and S. gordonii under such conditions remains unknown. In this study, C. albicans and S. gordonii were cocultured in heart infusion broth with a low level of fermentable carbohydrate. Planktonic growth, biofilm formation, cell aggregation, and GH activities of monocultures and cocultures were examined. The results revealed that the planktonic growth of cocultured S. gordonii in a low-carbohydrate environment was elevated, while that of cocultured C. albicans was reduced. The biomass of S. gordonii in dual-species biofilms was higher than that of monocultures, while that of cocultured C. albicans was decreased. GH activity was observed in S. gordonii, and elevated activity of GHs was detected in S. gordonii-C. albicans cocultures, with elevated expression of GH-related genes of S. gordonii. By screening a mutant library of C. albicans, we identified a tec1Δ/Δ mutant strain that showed reduced ability to promote the growth and GH activities of S. gordonii compared with the wild-type strain. Altogether, the findings of this study demonstrate the involvement of GHs in the cross-kingdom metabolic interactions between C. albicans and S. gordonii in an environment with low level of fermentable carbohydrates. IMPORTANCE Cross-kingdom interactions between Candida albicans and oral streptococci such as Streptococcus gordonii have been reported. However, their interactions in a low-fermentable-carbohydrate environment like saliva is not clear. The current study revealed glycoside hydrolase-related cross-kingdom communications between S. gordonii and C. albicans under the low-fermentable-carbohydrate condition. We demonstrate that C. albicans can promote the growth and metabolic activities of S. gordonii by elevating the activities of cell-wall-anchored glycoside hydrolases of S. gordonii. C. albicans gene TEC1 is critical for this cross-kingdom metabolic communication.
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4
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Pohl CH. Recent Advances and Opportunities in the Study of Candida albicans Polymicrobial Biofilms. Front Cell Infect Microbiol 2022; 12:836379. [PMID: 35252039 PMCID: PMC8894716 DOI: 10.3389/fcimb.2022.836379] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 01/26/2022] [Indexed: 01/11/2023] Open
Abstract
It is well known that the opportunistic pathogenic yeast, Candida albicans, can form polymicrobial biofilms with a variety of bacteria, both in vitro and in vivo, and that these polymicrobial biofilms can impact the course and management of disease. Although specific interactions are often described as either synergistic or antagonistic, this may be an oversimplification. Polymicrobial biofilms are complex two-way interacting communities, regulated by inter-domain (inter-kingdom) signaling and various molecular mechanisms. This review article will highlight advances over the last six years (2016-2021) regarding the unique biology of polymicrobial biofilms formed by C. albicans and bacteria, including regulation of their formation. In addition, some of the consequences of these interactions, such as the influence of co-existence on antimicrobial susceptibility and virulence, will be discussed. Since the aim of this knowledge is to inform possible alternative treatment options, recent studies on the discovery of novel anti-biofilm compounds will also be included. Throughout, an attempt will be made to identify ongoing challenges in this area.
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Liu T, Yang R, Zhou J, Lu X, Yuan Z, Wei X, Guo L. Interactions Between Streptococcus gordonii and Fusobacterium nucleatum Altered Bacterial Transcriptional Profiling and Attenuated the Immune Responses of Macrophages. Front Cell Infect Microbiol 2022; 11:783323. [PMID: 35071038 PMCID: PMC8776643 DOI: 10.3389/fcimb.2021.783323] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Accepted: 12/15/2021] [Indexed: 12/24/2022] Open
Abstract
Interspecies coaggregation promotes transcriptional changes in oral bacteria, affecting bacterial pathogenicity. Streptococcus gordonii (S. gordonii) and Fusobacterium nucleatum (F. nucleatum) are common oral inhabitants. The present study investigated the transcriptional profiling of S. gordonii and F. nucleatum subsp. polymorphum in response to the dual-species coaggregation using RNA-seq. Macrophages were infected with both species to explore the influence of bacterial coaggregation on both species' abilities to survive within macrophages and induce inflammatory responses. Results indicated that, after the 30-min dual-species coaggregation, 116 genes were significantly up-regulated, and 151 genes were significantly down-regulated in S. gordonii; 97 genes were significantly down-regulated, and 114 genes were significantly up-regulated in F. nucleatum subsp. polymorphum. Multiple S. gordonii genes were involved in the biosynthesis and export of cell-wall proteins and carbohydrate metabolism. F. nucleatum subsp. polymorphum genes were mostly associated with translation and protein export. The coaggregation led to decreased expression levels of genes associated with lipopolysaccharide and peptidoglycan biosynthesis. Coaggregation between S. gordonii and F. nucleatum subsp. polymorphum significantly promoted both species' intracellular survival within macrophages and attenuated the production of pro-inflammatory cytokines IL-6 and IL-1β. Physical interactions between these two species promoted a symbiotic lifestyle and repressed macrophage's killing and pro-inflammatory responses.
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Affiliation(s)
- Tingjun Liu
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Ruiqi Yang
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Jiani Zhou
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Xianjun Lu
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Zijian Yuan
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Xi Wei
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Lihong Guo
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
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6
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Du Q, Yuan S, Zhao S, Fu D, Chen Y, Zhou Y, Cao Y, Gao Y, Xu X, Zhou X, He J. Coexistence of Candida albicans and Enterococcus faecalis increases biofilm virulence and periapical lesions in rats. BIOFOULING 2021; 37:964-974. [PMID: 34839774 DOI: 10.1080/08927014.2021.1993836] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The present study utilized an in vitro dual-species biofilm model and an in vivo rat post-treatment endodontic disease (PTED) model to investigate whether co-infection of Candida albicans and Enterococcus faecalis would aggravate periapical lesions. The results showed that co-culturing yielded a thicker and denser biofilm more tolerant to detrimental stresses compared with the mono-species biofilm, such as a starvation-alkalinity environment, mechanical shear force and bactericidal chemicals. Consistently, co-inoculation of E. faecalis and C. albicans significantly increased the extent of in vivo periapical lesions compared with mono-species infection. Specifically, coexistence of both microorganisms increased osteoclastic bone resorption and suppressed osteoblastic bone formation. The synergistic effects also up-regulated inflammatory cytokines including TNF-α and IL-6. In summary, coexistence of C. albicans and E. faecalis increased periapical lesions by enhanced biofilm virulence.
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Affiliation(s)
- Qian Du
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, China.,Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Hangzhou, China Laboratory of Oral Biomedical Research of Zhejiang Province, Hangzhou, China
| | - Shasha Yuan
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, China.,Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Shuangyuan Zhao
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, China
| | - Di Fu
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, China
| | - Yifei Chen
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, China
| | - Yuan Zhou
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, China.,Department of Pediatrics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yangpei Cao
- Woody L. Hunt School of Dental Medicine, Texas Tech University Health Sciences Center, EI Paso, TX, USA
| | - Yuan Gao
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, China.,Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xin Xu
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, China.,Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xuedong Zhou
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, China.,Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jinzhi He
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, China.,Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
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7
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Shokeen B, Dinis MDB, Haghighi F, Tran NC, Lux R. Omics and interspecies interaction. Periodontol 2000 2020; 85:101-111. [PMID: 33226675 DOI: 10.1111/prd.12354] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Interspecies interactions are key determinants in biofilm behavior, ecology, and architecture. The cellular responses of microorganisms to each other at transcriptional, proteomic, and metabolomic levels ultimately determine the characteristics of biofilm and the corresponding implications for health and disease. Advances in omics technologies have revolutionized our understanding of microbial community composition and their activities as a whole. Large-scale analyses of the complex interaction between the many microbial species residing within a biofilm, however, are currently still hampered by technical and bioinformatics challenges. Thus, studies of interspecies interactions have largely focused on the transcriptional and proteomic changes that occur during the contact of a few prominent species, such as Porphyromonas gingivalis, Streptococcus mutans, Candida albicans, and a few others, with selected partner species. Expansion of available tools is necessary to grow the revealing, albeit limited, insight these studies have provided into a profound understanding of the nature of individual microbial responses to the presence of others. This will allow us to answer important questions including: Which intermicrobial interactions orchestrate the myriad of cooperative, synergistic, antagonistic, manipulative, and other types of relationships and activities in the complex biofilm environment, and what are the implications for oral health and disease?
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Affiliation(s)
- Bhumika Shokeen
- Section of Periodontics, School of Dentistry, University of California at Los Angeles, Los Angeles, CA, USA
| | - Marcia Dalila Botelho Dinis
- Section of Pediatric Dentistry, School of Dentistry, University of California at Los Angeles, Los Angeles, CA, USA
| | - Farnoosh Haghighi
- Section of Periodontics, School of Dentistry, University of California at Los Angeles, Los Angeles, CA, USA
| | - Nini Chaichanasakul Tran
- Section of Pediatric Dentistry, School of Dentistry, University of California at Los Angeles, Los Angeles, CA, USA
| | - Renate Lux
- Section of Periodontics, School of Dentistry, University of California at Los Angeles, Los Angeles, CA, USA
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Deng L, Xue J, Jiang L, Zou L, Li W. [Research progress on interactions between Candida albicans and common oral pathogens]. HUA XI KOU QIANG YI XUE ZA ZHI = HUAXI KOUQIANG YIXUE ZAZHI = WEST CHINA JOURNAL OF STOMATOLOGY 2019; 37:671-676. [PMID: 31875449 DOI: 10.7518/hxkq.2019.06.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Increasing numbers of microbiome studies have enabled the development of a greater understanding of how antagonistic and synergetic microbial interactions influence disease outcomes. Candida albicans is an opportunistic pathogen that is commonly found in human oral microflora. In a healthy oral environment, Candida albicans may potentially but sig-nificantly influence the balance between the oral bacterial ecosystem and the host, leading tooral diseases. The aim of this study is to review the correlation between Candida albicans and oral pathogens and provide a deeper understanding of the nature of oral infec-tious diseases.
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Affiliation(s)
- Ling Deng
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Jing Xue
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Dept. of Conservative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Li Jiang
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Dept. of General Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Ling Zou
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Dept. of Conservative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Wei Li
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
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Robinson J, Rostami N, Casement J, Vollmer W, Rickard A, Jakubovics N. ArcR modulates biofilm formation in the dental plaque colonizerStreptococcus gordonii. Mol Oral Microbiol 2018; 33:143-154. [DOI: 10.1111/omi.12207] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/09/2017] [Indexed: 01/20/2023]
Affiliation(s)
- J.C. Robinson
- School of Dental Sciences; Newcastle University; Newcastle upon Tyne UK
| | - N. Rostami
- School of Dental Sciences; Newcastle University; Newcastle upon Tyne UK
| | - J. Casement
- Bioinformatics Support Unit; Newcastle University; Newcastle upon Tyne UK
| | - W. Vollmer
- Centre for Bacterial Cell Biology; Newcastle University; Newcastle upon Tyne UK
| | - A.H. Rickard
- Department of Epidemiology; School of Public Health; University of Michigan; Ann Arbor MI USA
| | - N.S. Jakubovics
- School of Dental Sciences; Newcastle University; Newcastle upon Tyne UK
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10
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Coordinated Regulation of the EII Man and fruRKI Operons of Streptococcus mutans by Global and Fructose-Specific Pathways. Appl Environ Microbiol 2017; 83:AEM.01403-17. [PMID: 28821551 DOI: 10.1128/aem.01403-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 08/15/2017] [Indexed: 11/20/2022] Open
Abstract
The glucose/mannose-phosphotransferase system (PTS) permease EIIMan encoded by manLMN in the dental caries pathogen Streptococcus mutans has a dominant influence on sugar-specific, CcpA-independent catabolite repression (CR). Mutations in manL affect energy metabolism and virulence-associated traits, including biofilm formation, acid tolerance, and competence. Using promoter::reporter fusions, expression of the manLMN and the fruRKI operons, encoding a transcriptional regulator, a fructose-1-phosphate kinase and a fructose-PTS permease EIIFru, respectively, was monitored in response to carbohydrate source and in mutants lacking CcpA, FruR, and components of EIIMan Expression of genes for EIIMan and EIIFru was directly regulated by CcpA and CR, as evinced by in vivo and in vitro methods. Unexpectedly, not only was the fruRKI operon negatively regulated by FruR, but also so was manLMN Carbohydrate transport by EIIMan had a negative influence on expression of manLMN but not fruRKI In agreement with the proposed role of FruR in regulating these PTS operons, loss of fruR or fruK substantially altered growth on a number of carbohydrates, including fructose. RNA deep sequencing revealed profound changes in gene regulation caused by deletion of fruK or fruR Collectively, these findings demonstrate intimate interconnection of the regulation of two major PTS permeases in S. mutans and reveal novel and important contributions of fructose metabolism to global regulation of gene expression.IMPORTANCE The ability of Streptococcus mutans and other streptococcal pathogens to survive and cause human diseases is directly dependent upon their capacity to metabolize a variety of carbohydrates, including glucose and fructose. Our research reveals that metabolism of fructose has broad influences on the regulation of utilization of glucose and other sugars, and mutants with changes in certain genes involved in fructose metabolism display profoundly different abilities to grow and express virulence-related traits. Mutants lacking the FruR regulator or a particular phosphofructokinase, FruK, display changes in expression of a large number of genes encoding transcriptional regulators, enzymes required for energy metabolism, biofilm development, biosynthetic and degradative processes, and tolerance of a spectrum of environmental stressors. Since fructose is a major component of the modern human diet, the results have substantial significance in the context of oral health and the development of dental caries.
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