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Rostami N, Shields RC, Serrage HJ, Lawler C, Brittan JL, Yassin S, Ahmed H, Treumann A, Thompson P, Waldron KJ, Nobbs AH, Jakubovics NS. Interspecies competition in oral biofilms mediated by Streptococcus gordonii extracellular deoxyribonuclease SsnA. NPJ Biofilms Microbiomes 2022; 8:96. [PMID: 36509765 PMCID: PMC9744736 DOI: 10.1038/s41522-022-00359-z] [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: 11/15/2021] [Accepted: 11/21/2022] [Indexed: 12/14/2022] Open
Abstract
Extracellular DNA (eDNA) is a key component of many microbial biofilms including dental plaque. However, the roles of extracellular deoxyribonuclease (DNase) enzymes within biofilms are poorly understood. Streptococcus gordonii is a pioneer colonizer of dental plaque. Here, we identified and characterised SsnA, a cell wall-associated protein responsible for extracellular DNase activity of S. gordonii. The SsnA-mediated extracellular DNase activity of S. gordonii was suppressed following growth in sugars. SsnA was purified as a recombinant protein and shown to be inactive below pH 6.5. SsnA inhibited biofilm formation by Streptococcus mutans in a pH-dependent manner. Further, SsnA inhibited the growth of oral microcosm biofilms in human saliva. However, inhibition was ameliorated by the addition of sucrose. Together, these data indicate that S. gordonii SsnA plays a key role in interspecies competition within oral biofilms. Acidification of the medium through sugar catabolism could be a strategy for cariogenic species such as S. mutans to prevent SsnA-mediated exclusion from biofilms.
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Affiliation(s)
- Nadia Rostami
- grid.1006.70000 0001 0462 7212School of Dental Sciences, Faculty of Medical Sciences, Newcastle University, Newcastle, UK
| | - Robert C. Shields
- grid.1006.70000 0001 0462 7212School of Dental Sciences, Faculty of Medical Sciences, Newcastle University, Newcastle, UK ,grid.252381.f0000 0001 2169 5989Department of Biological Sciences, Arkansas State University, Jonesboro, AR USA
| | - Hannah J. Serrage
- grid.5337.20000 0004 1936 7603Bristol Dental School, University of Bristol, Bristol, UK
| | - Catherine Lawler
- grid.5337.20000 0004 1936 7603Bristol Dental School, University of Bristol, Bristol, UK
| | - Jane L. Brittan
- grid.5337.20000 0004 1936 7603Bristol Dental School, University of Bristol, Bristol, UK
| | - Sufian Yassin
- grid.1006.70000 0001 0462 7212School of Dental Sciences, Faculty of Medical Sciences, Newcastle University, Newcastle, UK ,grid.265892.20000000106344187Department of Restorative Sciences, University of Alabama at Birmingham, Birmingham, AL USA
| | - Halah Ahmed
- grid.1006.70000 0001 0462 7212School of Dental Sciences, Faculty of Medical Sciences, Newcastle University, Newcastle, UK
| | - Achim Treumann
- grid.1006.70000 0001 0462 7212Protein and Proteome Analysis Facility, Faculty of Medical Sciences, Newcastle University, Newcastle, UK ,KBI Biopharma BV, Leuven, Belgium
| | - Paul Thompson
- grid.1006.70000 0001 0462 7212Protein and Proteome Analysis Facility, Faculty of Medical Sciences, Newcastle University, Newcastle, UK
| | - Kevin J. Waldron
- grid.1006.70000 0001 0462 7212Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle, UK
| | - Angela H. Nobbs
- grid.5337.20000 0004 1936 7603Bristol Dental School, University of Bristol, Bristol, UK
| | - Nicholas S. Jakubovics
- grid.1006.70000 0001 0462 7212School of Dental Sciences, Faculty of Medical Sciences, Newcastle University, Newcastle, UK
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Liu T, Yang R, Zhou J, Lu X, Yuan Z, Wei X, Guo L. Interactions Between Streptococcus gordonii and Fusobacterium nucleatum Altered Bacterial Transcriptional Profiling and Attenuated the Immune Responses of Macrophages. Front Cell Infect Microbiol 2022; 11:783323. [PMID: 35071038 PMCID: PMC8776643 DOI: 10.3389/fcimb.2021.783323] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Accepted: 12/15/2021] [Indexed: 12/24/2022] Open
Abstract
Interspecies coaggregation promotes transcriptional changes in oral bacteria, affecting bacterial pathogenicity. Streptococcus gordonii (S. gordonii) and Fusobacterium nucleatum (F. nucleatum) are common oral inhabitants. The present study investigated the transcriptional profiling of S. gordonii and F. nucleatum subsp. polymorphum in response to the dual-species coaggregation using RNA-seq. Macrophages were infected with both species to explore the influence of bacterial coaggregation on both species' abilities to survive within macrophages and induce inflammatory responses. Results indicated that, after the 30-min dual-species coaggregation, 116 genes were significantly up-regulated, and 151 genes were significantly down-regulated in S. gordonii; 97 genes were significantly down-regulated, and 114 genes were significantly up-regulated in F. nucleatum subsp. polymorphum. Multiple S. gordonii genes were involved in the biosynthesis and export of cell-wall proteins and carbohydrate metabolism. F. nucleatum subsp. polymorphum genes were mostly associated with translation and protein export. The coaggregation led to decreased expression levels of genes associated with lipopolysaccharide and peptidoglycan biosynthesis. Coaggregation between S. gordonii and F. nucleatum subsp. polymorphum significantly promoted both species' intracellular survival within macrophages and attenuated the production of pro-inflammatory cytokines IL-6 and IL-1β. Physical interactions between these two species promoted a symbiotic lifestyle and repressed macrophage's killing and pro-inflammatory responses.
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Affiliation(s)
- Tingjun Liu
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Ruiqi Yang
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Jiani Zhou
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Xianjun Lu
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Zijian Yuan
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Xi Wei
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Lihong Guo
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
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Spontaneous Mutants of Streptococcus sanguinis with Defects in the Glucose-Phosphotransferase System Show Enhanced Post-Exponential-Phase Fitness. J Bacteriol 2021; 203:e0037521. [PMID: 34460310 DOI: 10.1128/jb.00375-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Genetic truncations in a gene encoding a putative glucose-phosphotransferase system (PTS) protein (manL, EIIABMan) were identified in subpopulations of two separate laboratory stocks of Streptococcus sanguinis SK36; the mutants had reduced PTS activities on glucose and other monosaccharides. To understand the emergence of these mutants, we engineered deletion mutants of manL and showed that the ManL-deficient strain had improved bacterial viability in the stationary phase and was better able to inhibit the growth of the dental caries pathogen Streptococcus mutans. Transcriptional analysis and biochemical assays suggested that the manL mutant underwent reprograming of central carbon metabolism that directed pyruvate away from production of lactate, increasing production of hydrogen peroxide (H2O2) and excretion of pyruvate. Addition of pyruvate to the medium enhanced the survival of SK36 in overnight cultures. Meanwhile, elevated pyruvate levels were detected in the cultures of a small but significant percentage (∼10%) of clinical isolates of oral commensal bacteria. Furthermore, the manL mutant showed higher expression of the arginine deiminase system than the wild type, which enhanced the ability of the mutant to raise environmental pH when arginine was present. To our surprise, significant discrepancies in genome sequence were identified between strain SK36 obtained from ATCC and the sequence deposited in GenBank. As the conditions that are likely associated with the emergence of spontaneous manL mutations, i.e., excess carbohydrates and low pH, are those associated with caries development, we propose that glucose-PTS strongly influences commensal-pathogen interactions by altering the production of ammonia, pyruvate, and H2O2. IMPORTANCE A health-associated dental microbiome provides a potent defense against pathogens and diseases. Streptococcus sanguinis is an abundant member of a health-associated oral flora that antagonizes pathogens by producing hydrogen peroxide. There is a need for a better understanding of the mechanisms that allow bacteria to survive carbohydrate-rich and acidic environments associated with the development of dental caries. We report the isolation and characterization of spontaneous mutants of S. sanguinis with impairment in glucose transport. The resultant reprograming of the central metabolism in these mutants reduced the production of lactic acid and increased pyruvate accumulation; the latter enables these bacteria to better cope with hydrogen peroxide and low pH. The implications of these discoveries in the development of dental caries are discussed.
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Amino Sugars Reshape Interactions between Streptococcus mutans and Streptococcus gordonii. Appl Environ Microbiol 2020; 87:AEM.01459-20. [PMID: 33097515 DOI: 10.1128/aem.01459-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 10/13/2020] [Indexed: 12/19/2022] Open
Abstract
Amino sugars, particularly glucosamine (GlcN) and N-acetylglucosamine (GlcNAc), are abundant carbon and nitrogen sources supplied in host secretions and in the diet to the biofilms colonizing the human oral cavity. Evidence is emerging that these amino sugars provide ecological advantages to beneficial commensals over oral pathogens and pathobionts. Here, we performed transcriptome analysis on Streptococcus mutans and Streptococcus gordonii growing in single-species or dual-species cultures with glucose, GlcN, or GlcNAc as the primary carbohydrate source. Compared to glucose, GlcN caused drastic transcriptomic shifts in each species of bacteria when it was cultured alone. Likewise, cocultivation in the presence of GlcN yielded transcriptomic profiles that were dramatically different from the single-species results from GlcN-grown cells. In contrast, GlcNAc elicited only minor changes in the transcriptome of either organism in single- and dual-species cultures. Interestingly, genes involved in pyruvate metabolism were among the most significantly affected by GlcN in both species, and these changes were consistent with measurements of pyruvate in culture supernatants. Differing from what was found in a previous report, growth of S. mutans alone with GlcN inhibited the expression of multiple operons required for mutacin production. Cocultivation with S. gordonii consistently increased the expression of two manganese transporter operons (slo and mntH) and decreased expression of mutacin genes in S. mutans Conversely, S. gordonii appeared to be less affected by the presence of S. mutans but did show increases in genes for biosynthetic processes in the cocultures. In conclusion, amino sugars profoundly alter the interactions between pathogenic and commensal streptococci by reprogramming central metabolism.IMPORTANCE Carbohydrate metabolism is central to the development of dental caries. A variety of sugars available to dental microorganisms influence the development of caries by affecting the physiology, ecology, and pathogenic potential of tooth biofilms. Using two well-characterized oral bacteria, one pathogen (Streptococcus mutans) and one commensal (Streptococcus gordonii), in an RNA deep-sequencing analysis, we studied the impact of two abundant amino sugars on bacterial gene expression and interspecies interactions. The results indicated large-scale remodeling of gene expression induced by GlcN in particular, affecting bacterial energy generation, acid production, protein synthesis, and release of antimicrobial molecules. Our study provides novel insights into how amino sugars modify bacterial behavior, information that will be valuable in the design of new technologies to detect and prevent oral infectious diseases.
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Zeng L, Burne RA. Subpopulation behaviors in lactose metabolism by Streptococcus mutans. Mol Microbiol 2020; 115:58-69. [PMID: 32881164 DOI: 10.1111/mmi.14596] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 08/17/2020] [Accepted: 08/24/2020] [Indexed: 01/08/2023]
Abstract
When Streptococcus mutans is transferred from a preferred carbohydrate (glucose or fructose) to lactose, initiation of growth can take several hours, and substantial amounts of glucose are released during growth. Here, S. mutans strains UA159 and GS-5 were examined for stochastic behaviors in transcription of the lac operon. Using a gfp reporter fusion, we demonstrated that induction of the lac operon occurs in only a fraction of the population, with prior exposure to carbohydrate source and strain influencing the magniture of the sub-population response. Lower glucokinase activity in GS-5 was associated with release of substantially more glucose than UA159 and significantly lower lac expression. Mutants unable to use lactose grew on lactose as the sole carbohydrate when strains with an intact lac operon were also present in the cultures, indicative of the potential for population cheating. Utilizing a set of engineered obligate cheating and non-cheating strains, we confirmed that cheating can sustain a heterogeneous population. Futher, obligate cheaters of GS-5 competed well with the non-cheaters and showed a high degree of competitive fitness in a human-derived consortium biofilm model. The results show that bet-hedging behaviors in carbohydrate metabolism may substantially influence the composition and pathogenic potential of oral biofilms.
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Affiliation(s)
- Lin Zeng
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL, USA
| | - Robert A Burne
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL, USA
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Zeng L, Burne RA. Molecular mechanisms controlling fructose-specific memory and catabolite repression in lactose metabolism by Streptococcus mutans. Mol Microbiol 2020; 115:70-83. [PMID: 32881130 DOI: 10.1111/mmi.14597] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 08/17/2020] [Accepted: 08/24/2020] [Indexed: 01/26/2023]
Abstract
Lactose is an abundant dietary carbohydrate metabolized by the dental pathogen Streptococcus mutans. Lactose metabolism presents both classic diauxic behaviors and long-term memory, where the bacteria can pause for >11 h before initiating growth on lactose. Here, we explored mechanisms contributing to unusual aspects of regulation of the lac operon. The fructose-phosphate metabolites, F-1-P and F-6-P, could modulate the DNA-binding activities of the lactose repressor. Recombinant LacR proteins bound upstream of lacA and Gal-6-P induced the formation of different LacR-DNA complexes. Deletion of lacR resulted in strain-specific growth phenotypes on lactose, but also on a number of mono- and di-saccharides that involve the glucose-PTS or glucokinase in their catabolism. The phenotypes were consistent with the novel findings that loss of LacR altered glucose-PTS activity and expression of the gene for glucokinase. CcpA was also shown to affect lactose metabolism in vivo and to bind to the lacA promoter region in vitro. Collectively, our study reveals complex molecular circuits controlling lactose metabolism in S. mutans, where LacR and CcpA integrate cellular and environmental cues to regulate metabolism of a variety of carbohydrates that are critical to persistence and pathogenicity of S. mutans.
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Affiliation(s)
- Lin Zeng
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
| | - Robert A Burne
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
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Cheng X, Redanz S, Treerat P, Qin H, Choi D, Zhou X, Xu X, Merritt J, Kreth J. Magnesium-Dependent Promotion of H 2O 2 Production Increases Ecological Competitiveness of Oral Commensal Streptococci. J Dent Res 2020; 99:847-854. [PMID: 32197054 PMCID: PMC7313347 DOI: 10.1177/0022034520912181] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The pyruvate oxidase (SpxB)-dependent production of H2O2 is widely distributed among oral commensal streptococci. Several studies confirmed the ability of H2O2 to antagonize susceptible oral bacterial species, including caries-associated Streptococcus mutans as well as several periodontal pathobionts. Here we report a potential mechanism to bolster oral commensal streptococcal H2O2 production by magnesium (Mg2+) supplementation. Magnesium is a cofactor for SpxB catalytic activity, and supplementation increases the production of H2O2 in vitro. We demonstrate that Mg2+ affects spxB transcription and SpxB abundance in Streptococcus sanguinis and Streptococcus gordonii. The competitiveness of low-passage commensal streptococcal clinical isolates is positively influenced in antagonism assays against S. mutans. In growth conditions normally selective for S. mutans, Mg2+ supplementation is able to increase the abundance of S. sanguinis in dual-species biofilms. Using an in vivo biophotonic imaging platform, we further demonstrate that dietary Mg2+ supplementation significantly improves S. gordonii oral colonization in mice. In summary, our results support a role for Mg2+ supplementation as a potential prebiotic to promote establishment of oral health-associated commensal streptococci.
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Affiliation(s)
- X. Cheng
- The State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China,Department of Geriatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - S. Redanz
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR, USA
| | - P. Treerat
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR, USA
| | - H. Qin
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR, USA
| | - D. Choi
- Department of Community Dentistry, School of Dentistry, Oregon Health & Science University, Portland, OR, USA,School of Public Health, Oregon Health & Science University, Portland, OR, USA
| | - X. Zhou
- The State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China,Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - X. Xu
- The State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China,Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - J. Merritt
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR, USA,Department of Restorative Dentistry, Oregon Health and Science University, Portland, OR, USA
| | - J. Kreth
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR, USA,Department of Restorative Dentistry, Oregon Health and Science University, Portland, OR, USA,J. Kreth, Oregon Health and Science University, 3181 SW Sam Jackson Park Rd., MRB433, Portland, OR 97239, USA.
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Iskandar CF, Cailliez-Grimal C, Borges F, Revol-Junelles AM. Review of lactose and galactose metabolism in Lactic Acid Bacteria dedicated to expert genomic annotation. Trends Food Sci Technol 2019. [DOI: 10.1016/j.tifs.2019.03.020] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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9
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Amino Sugars Modify Antagonistic Interactions between Commensal Oral Streptococci and Streptococcus mutans. Appl Environ Microbiol 2019; 85:AEM.00370-19. [PMID: 30877119 DOI: 10.1128/aem.00370-19] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 03/12/2019] [Indexed: 02/05/2023] Open
Abstract
N-Acetylglucosamine (GlcNAc) and glucosamine (GlcN) enhance the competitiveness of the laboratory strain DL1 of Streptococcus gordonii against the caries pathogen Streptococcus mutans Here, we examine how amino sugars affect the interaction of five low-passage-number clinical isolates of abundant commensal streptococci with S. mutans by utilizing a dual-species biofilm model. Compared to that for glucose, growth on GlcN or GlcNAc significantly reduced the viability of S. mutans in cocultures with most commensals, shifting the proportions of species. Consistent with these results, production of H2O2 was increased in most commensals when growing on amino sugars, and inhibition of S. mutans by Streptococcus cristatus, Streptococcus oralis, or S. gordonii was enhanced by amino sugars on agar plates. All commensals except S. oralis had higher arginine deiminase activities when grown on GlcN and, in some cases, GlcNAc. In ex vivo biofilms formed using pooled cell-containing saliva (CCS), the proportions of S. mutans were drastically diminished when GlcNAc was the primary carbohydrate. Increased production of H2O2 could account in large part for the inhibitory effects of CCS biofilms. Surprisingly, amino sugars appeared to improve mutacin production by S. mutans on agar plates, suggesting that the commensals have mechanisms to actively subvert antagonism by S. mutans in cocultures. Collectively, these findings demonstrate that amino sugars can enhance the beneficial properties of low-passage-number commensal oral streptococci and highlight their potential for moderating the cariogenicity of oral biofilms.IMPORTANCE Dental caries is driven by dysbiosis of oral biofilms in which dominance by acid-producing and acid-tolerant bacteria results in loss of tooth mineral. Our previous work demonstrated the beneficial effects of amino sugars GlcNAc and GlcN in promoting the antagonistic properties of a health-associated oral bacterium, Streptococcus gordonii, in competition with the major caries pathogen Streptococcus mutans Here, we investigated 5 low-passage-number clinical isolates of the most common streptococcal species to establish how amino sugars may influence the ecology and virulence of oral biofilms. Using multiple in vitro models, including a human saliva-derived microcosm biofilm, experiments showed significant enhancement by at least one amino sugar in the ability of most of these bacteria to suppress the caries pathogen. Therefore, our findings demonstrated the mechanism of action by which amino sugars may affect human oral biofilms to promote health.
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Mutha NVR, Mohammed WK, Krasnogor N, Tan GYA, Choo SW, Jakubovics NS. Transcriptional responses of Streptococcus gordonii
and Fusobacterium nucleatum
to coaggregation. Mol Oral Microbiol 2018; 33:450-464. [DOI: 10.1111/omi.12248] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 09/14/2018] [Accepted: 10/12/2018] [Indexed: 12/30/2022]
Affiliation(s)
- Naresh V. R. Mutha
- Institute of Biological Sciences, Faculty of Science; University of Malaya; Kuala Lumpur Malaysia
| | - Waleed K. Mohammed
- School of Dental Sciences; Centre for Oral Health Research, Newcastle University; Newcastle upon Tyne UK
- Department of Basic Science, College of Dentistry; University of Anbar; Anbar Iraq
| | - Natalio Krasnogor
- Interdisciplinary Computing and Complex Biosystems (ICOS) Research Group, School of Computing; Newcastle University; Newcastle upon Tyne UK
| | - Geok Y. A. Tan
- Institute of Biological Sciences, Faculty of Science; University of Malaya; Kuala Lumpur Malaysia
| | - Siew W. Choo
- Department of Biological Sciences; Xi’an Jiaotong-Liverpool University, Suzhou Dushu Lake Science and Education Innovation District; Suzhou China
- Suzhou Genome Centre (SGC); Health Technologies University Research Centre (HT-URC), Xi’an Jiaotong-Liverpool University, Suzhou Dushu Lake Science and Education Innovation District; Suzhou China
| | - Nicholas S. Jakubovics
- School of Dental Sciences; Centre for Oral Health Research, Newcastle University; Newcastle upon Tyne UK
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Plasticity of the Pyruvate Node Modulates Hydrogen Peroxide Production and Acid Tolerance in Multiple Oral Streptococci. Appl Environ Microbiol 2018; 84:AEM.01697-17. [PMID: 29079629 DOI: 10.1128/aem.01697-17] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 10/19/2017] [Indexed: 02/05/2023] Open
Abstract
Commensal Streptococcus sanguinis and Streptococcus gordonii are pioneer oral biofilm colonizers. Characteristic for both is the SpxB-dependent production of H2O2, which is crucial for inhibiting competing biofilm members, especially the cariogenic species Streptococcus mutans H2O2 production is strongly affected by environmental conditions, but few mechanisms are known. Dental plaque pH is one of the key parameters dictating dental plaque ecology and ultimately oral health status. Therefore, the objective of the current study was to characterize the effects of environmental pH on H2O2 production by S. sanguinis and S. gordoniiS. sanguinis H2O2 production was not found to be affected by moderate changes in environmental pH, whereas S. gordonii H2O2 production declined markedly in response to lower pH. Further investigation into the pyruvate node, the central metabolic switch modulating H2O2 or lactic acid production, revealed increased lactic acid levels for S. gordonii at pH 6. The bias for lactic acid production at pH 6 resulted in concomitant improvement in the survival of S. gordonii at low pH and seems to constitute part of the acid tolerance response of S. gordonii Differential responses to pH similarly affect other oral streptococcal species, suggesting that the observed results are part of a larger phenomenon linking environmental pH, central metabolism, and the capacity to produce antagonistic amounts of H2O2IMPORTANCE Oral biofilms are subject to frequent and dramatic changes in pH. S. sanguinis and S. gordonii can compete with caries- and periodontitis-associated pathogens by generating H2O2 Therefore, it is crucial to understand how S. sanguinis and S. gordonii adapt to low pH and maintain their competitiveness under acid stress. The present study provides evidence that certain oral bacteria respond to environmental pH changes by tuning their metabolic output in favor of lactic acid production, to increase their acid survival, while others maintain their H2O2 production at a constant level. The differential control of H2O2 production provides important insights into the role of environmental conditions for growth competition of the oral flora.
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12
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Huang X, Browngardt CM, Jiang M, Ahn SJ, Burne RA, Nascimento MM. Diversity in Antagonistic Interactions between Commensal Oral Streptococci and Streptococcus mutans. Caries Res 2017; 52:88-101. [PMID: 29258070 PMCID: PMC5828942 DOI: 10.1159/000479091] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Accepted: 06/29/2017] [Indexed: 12/28/2022] Open
Abstract
Arginine metabolism via the arginine deiminase system (ADS) of oral bacteria generates ammonia, which can increase the pH of oral biofilms and decrease the risk for dental caries. Antagonistic interactions between ADS-positive and cariogenic bacteria in oral biofilms may be an important ecological determinant of caries. This study investigated the antagonistic potential and mechanisms of clinical isolates of arginolytic streptococci on and by Streptococcus mutans UA159, a well-characterized cariogenic human isolate. Low-passage isolates of Streptococcus gordonii, Streptococcus sanguinis, Streptococcus parasanguinis, Streptococcus australis, and Streptococcus cristatus inhibited the growth of S. mutans to various degrees when they were inoculated on growth media first or simultaneously with S. mutans. The antagonistic effects of arginolytic strains against S. mutans and the production of H2O2 by these strains were enhanced during growth in a less-rich medium or when galactose was substituted for glucose as the primary carbohydrate source. Pyruvate oxidase was the dominant pathway for H2O2 production by arginolytic strains, but lactate oxidase activity was also detected in some strains of S. gordonii and S. cristatus. UA159 inhibited the growth of all tested arginolytic strains when inoculated first, especially in aerobic conditions. However, the antagonistic effects of S. mutans on certain strains of S. gordonii and S. australis were not observed during anaerobic growth in the presence of arginine. Thus, arginolytic commensal streptococci may have a synergistically positive impact on the ecology of oral biofilms by moderating biofilm pH while antagonizing the growth and virulence of caries pathogens.
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Affiliation(s)
- Xuelian Huang
- Division of General Dentistry, Eastman Institute for Oral Health, University of Rochester, Rochester, NY, USA
| | | | - Min Jiang
- Department of Epidemiology and Biostatistics, West China School of Public Health, Sichuan University, Chengdu, Sichuan, China
| | - Sang-Joon Ahn
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
| | - Robert A. Burne
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
| | - Marcelle M. Nascimento
- Department of Restorative Dental Sciences, Division of Operative Dentistry, College of Dentistry, University of Florida, Gainesville, FL, USA
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Ravcheev DA, Thiele I. Comparative Genomic Analysis of the Human Gut Microbiome Reveals a Broad Distribution of Metabolic Pathways for the Degradation of Host-Synthetized Mucin Glycans and Utilization of Mucin-Derived Monosaccharides. Front Genet 2017; 8:111. [PMID: 28912798 PMCID: PMC5583593 DOI: 10.3389/fgene.2017.00111] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 08/11/2017] [Indexed: 12/27/2022] Open
Abstract
The colonic mucus layer is a dynamic and complex structure formed by secreted and transmembrane mucins, which are high-molecular-weight and heavily glycosylated proteins. Colonic mucus consists of a loose outer layer and a dense epithelium-attached layer. The outer layer is inhabited by various representatives of the human gut microbiota (HGM). Glycans of the colonic mucus can be used by the HGM as a source of carbon and energy when dietary fibers are not sufficiently available. Both commensals and pathogens can utilize mucin glycans. Commensals are mostly involved in the cleavage of glycans, while pathogens mostly utilize monosaccharides released by commensals. This HGM-derived degradation of the mucus layer increases pathogen susceptibility and causes many other health disorders. Here, we analyzed 397 individual HGM genomes to identify pathways for the cleavage of host-synthetized mucin glycans to monosaccharides as well as for the catabolism of the derived monosaccharides. Our key results are as follows: (i) Genes for the cleavage of mucin glycans were found in 86% of the analyzed genomes, which significantly higher than a previous estimation. (ii) Genes for the catabolism of derived monosaccharides were found in 89% of the analyzed genomes. (iii) Comparative genomic analysis identified four alternative forms of the monosaccharide-catabolizing enzymes and four alternative forms of monosaccharide transporters. (iv) Eighty-five percent of the analyzed genomes may be involved in potential feeding pathways for the monosaccharides derived from cleaved mucin glycans. (v) The analyzed genomes demonstrated different abilities to degrade known mucin glycans. Generally, the ability to degrade at least one type of mucin glycan was predicted for 81% of the analyzed genomes. (vi) Eighty-two percent of the analyzed genomes can form mutualistic pairs that are able to degrade mucin glycans and are not degradable by any of the paired organisms alone. Taken together, these findings provide further insight into the inter-microbial communications of the HGM as well as into host-HGM interactions.
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Affiliation(s)
- Dmitry A Ravcheev
- Luxembourg Centre for Systems Biomedicine, University of LuxembourgEsch-sur-Alzette, Luxembourg
| | - Ines Thiele
- Luxembourg Centre for Systems Biomedicine, University of LuxembourgEsch-sur-Alzette, Luxembourg
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Galinier A, Deutscher J. Sophisticated Regulation of Transcriptional Factors by the Bacterial Phosphoenolpyruvate: Sugar Phosphotransferase System. J Mol Biol 2017; 429:773-789. [PMID: 28202392 DOI: 10.1016/j.jmb.2017.02.006] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 02/01/2017] [Accepted: 02/04/2017] [Indexed: 11/16/2022]
Abstract
The phosphoenolpyruvate:sugar phosphotransferase system (PTS) is a carbohydrate transport and phosphorylation system present in bacteria of all different phyla and in archaea. It is usually composed of three proteins or protein complexes, enzyme I, HPr, and enzyme II, which are phosphorylated at histidine or cysteine residues. However, in many bacteria, HPr can also be phosphorylated at a serine residue. The PTS not only functions as a carbohydrate transporter but also regulates numerous cellular processes either by phosphorylating its target proteins or by interacting with them in a phosphorylation-dependent manner. The target proteins can be catabolic enzymes, transporters, and signal transduction proteins but are most frequently transcriptional regulators. In this review, we will describe how PTS components interact with or phosphorylate proteins to regulate directly or indirectly the activity of transcriptional repressors, activators, or antiterminators. We will briefly summarize the well-studied mechanism of carbon catabolite repression in firmicutes, where the transcriptional regulator catabolite control protein A needs to interact with seryl-phosphorylated HPr in order to be functional. We will present new results related to transcriptional activators and antiterminators containing specific PTS regulation domains, which are the phosphorylation targets for three different types of PTS components. Moreover, we will discuss how the phosphorylation level of the PTS components precisely regulates the activity of target transcriptional regulators or antiterminators, with or without PTS regulation domain, and how the availability of PTS substrates and thus the metabolic status of the cell are connected with various cellular processes, such as biofilm formation or virulence of certain pathogens.
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Affiliation(s)
- Anne Galinier
- Laboratoire de Chimie Bactérienne, UPR 9043, CNRS, Aix Marseille Université, IMM, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
| | - Josef Deutscher
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France; Centre National de la Recherche Scientifique, UMR8261 (affiliated with the Univ. Paris Diderot, Sorbonne, Paris Cité), Expression Génétique Microbienne, Institut de Biologie Physico-Chimique, 75005 Paris, France.
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15
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Genomic Landscape of Intrahost Variation in Group A Streptococcus: Repeated and Abundant Mutational Inactivation of the fabT Gene Encoding a Regulator of Fatty Acid Synthesis. Infect Immun 2016; 84:3268-3281. [PMID: 27600505 DOI: 10.1128/iai.00608-16] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 08/08/2016] [Indexed: 01/03/2023] Open
Abstract
To obtain new information about Streptococcus pyogenes intrahost genetic variation during invasive infection, we sequenced the genomes of 2,954 serotype M1 strains recovered from a nonhuman primate experimental model of necrotizing fasciitis. A total of 644 strains (21.8%) acquired polymorphisms relative to the input parental strain. The fabT gene, encoding a transcriptional regulator of fatty acid biosynthesis genes, contained 54.5% of these changes. The great majority of polymorphisms were predicted to deleteriously alter FabT function. Transcriptome-sequencing (RNA-seq) analysis of a wild-type strain and an isogenic fabT deletion mutant strain found that between 3.7 and 28.5% of the S. pyogenes transcripts were differentially expressed, depending on the growth temperature (35°C or 40°C) and growth phase (mid-exponential or stationary phase). Genes implicated in fatty acid synthesis and lipid metabolism were significantly upregulated in the fabT deletion mutant strain. FabT also directly or indirectly regulated central carbon metabolism genes, including pyruvate hub enzymes and fermentation pathways and virulence genes. Deletion of fabT decreased virulence in a nonhuman primate model of necrotizing fasciitis. In addition, the fabT deletion strain had significantly decreased survival in human whole blood and during phagocytic interaction with polymorphonuclear leukocytes ex vivo We conclude that FabT mutant progeny arise during infection, constitute a metabolically distinct subpopulation, and are less virulent in the experimental models used here.
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Kamke J, Kittelmann S, Soni P, Li Y, Tavendale M, Ganesh S, Janssen PH, Shi W, Froula J, Rubin EM, Attwood GT. Rumen metagenome and metatranscriptome analyses of low methane yield sheep reveals a Sharpea-enriched microbiome characterised by lactic acid formation and utilisation. MICROBIOME 2016; 4:56. [PMID: 27760570 PMCID: PMC5069950 DOI: 10.1186/s40168-016-0201-2] [Citation(s) in RCA: 181] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 10/06/2016] [Indexed: 05/25/2023]
Abstract
BACKGROUND Enteric fermentation by farmed ruminant animals is a major source of methane and constitutes the second largest anthropogenic contributor to global warming. Reducing methane emissions from ruminants is needed to ensure sustainable animal production in the future. Methane yield varies naturally in sheep and is a heritable trait that can be used to select animals that yield less methane per unit of feed eaten. We previously demonstrated elevated expression of hydrogenotrophic methanogenesis pathway genes of methanogenic archaea in the rumens of high methane yield (HMY) sheep compared to their low methane yield (LMY) counterparts. Methane production in the rumen is strongly connected to microbial hydrogen production through fermentation processes. In this study, we investigate the contribution that rumen bacteria make to methane yield phenotypes in sheep. RESULTS Using deep sequence metagenome and metatranscriptome datasets in combination with 16S rRNA gene amplicon sequencing from HMY and LMY sheep, we show enrichment of lactate-producing Sharpea spp. in LMY sheep bacterial communities. Increased gene and transcript abundances for sugar import and utilisation and production of lactate, propionate and butyrate were also observed in LMY animals. Sharpea azabuensis and Megasphaera spp. act as important drivers of lactate production and utilisation according to phylogenetic analysis and read mappings. CONCLUSIONS Our findings show that the rumen microbiome in LMY animals supports a rapid heterofermentative growth, leading to lactate production. We postulate that lactate is subsequently metabolised mainly to butyrate in LMY animals, producing 2 mol of hydrogen and 0.5 mol of methane per mol hexose, which represents 24 % less than the 0.66 mol of methane formed from the 2.66 mol of hydrogen produced if hexose fermentation was directly to acetate and butyrate. These findings are consistent with the theory that a smaller rumen size with a higher turnover rate, where rapid heterofermentative growth would be an advantage, results in lower hydrogen production and lower methane formation. Together with previous methanogen gene expression data, this builds a strong concept of how animal traits and microbial communities shape the methane phenotype in sheep.
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Affiliation(s)
- Janine Kamke
- AgResearch Limited, Grasslands Research Centre, Tennent Drive, Palmerston North, 4442, New Zealand
| | - Sandra Kittelmann
- AgResearch Limited, Grasslands Research Centre, Tennent Drive, Palmerston North, 4442, New Zealand
| | - Priya Soni
- AgResearch Limited, Grasslands Research Centre, Tennent Drive, Palmerston North, 4442, New Zealand
| | - Yang Li
- AgResearch Limited, Grasslands Research Centre, Tennent Drive, Palmerston North, 4442, New Zealand
| | - Michael Tavendale
- AgResearch Limited, Grasslands Research Centre, Tennent Drive, Palmerston North, 4442, New Zealand
| | - Siva Ganesh
- AgResearch Limited, Grasslands Research Centre, Tennent Drive, Palmerston North, 4442, New Zealand
| | - Peter H Janssen
- AgResearch Limited, Grasslands Research Centre, Tennent Drive, Palmerston North, 4442, New Zealand
| | - Weibing Shi
- Department of Energy, Joint Genome Institute, Walnut Creek, CA, 94598, USA
- Genomic Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Jeff Froula
- Department of Energy, Joint Genome Institute, Walnut Creek, CA, 94598, USA
- Genomic Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Edward M Rubin
- Department of Energy, Joint Genome Institute, Walnut Creek, CA, 94598, USA
- Genomic Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Graeme T Attwood
- AgResearch Limited, Grasslands Research Centre, Tennent Drive, Palmerston North, 4442, New Zealand.
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Warda AK, Siezen RJ, Boekhorst J, Wells-Bennik MHJ, de Jong A, Kuipers OP, Nierop Groot MN, Abee T. Linking Bacillus cereus Genotypes and Carbohydrate Utilization Capacity. PLoS One 2016; 11:e0156796. [PMID: 27272929 PMCID: PMC4896439 DOI: 10.1371/journal.pone.0156796] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 05/19/2016] [Indexed: 11/19/2022] Open
Abstract
We characterised carbohydrate utilisation of 20 newly sequenced Bacillus cereus strains isolated from food products and food processing environments and two laboratory strains, B. cereus ATCC 10987 and B. cereus ATCC 14579. Subsequently, genome sequences of these strains were analysed together with 11 additional B. cereus reference genomes to provide an overview of the different types of carbohydrate transporters and utilization systems found in B. cereus strains. The combined application of API tests, defined growth media experiments and comparative genomics enabled us to link the carbohydrate utilisation capacity of 22 B. cereus strains with their genome content and in some cases to the panC phylogenetic grouping. A core set of carbohydrates including glucose, fructose, maltose, trehalose, N-acetyl-glucosamine, and ribose could be used by all strains, whereas utilisation of other carbohydrates like xylose, galactose, and lactose, and typical host-derived carbohydrates such as fucose, mannose, N-acetyl-galactosamine and inositol is limited to a subset of strains. Finally, the roles of selected carbohydrate transporters and utilisation systems in specific niches such as soil, foods and the human host are discussed.
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Affiliation(s)
- Alicja K. Warda
- TI Food and Nutrition, Wageningen, The Netherlands
- Laboratory of Food Microbiology, Wageningen University, Wageningen, The Netherlands
- Wageningen UR Food & Biobased Research, Wageningen, The Netherlands
| | - Roland J. Siezen
- TI Food and Nutrition, Wageningen, The Netherlands
- Center for Molecular and Biomolecular Informatics, RadboudUMC, Nijmegen, The Netherlands
- Microbial Bioinformatics, Ede, The Netherlands
| | - Jos Boekhorst
- TI Food and Nutrition, Wageningen, The Netherlands
- Center for Molecular and Biomolecular Informatics, RadboudUMC, Nijmegen, The Netherlands
- NIZO Food Research B.V., Ede, The Netherlands
| | | | - Anne de Jong
- TI Food and Nutrition, Wageningen, The Netherlands
- Department of Molecular Genetics, University of Groningen, Groningen, The Netherlands
| | - Oscar P. Kuipers
- TI Food and Nutrition, Wageningen, The Netherlands
- Department of Molecular Genetics, University of Groningen, Groningen, The Netherlands
| | - Masja N. Nierop Groot
- TI Food and Nutrition, Wageningen, The Netherlands
- Wageningen UR Food & Biobased Research, Wageningen, The Netherlands
| | - Tjakko Abee
- TI Food and Nutrition, Wageningen, The Netherlands
- Laboratory of Food Microbiology, Wageningen University, Wageningen, The Netherlands
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18
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Amino Sugars Enhance the Competitiveness of Beneficial Commensals with Streptococcus mutans through Multiple Mechanisms. Appl Environ Microbiol 2016; 82:3671-82. [PMID: 27084009 DOI: 10.1128/aem.00637-16] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 04/11/2016] [Indexed: 12/17/2022] Open
Abstract
UNLABELLED Biochemical and genetic aspects of the metabolism of the amino sugars N-acetylglucosamine (GlcNAc) and glucosamine (GlcN) by commensal oral streptococci and the effects of these sugars on interspecies competition with the dental caries pathogen Streptococcus mutans were explored. Multiple S. mutans wild-type isolates displayed long lag phases when transferred from glucose-containing medium to medium with GlcNAc as the primary carbohydrate source, but commensal streptococci did not. Competition in liquid coculture or dual-species biofilms between S. mutans and Streptococcus gordonii showed that S. gordonii was particularly dominant when the primary carbohydrate was GlcN or GlcNAc. Transcriptional and enzymatic assays showed that the catabolic pathway for GlcNAc was less highly induced in S. mutans than in S. gordonii Exposure to H2O2, which is produced by S. gordonii and antagonizes the growth of S. mutans, led to reduced mRNA levels of nagA and nagB in S. mutans When the gene for the transcriptional regulatory NagR was deleted in S. gordonii, the strain produced constitutively high levels of nagA (GlcNAc-6-P deacetylase), nagB (GlcN-6-P deaminase), and glmS (GlcN-6-P synthase) mRNA. Similar to NagR of S. mutans (NagRSm), the S. gordonii NagR protein (NagRSg) could bind to consensus binding sites (dre) in the nagA, nagB, and glmS promoter regions of S. gordonii Notably, NagRSg binding was inhibited by GlcN-6-P, but G-6-P had no effect, unlike for NagRSm This study expands the understanding of amino sugar metabolism and NagR-dependent gene regulation in streptococci and highlights the potential for therapeutic applications of amino sugars to prevent dental caries. IMPORTANCE Amino sugars are abundant in the biosphere, so the relative efficiency of particular bacteria in a given microbiota to metabolize these sources of carbon and nitrogen might have a profound impact on the ecology of the community. Our investigation reveals that several oral commensal bacteria have a much greater capacity to utilize amino sugars than the dental pathogen Streptococcus mutans and that the ability of the model commensal Streptococcus gordonii to compete against S. mutans is substantively enhanced by the presence of amino sugars commonly found in the oral cavity. The mechanisms underlying the greater capacity and competitive enhancements of the commensal are shown to depend on how the genes for the catabolic enzymes are regulated, the role of the allosteric modulators affecting such regulation, and the ability of amino sugars to enhance certain activities of the commensal that are antagonistic to S. mutans.
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Genes associated to lactose metabolism illustrate the high diversity of Carnobacterium maltaromaticum. Food Microbiol 2016; 58:79-86. [PMID: 27217362 DOI: 10.1016/j.fm.2016.03.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2015] [Revised: 03/02/2016] [Accepted: 03/11/2016] [Indexed: 11/20/2022]
Abstract
The dairy population of Carnobacterium maltaromaticum is characterized by a high diversity suggesting a high diversity of the genetic traits linked to the dairy process. As lactose is the main carbon source in milk, the genetics of lactose metabolism was investigated in this LAB. Comparative genomic analysis revealed that the species C. maltaromaticum exhibits genes related to the Leloir and the tagatose-6-phosphate (Tagatose-6P) pathways. More precisely, strains can bear genes related to one or both pathways and several strains apparently do not contain homologs related to these pathways. Analysis at the population scale revealed that the Tagatose-6P and the Leloir encoding genes are disseminated in multiple phylogenetic lineages of C. maltaromaticum: genes of the Tagatose-6P pathway are present in the lineages I, II and III, and genes of the Leloir pathway are present in the lineages I, III and IV. These data suggest that these genes evolved thanks to horizontal transfer, genetic duplication and translocation. We hypothesize that the lac and gal genes evolved in C. maltaromaticum according to a complex scenario that mirrors the high population diversity.
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20
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Celebioglu HU, Ejby M, Majumder A, Købler C, Goh YJ, Thorsen K, Schmidt B, O'Flaherty S, Abou Hachem M, Lahtinen SJ, Jacobsen S, Klaenhammer TR, Brix S, Mølhave K, Svensson B. Differential proteome and cellular adhesion analyses of the probiotic bacterium Lactobacillus acidophilus NCFM grown on raffinose - an emerging prebiotic. Proteomics 2016; 16:1361-75. [PMID: 26959526 DOI: 10.1002/pmic.201500212] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 01/29/2016] [Accepted: 03/02/2016] [Indexed: 12/28/2022]
Abstract
Whole cell and surface proteomes were analyzed together with adhesive properties of the probiotic bacterium Lactobacillus acidophilus NCFM (NCFM) grown on the emerging prebiotic raffinose, exemplifying a synbiotic. Adhesion of NCFM to mucin and intestinal HT-29 cells increased three-fold after culture with raffinose versus glucose, as also visualized by scanning electron microscopy. Comparative proteomics using 2D-DIGE showed 43 unique proteins to change in relative abundance in whole cell lysates from NCFM grown on raffinose compared to glucose. Furthermore, 14 unique proteins in 18 spots of the surface subproteome underwent changes identified by differential 2DE, including elongation factor G, thermostable pullulanase, and phosphate starvation inducible stress-related protein increasing in a range of +2.1 - +4.7 fold. By contrast five known moonlighting proteins decreased in relative abundance by up to -2.4 fold. Enzymes involved in raffinose catabolism were elevated in the whole cell proteome; α-galactosidase (+13.9 fold); sucrose phosphorylase (+5.4 fold) together with metabolic enzymes from the Leloir pathway for galactose utilization and the glycolysis; β-galactosidase (+5.7 fold); galactose (+2.9/+3.1 fold) and fructose (+2.8 fold) kinases. The insights at the molecular and cellular levels contributed to the understanding of the interplay of a synbiotic composed of NCFM and raffinose with the host.
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Affiliation(s)
- Hasan Ufuk Celebioglu
- Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark, Elektrovej, Lyngby, Denmark
| | - Morten Ejby
- Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark, Elektrovej, Lyngby, Denmark
| | - Avishek Majumder
- Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark, Elektrovej, Lyngby, Denmark
| | - Carsten Købler
- Department of Micro- and Nanotechnology, Technical University of Denmark, Ørsteds Plads, Lyngby, Denmark
| | - Yong Jun Goh
- Department of Food, Bioprocessing & Nutrition Sciences, North Carolina State University, Raleigh, NC, USA
| | - Kristian Thorsen
- Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark, Elektrovej, Lyngby, Denmark
| | - Bjarne Schmidt
- Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark, Elektrovej, Lyngby, Denmark
| | - Sarah O'Flaherty
- Department of Food, Bioprocessing & Nutrition Sciences, North Carolina State University, Raleigh, NC, USA
| | - Maher Abou Hachem
- Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark, Elektrovej, Lyngby, Denmark
| | | | - Susanne Jacobsen
- Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark, Elektrovej, Lyngby, Denmark
| | - Todd R Klaenhammer
- Department of Food, Bioprocessing & Nutrition Sciences, North Carolina State University, Raleigh, NC, USA
| | - Susanne Brix
- Center for Biological Sequence Analysis, Department of Systems Biology, Technical University of Denmark, Søltofts Plads, Lyngby, Denmark
| | - Kristian Mølhave
- Department of Micro- and Nanotechnology, Technical University of Denmark, Ørsteds Plads, Lyngby, Denmark
| | - Birte Svensson
- Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark, Elektrovej, Lyngby, Denmark
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21
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Yadav MK, Go YY, Chae SW, Song JJ. The Small Molecule DAM Inhibitor, Pyrimidinedione, Disrupts Streptococcus pneumoniae Biofilm Growth In Vitro. PLoS One 2015; 10:e0139238. [PMID: 26431532 PMCID: PMC4592238 DOI: 10.1371/journal.pone.0139238] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 09/10/2015] [Indexed: 01/25/2023] Open
Abstract
Streptococcus pneumoniae persist in the human nasopharynx within organized biofilms. However, expansion to other tissues may cause severe infections such as pneumonia, otitis media, bacteremia, and meningitis, especially in children and the elderly. Bacteria within biofilms possess increased tolerance to antibiotics and are able to resist host defense systems. Bacteria within biofilms exhibit different physiology, metabolism, and gene expression profiles than planktonic cells. These differences underscore the need to identify alternative therapeutic targets and novel antimicrobial compounds that are effective against pneumococcal biofilms. In bacteria, DNA adenine methyltransferase (Dam) alters pathogenic gene expression and catalyzes the methylation of adenine in the DNA duplex and of macromolecules during the activated methyl cycle (AMC). In pneumococci, AMC is involved in the biosynthesis of quorum sensing molecules that regulate competence and biofilm formation. In this study, we examine the effect of a small molecule Dam inhibitor, pyrimidinedione, on Streptococcus pneumoniae biofilm formation and evaluate the changes in global gene expression within biofilms via microarray analysis. The effects of pyrimidinedione on in vitro biofilms were studied using a static microtiter plate assay, and the architecture of the biofilms was viewed using confocal and scanning electron microscopy. The cytotoxicity of pyrimidinedione was tested on a human middle ear epithelium cell line by CCK-8. In situ oligonucleotide microarray was used to compare the global gene expression of Streptococcus pneumoniae D39 within biofilms grown in the presence and absence of pyrimidinedione. Real-time RT-PCR was used to study gene expression. Pyrimidinedione inhibits pneumococcal biofilm growth in vitro in a concentration-dependent manner, but it does not inhibit planktonic cell growth. Confocal microscopy analysis revealed the absence of organized biofilms, where cell-clumps were scattered and attached to the bottom of the plate when cells were grown in the presence of pyrimidinedione. Scanning electron microscopy analysis demonstrated the absence of an extracellular polysaccharide matrix in pyrimidinedione-grown biofilms compared to control-biofilms. Pyrimidinedione also significantly inhibited MRSA, MSSA, and Staphylococcus epidermidis biofilm growth in vitro. Furthermore, pyrimidinedione does not exhibit eukaryotic cell toxicity. In a microarray analysis, 56 genes were significantly up-regulated and 204 genes were significantly down-regulated. Genes involved in galactose metabolism were exclusively up-regulated in pyrimidinedione-grown biofilms. Genes related to DNA replication, cell division and the cell cycle, pathogenesis, phosphate-specific transport, signal transduction, fatty acid biosynthesis, protein folding, homeostasis, competence, and biofilm formation were down regulated in pyrimidinedione-grown biofilms. This study demonstrated that the small molecule Dam inhibitor, pyrimidinedione, inhibits pneumococcal biofilm growth in vitro at concentrations that do not inhibit planktonic cell growth and down regulates important metabolic-, virulence-, competence-, and biofilm-related genes. The identification of a small molecule (pyrimidinedione) with S. pneumoniae biofilm-inhibiting capabilities has potential for the development of new compounds that prevent biofilm formation.
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Affiliation(s)
- Mukesh Kumar Yadav
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, South Korea
- Institute for Medical Device Clinical Trials, Korea University College of Medicine, Seoul, South Korea
| | - Yoon Young Go
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, South Korea
| | - Sung-Won Chae
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, South Korea
| | - Jae-Jun Song
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, South Korea
- * E-mail:
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22
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Mitchell WJ. The Phosphotransferase System in Solventogenic Clostridia. J Mol Microbiol Biotechnol 2015; 25:129-42. [DOI: 10.1159/000375125] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The acetone-butanol-ethanol fermentation employing solventogenic clostridia was a major industrial process during the 20th century, but declined for economic reasons. In recent times, interest in the process has been revived due to the perceived potential of butanol as a superior biofuel. Redevelopment of an efficient fermentation process will require a detailed understanding of the physiology of carbohydrate utilization by the bacteria. Genome sequences have revealed that, as in other anaerobes, the phosphotransferase system (PTS) and associated regulatory functions are likely to play an important role in sugar uptake and its regulation. The genomes of <i>Clostridium acetobutylicum</i> and <i>C. beijerinckii</i> encode 13 and 43 phosphotransferases, respectively. Characterization of clostridial phosphotransferases has demonstrated that they are involved in the uptake and phosphorylation of hexoses, hexose derivatives and disaccharides, although the functions of many systems remain to be determined. Glucose is a dominant sugar which represses the utilization of other carbon sources, including the non-PTS pentose sugars xylose and arabinose, by the clostridia. Targeting of the CcpA-dependent mechanism of carbon catabolite repression has been shown to be an effective strategy for reducing the repressive effects of glucose, indicating potential for developing strains with improved fermentation performance.
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23
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Fleming E, Lazinski DW, Camilli A. Carbon catabolite repression by seryl phosphorylated HPr is essential to Streptococcus pneumoniae in carbohydrate-rich environments. Mol Microbiol 2015; 97:360-80. [PMID: 25898857 PMCID: PMC4836947 DOI: 10.1111/mmi.13033] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/16/2015] [Indexed: 11/29/2022]
Abstract
Carbon catabolite repression (CCR) is a regulatory phenomenon implemented by bacteria to hierarchically organize carbohydrate utilization in order to achieve maximal growth. CCR is likely of great importance to Streptococcus pneumoniae because the human host sites inhabited by this pathogen represent complex carbohydrate environments. In this species, inactivation of the prototypical Gram-positive CCR master regulator, ccpA, attenuates virulence in mice but does not relieve CCR of most metabolic enzymes, suggesting CcpA-independent CCR mechanisms predominate. Here we show the activities of three transcriptional regulators constitute the majority of transcriptional CCR of galactose metabolism operons. We determined seryl-phosphorylated histidine phosphocarrier protein (HPr-Ser∼P)-mediated regulation is a major CCR mechanism and an essential activity in the pneumococcus, as an HPr point mutation abolishing HPrK/P-dependent phosphorylation was not tolerated nor was deletion of hprk/p. The HPr-Ser∼P phosphomimetic mutant HPr S46D had reduced phosphotransferase system transport rates and limited induction of CCR-repressed genes. These results support a model of pneumococcal CCR in which HPr-Ser∼P directly affects the activity of CcpA while indirectly affecting the activity of pathway-specific transactional regulators. This report describes the first CcpA-independent CCR mechanism identified in the pneumococcus and the first example of lethality from loss of HPr-Ser∼P-mediated CCR in any species.
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Affiliation(s)
- Eleanor Fleming
- Howard Hughes Medical Institute and Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - David W Lazinski
- Howard Hughes Medical Institute and Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Andrew Camilli
- Howard Hughes Medical Institute and Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
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Cheng L, Wang J, Fu Q, Miao L, Yang X, Li S, Li F, Shen Z. Optimization of carbon and nitrogen sources and substrate feeding strategy to increase the cell density ofStreptococcus suis. BIOTECHNOL BIOTEC EQ 2015. [DOI: 10.1080/13102818.2015.1039465] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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25
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Paixão L, Oliveira J, Veríssimo A, Vinga S, Lourenço EC, Ventura MR, Kjos M, Veening JW, Fernandes VE, Andrew PW, Yesilkaya H, Neves AR. Host glycan sugar-specific pathways in Streptococcus pneumoniae: galactose as a key sugar in colonisation and infection [corrected]. PLoS One 2015; 10:e0121042. [PMID: 25826206 PMCID: PMC4380338 DOI: 10.1371/journal.pone.0121042] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Accepted: 02/12/2015] [Indexed: 01/13/2023] Open
Abstract
The human pathogen Streptococcus pneumoniae is a strictly fermentative organism that relies on glycolytic metabolism to obtain energy. In the human nasopharynx S. pneumoniae encounters glycoconjugates composed of a variety of monosaccharides, which can potentially be used as nutrients once depolymerized by glycosidases. Therefore, it is reasonable to hypothesise that the pneumococcus would rely on these glycan-derived sugars to grow. Here, we identified the sugar-specific catabolic pathways used by S. pneumoniae during growth on mucin. Transcriptome analysis of cells grown on mucin showed specific upregulation of genes likely to be involved in deglycosylation, transport and catabolism of galactose, mannose and N acetylglucosamine. In contrast to growth on mannose and N-acetylglucosamine, S. pneumoniae grown on galactose re-route their metabolic pathway from homolactic fermentation to a truly mixed acid fermentation regime. By measuring intracellular metabolites, enzymatic activities and mutant analysis, we provide an accurate map of the biochemical pathways for galactose, mannose and N-acetylglucosamine catabolism in S. pneumoniae. Intranasal mouse infection models of pneumococcal colonisation and disease showed that only mutants in galactose catabolic genes were attenuated. Our data pinpoint galactose as a key nutrient for growth in the respiratory tract and highlights the importance of central carbon metabolism for pneumococcal pathogenesis.
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Affiliation(s)
- Laura Paixão
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Joana Oliveira
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - André Veríssimo
- Centre for Intelligent Systems, LAETA, IDMEC, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - Susana Vinga
- Centre for Intelligent Systems, LAETA, IDMEC, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - Eva C. Lourenço
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - M. Rita Ventura
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Morten Kjos
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, Groningen, The Netherlands
| | - Jan-Willem Veening
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, Groningen, The Netherlands
| | - Vitor E. Fernandes
- Department of Infection, Immunity & Inflammation, University of Leicester, Leicester, United Kingdom
| | - Peter W. Andrew
- Department of Infection, Immunity & Inflammation, University of Leicester, Leicester, United Kingdom
| | - Hasan Yesilkaya
- Department of Infection, Immunity & Inflammation, University of Leicester, Leicester, United Kingdom
| | - Ana Rute Neves
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
- * E-mail:
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26
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Moye ZD, Zeng L, Burne RA. Fueling the caries process: carbohydrate metabolism and gene regulation by Streptococcus mutans. J Oral Microbiol 2014; 6:24878. [PMID: 25317251 PMCID: PMC4157138 DOI: 10.3402/jom.v6.24878] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Revised: 08/08/2014] [Accepted: 08/11/2014] [Indexed: 11/17/2022] Open
Abstract
The nature of the oral cavity and host behaviors has mandated that the oral microbiota evolve mechanisms for coping with environmental fluctuations, especially changes in the type and availability of carbohydrates. In the case of human dental caries, the presence of excess carbohydrates is often responsible for altering the local environment to be more favorable for species associated with the initiation and progression of disease, including Streptococcus mutans. Some of the earliest endeavors to understand how cariogenic species respond to environmental perturbations were carried out using chemostat cultivation, which provides fine control over culture conditions and bacterial behaviors. The development of genome-scale methodologies has allowed for the combination of sophisticated cultivation technologies with genome-level analysis to more thoroughly probe how bacterial pathogens respond to environmental stimuli. Recent investigations in S. mutans and other closely related streptococci have begun to reveal that carbohydrate metabolism can drastically impact pathogenic potential and highlight the important influence that nutrient acquisition has on the success of pathogens; inside and outside of the oral cavity. Collectively, research into pathogenic streptococci, which have evolved in close association with the human host, has begun to unveil the essential nature of careful orchestration of carbohydrate acquisition and catabolism to allow the organisms to persist and, when conditions allow, initiate or worsen disease.
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Affiliation(s)
- Zachary D Moye
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
| | - Lin Zeng
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
| | - Robert A Burne
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
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LacR is a repressor of lacABCD and LacT is an activator of lacTFEG, constituting the lac gene cluster in Streptococcus pneumoniae. Appl Environ Microbiol 2014; 80:5349-58. [PMID: 24951784 DOI: 10.1128/aem.01370-14] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Comparison of the transcriptome of Streptococcus pneumoniae strain D39 grown in the presence of either lactose or galactose with that of the strain grown in the presence of glucose revealed the elevated expression of various genes and operons, including the lac gene cluster, which is organized into two operons, i.e., lac operon I (lacABCD) and lac operon II (lacTFEG). Deletion of the DeoR family transcriptional regulator lacR that is present downstream of the lac gene cluster revealed elevated expression of lac operon I even in the absence of lactose. This suggests a function of LacR as a transcriptional repressor of lac operon I, which encodes enzymes involved in the phosphorylated tagatose pathway in the absence of lactose or galactose. Deletion of lacR did not affect the expression of lac operon II, which encodes a lactose-specific phosphotransferase. This finding was further confirmed by β-galactosidase assays with PlacA-lacZ and PlacT-lacZ in the presence of either lactose or glucose as the sole carbon source in the medium. This suggests the involvement of another transcriptional regulator in the regulation of lac operon II, which is the BglG-family transcriptional antiterminator LacT. We demonstrate the role of LacT as a transcriptional activator of lac operon II in the presence of lactose and CcpA-independent regulation of the lac gene cluster in S. pneumoniae.
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28
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Jung WS, Singh RK, Lee JK, Pan CH. Crystal structure and substrate specificity of D-galactose-6-phosphate isomerase complexed with substrates. PLoS One 2013; 8:e72902. [PMID: 24015281 PMCID: PMC3755991 DOI: 10.1371/journal.pone.0072902] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 07/14/2013] [Indexed: 11/29/2022] Open
Abstract
D-Galactose-6-phosphate isomerase from Lactobacillus rhamnosus (LacAB; EC 5.3.1.26), which is encoded by the tagatose-6-phosphate pathway gene cluster (lacABCD), catalyzes the isomerization of D-galactose-6-phosphate to D-tagatose-6-phosphate during lactose catabolism and is used to produce rare sugars as low-calorie natural sweeteners. The crystal structures of LacAB and its complex with D-tagatose-6-phosphate revealed that LacAB is a homotetramer of LacA and LacB subunits, with a structure similar to that of ribose-5-phosphate isomerase (Rpi). Structurally, LacAB belongs to the RpiB/LacAB superfamily, having a Rossmann-like αβα sandwich fold as has been identified in pentose phosphate isomerase and hexose phosphate isomerase. In contrast to other family members, the LacB subunit also has a unique α7 helix in its C-terminus. One active site is distinctly located at the interface between LacA and LacB, whereas two active sites are present in RpiB. In the structure of the product complex, the phosphate group of D-tagatose-6-phosphate is bound to three arginine residues, including Arg-39, producing a different substrate orientation than that in RpiB, where the substrate binds at Asp-43. Due to the proximity of the Arg-134 residue and backbone Cα of the α6 helix in LacA to the last Asp-172 residue of LacB with a hydrogen bond, a six-carbon sugar-phosphate can bind in the larger pocket of LacAB, compared with RpiB. His-96 in the active site is important for ring opening and substrate orientation, and Cys-65 is essential for the isomerization activity of the enzyme. Two rare sugar substrates, D-psicose and D-ribulose, show optimal binding in the LacAB-substrate complex. These findings were supported by the results of LacA activity assays.
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Affiliation(s)
- Woo-Suk Jung
- Functional Food Center, Korea Institute of Science and Technology Gangneung Institute, Gangneung, Korea
| | - Raushan Kumar Singh
- Department of Chemical Engineering, Konkuk University, Gwangjin-Gu, Seoul, Korea
| | - Jung-Kul Lee
- Department of Chemical Engineering, Konkuk University, Gwangjin-Gu, Seoul, Korea
| | - Cheol-Ho Pan
- Functional Food Center, Korea Institute of Science and Technology Gangneung Institute, Gangneung, Korea
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A pathway closely related to the (D)-tagatose pathway of gram-negative enterobacteria identified in the gram-positive bacterium Bacillus licheniformis. Appl Environ Microbiol 2013; 79:3511-5. [PMID: 23524682 DOI: 10.1128/aem.03918-12] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report the first identification of a gene cluster involved in d-tagatose catabolism in Bacillus licheniformis. The pathway is closely related to the d-tagatose pathway of the Gram-negative bacterium Klebsiella oxytoca, in contrast to the d-tagatose 6-phosphate pathway described in the Gram-positive bacterium Staphylococcus aureus.
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30
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Zeng L, Xue P, Stanhope MJ, Burne RA. A galactose-specific sugar: phosphotransferase permease is prevalent in the non-core genome of Streptococcus mutans. Mol Oral Microbiol 2013; 28:292-301. [PMID: 23421335 DOI: 10.1111/omi.12025] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/18/2013] [Indexed: 12/01/2022]
Abstract
Three genes predicted to encode the A, B and C domains of a sugar : phosphotransferase system (PTS) permease specific for galactose\(EII(Gal) ) were identified in the genomes of 35 of 57 recently sequenced isolates of Streptococcus mutans, the primary etiological agent of human dental caries. Mutants defective in the EII(Gal) complex were constructed in six of the isolates and showed markedly reduced growth rates on galactose-based medium relative to the parental strains. An EII(Gal) -deficient strain constructed using the invasive serotype f strain OMZ175 (OMZ/IIGal) expressed significantly lower PTS activity when galactose was present as the substrate. Galactose was shown to be an effective inducer of catabolite repression in OMZ175, but not in the EII(Gal) -deficient strain. In a mixed-species competition assay with galactose as the sole carbohydrate source, OMZ/IIGal was less effective than the parental strain at competing with the oral commensal bacterium Streptococcus gordonii, which has a high-affinity galactose transporter. Hence, a significant proportion of S. mutans strains encode a galactose PTS permease that could enhance the ability of these isolates to compete more effectively with commensal streptococci for galactose in salivary constituents and the diet.
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Affiliation(s)
- L Zeng
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA
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