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Pezzotti G, Ofuji S, Imamura H, Adachi T, Yamamoto T, Kanamura N, Ohgitani E, Marin E, Zhu W, Mazda O, Togo A, Kimura S, Iwata T, Shiba H, Ouhara K, Aoki T, Kawai T. In Situ Raman Analysis of Biofilm Exopolysaccharides Formed in Streptococcus mutans and Streptococcus sanguinis Commensal Cultures. Int J Mol Sci 2023; 24:ijms24076694. [PMID: 37047667 PMCID: PMC10095091 DOI: 10.3390/ijms24076694] [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: 02/17/2023] [Revised: 03/23/2023] [Accepted: 03/27/2023] [Indexed: 04/14/2023] Open
Abstract
This study probed in vitro the mechanisms of competition/coexistence between Streptococcus sanguinis (known for being correlated with health in the oral cavity) and Streptococcus mutans (responsible for aciduric oral environment and formation of caries) by means of quantitative Raman spectroscopy and imaging. In situ Raman assessments of live bacterial culture/coculture focusing on biofilm exopolysaccharides supported the hypothesis that both species engaged in antagonistic interactions. Experiments of simultaneous colonization always resulted in coexistence, but they also revealed fundamental alterations of the biofilm with respect to their water-insoluble glucan structure. Raman spectra (collected at fixed time but different bacterial ratios) showed clear changes in chemical bonds in glucans, which pointed to an action by Streptococcus sanguinis to discontinue the impermeability of the biofilm constructed by Streptococcus mutans. The concurrent effects of glycosidic bond cleavage in water-insoluble α - 1,3-glucan and oxidation at various sites in glucans' molecular chains supported the hypothesis that secretion of oxygen radicals was the main "chemical weapon" used by Streptococcus sanguinis in coculture.
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Affiliation(s)
- Giuseppe Pezzotti
- Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, Kyoto 606-8585, Japan
- Department of Immunology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kamigyo-ku, 465 Kajii-cho, Kyoto 602-8566, Japan
- Department of Orthopedic Surgery, Tokyo Medical University, 6-7-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo 160-0023, Japan
- Department of Dental Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kamigyo-ku, Kyoto 602-8566, Japan
- Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy
- Department of Molecular Science and Nanosystems, Ca' Foscari University of Venice, Via Torino 155, 30172 Venice, Italy
| | - Satomi Ofuji
- Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, Kyoto 606-8585, Japan
| | - Hayata Imamura
- Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, Kyoto 606-8585, Japan
- Department of Dental Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kamigyo-ku, Kyoto 602-8566, Japan
| | - Tetsuya Adachi
- Department of Dental Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kamigyo-ku, Kyoto 602-8566, Japan
| | - Toshiro Yamamoto
- Department of Dental Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kamigyo-ku, Kyoto 602-8566, Japan
| | - Narisato Kanamura
- Department of Dental Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kamigyo-ku, Kyoto 602-8566, Japan
| | - Eriko Ohgitani
- Department of Immunology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kamigyo-ku, 465 Kajii-cho, Kyoto 602-8566, Japan
| | - Elia Marin
- Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, Kyoto 606-8585, Japan
- Department of Dental Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kamigyo-ku, Kyoto 602-8566, Japan
| | - Wenliang Zhu
- Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, Kyoto 606-8585, Japan
| | - Osam Mazda
- Department of Immunology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kamigyo-ku, 465 Kajii-cho, Kyoto 602-8566, Japan
| | - Azusa Togo
- Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Satoshi Kimura
- Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Tadahisa Iwata
- Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Hideki Shiba
- Department of Biological Endodontics, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Kazuhisa Ouhara
- Department of Periodontal Medicine, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Takashi Aoki
- Faculty of Fiber Science and Engineering, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, Kyoto 606-8585, Japan
| | - Toshihisa Kawai
- Department of Oral Science and Translational Research, College of Dental Medicine, Nova Southeastern University, 3301 College Ave, Fort Lauderdale, FL 33314, USA
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Cui G, Li P, Wu R, Lin H. Streptococcus mutans membrane vesicles inhibit the biofilm formation of Streptococcus gordonii and Streptococcus sanguinis. AMB Express 2022; 12:154. [PMID: 36508003 PMCID: PMC9743899 DOI: 10.1186/s13568-022-01499-3] [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: 09/08/2022] [Accepted: 12/02/2022] [Indexed: 12/14/2022] Open
Abstract
Streptococcus mutans, whose main virulence factor is glucosyltransferase (Gtf), has a substantial impact on the development of dental caries. S. mutans membrane vesicles (MVs), which are rich in Gtfs, have been shown to affect biofilm formation of other microorganisms. Streptococcus gordonii and Streptococcus sanguinis are initial colonizers of tooth surfaces, which provide attachment sites for subsequent microorganisms and are crucial in the development of oral biofilms. S. mutans and S. gordonii, as well as S. mutans and S. sanguinis, have a complex competitive and cooperative relationship, but it is unclear whether S. mutans MVs play a role in these interspecific interactions. Therefore, we co-cultured S. mutans MVs, having or lacking Gtfs, with S. gordonii and S. sanguinis. Our results showed that S. mutans MVs inhibited biofilm formation of S. gordonii and S. sanguinis but did not affect their planktonic growth; contrastingly, S. mutans ΔgtfBC mutant MVs had little effect on both their growth and biofilm formation. Additionally, there were fewer and more dispersed bacteria in the biofilms of the S. mutans MV-treated group than that in the control group. Furthermore, the expression levels of the biofilm-related virulence factors GtfG, GtfP, and SpxB in S. gordonii and S. sanguinis were significantly downregulated in response to S. mutans MVs. In conclusion, the results of our study showed that S. mutans MVs inhibited biofilm formation of S. gordonii and S. sanguinis, revealing an important role for MVs in interspecific interactions.
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Affiliation(s)
- Guxin Cui
- grid.12981.330000 0001 2360 039XHospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China ,grid.12981.330000 0001 2360 039XGuangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Pengpeng Li
- grid.12981.330000 0001 2360 039XHospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China ,grid.12981.330000 0001 2360 039XGuangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Ruixue Wu
- grid.12981.330000 0001 2360 039XHospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China ,grid.12981.330000 0001 2360 039XGuangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Huancai Lin
- grid.12981.330000 0001 2360 039XHospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China ,grid.12981.330000 0001 2360 039XGuangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
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Okahashi N, Nakata M, Kuwata H, Kawabata S. Oral mitis group streptococci: A silent majority in our oral cavity. Microbiol Immunol 2022; 66:539-551. [PMID: 36114681 DOI: 10.1111/1348-0421.13028] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 09/11/2022] [Accepted: 09/12/2022] [Indexed: 12/13/2022]
Abstract
Members of the oral mitis group streptococci including Streptococcus oralis, Streptococcus sanguinis, and Streptococcus gordonii are the most abundant inhabitants of human oral cavity and dental plaque, and have been implicated in infectious complications such as bacteremia and infective endocarditis. Oral mitis group streptococci are genetically close to Streptococcus pneumoniae; however, they do not produce cytolysin (pneumolysin), which is a key virulence factor of S. pneumoniae. Similar to S. pneumoniae, oral mitis group streptococci possess several cell surface proteins that bind to the cell surface components of host mammalian cells. S. sanguinis expresses long filamentous pili that bind to the matrix proteins of host cells. The cell wall-anchored nuclease of S. sanguinis contributes to the evasion of the neutrophil extracellular trap by digesting its web-like extracellular DNA. Oral mitis group streptococci produce glucosyltransferases, which synthesize glucan (glucose polymer) from sucrose of dietary origin. Neuraminidase (NA) is a virulent factor in oral mitis group streptococci. Influenza type A virus (IAV) relies on viral NA activity to release progeny viruses from infected cells and spread the infection, and NA-producing oral streptococci elevate the risk of IAV infection. Moreover, oral mitis group streptococci produce hydrogen peroxide (H2 O2 ) as a by-product of sugar metabolism. Although the concentrations of streptococcal H2 O2 are low (1-2 mM), they play important roles in bacterial competition in the oral cavity and evasion of phagocytosis by host macrophages and neutrophils. In this review, we intended to describe the diverse pathogenicity of oral mitis group streptococci.
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Affiliation(s)
- Nobuo Okahashi
- Department of Oral and Molecular Microbiology, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan.,Center for Frontier Oral Science, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan
| | - Masanobu Nakata
- Department of Oral Microbiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Hirotaka Kuwata
- Department of Oral Microbiology and Immunology, School of Dentistry, Showa University, Shinagawa, Tokyo, Japan
| | - Shigetada Kawabata
- Department of Oral and Molecular Microbiology, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan
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Hoshino T, Fujiwara T. The findings of glucosyltransferase enzymes derived from oral streptococci. JAPANESE DENTAL SCIENCE REVIEW 2022; 58:328-335. [PMID: 36340584 PMCID: PMC9630777 DOI: 10.1016/j.jdsr.2022.10.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Revised: 10/18/2022] [Accepted: 10/21/2022] [Indexed: 11/07/2022] Open
Abstract
Glucosyltransferase enzymes (Gtfs) distribute among some streptococcal species in oral cavity and are known as key enzymes contributing to the development of oral biofilm such as dental plaque. In 18 streptococcal species, 45 glucosyltransferase genes (gtf) are detected from genome database. Gtfs catalyze the synthesis of the glucans, which are polymers of glucose, from sucrose and they are main component of oral biofilm. Especially, the Gtfs from Streptococcus mutans are recognized as one of dental caries pathogens since they contribute to the formation of dental plaque and the establishment of S. mutans in the tooth surface. Therefore, Gtfs has been studied particularly by many researchers in the dentistry field to develop the anti- caries vaccine. However, it is not still accomplished. In these days, the phylogenetic and crystal structure analyses of Gtfs were performed and the study of Gtfs will enter new situation from the technique in the past old viewpoint. The findings from those analyses will affect the development of the anti-caries vaccine very much after this. In this review, we summarize the findings of oral streptococcal Gtfs and consider the perspectives of the dental caries prevention which targeted Gtf.
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Molina M, Cioci G, Moulis C, Séverac E, Remaud-Siméon M. Bacterial α-Glucan and Branching Sucrases from GH70 Family: Discovery, Structure-Function Relationship Studies and Engineering. Microorganisms 2021; 9:microorganisms9081607. [PMID: 34442685 PMCID: PMC8398850 DOI: 10.3390/microorganisms9081607] [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: 07/06/2021] [Revised: 07/22/2021] [Accepted: 07/25/2021] [Indexed: 01/12/2023] Open
Abstract
Glucansucrases and branching sucrases are classified in the family 70 of glycoside hydrolases. They are produced by lactic acid bacteria occupying very diverse ecological niches (soil, buccal cavity, sourdough, intestine, dairy products, etc.). Usually secreted by their producer organisms, they are involved in the synthesis of α-glucans from sucrose substrate. They contribute to cell protection while promoting adhesion and colonization of different biotopes. Dextran, an α-1,6 linked linear α-glucan, was the first microbial polysaccharide commercialized for medical applications. Advances in the discovery and characterization of these enzymes have remarkably enriched the available diversity with new catalysts. Research into their molecular mechanisms has highlighted important features governing their peculiarities thus opening up many opportunities for engineering these catalysts to provide new routes for the transformation of sucrose into value-added molecules. This article reviews these different aspects with the ambition to show how they constitute the basis for promising future developments.
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Lyu X, Wang L, Shui Y, Jiang Q, Chen L, Yang W, He X, Zeng J, Li Y. Ursolic acid inhibits multi-species biofilms developed by Streptococcus mutans, Streptococcus sanguinis, and Streptococcus gordonii. Arch Oral Biol 2021; 125:105107. [PMID: 33735629 DOI: 10.1016/j.archoralbio.2021.105107] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 03/09/2021] [Accepted: 03/10/2021] [Indexed: 10/21/2022]
Abstract
OBJECTIVE The current study aimed to assess the antimicrobial activity of ursolic acid (UA) against multi-species biofilms formed by Streptococcus mutans, Streptococcus sanguinis, and Streptococcus gordonii, as well as to measure its biocompatibility. METHODS Crystal violet staining, CFU counting, CCK-8 assays and scanning electron microscopy (SEM) were applied to investigate the effect of UA on multi-species biofilms. UA's effect on exopolysaccharides (EPS) production was measured using confocal laser scanning microscopy (CLSM) and the anthrone-sulfuric acid method. Fluorescent in situ hybridization (FISH) was applied to visualize and quantify the microbial composition of multi-species biofilms. Quantitative real-time PCR (qRT-PCR) was used to measure the expression of virulence genes of S. mutans, S. sanguinis, and S. gordonii under UA treatment. Moreover, CCK-8 assays were performed to evaluate its cytotoxicity against human oral keratinocytes (HOKs) and human gingival epithelial cells (HGEs). RESULTS The results showed that UA had significant antimicrobial activity against common oral streptococci. UA also reduced the EPS synthesis of oral streptococci and suppressed gtf genes' expression. In addition, UA reduced the proportion of S. mutans in multi-species biofilms. Besides, UA had low cytotoxicity against HOKs and HGEs. CONCLUSIONS UA exhibited antibiofilm activity against oral pathogenic bacteria and had the potential to be used in dental caries treatment.
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Affiliation(s)
- Xiaoying Lyu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China School of Stomatology, Sichuan University, Chengdu, Sichuan 610041, China
| | - Liang Wang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China School of Stomatology, Sichuan University, Chengdu, Sichuan 610041, China
| | - Yusen Shui
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China School of Stomatology, Sichuan University, Chengdu, Sichuan 610041, China
| | - Qingsong Jiang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China School of Stomatology, Sichuan University, Chengdu, Sichuan 610041, China
| | - Lan Chen
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China School of Stomatology, Sichuan University, Chengdu, Sichuan 610041, China
| | - Wen Yang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China School of Stomatology, Sichuan University, Chengdu, Sichuan 610041, China
| | - Xiaoya He
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China School of Stomatology, Sichuan University, Chengdu, Sichuan 610041, China
| | - Jumei Zeng
- West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, Sichuan 610041, China.
| | - Yuqing Li
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China School of Stomatology, Sichuan University, Chengdu, Sichuan 610041, China.
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Veerapandian R, Vediyappan G. Gymnemic Acids Inhibit Adhesive Nanofibrillar Mediated Streptococcus gordonii-Candida albicans Mono-Species and Dual-Species Biofilms. Front Microbiol 2019; 10:2328. [PMID: 31681200 PMCID: PMC6797559 DOI: 10.3389/fmicb.2019.02328] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 09/24/2019] [Indexed: 12/17/2022] Open
Abstract
Dental caries and periodontitis are the most common oral disease of all age groups, affecting billions of people worldwide. These oral diseases are mostly associated with microbial biofilms in the oral cavity. Streptococcus gordonii, an early tooth colonizing bacterium and Candida albicans, an opportunistic pathogenic fungus, are the two abundant oral microbes that form mixed biofilms with augmented virulence, affecting oral health negatively. Understanding the molecular mechanisms of the pathogen interactions and identifying non-toxic compounds that block the growth of biofilms are important steps in the development of effective therapeutic approaches. In this in vitro study we report the inhibition of mono-species or dual-species biofilms of S. gordonii and C. albicans, and decreased levels of biofilm extracellular DNA (eDNA), when biofilms were grown in the presence of gymnemic acids (GAs), a non-toxic small molecule inhibitor of fungal hyphae. Scanning electron microscopic images of biofilms on saliva-coated hydroxyapatite (sHA) surfaces revealed attachment of S. gordonii cells to C. albicans hyphae and to sHA surfaces via nanofibrils only in the untreated control, but not in the GAs-treated biofilms. Interestingly, C. albicans produced fibrillar adhesive structures from hyphae when grown with S. gordonii as a mixed biofilm; addition of GAs abrogated the nanofibrils and reduced the growth of both hyphae and the biofilm. To our knowledge, this is the first report that C. albicans produces adhesive fibrils from hyphae in response to S. gordonii mixed biofilm growth. Semi-quantitative PCR of selected genes related to biofilms from both microbes showed differential expression in control vs. treated biofilms. Further, GAs inhibited the activity of recombinant S. gordonii glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Taken together, our results suggest that S. gordonii stimulates the expression of adhesive materials in C. albicans by direct interaction and/or signaling, and the adhesive material expression can be inhibited by GAs.
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Affiliation(s)
- Raja Veerapandian
- Division of Biology, Kansas State University, Manhattan, KS, United States
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Wu J, Li M, Huang R. The effect of smoking on caries-related microorganisms. Tob Induc Dis 2019; 17:32. [PMID: 31516475 PMCID: PMC6662784 DOI: 10.18332/tid/105913] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 03/23/2019] [Accepted: 03/24/2019] [Indexed: 02/05/2023] Open
Abstract
INTRODUCTION Epidemiological studies have shown a close relationship between smoking and dental caries. Bacteria are one of the essential factors of caries formation. The imbalance of cariogenic bacteria and commensal bacteria in dental plaque results in higher production of acid that can corrode dental hard tissue. The aim of our review is to summarize the effect of smoking on caries-related bacteria. METHODS English articles available in Pubmed and ScienceDirect databases and published before December 2018 were searched. A variety of evidence was collected including not only the influence of cigarette products on bacteria strains in vitro but also their effect on bacterial composition in saliva and dental plaque in vivo. We particularly emphasize the mechanisms by which nicotine acts on oral bacteria. RESULTS The components of cigarettes promote the growth of cariogenic microorganisms. The mechanisms of how nicotine enhances Streptococcus mutans, Lactobacilli, Streptococcus gordonii, Actinomyces and Candida albicans are described separately in detail. The commensal bacteria, Streptococcus sanguinis, show less competitive capability in the presence of nicotine. Smoking influences saliva by lowering the buffer capability, altering its chemical agent and bacterial components, and therefore promotes the formation of a caries-susceptible environment. CONCLUSIONS Cigarette smoking and nicotine exposure promote the cariogenic activity of oral microorganisms and the formation of a caries-susceptible environment. This suggests that smokers should quit smoking, amongst other health reasons, also for their oral health.
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Affiliation(s)
- Jiayi Wu
- Department of Endodontic Dentistry, State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Mingyun Li
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Ruijie Huang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China
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Xu RR, Yang WD, Niu KX, Wang B, Wang WM. An Update on the Evolution of Glucosyltransferase ( Gtf) Genes in Streptococcus. Front Microbiol 2018; 9:2979. [PMID: 30568640 PMCID: PMC6290343 DOI: 10.3389/fmicb.2018.02979] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 11/19/2018] [Indexed: 11/13/2022] Open
Abstract
In many caries-promoting Streptococcus species, glucosyltransferases (Gtfs) are recognized as key enzymes contributing to the modification of biofilm structures, disruption of homeostasis of healthy microbiota community and induction of caries development. It is therefore of great interest to investigate how Gtf genes have evolved in Streptococcus. In this study, we conducted a comprehensive survey of Gtf genes among 872 streptococci genomes of 37 species and identified Gtf genes from 364 genomes of 18 species. To clarify the relationships of these Gtf genes, 45 representative sequences were used for phylogenic analysis, which revealed two clear clades. Clade I included 12 Gtf genes from nine caries-promoting species of the Mutans and Downei groups, which produce enzymes known to synthesize sticky, water-insoluble glucans (WIG) that are critical for modifying biofilm structures. Clade II primarily contained Gtf genes responsible for synthesizing water-soluble glucans (WSG) from all 18 species, and this clade further diverged into three subclades (IIA, IIB, and IIC). An analysis of 16 pairs of duplicated Gtf genes revealed high divergence levels at the C-terminal repeat regions, with ratios of the non-synonymous substitution rate (dN) to synonymous substitution rate (dS) ranging from 0.60 to 1.03, indicating an overall relaxed constraint in this region. However, among the clade I Gtf genes, some individual repeat units possessed strong functional constraints by the same criterion. Structural variations in the repeat regions were also observed, with detection of deletions or recent duplications of individual repeat units. Overall, by establishing an updated phylogeny and further elucidating their evolutionary patterns, this work enabled us to gain a greater understanding of the origination and divergence of Gtf genes in Streptococcus.
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Affiliation(s)
- Rong-Rong Xu
- Nanjing Stomatological Hospital, Nanjing University Medical School, Nanjing, China
| | - Wei-Dong Yang
- Nanjing Stomatological Hospital, Nanjing University Medical School, Nanjing, China
| | - Ke-Xin Niu
- Laboratory of Plant Genetics and Molecular Evolution, School of Life Sciences, Nanjing University, Nanjing, China
| | - Bin Wang
- Laboratory of Plant Genetics and Molecular Evolution, School of Life Sciences, Nanjing University, Nanjing, China
| | - Wen-Mei Wang
- Nanjing Stomatological Hospital, Nanjing University Medical School, Nanjing, China
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Draft Genome Sequence of Weissella confusa MBF8-1, a Glucansucrase- and Bacteriocin-Producing Strain Isolated from a Homemade Soy Product. GENOME ANNOUNCEMENTS 2017; 5:5/4/e01497-16. [PMID: 28126938 PMCID: PMC5270697 DOI: 10.1128/genomea.01497-16] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We report here the draft genome sequence of Weissella confusa MBF8-1, an isolate from a homemade fermented soybean product that produces sucrases and exhibits antibacterial (bacteriocin) activity. The draft genome of W. confusa MBF8-1 comprises a 2.2-Mbp chromosome and a 17.8-kbp bacteriocin-encoding plasmid. Two putative glucansucrase genes were also identified.
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Vickerman MM, Mansfield JM, Zhu M, Walters KS, Banas JA. Codon-optimized fluorescent mTFP and mCherry for microscopic visualization and genetic counterselection of streptococci and enterococci. J Microbiol Methods 2015; 116:15-22. [PMID: 26122309 PMCID: PMC4522221 DOI: 10.1016/j.mimet.2015.06.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 06/19/2015] [Accepted: 06/19/2015] [Indexed: 01/20/2023]
Abstract
Despite the powerful potential of fluorescent proteins for labeling bacteria, their use has been limited in multi-species oral biofilm models. Fermentative metabolism by streptococcal species that initiate biofilm colonization results in an acidic, reduced microenvironment that may limit the activities of some fluorescent proteins which are influenced by pH and oxygen availability. The need to reliably distinguish morphologically similar strains within biofilms was the impetus for this work. Teal fluorescent protein (mTFP1) and red fluorescent protein (mCherry) were chosen because their fluorescent properties made them promising candidates. Since tRNA availability has been implicated in efficient translation of sufficient quantities of protein for maximum fluorescence, a streptococcal codon optimization approach was used. DNA was synthesized to encode either protein using codons most frequently used in streptococci; each coding region was preceded by an engineered ribosomal binding site and restriction sites for cloning a promoter. Plasmids carrying this synthesized DNA under control of the Streptococcus mutans lactate dehydrogenase promoter conferred fluorescence to nine representative streptococcal and two Enterococcus faecalis strains. Further characterization in Streptococcus gordonii showed that mTFP1 and mCherry expressions could be detected in cells grown planktonically, in biofilms, or in colonies on agar when expressed on an extrachromosomal plasmid or in single copy integrated into the chromosome. This latter property facilitated counterselection of chromosomal mutations demonstrating value for bacterial strain construction. Fluorescent and non-fluorescent bacteria were distinguishable at acidic pH. These codon-optimized versions of mTFP1 and mCherry have promising potential for use in multiple experimental applications.
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Affiliation(s)
- M Margaret Vickerman
- Department of Periodontics and Endodontics, University at Buffalo School of Dental Medicine, Buffalo, NY, USA; Department of Oral Biology, University at Buffalo School of Dental Medicine, Buffalo, NY, USA.
| | - Jillian M Mansfield
- Department of Periodontics and Endodontics, University at Buffalo School of Dental Medicine, Buffalo, NY, USA; Department of Oral Biology, University at Buffalo School of Dental Medicine, Buffalo, NY, USA
| | - Min Zhu
- Dows Institute for Research, University of Iowa College of Dentistry, Iowa City, IA, USA
| | - Katherine S Walters
- Central Microscopy Research Facility, University of Iowa, Iowa City, IA, USA
| | - Jeffrey A Banas
- Dows Institute for Research, University of Iowa College of Dentistry, Iowa City, IA, USA
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Huang R, Li M, Ye M, Yang K, Xu X, Gregory RL. Effects of Nicotine on Streptococcus gordonii Growth, Biofilm Formation, and Cell Aggregation. Appl Environ Microbiol 2014; 80:7212-8. [PMID: 25217021 PMCID: PMC4249166 DOI: 10.1128/aem.02395-14] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 09/09/2014] [Indexed: 02/05/2023] Open
Abstract
Streptococcus gordonii is a commensal species of human oral flora. It initiates dental biofilm formation and provides binding sites for later colonizers to attach to and generate mature biofilm. Smoking is the second highest risk factor for periodontal disease, and cigarette smoke extract has been reported to facilitate Porphyromonas gingivalis-S. gordonii dual-species biofilm formation. Our hypothesis is that nicotine, one of the most important and active components of tobacco, stimulates S. gordonii multiplication and aggregation. In the present study, S. gordonii planktonic cell growth (kinetic absorbance and CFU), biofilm formation (crystal violet stain and confocal laser scanning microscopy [CLSM]), aggregation with/without sucrose, and 11 genes that encode binding proteins or regulators of gene expression were investigated. Results demonstrated planktonic cell growth was stimulated by 1 to 4 mg/ml nicotine treatment. Biofilm formation was increased at 0.5 to 4 mg/ml nicotine. CLSM indicated bacterial cell mass was increased by 2 and 4 mg/ml nicotine, but biofilm extracellular polysaccharide was not significantly affected by nicotine. Cell aggregation was upregulated by 4, 8, and 16 mg/ml nicotine with sucrose and by 16 mg/ml nicotine without sucrose. Quantitative reverse transcriptase PCR indicated S. gordonii abpA, scaA, ccpA, and srtA were upregulated in planktonic cells by 2 mg/ml nicotine. In conclusion, nicotine stimulates S. gordonii planktonic cell growth, biofilm formation, aggregation, and gene expression of binding proteins. Those effects may promote later pathogen attachment to tooth surfaces, the accumulation of tooth calculus, and the development of periodontal disease in cigarette smokers.
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Affiliation(s)
- R Huang
- Department of Oral Biology and Tobacco Cessation and Biobehavioral Group, School of Dentistry, Indiana University, Indianapolis, Indiana, USA State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - M Li
- Department of Oral Biology and Tobacco Cessation and Biobehavioral Group, School of Dentistry, Indiana University, Indianapolis, Indiana, USA State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - M Ye
- Department of Microbiology and Immunology, School of Medicine, Indiana University, Indianapolis, Indiana, USA
| | - K Yang
- Department of Electrical and Computer Engineering, Indiana University-Purdue University, Indianapolis, Indiana, USA
| | - X Xu
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - R L Gregory
- Department of Oral Biology and Tobacco Cessation and Biobehavioral Group, School of Dentistry, Indiana University, Indianapolis, Indiana, USA Department of Pathology and Laboratory Medicine, School of Medicine, Indiana University, Indianapolis, Indiana, USA
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Designing of a novel dextransucrase efficient in acceptor reactions. Carbohydr Res 2014; 386:41-7. [DOI: 10.1016/j.carres.2014.01.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 01/02/2014] [Accepted: 01/07/2014] [Indexed: 11/21/2022]
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14
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Ricker A, Vickerman M, Dongari-Bagtzoglou A. Streptococcus gordonii glucosyltransferase promotes biofilm interactions with Candida albicans. J Oral Microbiol 2014; 6:23419. [PMID: 24490004 PMCID: PMC3907680 DOI: 10.3402/jom.v6.23419] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 01/03/2014] [Accepted: 01/06/2014] [Indexed: 12/02/2022] Open
Abstract
Background Candida albicans co-aggregates with Streptococcus gordonii to form biofilms and their interactions in mucosal biofilms may lead to pathogenic synergy. Although the functions of glucosyltransferases (Gtf) of Mutans streptococci have been well characterized, the biological roles of these enzymes in commensal oral streptococci, such as S. gordonii, in oral biofilm communities are less clear. Objective The objective of this work was to explore the role of GtfG, the single Gtf enzyme of S. gordonii, in biofilm interactions with C. albicans. Design Biofilms were grown under salivary flow in flow cells in vitro, or under static conditions in 96 well plates. A panel of isogenic S. gordonii CH1 gtfG mutants and complemented strains were co-inoculated with C. albicans strain SC5314 to form mixed biofilms. Biofilm accretion and binding interactions between the two organisms were tested. Biofilms were quantified using confocal microscopy or the crystal violet assay. Results The presence of GtfG enhanced dual biofilm accretion, and sucrose supplementation further augmented dual biofilm formation, pointing to a role of newly synthesized glucans. GtfG also promoted binding to C. albicans preformed biofilms. Soluble α-1,6-glucans played a role in these interactions since: 1) a strain producing only soluble glucans (CH107) formed robust dual biofilms under conditions of salivary flow; and 2) the dual biofilm was susceptible to enzymatic breakdown by dextranase which specifically degrades soluble α-1,6-glucans. Conclusion Our work identified a novel molecular mechanism for C. albicans and S. gordonii biofilm interactions, mediated by GtfG. This protein promotes early biofilm binding of S. gordonii to C. albicans which leads to increased accretion of streptococcal cells in mixed biofilms. We also showed that soluble glucans, with α-1,6-linkages, promoted inter-generic adhesive interactions.
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Affiliation(s)
- Austin Ricker
- School of Dental Medicine, University of Connecticut Health Center, Farmington, CT, USA
| | - Margaret Vickerman
- School of Dental Medicine, State University of New York at Buffalo, Buffalo, NY, USA
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Clewell DB. Tales of conjugation and sex pheromones: A plasmid and enterococcal odyssey. Mob Genet Elements 2011; 1:38-54. [PMID: 22016844 PMCID: PMC3190283 DOI: 10.4161/mge.1.1.15409] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Accepted: 03/03/2011] [Indexed: 12/11/2022] Open
Abstract
This review covers highlights of the author's experience becoming and working as a plasmid biologist. The account chronicles a progression from studies of ColE1 DNA in Escherichia coli to Gram-positive bacteria with an emphasis on conjugation in enterococci. It deals with gene amplification, conjugative transposons and sex pheromones in the context of bacterial antibiotic resistance.
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Affiliation(s)
- Don B Clewell
- Biologic and Materials Sciences; School of Dentistry and Microbiology and Immunology; Medical School; The University of Michigan; Ann Arbor, MI USA
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16
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Park HK, Lee HJ, Jeong EG, Shin HS, Kim W. The rgg gene is a specific marker for Streptococcus oralis. J Dent Res 2010; 89:1299-303. [PMID: 20739692 DOI: 10.1177/0022034510378426] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Although the pathogenesis of Streptococcus oralis may be different from that of other viridans group streptococci, S. oralis shares a high degree of DNA sequence similarity with these streptococci. As a result, discrimination of S. oralis from its close relatives has long been considered difficult. This study was conducted to find specific genes that allow for the in vitro identification of S. oralis, but not other oral commensals. Four hundred ninety S. oralis clones obtained by suppressive subtractive hybridization were used for Southern hybridization, and positive clones were sequenced. Of 5 S. oralis-specific clones, newly designed primer sets based on the glucosyltransferase regulatory gene amplified genomic DNA only from S. oralis strains, but not from any of the other 125 strains tested. Our findings may be useful for the future development of efficient diagnostic tools for the rapid identification and differentiation of S. oralis from other oral streptococci strains.
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Affiliation(s)
- H K Park
- Department of Microbiology & Research Institute for Translational System Biomics, Chung-Ang University College of Medicine, 221 Heukseok-dong, Dongjak-ku, Seoul 156-756, Republic of Korea
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André I, Potocki-Véronèse G, Morel S, Monsan P, Remaud-Siméon M. Sucrose-Utilizing Transglucosidases for Biocatalysis. Top Curr Chem (Cham) 2010; 294:25-48. [DOI: 10.1007/128_2010_52] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Nobbs AH, Lamont RJ, Jenkinson HF. Streptococcus adherence and colonization. Microbiol Mol Biol Rev 2009; 73:407-50, Table of Contents. [PMID: 19721085 PMCID: PMC2738137 DOI: 10.1128/mmbr.00014-09] [Citation(s) in RCA: 425] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Streptococci readily colonize mucosal tissues in the nasopharynx; the respiratory, gastrointestinal, and genitourinary tracts; and the skin. Each ecological niche presents a series of challenges to successful colonization with which streptococci have to contend. Some species exist in equilibrium with their host, neither stimulating nor submitting to immune defenses mounted against them. Most are either opportunistic or true pathogens responsible for diseases such as pharyngitis, tooth decay, necrotizing fasciitis, infective endocarditis, and meningitis. Part of the success of streptococci as colonizers is attributable to the spectrum of proteins expressed on their surfaces. Adhesins enable interactions with salivary, serum, and extracellular matrix components; host cells; and other microbes. This is the essential first step to colonization, the development of complex communities, and possible invasion of host tissues. The majority of streptococcal adhesins are anchored to the cell wall via a C-terminal LPxTz motif. Other proteins may be surface anchored through N-terminal lipid modifications, while the mechanism of cell wall associations for others remains unclear. Collectively, these surface-bound proteins provide Streptococcus species with a "coat of many colors," enabling multiple intimate contacts and interplays between the bacterial cell and the host. In vitro and in vivo studies have demonstrated direct roles for many streptococcal adhesins as colonization or virulence factors, making them attractive targets for therapeutic and preventive strategies against streptococcal infections. There is, therefore, much focus on applying increasingly advanced molecular techniques to determine the precise structures and functions of these proteins, and their regulatory pathways, so that more targeted approaches can be developed.
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Affiliation(s)
- Angela H Nobbs
- Oral Microbiology Unit, Department of Oral and Dental Science, University of Bristol, Bristol BS1 2LY, United Kingdom
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Interaction of salivary alpha-amylase and amylase-binding-protein A (AbpA) of Streptococcus gordonii with glucosyltransferase of S. gordonii and Streptococcus mutans. BMC Microbiol 2007; 7:60. [PMID: 17593303 PMCID: PMC3225810 DOI: 10.1186/1471-2180-7-60] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2006] [Accepted: 06/25/2007] [Indexed: 11/16/2022] Open
Abstract
Background Glucosyltransferases (Gtfs), enzymes that produce extracellular glucans from dietary sucrose, contribute to dental plaque formation by Streptococcus gordonii and Streptococcus mutans. The alpha-amylase-binding protein A (AbpA) of S. gordonii, an early colonizing bacterium in dental plaque, interacts with salivary amylase and may influence dental plaque formation by this organism. We examined the interaction of amylase and recombinant AbpA (rAbpA), together with Gtfs of S. gordonii and S. mutans. Results The addition of salivary alpha-amylase to culture supernatants of S. gordonii precipitated a protein complex containing amylase, AbpA, amylase-binding protein B (AbpB), and the glucosyltransferase produced by S. gordonii (Gtf-G). rAbpA was expressed from an inducible plasmid, purified from Escherichia coli and characterized. Purified rAbpA, along with purified amylase, interacted with and precipitated Gtfs from culture supernatants of both S. gordonii and S. mutans. The presence of amylase and/or rAbpA increased both the sucrase and transferase component activities of S. mutans Gtf-B. Enzyme-linked immunosorbent assay (ELISA) using anti-Gtf-B antibody verified the interaction of rAbpA and amylase with Gtf-B. A S. gordonii abpA-deficient mutant showed greater biofilm growth under static conditions than wild-type in the presence of sucrose. Interestingly, biofilm formation by every strain was inhibited in the presence of saliva. Conclusion The results suggest that an extracellular protein network of AbpA-amylase-Gtf may influence the ecology of oral biofilms, likely during initial phases of colonization.
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20
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van Hijum SAFT, Kralj S, Ozimek LK, Dijkhuizen L, van Geel-Schutten IGH. Structure-function relationships of glucansucrase and fructansucrase enzymes from lactic acid bacteria. Microbiol Mol Biol Rev 2006; 70:157-76. [PMID: 16524921 PMCID: PMC1393251 DOI: 10.1128/mmbr.70.1.157-176.2006] [Citation(s) in RCA: 316] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lactic acid bacteria (LAB) employ sucrase-type enzymes to convert sucrose into homopolysaccharides consisting of either glucosyl units (glucans) or fructosyl units (fructans). The enzymes involved are labeled glucansucrases (GS) and fructansucrases (FS), respectively. The available molecular, biochemical, and structural information on sucrase genes and enzymes from various LAB and their fructan and alpha-glucan products is reviewed. The GS and FS enzymes are both glycoside hydrolase enzymes that act on the same substrate (sucrose) and catalyze (retaining) transglycosylation reactions that result in polysaccharide formation, but they possess completely different protein structures. GS enzymes (family GH70) are large multidomain proteins that occur exclusively in LAB. Their catalytic domain displays clear secondary-structure similarity with alpha-amylase enzymes (family GH13), with a predicted permuted (beta/alpha)(8) barrel structure for which detailed structural and mechanistic information is available. Emphasis now is on identification of residues and regions important for GS enzyme activity and product specificity (synthesis of alpha-glucans differing in glycosidic linkage type, degree and type of branching, glucan molecular mass, and solubility). FS enzymes (family GH68) occur in both gram-negative and gram-positive bacteria and synthesize beta-fructan polymers with either beta-(2-->6) (inulin) or beta-(2-->1) (levan) glycosidic bonds. Recently, the first high-resolution three-dimensional structures have become available for FS (levansucrase) proteins, revealing a rare five-bladed beta-propeller structure with a deep, negatively charged central pocket. Although these structures have provided detailed mechanistic insights, the structural features in FS enzymes dictating the synthesis of either beta-(2-->6) or beta-(2-->1) linkages, degree and type of branching, and fructan molecular mass remain to be identified.
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Affiliation(s)
- Sacha A F T van Hijum
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, P.O. Box 14, 9750 AA Haren, The Netherlands.
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21
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Nagamune H, Ohkura K, Ohkuni H. Molecular basis of group A streptococcal pyrogenic exotoxin B. J Infect Chemother 2005; 11:1-8. [PMID: 15729480 DOI: 10.1007/s10156-004-0354-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2004] [Indexed: 01/23/2023]
Affiliation(s)
- Hideaki Nagamune
- Department of Biological Science and Technology, Faculty of Engineering, University of Tokushima, Tokushima, Japan
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22
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Shah DSH, Joucla G, Remaud-Simeon M, Russell RRB. Conserved repeat motifs and glucan binding by glucansucrases of oral streptococci and Leuconostoc mesenteroides. J Bacteriol 2005; 186:8301-8. [PMID: 15576779 PMCID: PMC532428 DOI: 10.1128/jb.186.24.8301-8308.2004] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Glucansucrases of oral streptococci and Leuconostoc mesenteroides have a common pattern of structural organization and characteristically contain a domain with a series of tandem amino acid repeats in which certain residues are highly conserved, particularly aromatic amino acids and glycine. In some glucosyltransferases (GTFs) the repeat region has been identified as a glucan binding domain (GBD). Such GBDs are also found in several glucan binding proteins (GBP) of oral streptococci that do not have glucansucrase activity. Alignment of the amino acid sequences of 20 glucansucrases and GBP showed the widespread conservation of the 33-residue A repeat first identified in GtfI of Streptococcus downei. Site-directed mutagenesis of individual highly conserved residues in recombinant GBD of GtfI demonstrated the importance of the first tryptophan and the tyrosine-phenylalanine pair in the binding of dextran, as well as the essential contribution of a basic residue (arginine or lysine). A microplate binding assay was developed to measure the binding affinity of recombinant GBDs. GBD of GtfI was shown to be capable of binding glucans with predominantly alpha-1,3 or alpha-1,6 links, as well as alternating alpha-1,3 and alpha-1,6 links (alternan). Western blot experiments using biotinylated dextran or alternan as probes demonstrated a difference between the binding of streptococcal GTF and GBP and that of Leuconostoc glucansucrases. Experimental data and bioinformatics analysis showed that the A repeat motif is distinct from the 20-residue CW motif, which also has conserved aromatic amino acids and glycine and which occurs in the choline-binding proteins of Streptococcus pneumoniae and other organisms.
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Affiliation(s)
- Deepan S H Shah
- Oral Biology, School of Dental Sciences, University of Newcastle, Newcastle upon Tyne NE2 4BW, United Kingdom
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Shah DSH, Russell RRB. A novel glucan-binding protein with lipase activity from the oral pathogen Streptococcus mutans. MICROBIOLOGY-SGM 2004; 150:1947-1956. [PMID: 15184580 DOI: 10.1099/mic.0.26955-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Streptococcus mutans produces extracellular glucosyltransferases (GTFs) that synthesize glucans from sucrose. These glucans are important in determining the permeability properties and adhesiveness of dental plaque. GTFs and the GbpA glucan-binding protein are characterized by a binding domain containing a series of 33-amino-acid repeats, called 'A' repeats. The S. mutans genome sequence was searched for ORFs containing 'A' repeats, and one novel gene, gbpD, which appears to be unique to the mutans group of streptococci, was identified. The GbpD sequence revealed the presence of three 'A' repeats, in the middle of the protein, and a novel glucan-binding assay showed that GbpD binds to dextran with a K(D) of 2-3 nM. Construction of truncated derivatives of GbpD confirmed that the 'A' repeat region was essential for binding. Furthermore, a gbpD knockout mutant was modified in the extent of aggregation induced by polymers derived from sucrose. The N-terminus of GbpD has a signal sequence, followed by a region with no homologues in the public databases, while the C-terminus has homology to the alpha/beta hydrolase family (including lipases and carboxylesterases). GbpD contains the two regions typical of these enzymes: a GxSxG active site 'lipase box' and an 'oxyanion hole'. GbpD released free fatty acids (FFAs) from a range of triglycerides in the presence of calcium, indicating a lipase activity. The glucan binding/lipase bifunctionality suggested the natural substrate for the enzyme may be a surface macromolecule consisting of carbohydrate linked to lipid. The gbpD mutant was less hydrophobic than wild-type and pure recombinant GbpD reduced the hydrophobicity of S. mutans and another plaque bacterium, Streptococcus sanguinis. GbpD bound to and released FFA from lipoteichoic acid (LTA) of S. sanguinis, but had no effect on LTA from S. mutans. These results raise the intriguing possibility that GbpD may be involved in direct interspecies competition within the plaque biofilm.
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Affiliation(s)
- Deepan S H Shah
- School of Dental Sciences, University of Newcastle, Newcastle upon Tyne NE2 4BW, UK
| | - Roy R B Russell
- School of Dental Sciences, University of Newcastle, Newcastle upon Tyne NE2 4BW, UK
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Banas JA, Vickerman MM. Glucan-binding proteins of the oral streptococci. CRITICAL REVIEWS IN ORAL BIOLOGY AND MEDICINE : AN OFFICIAL PUBLICATION OF THE AMERICAN ASSOCIATION OF ORAL BIOLOGISTS 2003; 14:89-99. [PMID: 12764072 DOI: 10.1177/154411130301400203] [Citation(s) in RCA: 225] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The synthesis of extracellular glucan is an integral component of the sucrose-dependent colonization of tooth surfaces by species of the mutans streptococci. In investigators' attempts to understand the mechanisms of plaque biofilm development, several glucan-binding proteins (GBPs) have been discovered. Some of these, the glucosyltransferases, catalyze the synthesis of glucan, whereas others, designated only as glucan-binding proteins, have affinities for different forms of glucan and contribute to aspects of the biology of their host organisms. The functions of these latter glucan-binding proteins include dextran-dependent aggregation, dextranase inhibition, plaque cohesion, and perhaps cell wall synthesis. In some instances, their glucan-binding domains share common features, whereas in others the mechanism for glucan binding remains unknown. Recent studies indicate that at least some of the glucan-binding proteins modulate virulence and some can act as protective immunogens within animal models. Overall, the multiplicity of GBPs and their aforementioned properties are testimonies to their importance. Future studies will greatly advance the understanding of the distribution, function, and regulation of the GBPs and place into perspective the facets of their contributions to the biology of the oral streptococci.
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Affiliation(s)
- J A Banas
- Center for Immunology and Microbial Disease, Albany Medical College, NY 12208, USA.
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Ando T, Tsumori H, Shimamura A, Sato Y, Mukasa H. Classification of oral streptococci by two-dimensional gel electrophoresis with direct activity stain for glycosyltransferases. ORAL MICROBIOLOGY AND IMMUNOLOGY 2003; 18:171-5. [PMID: 12753469 DOI: 10.1034/j.1399-302x.2003.00062.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Thirty eight strains of oral streptococci were divided into six types by two-dimensional gel electrophoresis (2-DE) followed by glycosyltransferase (GLT) activity stain: Type 1, Streptococcus mutans; Type 2, Streptococcus rattus; Type 3, Streptococcus sobrinus and Streptococcus downei; Type 4, Streptococcus cricetus; Type 5, Streptococcus salivarius; and Type 6, Streptococcus sanguis, Streptococcus oralis and Streptococcus gordonii. In Types 1, 2 and 5, two glucosyltransferases synthesizing water-insoluble (GTF-I) and water-soluble glucans (GTF-S) and a fructosyltransferase (FTF) were detected. In Types 3 and 4, GTF-I and two GTF-Ss were detected. Only one GTF-S was detected in Type 6. The 2-DE patterns for these six types were clearly distinguished from each other based on the kind, number and location of GLTs in gel.
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Affiliation(s)
- T Ando
- Department of Oral and Maxillofacial Surgery, National Defense Medical College, Saitama, Japan
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Vickerman MM, Minick PE. Genetic analysis of the rgg-gtfG junctional region and its role in Streptococcus gordonii glucosyltransferase activity. Infect Immun 2002; 70:1703-14. [PMID: 11895932 PMCID: PMC127849 DOI: 10.1128/iai.70.4.1703-1714.2002] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Glucans synthesized by glucosyltransferase enzymes of oral streptococci facilitate bacterial accumulation on surfaces. The Streptococcus gordonii glucosyltransferase gene, gtfG, is positively regulated by rgg, which encodes a putative cytoplasmic protein. The gtfG promoter and ribosomal binding sequences are located within a DNA inverted repeat immediately downstream of rgg. Polycistronic rgg-gtfG as well as rgg- and gtfG-specific transcripts are associated with this chromosomal region. Previous studies have shown that the rgg product acts in trans near the gtfG promoter to increase the level of gtfG transcript, but it does not affect the level of rgg-gtfG transcript. To further analyze regulation by rgg, a series of strain Challis derivatives was constructed and glucosyltransferase activities were determined. Strains in which rgg was separated from gtfG by integrated vector sequences had decreased levels of glucosyltransferase activity; plasmid-borne rgg could not increase activity to parental levels. As expected, strains with chromosomal deletions involving the rgg structural gene and either the rgg or gtfG promoter also showed decreased glucosyltransferase activity. Plasmid-borne rgg could increase glucosyltransferase activity only in strains which had a 36-bp chromosomal region beginning 72 nucleotides upstream of the gtfG transcriptional start site. Results suggest that these nucleotides, located within the 3' end of rgg, are necessary, either by direct involvement in binding or by indirectly affecting secondary structure, for Rgg to increase glucosyltransferase activity. Surprisingly, the presence of the rgg promoter upstream of this 36-bp region significantly increased the effects of plasmid-borne rgg. Implications for glucosyltransferase regulation and applicability to other rgg-like determinants are considered.
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Affiliation(s)
- M M Vickerman
- Department of Oral Surgery and Hospital Dentistry, School of Dentistry, Indiana University, Indianapolis, Indiana 46202, USA.
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Vickerman MM, Mather NM, Minick PE, Edwards CA. Initial characterization of the Streptococcus gordonii htpX gene. ORAL MICROBIOLOGY AND IMMUNOLOGY 2002; 17:22-31. [PMID: 11860552 DOI: 10.1046/j.0902-0055.2001.00000.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Examination of the Streptococcus gordonii chromosomal region, which lies immediately upstream of the glucosyltransferase positive regulatory determinant rgg, revealed two open reading frames. Based on nucleotide sequences, these genes were similar to the Listeria monocytogenes lemA gene, which is involved in antigen presentation, and the Escherichia coli htpX heat shock gene, which has an unknown function. Northern hybridization analysis indicated that S. gordonii lemA and htpX genes were associated with a ca. 1.7-kb polycistronic transcript. Although levels of the lemA/htpX transcript did not increase in response to heat to levels seen with dnaK controls, insertional inactivation of htpX resulted in changes in adhesiveness, cellular morphology and detergent-extractable surface antigens in cells grown at 41 degrees C, implying that htpX may be involved in surface protein expression. Insertional inactivation of lemA and htpX indicated that, despite their proximity to rgg and the structural gene, gtfG, these upstream genes do not affect S. gordonii glucosyltransferase activity.
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Affiliation(s)
- M M Vickerman
- Department of Oral Surgery and Hospital Dentistry, School of Dentistry, Indiana University, 1121 West Michigan Street, Indianapolis, IN 46202, USA
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28
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Vickerman MM, Minick PE, Mather NM. Characterization of the Streptococcus gordonii chromosomal region immediately downstream of the glucosyltransferase gene. MICROBIOLOGY (READING, ENGLAND) 2001; 147:3061-70. [PMID: 11700356 DOI: 10.1099/00221287-147-11-3061] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The Streptococcus gordonii glucosyltransferase gene, gtfG, is positively regulated by the upstream determinant rgg. In the present study, two ORFs, transcribed on the opposite DNA strand, were identified immediately downstream of gtfG. The first, designated dsg, shares a convergent putative transcriptional terminator with gtfG, and encodes a predicted 46 kDa transmembrane protein similar to the Yersinia enterocolitica TrsA involved in polysaccharide biosynthesis. Insertional inactivation of dsg resulted in only approximately approximately 60% of the parental level of glucosyltransferase activity. The 870 bp gene 5' to dsg is similar to the gtfG regulatory determinant. Designated rggD, this rgg-like determinant downstream of gtfG encodes a putative 33.6 kDa cytoplasmic protein. Despite their sequence similarity, the functions of rgg and rggD appear specific. Strains in which rggD was insertionally inactivated and strains containing plasmid-borne rggD had parental levels of glucosyltransferase activity. Northern blot hybridization analyses showed approximately 1.3 kb dsg-specific and approximately 1.0 kb rggD-specific mRNA transcripts associated with this region; no polycistronic transcript was observed. Although rgg-like gene products have been demonstrated to function as positive transcriptional regulators of adjacent genes in several streptococcal species, Northern blot analysis suggested that rggD did not influence the transcription of dsg or the divergent downstream ylbN-like determinant under the conditions in the present study. Comparison of this S. gordonii chromosome region to other streptococcal genomes, which do not contain the rgg/rggD-flanked region involved in glucan synthesis, raised intriguing possibilities about the origins of this chromosomal region, and also suggested that rggD might regulate a distally located gene.
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Affiliation(s)
- M M Vickerman
- Department of Oral Surgery and Hospital Dentistry, School of Dentistry, Indiana University, Indianapolis, IN 46202, USA.
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Janecek S, Svensson B, Russell RR. Location of repeat elements in glucansucrases of Leuconostoc and Streptococcus species. FEMS Microbiol Lett 2000; 192:53-7. [PMID: 11040428 DOI: 10.1111/j.1574-6968.2000.tb09358.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Glucosyltransferases of oral streptococci, dextransucrases and alternansucrase of Leuconostoc mesenteroides, collectively referred to as glucansucrases, are large extracellular enzymes that synthesise glucans with a variety of structures and properties. A characteristic of all these glucansucrases is the possession of a C-terminal domain consisting of a series of tandem amino acid repeats. These repeat units are thought to interact with glucan but closely resemble the cell wall binding domain motif found in choline binding proteins in Streptococcus pneumoniae and surface-located proteins in a range of other bacteria. Analysis of dextransucrase and alternansucrase sequences has now shown that they also contain these repeat motifs in the N-terminal region, raising questions about their evolutionary origin and functional importance.
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Affiliation(s)
- S Janecek
- Institute of Microbiology, Slovak Academy of Sciences, Bratislava, Slovak Republic
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Fujiwara T, Hoshino T, Ooshima T, Sobue S, Hamada S. Purification, characterization, and molecular analysis of the gene encoding glucosyltransferase from Streptococcus oralis. Infect Immun 2000; 68:2475-83. [PMID: 10768934 PMCID: PMC97449 DOI: 10.1128/iai.68.5.2475-2483.2000] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus oralis is a member of the oral streptococcal family and an early-colonizing microorganism in the oral cavity of humans. S. oralis is known to produce glucosyltransferase (GTase), which synthesizes glucans from sucrose. The enzyme was purified chromatographically from a culture supernatant of S. oralis ATCC 10557. The purified enzyme, GTase-R, had a molecular mass of 173 kDa and a pI of 6.3. This enzyme mainly synthesized water-soluble glucans with no primer dependency. The addition of GTase markedly enhanced the sucrose-dependent resting cell adhesion of Streptococcus mutans at a level similar to that found in growing cells of S. mutans. The antibody against GTase-R inhibited the glucan-synthesizing activities of Streptococcus gordonii and Streptococcus sanguis, as well as S. oralis. The N-terminal amino acid sequence of GTase-R exhibited no similarities to known GTase sequences of oral streptococci. Using degenerate PCR primers, an 8.1-kb DNA fragment, carrying the gene (gtfR) coding for GTase-R and its regulator gene (rgg), was cloned and sequenced. Comparison of the deduced amino acid sequence revealed that the rgg genes of S. oralis and S. gordonii exhibited a close similarity. The gtfR gene was found to possess a species-specific nucleotide sequence corresponding to the N-terminal 130 amino acid residues. Insertion of erm or aphA into the rgg or gtfR gene resulted in decreased GTase activity by the organism and changed the colony morphology of these transformants. These results indicate that S. oralis GTase may play an important role in the subsequent colonizing of mutans streptoccoci.
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Affiliation(s)
- T Fujiwara
- Department of Pedodontics, Osaka University Faculty of Dentistry, Suita-Osaka 565-0871, Japan.
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Chaussee MS, Ajdic D, Ferretti JJ. The rgg gene of Streptococcus pyogenes NZ131 positively influences extracellular SPE B production. Infect Immun 1999; 67:1715-22. [PMID: 10085009 PMCID: PMC96519 DOI: 10.1128/iai.67.4.1715-1722.1999] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus pyogenes produces several extracellular proteins, including streptococcal erythrogenic toxin B (SPE B), also known as streptococcal pyrogenic exotoxin B and streptococcal proteinase. Several reports suggest that SPE B contributes to the virulence associated with S. pyogenes; however, little is known about its regulation. Nucleotide sequence data revealed the presence, upstream of the speB gene, of a gene, designated rgg, that was predicted to encode a polypeptide similar to previously described positive regulatory factors. The putative Rgg polypeptide of S. pyogenes NZ131 consisted of 280 amino acids and had a predicted molecular weight of 33,246. To assess the potential role of Rgg in the production of SPE B, the rgg gene was insertionally inactivated in S. pyogenes NZ131, which resulted in markedly decreased SPE B production, as determined both by immunoblotting and caseinolytic activity on agar plates. However, the production of other extracellular products, including streptolysin O, streptokinase, and DNase, was not affected. Complementation of the rgg mutant with an intact rgg gene copy in S. pyogenes NZ131 could restore SPE B production and confirmed that the rgg gene product is involved in the production of SPE B.
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Affiliation(s)
- M S Chaussee
- Laboratory of Microbial Structure and Function, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840, USA.
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Lyon WR, Gibson CM, Caparon MG. A role for trigger factor and an rgg-like regulator in the transcription, secretion and processing of the cysteine proteinase of Streptococcus pyogenes. EMBO J 1998; 17:6263-75. [PMID: 9799235 PMCID: PMC1170952 DOI: 10.1093/emboj/17.21.6263] [Citation(s) in RCA: 214] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The ability of numerous microorganisms to cause disease relies upon the highly regulated expression of secreted proteinases. In this study, mutagenesis with a novel derivative of Tn4001 was used to identify genes required for the expression of the secreted cysteine proteinase (SCP) of the pathogenic Gram-positive bacterium Streptococcus pyogenes. Designated as Rop loci (regulation of proteinase), ropB is a rgg-like transcriptional activator required for transcription of the gene which encodes the proteinase. In contrast, ropA contributes post-transcriptionally to the secretion and processing of SCP and encodes a homologue of Trigger Factor, a peptidyl-prolyl isomerase and putative chaparone which is highly conserved in most bacterial species, but of unknown function. Analysis of additional ropA mutants demonstrated that RopA acts both to assist in targeting SCP to the secretory pathway and to promote the ability of the proprotein to establish an active conformation upon secretion. This latter function was dependent upon the peptidyl-prolyl isomerase domain of RopA and mutants that lacked this domain exhibited a bipartite deficiency manifested as a kinetic defect in autologous processing of the proprotein to the mature proteinase, and as a catalytic defect in the mature proteinase. These results provide insight into the function of Trigger Factor, the regulation of proteinase activity and the mechanism of secretion in Gram-positive bacteria.
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Affiliation(s)
- W R Lyon
- Department of Molecular Microbiology, Washington University School of Medicine, Box 8230, St Louis, MO 63110-1093, USA
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Monchois V, Remaud-Simeon M, Monsan P, Willemot RM. Cloning and sequencing of a gene coding for an extracellular dextransucrase (DSRB) from Leuconostoc mesenteroides NRRL B-1299 synthesizing only a alpha (1-6) glucan. FEMS Microbiol Lett 1998; 159:307-15. [PMID: 9503626 DOI: 10.1111/j.1574-6968.1998.tb12876.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The coding region for a novel Leuconostoc mesenteroides NRRL B-1299 dextransucrase gene (dsrB) was isolated and sequenced. Using degenerate primers homologous to a conserved region present in dextransucrases from Streptococcus (GTFs) and L. mesenteroides NRRL B-512F (DSRS) and conserved amino acid sequences located in the N-terminal catalytic region of these enzymes, about 60% of the DSRB encoding gene was isolated. Two sites, BamHI and HindIII, were identified which allowed one 0.5-kbp probe to be obtained to isolate the 5' and the 3' ends of dsrB. The nucleotide sequence of the dsrB gene was determined and found to consist of an open reading frame (ORF) of 4521 base pairs (bp) coding for a 1507-amino acid protein with an M1 of 168,511. The amino acid sequence is very close to that of DSRS. Like DSRS, the dextran produced appeared to be composed of only alpha (1-6) glucosidic bonds, and the oligosaccharides synthesized in the presence of acceptor maltose were also composed of alpha (1-6) linked glucosyl residues in addition to the maltosyl residue. DSRB thus appears to be a novel dextransucrase from L. mesenteroides NRRL B-1299. DSRB produces a dextran different from the typical dextran containing alpha (1-6) and alpha (1-2) linkages produced when this strain is grown in the presence of sucrose.
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Affiliation(s)
- V Monchois
- Centre de Bioingénierie Gilbert Durand, UMR CNRS 5504, LA INRA, INSA, Toulouse, France
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Vickerman MM, Clewell DB. Regulation of Streptococcus gordonii glucosyltransferase. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1997; 418:661-4. [PMID: 9331738 DOI: 10.1007/978-1-4899-1825-3_154] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- M M Vickerman
- Department of Microbiology and Immunology, School of Medicine, University of Michigan, Ann Arbor, USA
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Vickerman MM, Clewell DB. Deletions in the carboxyl-terminal region of Streptococcus gordonii glucosyltransferase affect cell-associated enzyme activity and sucrose-associated accumulation of growing cells. Appl Environ Microbiol 1997; 63:1667-73. [PMID: 9143100 PMCID: PMC168460 DOI: 10.1128/aem.63.5.1667-1673.1997] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The single glucosyltransferase (GTF) of Streptococcus gordonii Challis CH1 makes alpha 1,3- and alpha 1,6-linked glucans from sucrose. The GTF carboxyl-terminal region has six direct repeats thought to be involved in glucan binding. Strains with defined mutations in this region have been described recently (M. M. Vickerman, M. C. Sulavik, P. E. Minick, and D. B. Clewell, Infect. Immun. 64:5117-5128, 1996). Strain CH107 GTF has three internal direct repeats deleted; the 59 carboxyl-terminal amino acids are identical to those of the parental strain. This deletion resulted in decreased enzyme activity but did not affect the amount of cell-associated GTF protein. The GTFs of strains CH2RPE and CH4RPE have six and eight direct repeats, respectively, but are both missing the 14 carboxyl-terminal amino acids. Strain CH2RPE had significantly decreased levels of cell-associated GTF; this decrease was not obviated by the increased number of direct repeats in strain CH4RPE. Thus, the carboxyl-terminal amino acids appeared to influence the amount of cell-associated GTF more than the direct repeats. The qualitative and quantitative differences in the GTFs did not affect the abilities of these strains to accumulate on hydroxyapatite beads in the absence of sucrose. However, when sucrose was added as a substrate for GTF, the mutant strains were unable to accumulate on these surfaces to the same extent as the parent. These differences in sucrose-associated accumulation may be due to changes in the nature of the glucans produced by the different enzymes and/or cohesive interactions between these glucans and the GTF on the surfaces of the growing streptococci.
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Affiliation(s)
- M M Vickerman
- Department of Microbiology and Immunology, School of Medicine, University of Michigan, Ann Arbor 48109, USA.
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Vickerman MM, Jones GW, Clewell DB. Molecular analysis of representative Streptococcus gordonii Spp phase variants reveals no differences in the glucosyltransferase structural gene, gtfG. ORAL MICROBIOLOGY AND IMMUNOLOGY 1997; 12:82-90. [PMID: 9227131 DOI: 10.1111/j.1399-302x.1997.tb00622.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Streptococcus gordonii glucosyltransferase polymerizes sucrose to form glucans, which confer a hard, sucrose-promoted phenotype (Spp+) to colonies on sucrose agar plates. The glucosyltransferase structural gene, gtfG, is positively regulated by the upstream determinant, rgg. Strain Challis undergoes a spontaneous, reversible phase variation between high (Spp+) and low (Spp-) levels of glucosyltransferase activity. Representative strains were examined to gain insights into the basis of glucosyltransferase phase variation. Western blots indicated that the level of glucosyltransferase activity was related to the amount of extracellular glucosyltransferase protein produced by Spp- and Spp+ strains. The nucleotide sequence of rgg and gtfG of the Spp- strain CH97 was found to be identical to that of the Spp+ parent, indicating that DNA differences in these regions are not the basis for glucosyltransferase phase variation. Indeed, 13C-NMR spectroscopy suggested that glucans synthesized by strain CH97 glucosyltransferase were similar to those synthesized by glucosyltransferase of the Spp+ parental strain, indicating a quantitative rather than qualitative change. However, one Spp- strain, CH1C1, had a point mutation in rgg; replacement of the parent rgg with the CH1C1 allele resulted in decreased levels of glucosyltransferase protein and activity. The results indicate that glucosyltransferase phase variation can occur in more than one way, and suggest that glucosyltransferase regulation may involve distally located regulatory gene(s) that affect rgg and/or gtfG expression.
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Affiliation(s)
- M M Vickerman
- Department of Microbiology and Immunology, School of Medicine, Ann Arbor 48109-0620, USA
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