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Rush JS, Zamakhaeva S, Murner NR, Deng P, Morris AJ, Kenner CW, Black I, Heiss C, Azadi P, Korotkov KV, Widmalm G, Korotkova N. Structure and mechanism of biosynthesis of Streptococcus mutans cell wall polysaccharide. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.09.593426. [PMID: 38766245 PMCID: PMC11100793 DOI: 10.1101/2024.05.09.593426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Streptococcus mutans, the causative agent of human dental caries, expresses a cell wall attached Serotype c- specific Carbohydrate (SCC) that is critical for cell viability. SCC consists of a repeating →3)α-Rha(1→2)α-Rha(1→ polyrhamnose backbone, with glucose (Glc) side-chains and glycerol phosphate (GroP) decorations. This study reveals that SCC has one major and two minor Glc modifications. The major Glc modification, α-Glc, attached to position 2 of 3-rhamnose, is installed by SccN and SccM glycosyltransferases and is the site of the GroP addition. The minor Glc modifications are β-Glc linked to position 4 of 3-rhamnose installed by SccP and SccQ glycosyltransferases, and α-Glc attached to position 4 of 2-rhamnose installed by SccN working in tandem with an unknown enzyme. Both the major and the minor β-Glc modifications control bacterial morphology, but only the GroP and major Glc modifications are critical for biofilm formation.
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Chamlagain M, Hu J, Sionov RV, Steinberg D. Anti-bacterial and anti-biofilm activities of arachidonic acid against the cariogenic bacterium Streptococcus mutans. Front Microbiol 2024; 15:1333274. [PMID: 38596377 PMCID: PMC11002910 DOI: 10.3389/fmicb.2024.1333274] [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: 11/04/2023] [Accepted: 02/16/2024] [Indexed: 04/11/2024] Open
Abstract
Streptococcus mutans is a Gram-positive, facultative anaerobic bacterium, which causes dental caries after forming biofilms on the tooth surface while producing organic acids that demineralize enamel and dentin. We observed that the polyunsaturated arachidonic acid (AA) (ω-6; 20:4) had an anti-bacterial activity against S. mutans, which prompted us to investigate its mechanism of action. The minimum inhibitory concentration (MIC) of AA on S. mutans was 25 μg/ml in the presence of 5% CO2, while it was reduced to 6.25-12.5 μg/ml in the absence of CO2 supplementation. The anti-bacterial action was due to a combination of bactericidal and bacteriostatic effects. The minimum biofilm inhibitory concentration (MBIC) was the same as the MIC, suggesting that part of the anti-biofilm effect was due to the anti-bacterial activity. Gene expression studies showed decreased expression of biofilm-related genes, suggesting that AA also has a specific anti-biofilm effect. Flow cytometric analyses using potentiometric DiOC2(3) dye, fluorescent efflux pump substrates, and live/dead SYTO 9/propidium iodide staining showed that AA leads to immediate membrane hyperpolarization, altered membrane transport and efflux pump activities, and increased membrane permeability with subsequent membrane perforation. High-resolution scanning electron microscopy (HR-SEM) showed remnants of burst bacteria. Furthermore, flow cytometric analysis using the redox probe 2',7'-dichlorofluorescein diacetate (DCFHDA) showed that AA acts as an antioxidant in a dose-dependent manner. α-Tocopherol, an antioxidant that terminates the radical chain, counteracted the anti-bacterial activity of AA, suggesting that oxidation of AA in bacteria leads to the production of cytotoxic radicals that contribute to bacterial growth arrest and death. Importantly, AA was not toxic to normal Vero epithelial cells even at 100 μg/ml, and it did not cause hemolysis of erythrocytes. In conclusion, our study shows that AA is a potentially safe drug that can be used to reduce the bacterial burden of cariogenic S. mutans.
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Affiliation(s)
- Manoj Chamlagain
- Institute of Biomedical and Oral Research (IBOR), The Faculty of Dental Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
- Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong SAR, China
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Jieni Hu
- Institute of Biomedical and Oral Research (IBOR), The Faculty of Dental Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Ronit Vogt Sionov
- Institute of Biomedical and Oral Research (IBOR), The Faculty of Dental Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Doron Steinberg
- Institute of Biomedical and Oral Research (IBOR), The Faculty of Dental Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
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Huang X, Laird CG, Riley PP, Wen ZT. Impacts of a DUF2207 Family Protein on Streptococcus mutans Stress Tolerance Responses and Biofilm Formation. Microorganisms 2023; 11:1982. [PMID: 37630542 PMCID: PMC10457818 DOI: 10.3390/microorganisms11081982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 07/30/2023] [Accepted: 07/31/2023] [Indexed: 08/27/2023] Open
Abstract
Locus SMU.243 in Streptococcus mutans was annotated as a member of the DUF2207 family proteins highly conserved in all bacteria but with unknown function. To investigate its role in S. mutans physiology, a SMU.243-deficient mutant was constructed using allelic exchange mutagenesis, and the impacts of SMU.243 deletion on bacterial growth, stress tolerance response, and biofilm formation were analyzed. Compared to the wild-type UA159, S. mutans lacking SMU.243 displayed a reduced growth rate and a reduced overnight culture density (p < 0.01) when grown at low pH and in the presence of methyl viologen. Relative to the parent strain, the deficient mutant also had a reduced survival rate following incubation in a buffer of pH 2.8 (p < 0.01) and in a buffer containing hydrogen peroxide at 58 mM after 60 min (p < 0.001) and had a reduced capacity in biofilm formation especially in the presence of sucrose (p < 0.01). To study any ensuing functional/phenotypical links between SMU.243 and uppP, which is located immediately downstream of SMU.243 and encodes an undecaprenyl pyrophosphate phosphatase involved in recycling of carrier lipid undecaprenyl phosphate, a uppP deficient mutant was generated using allelic exchange mutagenesis. Unlike the SMU.243 mutant, deletion of uppP affected cell envelope biogenesis and caused major increases in susceptibility to bacitracin. In addition, two variant morphological mutants, one forming rough colonies and the other forming mucoid, smooth colonies, also emerged following the deletion of uppP. The results suggest that the SMU.243-encoded protein of the DUF2207 family in S. mutans plays an important role in stress tolerance response and biofilm formation, but unlike the downstream uppP, does not seem to be involved in cell envelope biogenesis, although the exact roles in S. mutans' physiology awaits further investigation.
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Affiliation(s)
- Xiaochang Huang
- Department of Oral and Craniofacial Biology, School of Dentistry, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA; (X.H.); (P.P.R.)
| | - Camile G. Laird
- Department of Oral and Craniofacial Biology, School of Dentistry, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA; (X.H.); (P.P.R.)
| | - Paul P. Riley
- Department of Oral and Craniofacial Biology, School of Dentistry, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA; (X.H.); (P.P.R.)
| | - Zezhang Tom Wen
- Department of Oral and Craniofacial Biology, School of Dentistry, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA; (X.H.); (P.P.R.)
- Department of Microbiology, Immunology and Parasitology, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
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Ke L, Wang J, Liu Y, Sun Z, Li Y, Xiao X. Identification of the antibacterial action mechanism of curcumin on Streptococcus mutans through transcriptome profiling. Arch Oral Biol 2023; 149:105655. [PMID: 36842372 DOI: 10.1016/j.archoralbio.2023.105655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 02/11/2023] [Accepted: 02/13/2023] [Indexed: 02/17/2023]
Abstract
OBJECTIVE The purpose of this study was to explore the effect and mechanism responsible for how curcumin affects the biofilm formation by Streptococcus mutans (S. mutans). DESIGN The antibacterial activity of curcumin was evaluated by measuring the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). The mass of the biofilm was measured by crystal violet staining. Transcriptome sequencing was used to obtain all the transcript information associated with the biological activity of curcumin-treated S. mutans. Real-time quantitative PCR (qRT-PCR) was performed to examine the expression levels of related biofilm formation genes. RESULTS The MIC value for curcumin was 64 μM. Curcumin inhibited the formation of a biofilm by S. mutans and degraded mature biofilms. A gene ontology enrichment analysis showed that the DEGs were significantly relevant to biofilm formation. In addition, 17 significantly enriched Kyoto Encyclopedia of Genes and Genomes pathways (p ≤ 0.01) were identified and were potentially associated with the biochemical metabolic processes of S. mutans. DEGs associated with the biofilm formation of S. mutants, including gtfB, gtfC, rgpG, spaP, spxA1, spxA2, bacA, lrgB, and gshAB. The qRT-PCR results were consistent with transcriptome sequencing that the expression levels of gtfB, gtfC, rgpG, and spaP significantly decreased in the curcumin-treated group, whereas the expression levels of spx1, spx2, bacA, lrgB, and gshAB were up-regulated. CONCLUSIONS Curcumin showed marked inhibitory effects against the formation of biofilms by S. mutans and degradation of formed biofilms.
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Affiliation(s)
- Li Ke
- Department of Critical Care Medicine, Zhongnan Hospital of Wuhan University, Wuhan, China.
| | - Jiajun Wang
- Department of Laboratory Medicine, Zhongnan Hospital of Wuhan University, Wuhan, China; Hubei Engineering Center for Infectious Disease Prevention, Control and Treatment, Wuhan, China; Wuhan Research Center for Infectious Diseases and Tumors of the Chinese Academy of Medical Science, Wuhan, China.
| | - Yanhua Liu
- Department of clinical laboratory, Hospital of China University of Geosciences, Wuhan, China.
| | - Zhongyi Sun
- Department of Critical Care Medicine, Zhongnan Hospital of Wuhan University, Wuhan, China.
| | - Yirong Li
- Department of Laboratory Medicine, Zhongnan Hospital of Wuhan University, Wuhan, China; Hubei Engineering Center for Infectious Disease Prevention, Control and Treatment, Wuhan, China; Wuhan Research Center for Infectious Diseases and Tumors of the Chinese Academy of Medical Science, Wuhan, China.
| | - Xiao Xiao
- Department of Laboratory Medicine, Zhongnan Hospital of Wuhan University, Wuhan, China; Hubei Engineering Center for Infectious Disease Prevention, Control and Treatment, Wuhan, China; Wuhan Research Center for Infectious Diseases and Tumors of the Chinese Academy of Medical Science, Wuhan, China.
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Andresen S, de Mojana di Cologna N, Archer-Hartmann S, Rogers AM, Samaddar S, Ganguly T, Black IM, Glushka J, Ng KKS, Azadi P, Lemos JA, Abranches J, Szymanski CM. Involvement of the Streptococcus mutans PgfE and GalE 4-epimerases in protein glycosylation, carbon metabolism, and cell division. Glycobiology 2023; 33:245-259. [PMID: 36637425 PMCID: PMC10114643 DOI: 10.1093/glycob/cwad004] [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: 09/07/2022] [Revised: 01/02/2023] [Accepted: 01/03/2023] [Indexed: 01/14/2023] Open
Abstract
Streptococcus mutans is a key pathogen associated with dental caries and is often implicated in infective endocarditis. This organism forms robust biofilms on tooth surfaces and can use collagen-binding proteins (CBPs) to efficiently colonize collagenous substrates, including dentin and heart valves. One of the best characterized CBPs of S. mutans is Cnm, which contributes to adhesion and invasion of oral epithelial and heart endothelial cells. These virulence properties were subsequently linked to post-translational modification (PTM) of the Cnm threonine-rich repeat region by the Pgf glycosylation machinery, which consists of 4 enzymes: PgfS, PgfM1, PgfE, and PgfM2. Inactivation of the S. mutans pgf genes leads to decreased collagen binding, reduced invasion of human coronary artery endothelial cells, and attenuated virulence in the Galleria mellonella invertebrate model. The present study aimed to better understand Cnm glycosylation and characterize the predicted 4-epimerase, PgfE. Using a truncated Cnm variant containing only 2 threonine-rich repeats, mass spectrometric analysis revealed extensive glycosylation with HexNAc2. Compositional analysis, complemented with lectin blotting, identified the HexNAc2 moieties as GlcNAc and GalNAc. Comparison of PgfE with the other S. mutans 4-epimerase GalE through structural modeling, nuclear magnetic resonance, and capillary electrophoresis demonstrated that GalE is a UDP-Glc-4-epimerase, while PgfE is a GlcNAc-4-epimerase. While PgfE exclusively participates in protein O-glycosylation, we found that GalE affects galactose metabolism and cell division. This study further emphasizes the importance of O-linked protein glycosylation and carbohydrate metabolism in S. mutans and identifies the PTM modifications of the key CBP, Cnm.
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Affiliation(s)
- Silke Andresen
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
- Department of Microbiology and Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
| | | | | | - Ashley M Rogers
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
- Department of Microbiology and Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
| | - Sandip Samaddar
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32603, USA
| | - Tridib Ganguly
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32603, USA
| | - Ian M Black
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
| | - John Glushka
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
| | - Kenneth K S Ng
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON N9B 3P4, Canada
| | - Parastoo Azadi
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
| | - José A Lemos
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32603, USA
| | - Jacqueline Abranches
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32603, USA
| | - Christine M Szymanski
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
- Department of Microbiology and Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
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Bipartite rgp Locus Diversity in Streptococcus thermophilus Corresponds to Backbone and Side Chain Differences of Its Rhamnose-Containing Cell Wall Polysaccharide. Appl Environ Microbiol 2022; 88:e0150422. [PMID: 36350137 PMCID: PMC9746298 DOI: 10.1128/aem.01504-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The rhamnose-glucose polysaccharide (Rgp) of Streptococcus thermophilus represents a major cell wall component, and the gene cluster responsible for its biosynthesis (termed rgp) has recently been identified. Significant genetic diversity among these loci has previously been reported, with five distinct rgp genotypes identified (designated rgp1 through -5). In the present study, two additional genotypes were identified (designated rgp6 and rgp7) through comparative analysis of the rgp loci of 78 Streptococcus thermophilus genomes. The rgp locus of a given S. thermophilus strain encoded the biosynthetic machinery for a rhamnan-rich backbone and a variable side chain component, the latter being associated with the highly specific interactions with many bacteriophages that infect this species. The chemical structure of the Rgp from three S. thermophilus strains, representing the rgp2, -3, and -4 genotypes, was elucidated, and based on bioinformatic and biochemical analyses we propose a model for Rgp biosynthesis in dairy streptococci. Furthermore, we exploited the genetic diversity within the S. thermophilus bipartite rgp locus to develop a two-step multiplex PCR system to classify strains based on gene content associated with the biosynthesis of the variable side chain structure as well as the rhamnan backbone. IMPORTANCE Streptococcus thermophilus is present and applied in industrial and artisanal dairy fermentations for the production of various cheeses and yogurt. During these fermentations, S. thermophilus is vulnerable to phage predation, and recent studies have identified the rhamnose-glucose polymer (Rgp) as the definitive receptor for at least one problematic phage species. Detailed analysis of S. thermophilus rgp loci has revealed an unprecedented level of genetic diversity, particularly within the glycosyltransferase-encoding gene content of a given locus. Our study shows that this genetic diversity reflects the biochemical structure(s) of S. thermophilus Rgp. As such, we harnessed the genetic diversity of S. thermophilus rgp loci to develop a two-step multiplex PCR method for the classification of strain collections and, ultimately, the formation of phage-robust rational starter sets.
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Guérin H, Kulakauskas S, Chapot-Chartier MP. Structural variations and roles of rhamnose-rich cell wall polysaccharides in Gram-positive bacteria. J Biol Chem 2022; 298:102488. [PMID: 36113580 PMCID: PMC9574508 DOI: 10.1016/j.jbc.2022.102488] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 09/08/2022] [Accepted: 09/10/2022] [Indexed: 11/17/2022] Open
Abstract
Rhamnose-rich cell wall polysaccharides (Rha-CWPSs) have emerged as crucial cell wall components of numerous Gram-positive, ovoid-shaped bacteria—including streptococci, enterococci, and lactococci—of which many are of clinical or biotechnological importance. Rha-CWPS are composed of a conserved polyrhamnose backbone with side-chain substituents of variable size and structure. Because these substituents contain phosphate groups, Rha-CWPS can also be classified as polyanionic glycopolymers, similar to wall teichoic acids, of which they appear to be functional homologs. Recent advances have highlighted the critical role of these side-chain substituents in bacterial cell growth and division, as well as in specific interactions between bacteria and infecting bacteriophages or eukaryotic hosts. Here, we review the current state of knowledge on the structure and biosynthesis of Rha-CWPS in several ovoid-shaped bacterial species. We emphasize the role played by multicomponent transmembrane glycosylation systems in the addition of side-chain substituents of various sizes as extracytoplasmic modifications of the polyrhamnose backbone. We provide an overview of the contribution of Rha-CWPS to cell wall architecture and biogenesis and discuss current hypotheses regarding their importance in the cell division process. Finally, we sum up the critical roles that Rha-CWPS can play as bacteriophage receptors or in escaping host defenses, roles that are mediated mainly through their side-chain substituents. From an applied perspective, increased knowledge of Rha-CWPS can lead to advancements in strategies for preventing phage infection of lactococci and streptococci in food fermentation and for combating pathogenic streptococci and enterococci.
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Affiliation(s)
- Hugo Guérin
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France
| | - Saulius Kulakauskas
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France
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Lavelle K, Sinderen DV, Mahony J. Cell wall polysaccharides of Gram positive ovococcoid bacteria and their role as bacteriophage receptors. Comput Struct Biotechnol J 2021; 19:4018-4031. [PMID: 34377367 PMCID: PMC8327497 DOI: 10.1016/j.csbj.2021.07.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 07/12/2021] [Accepted: 07/12/2021] [Indexed: 11/23/2022] Open
Abstract
Gram-positive bacterial cell walls are characterised by the presence of a thick peptidoglycan layer which provides protection from extracellular stresses, maintains cell integrity and determines cell morphology, while it also serves as a foundation to anchor a number of crucial polymeric structures. For ovococcal species, including streptococci, enterococci and lactococci, such structures are represented by rhamnose-containing cell wall polysaccharides, which at least in some instances appear to serve as a functional replacement for wall teichoic acids. The biochemical composition of several streptococcal, lactococcal and enterococcal rhamnose-containing cell wall polysaccharides have been elucidated, while associated functional genomic analyses have facilitated the proposition of models for individual biosynthetic pathways. Here, we review the genomic loci which encode the enzymatic machinery to produce rhamnose-containing, cell wall-associated polysaccharide (Rha cwps) structures of the afore-mentioned ovococcal bacteria with particular emphasis on gene content, biochemical structure and common biosynthetic steps. Furthermore, we discuss the role played by these saccharidic polymers as receptors for bacteriophages and the important role phages play in driving Rha cwps diversification and evolution.
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Affiliation(s)
- Katherine Lavelle
- School of Microbiology & APC Microbiome Ireland, University College Cork, Western Road, Cork T12 YT20, Ireland
| | - Douwe van Sinderen
- School of Microbiology & APC Microbiome Ireland, University College Cork, Western Road, Cork T12 YT20, Ireland
| | - Jennifer Mahony
- School of Microbiology & APC Microbiome Ireland, University College Cork, Western Road, Cork T12 YT20, Ireland
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Ellepola K, Huang X, Riley RP, Bitoun JP, Wen ZT. Streptococcus mutans Lacking sufCDSUB Is Viable, but Displays Major Defects in Growth, Stress Tolerance Responses and Biofilm Formation. Front Microbiol 2021; 12:671533. [PMID: 34248879 PMCID: PMC8264796 DOI: 10.3389/fmicb.2021.671533] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 05/11/2021] [Indexed: 11/13/2022] Open
Abstract
Streptococcus mutans appears to possess a sole iron-sulfur (Fe-S) cluster biosynthesis system encoded by the sufCDSUB cluster. This study was designed to examine the role of sufCDSUB in S. mutans physiology. Allelic exchange mutants deficient of the whole sufCDSUB cluster and in individual genes were constructed. Compared to the wild-type, UA159, the sufCDSUB-deficient mutant, Δsuf::kanr, had a significantly reduced growth rate, especially in medium with the absence of isoleucine, leucine or glutamate/glutamine, amino acids that require Fe-S clusters for biosynthesis and when grown with medium adjusted to pH 6.0 and under oxidative and nitrosative stress conditions. Relative to UA159, Δsuf::kanr had major defects in stress tolerance responses with reduced survival rate of > 2-logs following incubation at low pH environment or after hydrogen peroxide challenge. When compared to UA159, Δsuf::kanr tended to form aggregates in broth medium and accumulated significantly less biofilm. As shown by luciferase reporter fusion assays, the expression of sufCDSUB was elevated by > 5.4-fold when the reporter strain was transferred from iron sufficient medium to iron-limiting medium. Oxidative stress induced by methyl viologen increased sufCDSUB expression by > 2-fold, and incubation in a low pH environment led to reduction of sufCDSUB expression by > 7-fold. These results suggest that lacking of SufCDSUB in S. mutans causes major defects in various cellular processes of the deficient mutant, including growth, stress tolerance responses and biofilm formation. In addition, the viability of the deficient mutant also suggests that SUF, the sole Fe-S cluster machinery identified is non-essential in S. mutans, which is not known in any other bacterium lacking the NIF and/or ISC system. However, how the bacterium compensates the Fe-S deficiency and if any novel Fe-S assembly systems exist in this bacterium await further investigation.
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Affiliation(s)
- Kassapa Ellepola
- Department of Oral and Craniofacial Biology, School of Dentistry, Louisiana State University Health Sciences Center, New Orleans, LA, United States
| | - Xiaochang Huang
- Department of Oral and Craniofacial Biology, School of Dentistry, Louisiana State University Health Sciences Center, New Orleans, LA, United States
| | - Ryan P Riley
- Department of Oral and Craniofacial Biology, School of Dentistry, Louisiana State University Health Sciences Center, New Orleans, LA, United States
| | - Jacob P Bitoun
- Department of Microbiology, Tulane University, New Orleans, LA, United States
| | - Zezhang Tom Wen
- Department of Oral and Craniofacial Biology, School of Dentistry, Louisiana State University Health Sciences Center, New Orleans, LA, United States.,Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA, United States
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10
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Zamakhaeva S, Chaton CT, Rush JS, Ajay Castro S, Kenner CW, Yarawsky AE, Herr AB, van Sorge NM, Dorfmueller HC, Frolenkov GI, Korotkov KV, Korotkova N. Modification of cell wall polysaccharide guides cell division in Streptococcus mutans. Nat Chem Biol 2021; 17:878-887. [PMID: 34045745 DOI: 10.1038/s41589-021-00803-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Accepted: 04/21/2021] [Indexed: 02/07/2023]
Abstract
In ovoid-shaped, Gram-positive bacteria, MapZ guides FtsZ-ring positioning at cell equators. The cell wall of the ovococcus Streptococcus mutans contains peptidoglycan decorated with serotype c carbohydrates (SCCs). In the present study, we identify the major cell separation autolysin AtlA as an SCC-binding protein. AtlA binding to SCC is attenuated by the glycerol phosphate (GroP) modification. Using fluorescently labeled AtlA constructs, we mapped SCC distribution on the streptococcal surface, revealing enrichment of GroP-deficient immature SCCs at the cell poles and equators. The immature SCCs co-localize with MapZ at the equatorial rings throughout the cell cycle. In GroP-deficient mutants, AtlA is mislocalized, resulting in dysregulated cellular autolysis. These mutants display morphological abnormalities associated with MapZ mislocalization, leading to FtsZ-ring misplacement. Altogether, our data support a model in which maturation of a cell wall polysaccharide provides the molecular cues for the recruitment of cell division machinery, ensuring proper daughter cell separation and FtsZ-ring positioning.
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Affiliation(s)
- Svetlana Zamakhaeva
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky, Lexington, KY, USA
| | - Catherine T Chaton
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, USA
| | - Jeffrey S Rush
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, USA
| | - Sowmya Ajay Castro
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, UK
| | - Cameron W Kenner
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky, Lexington, KY, USA
| | - Alexander E Yarawsky
- Divisions of Immunobiology and Infectious Diseases, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Andrew B Herr
- Divisions of Immunobiology and Infectious Diseases, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Nina M van Sorge
- Department of Medical Microbiology and Infection Prevention, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,Netherlands Reference Laboratory for Bacterial Meningitis, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Helge C Dorfmueller
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, UK
| | | | - Konstantin V Korotkov
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, USA
| | - Natalia Korotkova
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky, Lexington, KY, USA. .,Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, USA.
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11
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Wagstaff BA, Zorzoli A, Dorfmueller HC. NDP-rhamnose biosynthesis and rhamnosyltransferases: building diverse glycoconjugates in nature. Biochem J 2021; 478:685-701. [PMID: 33599745 DOI: 10.1042/bcj20200505] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 01/25/2021] [Accepted: 01/26/2021] [Indexed: 11/17/2022]
Abstract
Rhamnose is an important 6-deoxy sugar present in many natural products, glycoproteins, and structural polysaccharides. Whilst predominantly found as the l-enantiomer, instances of d-rhamnose are also found in nature, particularly in the Pseudomonads bacteria. Interestingly, rhamnose is notably absent from humans and other animals, which poses unique opportunities for drug discovery targeted towards rhamnose utilizing enzymes from pathogenic bacteria. Whilst the biosynthesis of nucleotide-activated rhamnose (NDP-rhamnose) is well studied, the study of rhamnosyltransferases that synthesize rhamnose-containing glycoconjugates is the current focus amongst the scientific community. In this review, we describe where rhamnose has been found in nature, as well as what is known about TDP-β-l-rhamnose, UDP-β-l-rhamnose, and GDP-α-d-rhamnose biosynthesis. We then focus on examples of rhamnosyltransferases that have been characterized using both in vivo and in vitro approaches from plants and bacteria, highlighting enzymes where 3D structures have been obtained. The ongoing study of rhamnose and rhamnosyltransferases, in particular in pathogenic organisms, is important to inform future drug discovery projects and vaccine development.
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Affiliation(s)
- Ben A Wagstaff
- Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester, U.K
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
| | - Azul Zorzoli
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
| | - Helge C Dorfmueller
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
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12
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Modifications of cell wall polymers in Gram-positive bacteria by multi-component transmembrane glycosylation systems. Curr Opin Microbiol 2021; 60:24-33. [PMID: 33578058 PMCID: PMC8035078 DOI: 10.1016/j.mib.2021.01.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 01/12/2021] [Accepted: 01/22/2021] [Indexed: 11/22/2022]
Abstract
Secondary cell wall polymers fulfil diverse and important functions within the cell wall of Gram-positive bacteria. Here, we will provide a brief overview of the principles of teichoic acid and complex secondary cell wall polysaccharide biosynthesis pathways in Firmicutes and summarize the recently revised mechanism for the decoration of teichoic acids with d-alanines. Many cell wall polymers are decorated with glycosyl groups, either intracellularly or extracellularly. The main focus of this review will be on the extracellular glycosylation mechanism and recent advances that have been made in the identification of enzymes involved in this process. Based on the proteins involved, we propose to rename the system to multi-component transmembrane glycosylation system in place of three-component glycosylation system.
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13
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LytR-CpsA-Psr Glycopolymer Transferases: Essential Bricks in Gram-Positive Bacterial Cell Wall Assembly. Int J Mol Sci 2021; 22:ijms22020908. [PMID: 33477538 PMCID: PMC7831098 DOI: 10.3390/ijms22020908] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 01/14/2021] [Accepted: 01/14/2021] [Indexed: 12/28/2022] Open
Abstract
The cell walls of Gram-positive bacteria contain a variety of glycopolymers (CWGPs), a significant proportion of which are covalently linked to the peptidoglycan (PGN) scaffolding structure. Prominent CWGPs include wall teichoic acids of Staphylococcus aureus, streptococcal capsules, mycobacterial arabinogalactan, and rhamnose-containing polysaccharides of lactic acid bacteria. CWGPs serve important roles in bacterial cellular functions, morphology, and virulence. Despite evident differences in composition, structure and underlaying biosynthesis pathways, the final ligation step of CWGPs to the PGN backbone involves a conserved class of enzymes-the LytR-CpsA-Psr (LCP) transferases. Typically, the enzymes are present in multiple copies displaying partly functional redundancy and/or preference for a distinct CWGP type. LCP enzymes require a lipid-phosphate-linked glycan precursor substrate and catalyse, with a certain degree of promiscuity, CWGP transfer to PGN of different maturation stages, according to in vitro evidence. The prototype attachment mode is that to the C6-OH of N-acetylmuramic acid residues via installation of a phosphodiester bond. In some cases, attachment proceeds to N-acetylglucosamine residues of PGN-in the case of the Streptococcus agalactiae capsule, even without involvement of a phosphate bond. A novel aspect of LCP enzymes concerns a predicted role in protein glycosylation in Actinomyces oris. Available crystal structures provide further insight into the catalytic mechanism of this biologically important class of enzymes, which are gaining attention as new targets for antibacterial drug discovery to counteract the emergence of multidrug resistant bacteria.
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14
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Disruption of l-Rhamnose Biosynthesis Results in Severe Growth Defects in Streptococcus mutans. J Bacteriol 2020; 202:JB.00728-19. [PMID: 31871035 DOI: 10.1128/jb.00728-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 12/19/2019] [Indexed: 12/11/2022] Open
Abstract
The rhamnose-glucose cell wall polysaccharide (RGP) of Streptococcus mutans plays a significant role in cell division, virulence, and stress protection. Prior studies examined function of the RGP using strains carrying deletions in the machinery involved in RGP assembly. In this study, we explored loss of the substrate for RGP, l-rhamnose, via deletion of rmlD (encoding the protein responsible for the terminal step in l-rhamnose biosynthesis). We demonstrate that loss of rhamnose biosynthesis causes a phenotype similar to strains with disrupted RGP assembly (ΔrgpG and ΔrgpF strains). Deletion of rmlD not only caused a severe growth defect under nonstress growth conditions but also elevated susceptibility of the strain to acid and oxidative stress, common conditions found in the oral cavity. A genetic complement of the ΔrmlD strain completely restored wild-type levels of growth, whereas addition of exogenous rhamnose did not. The loss of rhamnose production also significantly disrupted biofilm formation, an important aspect of S. mutans growth in the oral cavity. Further, we demonstrate that loss of either rmlD or rgpG results in ablation of rhamnose content in the S. mutans cell wall. Taken together, these results highlight the importance of rhamnose production in both the fitness and the ability of S. mutans to overcome environmental stresses.IMPORTANCE Streptococcus mutans is a pathogenic bacterium that is the primary etiologic agent of dental caries, a disease that affects billions yearly. Rhamnose biosynthesis is conserved not only in streptococcal species but in other Gram-positive, as well as Gram-negative, organisms. This study highlights the importance of rhamnose biosynthesis in RGP production for protection of the organism against acid and oxidative stresses, the two major stressors that the organism encounters in the oral cavity. Loss of RGP also severely impacts biofilm formation, the first step in the onset of dental caries. The high conservation of the rhamnose synthesis enzymes, as well as their importance in S. mutans and other organisms, makes them favorable antibiotic targets for the treatment of disease.
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15
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Quantitative Proteomics Uncovers the Interaction between a Virulence Factor and Mutanobactin Synthetases in Streptococcus mutans. mSphere 2019; 4:4/5/e00429-19. [PMID: 31554721 PMCID: PMC6763767 DOI: 10.1128/msphere.00429-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Streptococcus mutans is the major bacterium associated with dental caries. In order to thrive on the highly populated tooth surface and cause disease, S. mutans must be able to protect itself from hydrogen peroxide-producing commensal bacteria and compete effectively against the neighboring microbes. S. mutans produces mutacins, small antimicrobial peptides which help control the population of competing bacterial species. In addition, S. mutans produces a peptide called mutanobactin, which offers S. mutans protection against oxidative stress. Here, we uncover a new link between the putative glycosyltransferase SMU_833 and the mutanobactin-synthesizing protein complex through quantitative proteomic analysis and a tandem-affinity protein purification scheme. Furthermore, we show that SMU_833 mediates bacterial sensitivity to oxidative stress and bacterial ability to compete with commensal streptococci. This study has revealed a previously unknown association between SMU_833 and mutanobactin and demonstrated the importance of SMU_833 in the fitness of S. mutans. Streptococcus mutans, the primary etiological agent of tooth decay, has developed multiple adhesion and virulence factors which enable it to colonize and compete with other bacteria. The putative glycosyltransferase SMU_833 is important for the virulence of S. mutans by altering the biofilm matrix composition and cariogenicity. In this study, we further characterized the smu_833 mutant by evaluating its effects on bacterial fitness. Loss of SMU_833 led to extracellular DNA-dependent bacterial aggregation. In addition, the mutant was more susceptible to oxidative stress and less competitive against H2O2 producing oral streptococci. Quantitative proteomics analysis revealed that SMU_833 deficiency resulted in the significant downregulation of 10 proteins encoded by a biosynthetic gene cluster responsible for the production of mutanobactin, a compound produced by S. mutans which helps it survive oxidative stress. Tandem affinity purification demonstrated that SMU_833 interacts with the synthetic enzymes responsible for the production of mutanobactin. Similar to the smu_833 mutant, the deletion of the mutanobactin gene cluster rendered the mutant less competitive against H2O2-producing streptococci. Our studies revealed a new link between SMU_833 virulence and mutanobactin, suggesting that SMU_833 represents a new virulent target that can be used to develop potential anticaries therapeutics. IMPORTANCEStreptococcus mutans is the major bacterium associated with dental caries. In order to thrive on the highly populated tooth surface and cause disease, S. mutans must be able to protect itself from hydrogen peroxide-producing commensal bacteria and compete effectively against the neighboring microbes. S. mutans produces mutacins, small antimicrobial peptides which help control the population of competing bacterial species. In addition, S. mutans produces a peptide called mutanobactin, which offers S. mutans protection against oxidative stress. Here, we uncover a new link between the putative glycosyltransferase SMU_833 and the mutanobactin-synthesizing protein complex through quantitative proteomic analysis and a tandem-affinity protein purification scheme. Furthermore, we show that SMU_833 mediates bacterial sensitivity to oxidative stress and bacterial ability to compete with commensal streptococci. This study has revealed a previously unknown association between SMU_833 and mutanobactin and demonstrated the importance of SMU_833 in the fitness of S. mutans.
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16
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Kovacs CJ, Faustoferri RC, Bischer AP, Quivey RG. Streptococcus mutans requires mature rhamnose-glucose polysaccharides for proper pathophysiology, morphogenesis and cellular division. Mol Microbiol 2019; 112:944-959. [PMID: 31210392 DOI: 10.1111/mmi.14330] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/11/2019] [Indexed: 12/30/2022]
Abstract
The cell wall of Gram-positive bacteria has been shown to mediate environmental stress tolerance, antibiotic susceptibility, host immune evasion and overall virulence. The majority of these traits have been demonstrated for the well-studied system of wall teichoic acid (WTA) synthesis, a common cell wall polysaccharide among Gram-positive organisms. Streptococcus mutans, a Gram-positive odontopathogen that contributes to the enamel-destructive disease dental caries, lacks the capabilities to generate WTA. Instead, the cell wall of S. mutans is highly decorated with rhamnose-glucose polysaccharides (RGP), for which functional roles are poorly defined. Here, we demonstrate that the RGP has a distinct role in protecting S. mutans from a variety of stress conditions pertinent to pathogenic capability. Mutant strains with disrupted RGP synthesis failed to properly localize cell division complexes, suffered from aberrant septum formation and exhibited enhanced cellular autolysis. Surprisingly, mutant strains of S. mutans with impairment in RGP side chain modification grew into elongated chains and also failed to properly localize the presumed cell wall hydrolase, GbpB. Our results indicate that fully mature RGP has distinct protective and morphogenic roles for S. mutans, and these structures are functionally homologous to the WTA of other Gram-positive bacteria.
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Affiliation(s)
- Christopher J Kovacs
- Department of Microbiology & Immunology, University of Rochester School of Medicine and Dentistry, Box 672, Rochester, NY, 14642, USA
| | - Roberta C Faustoferri
- Center for Oral Biology, University of Rochester School of Medicine and Dentistry, Box 611, Rochester, NY, 14642, USA
| | - Andrew P Bischer
- Department of Microbiology & Immunology, University of Rochester School of Medicine and Dentistry, Box 672, Rochester, NY, 14642, USA
| | - Robert G Quivey
- Department of Microbiology & Immunology, University of Rochester School of Medicine and Dentistry, Box 672, Rochester, NY, 14642, USA.,Center for Oral Biology, University of Rochester School of Medicine and Dentistry, Box 611, Rochester, NY, 14642, USA
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17
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Wagstaff BA, Rejzek M, Kuhaudomlarp S, Hill L, Mascia I, Nepogodiev SA, Dorfmueller HC, Field RA. Discovery of an RmlC/D fusion protein in the microalga Prymnesium parvum and its implications for NDP-β-l-rhamnose biosynthesis in microalgae. J Biol Chem 2019; 294:9172-9185. [PMID: 31010825 PMCID: PMC6556577 DOI: 10.1074/jbc.ra118.006440] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 04/19/2019] [Indexed: 11/06/2022] Open
Abstract
The 6-deoxy sugar l-rhamnose (l-Rha) is found widely in plant and microbial polysaccharides and natural products. The importance of this and related compounds in host-pathogen interactions often means that l-Rha plays an essential role in many organisms. l-Rha is most commonly biosynthesized as the activated sugar nucleotide uridine 5'-diphospho-β-l-rhamnose (UDP-β-l-Rha) or thymidine 5'-diphospho-β-l-rhamnose (TDP-β-l-Rha). Enzymes involved in the biosynthesis of these sugar nucleotides have been studied in some detail in bacteria and plants, but the activated form of l-Rha and the corresponding biosynthetic enzymes have yet to be explored in algae. Here, using sugar-nucleotide profiling in two representative algae, Euglena gracilis and the toxin-producing microalga Prymnesium parvum, we show that levels of UDP- and TDP-activated l-Rha differ significantly between these two algal species. Using bioinformatics and biochemical methods, we identified and characterized a fusion of the RmlC and RmlD proteins, two bacteria-like enzymes involved in TDP-β-l-Rha biosynthesis, from P. parvum Using this new sequence and also others, we explored l-Rha biosynthesis among algae, finding that although most algae contain sequences orthologous to plant-like l-Rha biosynthesis machineries, instances of the RmlC-RmlD fusion protein identified here exist across the Haptophyta and Gymnodiniaceae families of microalgae. On the basis of these findings, we propose potential routes for the evolution of nucleoside diphosphate β-l-Rha (NDP-β-l-Rha) pathways among algae.
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Affiliation(s)
- Ben A Wagstaff
- From the Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, United Kingdom.,Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, United Kingdom, and
| | - Martin Rejzek
- From the Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, United Kingdom
| | - Sakonwan Kuhaudomlarp
- From the Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, United Kingdom.,Université Grenoble Alpes, CNRS, CERMAV, 38000, Grenoble, France
| | - Lionel Hill
- From the Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, United Kingdom
| | - Ilaria Mascia
- From the Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, United Kingdom
| | - Sergey A Nepogodiev
- From the Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, United Kingdom
| | - Helge C Dorfmueller
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, United Kingdom, and
| | - Robert A Field
- From the Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, United Kingdom,
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18
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Lemos JA, Palmer SR, Zeng L, Wen ZT, Kajfasz JK, Freires IA, Abranches J, Brady LJ. The Biology of Streptococcus mutans. Microbiol Spectr 2019; 7:10.1128/microbiolspec.GPP3-0051-2018. [PMID: 30657107 PMCID: PMC6615571 DOI: 10.1128/microbiolspec.gpp3-0051-2018] [Citation(s) in RCA: 311] [Impact Index Per Article: 62.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Indexed: 12/30/2022] Open
Abstract
As a major etiological agent of human dental caries, Streptococcus mutans resides primarily in biofilms that form on the tooth surfaces, also known as dental plaque. In addition to caries, S. mutans is responsible for cases of infective endocarditis with a subset of strains being indirectly implicated with the onset of additional extraoral pathologies. During the past 4 decades, functional studies of S. mutans have focused on understanding the molecular mechanisms the organism employs to form robust biofilms on tooth surfaces, to rapidly metabolize a wide variety of carbohydrates obtained from the host diet, and to survive numerous (and frequent) environmental challenges encountered in oral biofilms. In these areas of research, S. mutans has served as a model organism for ground-breaking new discoveries that have, at times, challenged long-standing dogmas based on bacterial paradigms such as Escherichia coli and Bacillus subtilis. In addition to sections dedicated to carbohydrate metabolism, biofilm formation, and stress responses, this article discusses newer developments in S. mutans biology research, namely, how S. mutans interspecies and cross-kingdom interactions dictate the development and pathogenic potential of oral biofilms and how next-generation sequencing technologies have led to a much better understanding of the physiology and diversity of S. mutans as a species.
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Affiliation(s)
- JA Lemos
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL
| | - SR Palmer
- Division of Biosciences, College of Dentistry, Ohio State University, Columbus, OH
| | - L Zeng
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL
| | - ZT Wen
- Dapartment of Comprehensive Dentistry and Biomaterials and Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA
| | - JK Kajfasz
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL
| | - IA Freires
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL
| | - J Abranches
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL
| | - LJ Brady
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL
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19
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De A, Jorgensen AN, Beatty WL, Lemos J, Wen ZT. Deficiency of MecA in Streptococcus mutans Causes Major Defects in Cell Envelope Biogenesis, Cell Division, and Biofilm Formation. Front Microbiol 2018; 9:2130. [PMID: 30254619 PMCID: PMC6141683 DOI: 10.3389/fmicb.2018.02130] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 08/20/2018] [Indexed: 12/28/2022] Open
Abstract
MecA is an adaptor protein that guides the ClpC/P-mediated proteolysis. A S. mutans MecA-deficient mutant was constructed by double-crossover allelic exchange and analyzed for the effects of such a deficiency on cell biology and biofilm formation. Unlike the wild-type, UA159, the mecA mutant, TW416, formed mucoid and smooth colonies, severely clumped in broth and had a reduced growth rate. Transmission electron microscopy analysis revealed that TW416 grows primarily in chains of giant “swollen” cells with multiple asymmetric septa, unlike the coccoid form of UA159. As compared to UA159, biofilm formation by TW416 was significantly reduced regardless of the carbohydrate sources used for growth (P < 0.001). Western blot analysis of TW416 whole cell lysates showed a reduced expression of the glucosyltransferase GtfC and GtfB, as well as the P1 and WapA adhesins providing an explanation for the defective biofilm formation of TW416. When analyzed by a colorimetric assay, the cell wall phosphate of the mutant murein sacculi was almost 20-fold lower than the parent strain (P < 0.001). Interestingly, however, when analyzed using immunoblotting of the murein sacculi preps with UA159 whole cell antiserum as a probe, TW416 was shown to possess significantly higher signal intensity as compared to the wild-type. There is also evidence that MecA in S. mutans is more than an adaptor protein, although how it modulates the bacterial pathophysiology, including cell envelope biogenesis, cell division, and biofilm formation awaits further investigation.
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Affiliation(s)
- Arpan De
- Department of Comprehensive Dentistry and Biomaterials, University of Florida, Gainesville, FL, United States
| | - Ashton N Jorgensen
- Department of Comprehensive Dentistry and Biomaterials, University of Florida, Gainesville, FL, United States
| | - Wandy L Beatty
- Center of Oral and Craniofacial Biology, University of Florida, Gainesville, FL, United States
| | - Jose Lemos
- Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA, United States
| | - Zezhang T Wen
- Department of Comprehensive Dentistry and Biomaterials, University of Florida, Gainesville, FL, United States.,Department of Molecular Microbiology, Washington University in St. Louis, St. Louis, MO, United States.,Department of Oral Biology, University of Florida, Gainesville, FL, United States
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20
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RgpF Is Required for Maintenance of Stress Tolerance and Virulence in Streptococcus mutans. J Bacteriol 2017; 199:JB.00497-17. [PMID: 28924033 DOI: 10.1128/jb.00497-17] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 09/12/2017] [Indexed: 02/01/2023] Open
Abstract
Bacterial cell wall dynamics have been implicated as important determinants of cellular physiology, stress tolerance, and virulence. In Streptococcus mutans, the cell wall is composed primarily of a rhamnose-glucose polysaccharide (RGP) linked to the peptidoglycan. Despite extensive studies describing its formation and composition, the potential roles for RGP in S. mutans biology have not been well investigated. The present study characterizes the impact of RGP disruption as a result of the deletion of rgpF, the gene encoding a rhamnosyltransferase involved in the construction of the core polyrhamnose backbone of RGP. The ΔrgpF mutant strain displayed an overall reduced fitness compared to the wild type, with heightened sensitivities to various stress-inducing culture conditions and an inability to tolerate acid challenge. The loss of rgpF caused a perturbation of membrane-associated functions known to be critical for aciduricity, a hallmark of S. mutans acid tolerance. The proton gradient across the membrane was disrupted, and the ΔrgpF mutant strain was unable to induce activity of the F1Fo ATPase in cultures grown under low-pH conditions. Further, the virulence potential of S. mutans was also drastically reduced following the deletion of rgpF The ΔrgpF mutant strain produced significantly less robust biofilms, indicating an impairment in its ability to adhere to hydroxyapatite surfaces. Additionally, the ΔrgpF mutant lost competitive fitness against oral peroxigenic streptococci, and it displayed significantly attenuated virulence in an in vivoGalleria mellonella infection model. Collectively, these results highlight a critical function of the RGP in the maintenance of overall stress tolerance and virulence traits in S. mutansIMPORTANCE The cell wall of Streptococcus mutans, the bacterium most commonly associated with tooth decay, is abundant in rhamnose-glucose polysaccharides (RGP). While these structures are antigenically distinct to S. mutans, the process by which they are formed and the enzymes leading to their construction are well conserved among streptococci. The present study describes the consequences of the loss of RgpF, a rhamnosyltransferase involved in RGP construction. The deletion of rgpF resulted in severe ablation of the organism's overall fitness, culminating in significantly attenuated virulence. Our data demonstrate an important link between the RGP and cell wall physiology of S. mutans, affecting critical features used by the organism to cause disease and providing a potential novel target for inhibiting the pathogenesis of S. mutans.
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21
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Rush JS, Edgar RJ, Deng P, Chen J, Zhu H, van Sorge NM, Morris AJ, Korotkov KV, Korotkova N. The molecular mechanism of N-acetylglucosamine side-chain attachment to the Lancefield group A carbohydrate in Streptococcus pyogenes. J Biol Chem 2017; 292:19441-19457. [PMID: 29021255 DOI: 10.1074/jbc.m117.815910] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 10/06/2017] [Indexed: 12/21/2022] Open
Abstract
In many Lactobacillales species (i.e. lactic acid bacteria), peptidoglycan is decorated by polyrhamnose polysaccharides that are critical for cell envelope integrity and cell shape and also represent key antigenic determinants. Despite the biological importance of these polysaccharides, their biosynthetic pathways have received limited attention. The important human pathogen, Streptococcus pyogenes, synthesizes a key antigenic surface polymer, the Lancefield group A carbohydrate (GAC). GAC is covalently attached to peptidoglycan and consists of a polyrhamnose polymer, with N-acetylglucosamine (GlcNAc) side chains, which is an essential virulence determinant. The molecular details of the mechanism of polyrhamnose modification with GlcNAc are currently unknown. In this report, using molecular genetics, analytical chemistry, and mass spectrometry analysis, we demonstrated that GAC biosynthesis requires two distinct undecaprenol-linked GlcNAc-lipid intermediates: GlcNAc-pyrophosphoryl-undecaprenol (GlcNAc-P-P-Und) produced by the GlcNAc-phosphate transferase GacO and GlcNAc-phosphate-undecaprenol (GlcNAc-P-Und) produced by the glycosyltransferase GacI. Further investigations revealed that the GAC polyrhamnose backbone is assembled on GlcNAc-P-P-Und. Our results also suggested that a GT-C glycosyltransferase, GacL, transfers GlcNAc from GlcNAc-P-Und to polyrhamnose. Moreover, GacJ, a small membrane-associated protein, formed a complex with GacI and significantly stimulated its catalytic activity. Of note, we observed that GacI homologs perform a similar function in Streptococcus agalactiae and Enterococcus faecalis In conclusion, the elucidation of GAC biosynthesis in S. pyogenes reported here enhances our understanding of how other Gram-positive bacteria produce essential components of their cell wall.
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Affiliation(s)
- Jeffrey S Rush
- From the Department of Molecular and Cellular Biochemistry and
| | - Rebecca J Edgar
- From the Department of Molecular and Cellular Biochemistry and
| | - Pan Deng
- Division of Cardiovascular Medicine and the Gill Heart Institute, University of Kentucky, Lexington, Kentucky 40536 and
| | - Jing Chen
- From the Department of Molecular and Cellular Biochemistry and
| | - Haining Zhu
- From the Department of Molecular and Cellular Biochemistry and
| | - Nina M van Sorge
- the Department of Medical Microbiology, University Medical Center Utrecht, Utrecht 3584 CX, The Netherlands
| | - Andrew J Morris
- Division of Cardiovascular Medicine and the Gill Heart Institute, University of Kentucky, Lexington, Kentucky 40536 and
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22
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Another Brick in the Wall: a Rhamnan Polysaccharide Trapped inside Peptidoglycan of Lactococcus lactis. mBio 2017; 8:mBio.01303-17. [PMID: 28900021 PMCID: PMC5596347 DOI: 10.1128/mbio.01303-17] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Polysaccharides are ubiquitous components of the Gram-positive bacterial cell wall. In Lactococcus lactis, a polysaccharide pellicle (PSP) forms a layer at the cell surface. The PSP structure varies among lactococcal strains; in L. lactis MG1363, the PSP is composed of repeating hexasaccharide phosphate units. Here, we report the presence of an additional neutral polysaccharide in L. lactis MG1363 that is a rhamnan composed of α-l-Rha trisaccharide repeating units. This rhamnan is still present in mutants devoid of the PSP, indicating that its synthesis can occur independently of PSP synthesis. High-resolution magic-angle spinning nuclear magnetic resonance (HR-MAS NMR) analysis of whole bacterial cells identified a PSP at the surface of wild-type cells. In contrast, rhamnan was detected only at the surface of PSP-negative mutant cells, indicating that rhamnan is located underneath the surface-exposed PSP and is trapped inside peptidoglycan. The genetic determinants of rhamnan biosynthesis appear to be within the same genetic locus that encodes the PSP biosynthetic machinery, except the gene tagO encoding the initiating glycosyltransferase. We present a model of rhamnan biosynthesis based on an ABC transporter-dependent pathway. Conditional mutants producing reduced amounts of rhamnan exhibit strong morphological defects and impaired division, indicating that rhamnan is essential for normal growth and division. Finally, a mutation leading to reduced expression of lcpA, encoding a protein of the LytR-CpsA-Psr (LCP) family, was shown to severely affect cell wall structure. In lcpA mutant cells, in contrast to wild-type cells, rhamnan was detected by HR-MAS NMR, suggesting that LcpA participates in the attachment of rhamnan to peptidoglycan.IMPORTANCE In the cell wall of Gram-positive bacteria, the peptidoglycan sacculus is considered the major structural component, maintaining cell shape and integrity. It is decorated with other glycopolymers, including polysaccharides, the roles of which are not fully elucidated. In the ovococcus Lactococcus lactis, a polysaccharide with a different structure between strains forms a layer at the bacterial surface and acts as the receptor for various bacteriophages that typically exhibit a narrow host range. The present report describes the identification of a novel polysaccharide in the L. lactis cell wall, a rhamnan that is trapped inside the peptidoglycan and covalently bound to it. We propose a model of rhamnan synthesis based on an ABC transporter-dependent pathway. Rhamnan appears as a conserved component of the lactococcal cell wall playing an essential role in growth and division, thus highlighting the importance of polysaccharides in the cell wall integrity of Gram-positive ovococci.
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Deficiency of RgpG Causes Major Defects in Cell Division and Biofilm Formation, and Deficiency of LytR-CpsA-Psr Family Proteins Leads to Accumulation of Cell Wall Antigens in Culture Medium by Streptococcus mutans. Appl Environ Microbiol 2017; 83:AEM.00928-17. [PMID: 28687645 DOI: 10.1128/aem.00928-17] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 06/29/2017] [Indexed: 12/20/2022] Open
Abstract
Streptococcus mutans is known to possess rhamnose-glucose polysaccharide (RGP), a major cell wall antigen. S. mutans strains deficient in rgpG, encoding the first enzyme of the RGP biosynthesis pathway, were constructed by allelic exchange. The rgpG deficiency had no effect on growth rate but caused major defects in cell division and altered cell morphology. Unlike the coccoid wild type, the rgpG mutant existed primarily in chains of swollen, "squarish" dividing cells. Deficiency of rgpG also causes significant reduction in biofilm formation (P < 0.01). Double and triple mutants with deficiency in brpA and/or psr, genes coding for the LytR-CpsA-Psr family proteins BrpA and Psr, which were previously shown to play important roles in cell envelope biogenesis, were constructed using the rgpG mutant. There were no major differences in growth rates between the wild-type strain and the rgpG brpA and rgpG psr double mutants, but the growth rate of the rgpG brpA psr triple mutant was reduced drastically (P < 0.001). Under transmission electron microscopy, both double mutants resembled the rgpG mutant, while the triple mutant existed as giant cells with multiple asymmetric septa. When analyzed by immunoblotting, the rgpG mutant displayed major reductions in cell wall antigens compared to the wild type, while little or no signal was detected with the double and triple mutants and the brpA and psr single mutants. These results suggest that RgpG in S. mutans plays a critical role in cell division and biofilm formation and that BrpA and Psr may be responsible for attachment of cell wall antigens to the cell envelope.IMPORTANCEStreptococcus mutans, a major etiological agent of human dental caries, produces rhamnose-glucose polysaccharide (RGP) as the major cell wall antigen. This study provides direct evidence that deficiency of RgpG, the first enzyme of the RGP biosynthesis pathway, caused major defects in cell division and morphology and reduced biofilm formation by S. mutans, indicative of a significant role of RGP in cell division and biofilm formation in S. mutans These results are novel not only in S. mutans, but also other streptococci that produce RGP. This study also shows that the LytR-CpsA-Psr family proteins BrpA and Psr in S. mutans are involved in attachment of RGP and probably other cell wall glycopolymers to the peptidoglycan. In addition, the results also suggest that BrpA and Psr may play a direct role in cell division and biofilm formation in S. mutans This study reveals new potential targets to develop anticaries therapeutics.
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Al-Dabbagh B, Olatunji S, Crouvoisier M, El Ghachi M, Blanot D, Mengin-Lecreulx D, Bouhss A. Catalytic mechanism of MraY and WecA, two paralogues of the polyprenyl-phosphate N-acetylhexosamine 1-phosphate transferase superfamily. Biochimie 2016; 127:249-57. [DOI: 10.1016/j.biochi.2016.06.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Accepted: 06/07/2016] [Indexed: 10/21/2022]
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Zheng W, Tan TK, Paterson IC, Mutha NVR, Siow CC, Tan SY, Old LA, Jakubovics NS, Choo SW. StreptoBase: An Oral Streptococcus mitis Group Genomic Resource and Analysis Platform. PLoS One 2016; 11:e0151908. [PMID: 27138013 PMCID: PMC4854451 DOI: 10.1371/journal.pone.0151908] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 03/06/2016] [Indexed: 11/19/2022] Open
Abstract
The oral streptococci are spherical Gram-positive bacteria categorized under the phylum Firmicutes which are among the most common causative agents of bacterial infective endocarditis (IE) and are also important agents in septicaemia in neutropenic patients. The Streptococcus mitis group is comprised of 13 species including some of the most common human oral colonizers such as S. mitis, S. oralis, S. sanguinis and S. gordonii as well as species such as S. tigurinus, S. oligofermentans and S. australis that have only recently been classified and are poorly understood at present. We present StreptoBase, which provides a specialized free resource focusing on the genomic analyses of oral species from the mitis group. It currently hosts 104 S. mitis group genomes including 27 novel mitis group strains that we sequenced using the high throughput Illumina HiSeq technology platform, and provides a comprehensive set of genome sequences for analyses, particularly comparative analyses and visualization of both cross-species and cross-strain characteristics of S. mitis group bacteria. StreptoBase incorporates sophisticated in-house designed bioinformatics web tools such as Pairwise Genome Comparison (PGC) tool and Pathogenomic Profiling Tool (PathoProT), which facilitate comparative pathogenomics analysis of Streptococcus strains. Examples are provided to demonstrate how StreptoBase can be employed to compare genome structure of different S. mitis group bacteria and putative virulence genes profile across multiple streptococcal strains. In conclusion, StreptoBase offers access to a range of streptococci genomic resources as well as analysis tools and will be an invaluable platform to accelerate research in streptococci. Database URL: http://streptococcus.um.edu.my.
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Affiliation(s)
- Wenning Zheng
- Genome Informatics Research Laboratory, High Impact Research Building (HIR) Building, University of Malaya, 50603 Kuala Lumpur, Malaysia
- Department of Oral Biology and Biomedical Sciences, Faculty of Dentistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Tze King Tan
- Genome Informatics Research Laboratory, High Impact Research Building (HIR) Building, University of Malaya, 50603 Kuala Lumpur, Malaysia
- Department of Oral Biology and Biomedical Sciences, Faculty of Dentistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Ian C. Paterson
- Department of Oral Biology and Biomedical Sciences, Faculty of Dentistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
- Oral Cancer Research and Coordinating Centre, Faculty of Dentistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Naresh V. R. Mutha
- Genome Informatics Research Laboratory, High Impact Research Building (HIR) Building, University of Malaya, 50603 Kuala Lumpur, Malaysia
- Department of Oral Biology and Biomedical Sciences, Faculty of Dentistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Cheuk Chuen Siow
- Genome Informatics Research Laboratory, High Impact Research Building (HIR) Building, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Shi Yang Tan
- Genome Informatics Research Laboratory, High Impact Research Building (HIR) Building, University of Malaya, 50603 Kuala Lumpur, Malaysia
- Department of Oral Biology and Biomedical Sciences, Faculty of Dentistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Lesley A. Old
- Center for Oral Health Research, School of Dental Sciences, Newcastle University, Framlington Place, Newcastle upon Tyne, United Kingdom
| | - Nicholas S. Jakubovics
- Center for Oral Health Research, School of Dental Sciences, Newcastle University, Framlington Place, Newcastle upon Tyne, United Kingdom
- Genome Solutions Sdn Bhd, Suite 8, Innovation Incubator UM, Level 5, Research Management & Innovation Complex, University of Malaya, 50603 Kuala Lumpur, Malaysia
- * E-mail: (SWC); (NSJ)
| | - Siew Woh Choo
- Genome Informatics Research Laboratory, High Impact Research Building (HIR) Building, University of Malaya, 50603 Kuala Lumpur, Malaysia
- Department of Oral Biology and Biomedical Sciences, Faculty of Dentistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
- * E-mail: (SWC); (NSJ)
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Mistou MY, Sutcliffe IC, van Sorge NM. Bacterial glycobiology: rhamnose-containing cell wall polysaccharides in Gram-positive bacteria. FEMS Microbiol Rev 2016; 40:464-79. [PMID: 26975195 PMCID: PMC4931226 DOI: 10.1093/femsre/fuw006] [Citation(s) in RCA: 120] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/10/2016] [Indexed: 12/21/2022] Open
Abstract
The composition of the Gram-positive cell wall is typically described as containing peptidoglycan, proteins and essential secondary cell wall structures called teichoic acids, which comprise approximately half of the cell wall mass. The cell walls of many species within the genera Streptococcus, Enterococcus and Lactococcus contain large amounts of the sugar rhamnose, which is incorporated in cell wall-anchored polysaccharides (CWP) that possibly function as homologues of well-studied wall teichoic acids (WTA). The presence and chemical structure of many rhamnose-containing cell wall polysaccharides (RhaCWP) has sometimes been known for decades. In contrast to WTA, insight into the biosynthesis and functional role of RhaCWP has been lacking. Recent studies in human streptococcal and enterococcal pathogens have highlighted critical roles for these complex polysaccharides in bacterial cell wall architecture and pathogenesis. In this review, we provide an overview of the RhaCWP with regards to their biosynthesis, genetics and biological function in species most relevant to human health. We also briefly discuss how increased knowledge in this field can provide interesting leads for new therapeutic compounds and improve biotechnological applications. This review summarizes new insights into the genetics and function of rhamnose-containing cell wall polysaccharides expressed by lactic acid bacteria, which includes medically important pathogens, and discusses perspectives on possible future therapeutic and biotechnological applications.
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Affiliation(s)
- Michel-Yves Mistou
- Laboratory for Food Safety, Université Paris-Est, ANSES, F-94701 Maisons-Alfort, France
| | - Iain C Sutcliffe
- Department of Applied Sciences, Northumbria University, Newcastle upon Tyne, UK
| | - Nina M van Sorge
- Medical Microbiology, University Medical Center Utrecht, 3584 CX Utrecht, The Netherlands
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Identification and characterization of SMU.244 encoding a putative undecaprenyl pyrophosphate phosphatase protein required for cell wall biosynthesis and bacitracin resistance in Streptococcus mutans. Microbiology (Reading) 2015. [DOI: 10.1099/mic.0.000142] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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Signoretto C, Marchi A, Bertoncelli A, Burlacchini G, Papetti A, Pruzzo C, Zaura E, Lingström P, Ofek I, Pratten J, Spratt DA, Wilson M, Canepari P. The anti-adhesive mode of action of a purified mushroom (Lentinus edodes) extract with anticaries and antigingivitis properties in two oral bacterial phatogens. BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2014; 14:75. [PMID: 24564835 PMCID: PMC3938644 DOI: 10.1186/1472-6882-14-75] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Accepted: 02/18/2014] [Indexed: 11/12/2022]
Abstract
Background In previous works we have shown that a low-molecular-mass (LMM) fraction from mushroom (Lentinus edodes) homogenate interferes with binding of Streptococcus mutans to hydroxyapatite and Prevotella intermedia to gingival cells. Additionally, inhibition of biofilm formation of both odonto- and periodonto-pathogenic bacteria and detachment from preformed biofilms have been described for this compound. Further purification of mushroom extract has been recently achieved and a sub-fraction (i.e. # 5) has been identified as containing the majority of the mentioned biological activities. The aim of this study was to characterise the bacterial receptors for the purified mushroom sub-fraction #5 in order to better elucidate the mode of action of this compound when interfering with bacterial adhesion to host surfaces or with bacteria-bacteria interactions in the biofilm state. Methods Candidate bacterial molecules to act as target of this compound were bacterial surface molecules involved in cell adhesion and biofilm formation, and, thus, we have considered cell wall associated proteins (CWPs), teichoic acid (TA) and lipoteichoic acid (LTA) of S. mutans, and outer membrane proteins (OMPs) and lipopolysaccharide (LPS) of P. intermedia. Results Fifteen S. mutans CWPs and TA were capable of binding sub-fraction #5, while LTA did not. As far as P. intermedia is concerned, we show that five OMPs interact with sub-fraction # 5. Capacity of binding to P. intermedia LPS was also studied but in this case negative results were obtained. Conclusions Binding sub-fraction # 5 to surface molecules of S. mutans or P. intermedia may result in inactivation of their physiological functions. As a whole, these results indicate, at molecular level, the bacterial surface alterations affecting adhesion and biofim formation. For these antimicrobial properties, the compound may find use in daily oral hygiene.
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A novel gene involved in the survival of Streptococcus mutans under stress conditions. Appl Environ Microbiol 2013; 80:97-103. [PMID: 24123744 DOI: 10.1128/aem.02549-13] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A Streptococcus mutans mutant defective in aciduricity was constructed by random-insertion mutagenesis. Sequence analysis of the mutant revealed a mutation in gidA, which is known to be involved in tRNA modification in Streptococcus pyogenes. Complementation of gidA by S. pyogenes gidA recovered the acid tolerance of S. mutans. Although the gidA-inactivated S. pyogenes mutant exhibited significantly reduced expression of multiple extracellular virulence proteins, the S. mutans mutant did not. On the other hand, the gidA mutant of S. mutans showed reduced ability to withstand exposure to other stress conditions (high osmotic pressure, high temperature, and bacitracin stress) besides an acidic environment. In addition, loss of GidA decreased the capacity for glucose-dependent biofilm formation by over 50%. This study revealed that gidA plays critical roles in the survival of S. mutans under stress conditions, including lower pH.
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MecA protein acts as a negative regulator of genetic competence in Streptococcus mutans. J Bacteriol 2013; 195:5196-206. [PMID: 24039267 DOI: 10.1128/jb.00821-13] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Streptococcus mutans develops competence for genetic transformation through a complex network that receives inputs from at least two signaling peptides, competence-stimulating peptide (CSP) and sigX-inducing peptide (XIP). The key step of competence induction is the transcriptional activation of comX, which encodes an alternative sigma factor, SigX (σ(X)), controlling the expression of late competence genes essential for DNA uptake and recombination. In this study, we provide evidence that MecA acts as a negative regulator in the posttranslational regulation of SigX in S. mutans. Using luxAB transcriptional reporter strains, we demonstrate that MecA represses the expression of late competence genes in S. mutans grown in a complex medium that is subpermissive for competence induction by CSP. The negative regulation of competence by MecA requires the presence of a functional SigX. Accordingly, inactivation of MecA results in a prolonged competence state of S. mutans under this condition. We have also found that the AAA+ protease ClpC displays a similar repressing effect on late competence genes, suggesting that both MecA and ClpC function coordinately to regulate competence in the same regulatory circuit in S. mutans. This suggestion is strongly supported by the results of bacterial two-hybrid assays, which demonstrate that MecA interacts with both SigX and ClpC, forming a ternary SigX-MecA-ClpC complex. Western blot analysis also confirms that inactivation of MecA or ClpC results in the intracellular accumulation of the SigX in S. mutans. Together, our data support the notion that MecA mediates the formation of a ternary SigX-MecA-ClpC complex that sequesters SigX and thereby negatively regulates genetic competence in S. mutans.
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Bitoun JP, Liao S, McKey BA, Yao X, Fan Y, Abranches J, Beatty WL, Wen ZT. Psr is involved in regulation of glucan production, and double deficiency of BrpA and Psr is lethal in Streptococcus mutans. MICROBIOLOGY-SGM 2013; 159:493-506. [PMID: 23288544 DOI: 10.1099/mic.0.063032-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Streptococcus mutans, the primary causative agent of dental caries, contains two paralogues of the LytR-CpsA-Psr family proteins encoded by brpA and psr, respectively. Previous studies have shown that BrpA plays an important role in cell envelope biogenesis/homeostasis and affects stress responses and biofilm formation by Strep. mutans, traits critical to cariogenicity of this bacterium. In this study, a Psr-deficient mutant, TW251, was constructed. Characterization of TW251 showed that deficiency of Psr did not have any major impact on growth rate. However, when subjected to acid killing at pH 2.8, the survival rate of TW251 was decreased dramatically compared with the parent strain UA159. In addition, TW251 also displayed major defects in biofilm formation, especially during growth with sucrose. When compared to UA159, the biofilms of TW251 were mainly planar and devoid of extracellular glucans. Real-time-PCR and Western blot analyses revealed that deficiency of Psr significantly decreased the expression of glucosyltransferase C, a protein known to play a major role in biofilm formation by Strep. mutans. Transmission electron microscopy analysis showed that deficiency of BrpA caused alterations in cell envelope and cell division, and the most significant defects were observed in TW314, a Psr-deficient and BrpA-down mutant. No such effects were observed with Psr mutant TW251 under similar conditions. These results suggest that while there are similarities in functions between BrpA and Psr, distinctive differences also exist between these two paralogues. Like Bacillus subtilis but different from Staphylococcus aureus, a functional BrpA or Psr is required for viability in Strep. mutans.
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Affiliation(s)
- Jacob P Bitoun
- Department of Oral and Craniofacial Biology, School of Dentistry, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - Sumei Liao
- Department of Oral and Craniofacial Biology, School of Dentistry, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - Briggs A McKey
- Department of Oral and Craniofacial Biology, School of Dentistry, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - Xin Yao
- Department of Oral and Craniofacial Biology, School of Dentistry, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - Yuwei Fan
- Department of Comprehensive Dentistry and Biomaterials, School of Dentistry, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - Jacqueline Abranches
- Center for Oral Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Wandy L Beatty
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO, USA
| | - Zezhang T Wen
- Department of Microbiology, Immunology, and Parasitology, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA, USA.,Department of Oral and Craniofacial Biology, School of Dentistry, Louisiana State University Health Sciences Center, New Orleans, LA, USA
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Fenton M, Ross P, McAuliffe O, O'Mahony J, Coffey A. Recombinant bacteriophage lysins as antibacterials. Bioeng Bugs 2011; 1:9-16. [PMID: 21327123 DOI: 10.4161/bbug.1.1.9818] [Citation(s) in RCA: 145] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Accepted: 08/14/2009] [Indexed: 01/01/2023] Open
Abstract
With the increasing worldwide prevalence of antibiotic resistant bacteria, bacteriophage endolysins (lysins) represent a very promising novel alternative class of antibacterial in the fight against infectious disease. Lysins are phage-encoded peptidoglycan hydrolases which, when applied exogenously (as purified recombinant proteins) to Gram-positive bacteria, bring about rapid lysis and death of the bacterial cell. A number of studies have recently demonstrated the strong potential of these enzymes in human and veterinary medicine to control and treat pathogens on mucosal surfaces and in systemic infections. They also have potential in diagnostics and detection, bio-defence, elimination of food pathogens and control of phytopathogens. This review discusses the extensive research on recombinant bacteriophage lysins in the context of antibacterials, and looks forward to future development and potential.
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Affiliation(s)
- Mark Fenton
- Department of Biological Sciences, Cork Institute of Technology, Bishopstown, Cork, Ireland
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Hug I, Feldman MF. Analogies and homologies in lipopolysaccharide and glycoprotein biosynthesis in bacteria. Glycobiology 2010; 21:138-51. [PMID: 20871101 DOI: 10.1093/glycob/cwq148] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Bacteria generate and attach countless glycan structures to diverse macromolecules. Despite this diversity, the mechanisms of glycoconjugate biosynthesis are often surprisingly similar. The focus of this review is on the commonalities between lipopolysaccharide (LPS) and glycoprotein assembly pathways and their evolutionary relationship. Three steps that are essential for both pathways are completed by membrane proteins. These include the initiation of glycan assembly through the attachment of a first sugar residue onto the lipid carrier undecaprenyl pyrophosphate, the translocation across the plasma membrane and the final transfer onto proteins or lipid A-core. Two families of initiating enzymes have been described: the polyprenyl-P N-acetylhexosamine-1-P transferases and the polyprenyl-P hexosamine-1-P transferases, represented by Escherichia coli WecA and Salmonella enterica WbaP, respectively. Translocases are either Wzx-like flippases or adenosine triphosphate (ATP)-binding cassette transporters (ABC transporters). The latter can consist either of two polypeptides, Wzt and Wzm, or of a single polypeptide homolog to the Campylobacter jejuni PglK. Finally, there are two families of conjugating enzymes, the N-oligosaccharyltransferases (N-OTase), best represented by C. jejuni PglB, and the O-OTases, including Neisseria meningitidis PglL and the O antigen ligases involved in LPS biosynthesis. With the exception of the N-OTases, probably restricted to glycoprotein synthesis, members of all these transmembrane protein families can be involved in the synthesis of both glycoproteins and LPS. Because many translocation and conjugation enzymes display relaxed substrate specificity, these bacterial enzymes could be exploited in engineered living bacteria for customized glycoconjugate production, generating potential vaccines and therapeutics.
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Affiliation(s)
- Isabelle Hug
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
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The Bifidobacterium dentium Bd1 genome sequence reflects its genetic adaptation to the human oral cavity. PLoS Genet 2009; 5:e1000785. [PMID: 20041198 PMCID: PMC2788695 DOI: 10.1371/journal.pgen.1000785] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Accepted: 11/23/2009] [Indexed: 12/14/2022] Open
Abstract
Bifidobacteria, one of the relatively dominant components of the human intestinal microbiota, are considered one of the key groups of beneficial intestinal bacteria (probiotic bacteria). However, in addition to health-promoting taxa, the genus Bifidobacterium also includes Bifidobacterium dentium, an opportunistic cariogenic pathogen. The genetic basis for the ability of B. dentium to survive in the oral cavity and contribute to caries development is not understood. The genome of B. dentium Bd1, a strain isolated from dental caries, was sequenced to completion to uncover a single circular 2,636,368 base pair chromosome with 2,143 predicted open reading frames. Annotation of the genome sequence revealed multiple ways in which B. dentium has adapted to the oral environment through specialized nutrient acquisition, defences against antimicrobials, and gene products that increase fitness and competitiveness within the oral niche. B. dentium Bd1 was shown to metabolize a wide variety of carbohydrates, consistent with genome-based predictions, while colonization and persistence factors implicated in tissue adhesion, acid tolerance, and the metabolism of human saliva-derived compounds were also identified. Global transcriptome analysis demonstrated that many of the genes encoding these predicted traits are highly expressed under relevant physiological conditions. This is the first report to identify, through various genomic approaches, specific genetic adaptations of a Bifidobacterium taxon, Bifidobacterium dentium Bd1, to a lifestyle as a cariogenic microorganism in the oral cavity. In silico analysis and comparative genomic hybridization experiments clearly reveal a high level of genome conservation among various B. dentium strains. The data indicate that the genome of this opportunistic cariogen has evolved through a very limited number of horizontal gene acquisition events, highlighting the narrow boundaries that separate commensals from opportunistic pathogens.
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Nakano K, Ooshima T. Serotype classification of Streptococcus mutans and its detection outside the oral cavity. Future Microbiol 2009; 4:891-902. [PMID: 19722842 DOI: 10.2217/fmb.09.64] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Streptococcus mutans, generally known as a major pathogen of dental caries, is also a possible causative agent of bacteremia and infective endocarditis. S. mutans is classified into serotypes c, e, f and k based on the chemical composition of serotype-specific polysaccharides, with approximately 70-80% of strains found in the oral cavity classified as serotype c, followed by e (approximately 20%), and f and k (less than 5% each). Serotype k was recently designated as a novel serotype and shown to possess unique features, the most prominent being a defect of the glucose side chain in serotype-specific rhamnose-glucose polymers, which is related to a higher incidence of detection in cardiovascular specimens, owing to phagocytosis resistance. Molecular analyses of cardiovascular specimens showed a high detection frequency for S. mutans DNA, among which the detection rate for serotype k was quite high. These findings suggest that serotype k S. mutans possibly has a high level of virulence for systemic diseases.
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Affiliation(s)
- Kazuhiko Nakano
- Department of Pediatric Dentistry, Division of Oral Infections & Disease Control, Osaka University Graduate School of Dentistry, 1-8 Yamada-oka, Suita, Osaka 565-0871, Japan.
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Gene cloning and characterization of Streptococcus intermedius fimbriae involved in saliva-mediated aggregation. Res Microbiol 2009; 160:809-16. [PMID: 19819330 DOI: 10.1016/j.resmic.2009.09.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Revised: 09/22/2009] [Accepted: 09/22/2009] [Indexed: 11/23/2022]
Abstract
Streptococcus intermedius, an oral commensal and a cause of systemic pyogenic disease, expresses fimbriae. To identify the gene(s) encoding these fimbriae, we used a serum raised against purified fimbriae to screen libaries of recombinant lambda phages. The cloned gene cluster encoding S. intermedius fimbriae, (saliva-mediated aggregation and adherence-associated fimbriae), contained 4 ORFs, i.e. a putative ribonulease (Saf1), a putative adhesin (Saf2), the main pilus subunit (Saf3) and a sortase C (SrtC). Escherichia coli strains harboring recombinant phages and plasmids carrying the saf3 gene produced a 55kDa protein recognized by the antifimbriae serum. Saf3 contains an N-terminal signal sequence and a C-terminal cell-wall-anchoring motif LPXTG. Among strains of the Streptococcus anginosus group, only serotype g and untypable strains were found to contain the saf3 gene, to possess the fimbrial antigen and to exhibit saliva-mediated aggregation. Knockout mutants made by insertion of an erythromycin resistance gene into saf3 did not produce fimbrial structures or fimbrial antigens and did not participate in saliva-mediated aggregation. The adherent activity of mutants toward plastic wells coated with salivary agglutinin was about 65% that of the parental strain, and the reaction depended on calcium. There was no significant difference in adherence to hydroxyapatite beads pretreated with salivary agglutinin between the parental and mutant strains. These results demonstrated that Saf3 is associated with aggregation, and suggested that other molecule(s) are associated with adherence of S. intermedius.
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Holden MTG, Hauser H, Sanders M, Ngo TH, Cherevach I, Cronin A, Goodhead I, Mungall K, Quail MA, Price C, Rabbinowitsch E, Sharp S, Croucher NJ, Chieu TB, Mai NTH, Diep TS, Chinh NT, Kehoe M, Leigh JA, Ward PN, Dowson CG, Whatmore AM, Chanter N, Iversen P, Gottschalk M, Slater JD, Smith HE, Spratt BG, Xu J, Ye C, Bentley S, Barrell BG, Schultsz C, Maskell DJ, Parkhill J. Rapid evolution of virulence and drug resistance in the emerging zoonotic pathogen Streptococcus suis. PLoS One 2009; 4:e6072. [PMID: 19603075 PMCID: PMC2705793 DOI: 10.1371/journal.pone.0006072] [Citation(s) in RCA: 188] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Accepted: 04/22/2009] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Streptococcus suis is a zoonotic pathogen that infects pigs and can occasionally cause serious infections in humans. S. suis infections occur sporadically in human Europe and North America, but a recent major outbreak has been described in China with high levels of mortality. The mechanisms of S. suis pathogenesis in humans and pigs are poorly understood. METHODOLOGY/PRINCIPAL FINDINGS The sequencing of whole genomes of S. suis isolates provides opportunities to investigate the genetic basis of infection. Here we describe whole genome sequences of three S. suis strains from the same lineage: one from European pigs, and two from human cases from China and Vietnam. Comparative genomic analysis was used to investigate the variability of these strains. S. suis is phylogenetically distinct from other Streptococcus species for which genome sequences are currently available. Accordingly, approximately 40% of the approximately 2 Mb genome is unique in comparison to other Streptococcus species. Finer genomic comparisons within the species showed a high level of sequence conservation; virtually all of the genome is common to the S. suis strains. The only exceptions are three approximately 90 kb regions, present in the two isolates from humans, composed of integrative conjugative elements and transposons. Carried in these regions are coding sequences associated with drug resistance. In addition, small-scale sequence variation has generated pseudogenes in putative virulence and colonization factors. CONCLUSIONS/SIGNIFICANCE The genomic inventories of genetically related S. suis strains, isolated from distinct hosts and diseases, exhibit high levels of conservation. However, the genomes provide evidence that horizontal gene transfer has contributed to the evolution of drug resistance.
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Affiliation(s)
- Matthew T G Holden
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom.
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The LiaFSR system regulates the cell envelope stress response in Streptococcus mutans. J Bacteriol 2009; 191:2973-84. [PMID: 19251860 DOI: 10.1128/jb.01563-08] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Maintaining cell envelope integrity is critical for bacterial survival, including bacteria living in a complex and dynamic environment such as the human oral cavity. Streptococcus mutans, a major etiological agent of dental caries, uses two-component signal transduction systems (TCSTSs) to monitor and respond to various environmental stimuli. Previous studies have shown that the LiaSR TCSTS in S. mutans regulates virulence traits such as acid tolerance and biofilm formation. Although not examined in streptococci, homologs of LiaSR are widely disseminated in Firmicutes and function as part of the cell envelope stress response network. We describe here liaSR and its upstream liaF gene in the cell envelope stress tolerance of S. mutans strain UA159. Transcriptional analysis established liaSR as part of the pentacistronic liaFSR-ppiB-pnpB operon. A survey of cell envelope antimicrobials revealed that mutants deficient in one or all of the liaFSR genes were susceptible to Lipid II cycle interfering antibiotics and to chemicals that perturbed the cell membrane integrity. These compounds induced liaR transcription in a concentration-dependent manner. Notably, under bacitracin stress conditions, the LiaFSR signaling system was shown to induce transcription of several genes involved in membrane protein synthesis, peptidoglycan biosynthesis, envelope chaperone/proteases, and transcriptional regulators. In the absence of an inducer such as bacitracin, LiaF repressed LiaR-regulated expression, whereas supplementing cultures with bacitracin resulted in derepression of liaSR. While LiaF appears to be an integral component of the LiaSR signaling cascade, taken collectively, we report a novel role for LiaFSR in sensing cell envelope stress and preserving envelope integrity in S. mutans.
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Purification and characterization of the bacterial UDP-GlcNAc:undecaprenyl-phosphate GlcNAc-1-phosphate transferase WecA. J Bacteriol 2008; 190:7141-6. [PMID: 18723618 DOI: 10.1128/jb.00676-08] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
To date, the structural and functional characterization of proteins belonging to the polyprenyl-phosphate N-acetylhexosamine-1-phosphate transferase superfamily has been relentlessly held back by problems encountered with their overexpression and purification. In the present work and for the first time, the integral membrane protein WecA that catalyzes the transfer of the GlcNAc-1-phosphate moiety from UDP-GlcNAc onto the carrier lipid undecaprenyl phosphate, yielding undecaprenyl-pyrophosphoryl-GlcNAc, the lipid intermediate involved in the synthesis of various bacterial cell envelope components, was overproduced and purified to near homogeneity in milligram quantities. An enzymatic assay was developed, and the kinetic parameters of WecA as well as the effects of pH, salts, cations, detergents, and temperature on the enzyme activity were determined. A minimal length of 35 carbons was required for the lipid substrate, and tunicamycin was shown to inhibit the enzyme at submicromolar concentrations.
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Sutcliffe IC, Black GW, Harrington DJ. Bioinformatic insights into the biosynthesis of the Group B carbohydrate in Streptococcus agalactiae. MICROBIOLOGY-SGM 2008; 154:1354-1363. [PMID: 18451044 DOI: 10.1099/mic.0.2007/014522-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Streptococcus agalactiae is a major human and animal pathogen, most notable as a cause of life-threatening disease in neonates. S. agalactiae is also called the Group B Streptococcus in reference to the diagnostically significant Lancefield Group B typing antigen. Although the structure of this complex carbohydrate antigen has been solved, little is known of its biosynthesis beyond the identification of a relevant locus in sequenced S. agalactiae genomes. Analysis of the sugar linkages present in the Group B carbohydrate (GBC) structure has allowed us to deduce the minimum enzymology required to complete its biosynthesis. Most of the enzymes required to complete this biosynthesis can be identified within the putative biosynthetic locus. Surprisingly, however, three crucial N-acetylglucosamine transferases and enzymes required for activated precursor synthesis are not apparently located in this locus. A model for GBC biosynthesis wherein the complete polymer is assembled at the cytoplasmic face of the plasma membrane before translocation to the cell surface is proposed. These analyses also suggest that GBC is the major teichoic acid-like polymer in the cell wall of S. agalactiae, whereas lipoteichoic acid is the dominant poly(glycerophosphate) antigen. Genomic analysis has allowed us to predict the pathway leading to the biosynthesis of GBC of S. agalactiae.
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Affiliation(s)
| | - Gary W Black
- Northumbria University, Newcastle upon Tyne NE1 8ST, UK
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Nakano K, Lapirattanakul J, Nomura R, Nemoto H, Alaluusua S, Grönroos L, Vaara M, Hamada S, Ooshima T, Nakagawa I. Streptococcus mutans clonal variation revealed by multilocus sequence typing. J Clin Microbiol 2007; 45:2616-25. [PMID: 17567784 PMCID: PMC1951271 DOI: 10.1128/jcm.02343-06] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus mutans is the major pathogen of dental caries, a biofilm-dependent infectious disease, and occasionally causes infective endocarditis. S. mutans strains have been classified into four serotypes (c, e, f, and k). However, little is known about the S. mutans population, including the clonal relationships among strains of S. mutans, in relation to the particular clones that cause systemic diseases. To address this issue, we have developed a multilocus sequence typing (MLST) scheme for S. mutans. Eight housekeeping gene fragments were sequenced from each of 102 S. mutans isolates collected from the four serotypes in Japan and Finland. Between 14 and 23 alleles per locus were identified, allowing us theoretically to distinguish more than 1.2 x 10(10) sequence types. We identified 92 sequence types in these 102 isolates, indicating that S. mutans contains a diverse population. Whereas serotype c strains were widely distributed in the dendrogram, serotype e, f, and k strains were differentiated into clonal complexes. Therefore, we conclude that the ancestral strain of S. mutans was serotype c. No geographic specificity was identified. However, the distribution of the collagen-binding protein gene (cnm) and direct evidence of mother-to-child transmission were clearly evident. In conclusion, the superior discriminatory capacity of this MLST scheme for S. mutans may have important practical implications.
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Affiliation(s)
- Kazuhiko Nakano
- Departments of Pediatric Dentistry, Osaka University Graduate School of Dentistry, 1-8 Yamada-oka, Suita, Osaka 565-0871, Japan
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Nomura R, Nakano K, Ooshima T. Molecular analysis of the genes involved in the biosynthesis of serotype specific polysaccharide in the novel serotype k strains of Streptococcus mutans. ACTA ACUST UNITED AC 2005; 20:303-9. [PMID: 16101966 DOI: 10.1111/j.1399-302x.2005.00231.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
We previously reported the new serotype k of Streptococcus mutans, which, compared to serotypes c, e, and f, features a drastic reduction in the length of the glucose side chain linked to the rhamnose backbone of the serotype specific polysaccharide. The 5' region of the rgpF gene of serotype k strains contains a distinctive nucleotide sequence, which suggests that an alteration of the rgpF gene in serotype k strains may explain the shortened glucose side chain. However, in the present study, expression of the rgpF gene of MT8148 (serotype c) in serotype k isolates was not found to lead to serotype conversion. Furthermore, mRNA expression of rgpE, known to be associated with glucose side chain formation, was not detected in any of the tested serotype k isolates with an RT-PCR method. The nucleotide alignment of all genes known to be involved in the biosynthesis of serotype specific polysaccharide in serotype k strains was shown to be quite similar to that of serotype c strains, as compared to serotype e and f strains, especially in the region downstream of rgpF. Our results indicate that the common characteristics of serotype k isolates may be caused by a lack of expression of the gene involved in glucose side chain formation.
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Affiliation(s)
- R Nomura
- Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Osaka, Japan
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Shibata Y, Kawada M, Nakano Y, Toyoshima K, Yamashita Y. Identification and characterization of an autolysin-encoding gene of Streptococcus mutans. Infect Immun 2005; 73:3512-20. [PMID: 15908380 PMCID: PMC1111888 DOI: 10.1128/iai.73.6.3512-3520.2005] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We identified a gene (atlA) encoding autolytic activity from Streptococcus mutans Xc. The AtlA protein predicted to be encoded by atlA is composed of 979 amino acids with a molecular weight of 107,279 and has a conserved beta-1,4-N-acetylmuramidase (lysozyme) domain in the C-terminal portion. Sodium dodecyl sulfate extracts of strain Xc showed two major bacteriolytic bands with molecular masses of 107 and 79 kDa, both of which were absent from a mutant with inactivated atlA. Western blot analysis revealed that the 79-kDa band was derived from the 107-kDa peptide by cleavage of its N-terminal portion. The inactivation of atlA resulted in a marked decrease in autolysis and the formation of very long chains of cells compared to the case for the parent strain. Although both the parent and mutant strains formed biofilms in the presence of sucrose, the biofilms formed by the mutant had a sponge-like architecture with large gaps and contained 30% less biomass than those formed by the parent strain. Furthermore, strain Xc formed glucose-dependent, loose biofilms in the absence of sucrose, but the mutant lost this ability. These results suggest that AtlA may play an important role in biofilm formation by S. mutans. The antibody produced against the C-terminal peptide containing the beta-1,4-N-acetylmuramidase domain drastically inhibited the autolytic activity of strain Xc. This inhibition was specific among the oral streptococci to S. mutans. These results indicate that the catalytic domain of AtlA is located at the C terminus, suggesting that further characterization of this domain may provide a means to control cariogenic dental plaque formation.
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Affiliation(s)
- Yukie Shibata
- Department of Preventive Dentistry, Kyushu University Faculty of Dental Science, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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Nakano K, Nomura R, Nakagawa I, Hamada S, Ooshima T. Role of Glucose Side Chains with Serotype-Specific Polysaccharide in the Cariogenicity of Streptococcus mutans. Caries Res 2005; 39:262-8. [PMID: 15942184 DOI: 10.1159/000084831] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2004] [Accepted: 08/26/2004] [Indexed: 11/19/2022] Open
Abstract
Previously, we isolated and characterized a new Streptococcus mutans strain (serotype k) from human blood and oral cavity samples, and found that the serological properties of serotype k strains were similar to those of a gluA-inactivated mutant strain of MT8148 (MT8148GD). MT8148GD showed significantly lower sucrose-dependent adhesion to glass surfaces, sucrose-independent adhesion to saliva-coated hydroxyapatite, dextran-binding activity, and cell-associated glucosyltransferase (GTF) activity than the parent strain. Further, Western blot analysis revealed reduced GTFB and GTFC expression in serotype k strains as compared to MT8148, though the caries-inducing activities of MT8148GD and a serotype k oral isolate in rats were similar to that of MT8148. We conclude that a glucose side-chain defect in the serotype-specific polysaccharide of S. mutans may be associated with its cariogenicity, though to a lesser extent than its other major surface proteins.
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Affiliation(s)
- K Nakano
- Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Osaka, Japan
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Nakano K, Nomura R, Shimizu N, Nakagawa I, Hamada S, Ooshima T. Development of a PCR method for rapid identification of new Streptococcus mutans serotype k strains. J Clin Microbiol 2005; 42:4925-30. [PMID: 15528675 PMCID: PMC525190 DOI: 10.1128/jcm.42.11.4925-4930.2004] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In a previous study, we isolated and characterized a new serotype k of Streptococcus mutans from human blood and oral cavities. Analysis of the genes involved in biosynthesis of the serotype-specific polysaccharide of serotype k strains revealed that the serotype k-specific nucleotide alignment was commonly present in the 5' region of the rgpF gene (350 bp from the initial sequence) compared to the reference strains, and then a method for rapid identification of serotype k strains was developed by use of PCR with primers designed on the basis of the sequence of the variable region. PCR assays with primers specific for amplification of serotype k strains showed a negative reaction with serotype c, e, and f strains and a positive reaction with serotype k strains, with the sensitivity for identification of the serotype k strains shown to range from 5 to 50 cells. Next, the frequency of positive reactions for serotype k-specific primers was surveyed with DNA taken from saliva samples from 200 subjects (2 to 18 years of age), and 10 of those showed a positive reaction, which was higher than the frequency in our previous survey with a serological method. In addition, all saliva samples from subjects with serotype k strains in our previous study were shown to be positive with the serotype k-specific primers. These results indicate that this new PCR method is effective for identification of subjects with S. mutans serotype k.
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Affiliation(s)
- Kazuhiko Nakano
- Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, 1-8 Yamada-oka, Suita, Osaka 565-0871, Japan
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Shibata Y, Ozaki K, Seki M, Kawato T, Tanaka H, Nakano Y, Yamashita Y. Analysis of loci required for determination of serotype antigenicity in Streptococcus mutans and its clinical utilization. J Clin Microbiol 2003; 41:4107-12. [PMID: 12958233 PMCID: PMC193837 DOI: 10.1128/jcm.41.9.4107-4112.2003] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We recently identified the genes responsible for the serotype c-specific glucose side chain formation of rhamnose-glucose polysaccharide (RGP) in Streptococcus mutans. These genes were located downstream from the rgpA through rgpF locus that is involved in the synthesis of RGP. In the present study, the corresponding chromosomal regions were isolated from serotype e and f strains and characterized. The rgpA through rgpF homologs were well conserved among the three serotypes. By contrast, the regions downstream from the rgpF homolog differed considerably among the three serotypes. Replacement of these regions in the different serotype strains converted their serotypic phenotypes, suggesting that these regions participated in serotype-specific glucose side chain formation in each serotype strain. Based on the differences among the DNA sequences of these regions, a PCR method was developed to determine serotypes. S. mutans was isolated from 198 of 432 preschool children (3 to 4 years old). The serotypes of all but one S. mutans isolate were identified by serotyping PCR. Serotype c predominated (84.8%), serotype e was the next most common (13.3%), and serotype f occured rarely (1.9%) in Japanese preschool children. Caries experience in the group with a mixed infection by multiple serotypes of S. mutans was significantly higher than that in the group with a monoinfection by a single serotype.
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Affiliation(s)
- Yukie Shibata
- Department of Preventive Dentistry, Kyushu University Faculty of Dental Science, Fukuoka 812-8582, Japan
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Tsuda H, Yamashita Y, Shibata Y, Nakano Y, Koga T. Genes involved in bacitracin resistance in Streptococcus mutans. Antimicrob Agents Chemother 2002; 46:3756-64. [PMID: 12435673 PMCID: PMC132740 DOI: 10.1128/aac.46.12.3756-3764.2002] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus mutans is resistant to bacitracin, which is a peptide antibiotic produced by certain species of Bacillus. The purpose of this study was to clarify the bacitracin resistance mechanism of S. mutans. We cloned and sequenced two S. mutans loci that are involved in bacitracin resistance. The rgp locus, which is located downstream from rmlD, contains six rgp genes (rgpA to rgpF) that are involved in rhamnose-glucose polysaccharide (RGP) synthesis in S. mutans. The inactivation of RGP synthesis in S. mutans resulted in an approximately fivefold-higher sensitivity to bacitracin relative to that observed for the wild-type strain Xc. The second bacitracin resistance locus comprised four mbr genes (mbrA, mbrB, mbrC, and mbrD) and was located immediately downstream from gtfC, which encodes the water-insoluble glucan-synthesizing enzyme. Although the bacitracin sensitivities of mutants that had defects in flanking genes were similar to that of the parental strain Xc, mutants that were defective in mbrA, mbrB, mbrC, or mbrD were about 100 to 120 times more sensitive to bacitracin than strain Xc. In addition, a mutant that was defective in all of the mbrABCD genes and rgpA was more sensitive to bacitracin than either the RGP or Mbr mutants. We conclude that RGP synthesis is related to bacitracin resistance in S. mutans and that the mbr genes modulate resistance to bacitracin via an unknown mechanism that is independent of RGP synthesis.
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Affiliation(s)
- Hiromasa Tsuda
- Department of Preventive Dentistry, Kyushu University Faculty of Dental Science, Fukuoka 812-8582, Japan
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Ajdić D, McShan WM, McLaughlin RE, Savić G, Chang J, Carson MB, Primeaux C, Tian R, Kenton S, Jia H, Lin S, Qian Y, Li S, Zhu H, Najar F, Lai H, White J, Roe BA, Ferretti JJ. Genome sequence of Streptococcus mutans UA159, a cariogenic dental pathogen. Proc Natl Acad Sci U S A 2002; 99:14434-9. [PMID: 12397186 PMCID: PMC137901 DOI: 10.1073/pnas.172501299] [Citation(s) in RCA: 780] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2002] [Accepted: 08/19/2002] [Indexed: 12/20/2022] Open
Abstract
Streptococcus mutans is the leading cause of dental caries (tooth decay) worldwide and is considered to be the most cariogenic of all of the oral streptococci. The genome of S. mutans UA159, a serotype c strain, has been completely sequenced and is composed of 2,030,936 base pairs. It contains 1,963 ORFs, 63% of which have been assigned putative functions. The genome analysis provides further insight into how S. mutans has adapted to surviving the oral environment through resource acquisition, defense against host factors, and use of gene products that maintain its niche against microbial competitors. S. mutans metabolizes a wide variety of carbohydrates via nonoxidative pathways, and all of these pathways have been identified, along with the associated transport systems whose genes account for almost 15% of the genome. Virulence genes associated with extracellular adherent glucan production, adhesins, acid tolerance, proteases, and putative hemolysins have been identified. Strain UA159 is naturally competent and contains all of the genes essential for competence and quorum sensing. Mobile genetic elements in the form of IS elements and transposons are prominent in the genome and include a previously uncharacterized conjugative transposon and a composite transposon containing genes for the synthesis of antibiotics of the gramicidin/bacitracin family; however, no bacteriophage genomes are present.
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Affiliation(s)
- Dragana Ajdić
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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Shibata Y, Yamashita Y, Ozaki K, Nakano Y, Koga T. Expression and characterization of streptococcal rgp genes required for rhamnan synthesis in Escherichia coli. Infect Immun 2002; 70:2891-8. [PMID: 12010977 PMCID: PMC128017 DOI: 10.1128/iai.70.6.2891-2898.2002] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Six genes (rgpA through rgpF) that were involved in assembling the rhamnose-glucose polysaccharide (RGP) in Streptococcus mutans were previously identified (Y. Yamashita, Y. Tsukioka, K. Tomihisa, Y. Nakano, and T. Koga, J. Bacteriol. 180:5803-5807, 1998). The group-specific antigens of Lancefield group A, C, and E streptococci and the polysaccharide antigen of Streptococcus sobrinus have the same rhamnan backbone as the RGP of S. mutans. Escherichia coli harboring plasmid pRGP1 containing all six rgp genes did not synthesize complete RGP. However, E. coli carrying a plasmid with all of the rgp genes except for rgpE synthesized the rhamnan backbone of RGP without glucose side chains, suggesting that in addition to rgpE, another gene is required for glucose side-chain formation. Synthesis of the rhamnan backbone in E. coli required the initiation of transfer of N-acetylglucosamine to a lipid carrier and the expression of the rgpC and rgpD genes encoding the putative ABC transporter specific for RGP. The similarities in RGP synthesis between E. coli and S. mutans suggest common pathways for rhamnan synthesis. Therefore, we evaluated the rhamnosyl polymerization process in E. coli by high-resolution sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the lipooligosaccharide (LOS). An E. coli transformant harboring rgpA produced the LOS modified by the addition of a single rhamnose residue. Furthermore, the rgpA, rgpB, and rgpF genes of pRGP1 were independently mutated by an internal deletion, and the LOS chemotypes of their transformants were examined. The transformant with an rgpA deletion showed the same LOS profile as E. coli without a plasmid. The transformant with an rgpB deletion showed the same LOS profile as E. coli harboring rgpA alone. The transformant with an rgpF deletion showed the LOS band with the most retarded migration. On the basis of these results, we speculated that RgpA, RgpB, and RgpF, in that order, function in rhamnan polymerization.
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Affiliation(s)
- Yukie Shibata
- Department of Preventive Dentistry, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582, Japan
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