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Hall JW, Lima BP, Herbomel GG, Gopinath T, McDonald L, Shyne MT, Lee JK, Kreth J, Ross KF, Veglia G, Herzberg MC. An intramembrane sensory circuit monitors sortase A-mediated processing of streptococcal adhesins. Sci Signal 2019; 12:12/580/eaas9941. [PMID: 31064885 DOI: 10.1126/scisignal.aas9941] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Bacterial adhesins mediate adhesion to substrates and biofilm formation. Adhesins of the LPXTG family are posttranslationally processed by the cell membrane-localized peptidase sortase A, which cleaves the LPXTG motif. This generates a short C-terminal peptide (C-pep) that remains in the cell membrane, whereas the mature adhesin is incorporated into the cell wall. Genes encoding adhesins of the oral bacterium Streptococcus gordonii were differentially expressed depending on whether the bacteria were isolated from saliva or dental plaque and appeared to be coordinately regulated. Deletion of sspA and sspB (sspAB), both of which encode LPXTG-containing adhesins, unexpectedly enhanced adhesion and biofilm formation. C-peps produced from a model LPXTG-containing adhesin localized to the cell membrane and bound to and inhibited the intramembrane sensor histidine kinase SGO_1180, thus preventing activation of the cognate response regulator SGO_1181. The absence of SspAB C-peps induced the expression of the scaCBA operon encoding the lipoprotein adhesin ScaA, which was sufficient to preserve and even enhance biofilm formation. This C-pep-driven regulatory circuit also exists in pathogenic streptococci and is likely conserved among Gram-positive bacteria. This quality control mechanism ensures that the bacteria can form biofilms under diverse environmental conditions and may play a role in optimizing adhesion and biofilm formation.
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Affiliation(s)
- Jeffrey W Hall
- Department of Biological and Diagnostic Sciences, University of Minnesota, Minneapolis, MN 55455, USA
| | - Bruno P Lima
- Department of Biological and Diagnostic Sciences, University of Minnesota, Minneapolis, MN 55455, USA
| | | | - Tata Gopinath
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - LeAnna McDonald
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Michael T Shyne
- Biostatistical Design and Analysis Center (BDAC), Clinical and Translational Science Institute, University of Minnesota, Minneapolis, MN 55455, USA
| | - John K Lee
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Jens Kreth
- Department of Restorative Dentistry, Oregon Health and Science University, Portland, OR 97239, USA
| | - Karen F Ross
- Department of Biological and Diagnostic Sciences, University of Minnesota, Minneapolis, MN 55455, USA
| | - Gianluigi Veglia
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.,Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Mark C Herzberg
- Department of Biological and Diagnostic Sciences, University of Minnesota, Minneapolis, MN 55455, USA.
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2
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Norsworthy AN, Visick KL. Signaling between two interacting sensor kinases promotes biofilms and colonization by a bacterial symbiont. Mol Microbiol 2015; 96:233-48. [PMID: 25586643 DOI: 10.1111/mmi.12932] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/08/2014] [Indexed: 01/20/2023]
Abstract
Cells acclimate to fluctuating environments by utilizing sensory circuits. One common sensory pathway used by bacteria is two-component signaling (TCS), composed of an environmental sensor [the sensor kinase (SK)] and a cognate, intracellular effector [the response regulator (RR)]. The squid symbiont Vibrio fischeri uses an elaborate TCS phosphorelay containing a hybrid SK, RscS, and two RRs, SypE and SypG, to control biofilm formation and host colonization. Here, we found that another hybrid SK, SypF, was essential for biofilms by functioning downstream of RscS to directly control SypE and SypG. Surprisingly, although wild-type SypF functioned as an SK in vitro, this activity was dispensable for colonization. In fact, only a single non-enzymatic domain within SypF, the HPt domain, was critical in vivo. Remarkably, this domain within SypF interacted with RscS to permit a bypass of RscS's own HPt domain and SypF's enzymatic function. This represents the first in vivo example of a functional SK that exploits the enzymatic activity of another SK, an adaptation that demonstrates the elegant plasticity in the arrangement of TCS regulators.
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Affiliation(s)
- Allison N Norsworthy
- Department of Microbiology and Immunology, Loyola University Medical Center, 2160 S. First Ave., Maywood, IL, 60153, USA
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Guo L, He X, Shi W. Intercellular communications in multispecies oral microbial communities. Front Microbiol 2014; 5:328. [PMID: 25071741 PMCID: PMC4076886 DOI: 10.3389/fmicb.2014.00328] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2014] [Accepted: 06/14/2014] [Indexed: 01/22/2023] Open
Abstract
The oral cavity contains more than 700 microbial species that are engaged in extensive cell–cell interactions. These interactions contribute to the formation of highly structured multispecies communities, allow them to perform physiological functions, and induce synergistic pathogenesis. Co-adhesion between oral microbial species influences their colonization of oral cavity and effectuates, to a large extent, the temporal and spatial formation of highly organized polymicrobial community architecture. Individual species also compete and collaborate with other neighboring species through metabolic interactions, which not only modify the local microenvironment such as pH and the amount of oxygen, making it more suitable for the growth of other species, but also provide a metabolic framework for the participating microorganisms by maximizing their potential to extract energy from limited substrates. Direct physical contact of bacterial species with its neighboring co-habitants within microbial community could initiate signaling cascade and achieve modulation of gene expression in accordance with different species it is in contact with. In addition to communication through cell–cell contact, quorum sensing (QS) mediated by small signaling molecules such as competence-stimulating peptides (CSPs) and autoinducer-2 (AI-2), plays essential roles in bacterial physiology and ecology. This review will summarize the evidence that oral microbes participate in intercellular communications with co-inhabitants through cell contact-dependent physical interactions, metabolic interdependencies, as well as coordinative signaling systems to establish and maintain balanced microbial communities.
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Affiliation(s)
- Lihong Guo
- School of Dentistry, University of California-Los Angeles, Los Angeles CA, USA
| | - Xuesong He
- School of Dentistry, University of California-Los Angeles, Los Angeles CA, USA
| | - Wenyuan Shi
- School of Dentistry, University of California-Los Angeles, Los Angeles CA, USA
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5
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Fan J, Zhang Y, Chuang-Smith ON, Frank KL, Guenther BD, Kern M, Schlievert PM, Herzberg MC. Ecto-5'-nucleotidase: a candidate virulence factor in Streptococcus sanguinis experimental endocarditis. PLoS One 2012; 7:e38059. [PMID: 22685551 PMCID: PMC3369921 DOI: 10.1371/journal.pone.0038059] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 05/02/2012] [Indexed: 11/18/2022] Open
Abstract
Streptococcus sanguinis is the most common cause of infective endocarditis (IE). Since the molecular basis of virulence of this oral commensal bacterium remains unclear, we searched the genome of S. sanguinis for previously unidentified virulence factors. We identified a cell surface ecto-5′-nucleotidase (Nt5e), as a candidate virulence factor. By colorimetric phosphate assay, we showed that S. sanguinis Nt5e can hydrolyze extracellular adenosine triphosphate to generate adenosine. Moreover, a nt5e deletion mutant showed significantly shorter lag time (P<0.05) to onset of platelet aggregation than the wild-type strain, without affecting platelet-bacterial adhesion in vitro (P = 0.98). In the absence of nt5e, S. sanguinis caused IE (4 d) in a rabbit model with significantly decreased mass of vegetations (P<0.01) and recovered bacterial loads (log10CFU, P = 0.01), suggesting that Nt5e contributes to the virulence of S. sanguinis in vivo. As a virulence factor, Nt5e may function by (i) hydrolyzing ATP, a pro-inflammatory molecule, and generating adenosine, an immunosuppressive molecule to inhibit phagocytic monocytes/macrophages associated with valvular vegetations. (ii) Nt5e-mediated inhibition of platelet aggregation could also delay presentation of platelet microbicidal proteins to infecting bacteria on heart valves. Both plausible Nt5e-dependent mechanisms would promote survival of infecting S. sanguinis. In conclusion, we now show for the first time that streptococcal Nt5e modulates S. sanguinis-induced platelet aggregation and may contribute to the virulence of streptococci in experimental IE.
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Affiliation(s)
- Jingyuan Fan
- Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Yongshu Zhang
- Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Olivia N. Chuang-Smith
- Department of Microbiology, University of Minnesota Medical School, Minneapolis, Minnesota, United States of America
| | - Kristi L. Frank
- Department of Microbiology, University of Minnesota Medical School, Minneapolis, Minnesota, United States of America
| | - Brian D. Guenther
- Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Marissa Kern
- Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Patrick M. Schlievert
- Department of Microbiology, University of Minnesota Medical School, Minneapolis, Minnesota, United States of America
| | - Mark C. Herzberg
- Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, Minnesota, United States of America
- Mucosal and Vaccine Research Center, Minneapolis Veterans Affairs Medical Center, Minneapolis, Minnesota, United States of America
- * E-mail:
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Zheng L, Chen Z, Itzek A, Herzberg MC, Kreth J. CcpA regulates biofilm formation and competence in Streptococcus gordonii. Mol Oral Microbiol 2011; 27:83-94. [PMID: 22394467 DOI: 10.1111/j.2041-1014.2011.00633.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Streptococcus gordonii is an important member of the oral biofilm community. As an oral commensal streptococcus, S. gordonii is considered beneficial in promoting biofilm homeostasis. CcpA is known as the central regulator of carbon catabolite repression in Gram-positive bacteria and is also involved in the control of virulence gene expression. To further establish the role of CcpA as central regulator in S. gordonii, the effect of CcpA on biofilm formation and natural competence of S. gordonii was investigated. These phenotypic traits have been suggested to be important to oral streptococci in coping with environmental stress. Here we demonstrate that a CcpA mutant was severely impaired in its biofilm-forming ability, showed a defect in extracellular polysaccharide production and reduced competence. The data suggest that CcpA is involved in the regulation of biofilm formation and competence development in S. gordonii.
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Affiliation(s)
- L Zheng
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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Lei Y, Zhang Y, Guenther BD, Kreth J, Herzberg MC. Mechanism of adhesion maintenance by methionine sulphoxide reductase in Streptococcus gordonii. Mol Microbiol 2011; 80:726-38. [PMID: 21410565 DOI: 10.1111/j.1365-2958.2011.07603.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Methionine sulphoxide reductase maintains adhesin function during oxidative stress. Using Streptococcus gordonii as a model, we now show the mechanistic basis of adhesin maintenance provided by MsrA. In biofilms, S. gordonii selectively expresses the msrA gene. When the wild-type strain was grown with exogenous hydrogen peroxide (H(2)O(2)), msrA-specific mRNA expression significantly increased, while acid production was unaffected. In the presence of H(2)O(2), a msrA-deletion mutant (ΔMsrA) showed a 6 h delay in lag phase growth, a 30% lower yield of H(2)O(2), significantly greater inhibition by H(2)O(2) on agar plates (reversed by complementation), 30% less adhesion to saliva-coated hydroxyapatite, 87% less biofilm formation and an altered electrophoretic pattern of SspAB protein adhesins. Using mass spectrometry, methionine residues in the Met-rich central region of SspB were shown to be oxidized by H(2)O(2) and reduced by MsrA. In intact wild-type cells, MsrA colocalized with a cell wall-staining dye, and MsrA was detected in both cell wall and cytosolic fractions. To maintain normal adhesion and biofilm function of S. gordonii in response to exogenous oxidants therefore msrA is upregulated, methionine oxidation of adhesins and perhaps other proteins is reversed, and adhesion and biofilm formation is maintained.
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Affiliation(s)
- Y Lei
- Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, MN 55455, USA
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8
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Multiple two-component systems modulate alkali generation in Streptococcus gordonii in response to environmental stresses. J Bacteriol 2009; 191:7353-62. [PMID: 19783634 DOI: 10.1128/jb.01053-09] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The oral commensal Streptococcus gordonii must adapt to constantly fluctuating and often hostile environmental conditions to persist in the oral cavity. The arginine deiminase system (ADS) of S. gordonii enables cells to produce, ornithine, ammonia, CO(2), and ATP from arginine hydrolysis, augmenting the acid tolerance of the organism. The ADS genes are substrate inducible and sensitive to catabolite repression, mediated through ArcR and CcpA, respectively, but the system also requires low pH and anaerobic conditions for optimal activation. Here, we demonstrate that the CiaRH and ComDE two-component systems (TCS) are required for low-pH-dependent expression of ADS genes in S. gordonii. Further, the VicRK TCS is required for optimal ADS gene expression under anaerobic conditions and enhances the sensitivity of the operon to repression by oxygen. The known anaerobic activator of the ADS, Fnr-like protein (Flp), appeared to act independently of the Vic TCS. Mutants of S. gordonii lacking components of the CiaRH, ComDE, or VicRK grew more slowly in acidified media and were more sensitive to killing at lethal pH values and to agents that induce oxidative stress. This study provides the first evidence that TCS can regulate the ADS of bacteria in response to specific environmental signals and reveals some notable differences in the contribution of CiaRH, ComDE, and VicRK to viability and stress tolerance between the oral commensal S. gordonii and the oral pathogen Streptococcus mutans.
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9
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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: 429] [Impact Index Per Article: 28.6] [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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10
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Zhang Y, Whiteley M, Kreth J, Lei Y, Khammanivong A, Evavold JN, Fan J, Herzberg MC. The two-component system BfrAB regulates expression of ABC transporters in Streptococcus gordonii and Streptococcus sanguinis. MICROBIOLOGY-SGM 2009; 155:165-173. [PMID: 19118357 DOI: 10.1099/mic.0.023168-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The putative two-component system BfrAB is involved in Streptococcus gordonii biofilm development. Here, we provide evidence that BfrAB regulates the expression of bfrCD and bfrEFG, which encode two ATP-binding cassette (ABC) transporters, and bfrH, which encodes a CAAX amino-terminal protease family protein. BfrC and BfrE are ATP-binding proteins, and BfrD, BfrF and BfrG are homologous membrane-spanning polypeptides. Similarly, BfrABss, the BfrAB homologous system in Streptococcus sanguinis, controls the expression of two bfrCD-homologous operons (bfrCDss and bfrXYss), a bfrH-homologous gene (bfrH1ss) and another CAAX amino-terminal protease family protein gene (bfrH2ss). Furthermore, we demonstrate that the purified BfrA DNA-binding domain from S. gordonii binds to the promoter regions of bfrCD, bfrEFG, bfrH, bfrCDss, bfrXYss and bfrH1ss in vitro. Finally, we show that the BfrA DNA-binding domain recognizes a conserved DNA motif with a consensus sequence of TTTCTTTAGAAATATTTTAGAATT. These data suggest, therefore, that S. gordonii BfrAB controls biofilm formation by regulating multiple ABC-transporter systems.
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Affiliation(s)
- Yongshu Zhang
- Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Marvin Whiteley
- Section of Molecular Genetics and Microbiology, the University of Texas at Austin, Austin, TX 78712, USA
| | - Jens Kreth
- Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Yu Lei
- Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Ali Khammanivong
- Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Jamie N Evavold
- Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Jingyuan Fan
- Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Mark C Herzberg
- Mucosal and Vaccine Research Center, Minneapolis VA Medical Center, Minneapolis, MN 55417, USA.,Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, MN 55455, USA
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Sortase A utilizes an ancillary protein anchor for efficient cell wall anchoring of pili in Streptococcus agalactiae. Infect Immun 2008; 76:3550-60. [PMID: 18541657 DOI: 10.1128/iai.01613-07] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pili are putative virulence factors and promising vaccine candidates in Streptococcus agalactiae (group B Streptococcus [GBS]) infection, a leading cause of neonatal sepsis and meningitis. The genes necessary for pilus synthesis and assembly are clustered in pilus islands (PI). Each gene encodes three structural subunits (a backbone and two ancillary proteins) bearing a C-terminal LPXTG motif and two subfamily C sortases (SrtC) involved in covalent polymerization of the subunits. GBS strains also possess the conserved "housekeeping" sortase A (SrtA), but its role in pilus assembly is unclear. To address this issue, pilus expression and cell wall anchoring were analyzed in srtA deletion mutants. Loss of SrtA did not affect pilus polymerization. However, pilus expression on the cell surface was reduced, and pili accumulated in the culture supernatant. Furthermore, cell-associated pili could be readily released by detergent treatment, indicating that SrtA is involved in covalent anchoring of pili to the cell wall. When each of the genes comprising PI-2a was systematically deleted, only the absence of ancillary subunit GBS150 or the SrtC required for incorporation of GBS150 into pili mimicked the srtA mutant phenotype. Thus, from these data a model for GBS pilus assembly can be proposed in which PI sortases are responsible for polymerization of the pilus structure, while SrtA is required to covalently attach it to the cell wall, utilizing ancillary pilus subunit GBS150 as the anchor protein.
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12
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Streptococcal antagonism in oral biofilms: Streptococcus sanguinis and Streptococcus gordonii interference with Streptococcus mutans. J Bacteriol 2008; 190:4632-40. [PMID: 18441055 DOI: 10.1128/jb.00276-08] [Citation(s) in RCA: 295] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Biofilms are polymicrobial, with diverse bacterial species competing for limited space and nutrients. Under healthy conditions, the different species in biofilms maintain an ecological balance. This balance can be disturbed by environmental factors and interspecies interactions. These perturbations can enable dominant growth of certain species, leading to disease. To model clinically relevant interspecies antagonism, we studied three well-characterized and closely related oral species, Streptococcus gordonii, Streptococcus sanguinis, and cariogenic Streptococcus mutans. S. sanguinis and S. gordonii used oxygen availability and the differential production of hydrogen peroxide (H(2)O(2)) to compete effectively against S. mutans. Interspecies antagonism was influenced by glucose with reduced production of H(2)O(2). Furthermore, aerobic conditions stimulated the competence system and the expression of the bacteriocin mutacin IV of S. mutans, as well as the H(2)O(2)-dependent release of heterologous DNA from mixed cultures of S. sanguinis and S. gordonii. These data provide new insights into ecological factors that determine the outcome of competition between pioneer colonizing oral streptococci and the survival mechanisms of S. mutans in the oral biofilm.
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13
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Identification of Streptococcus sanguinis genes required for biofilm formation and examination of their role in endocarditis virulence. Infect Immun 2008; 76:2551-9. [PMID: 18390999 DOI: 10.1128/iai.00338-08] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus sanguinis is one of the pioneers in the bacterial colonization of teeth and is one of the most abundant species in the oral biofilm called dental plaque. S. sanguinis is also the most common viridans group streptococcal species implicated in infective endocarditis. To investigate the association of biofilm and endocarditis, we established a biofilm assay and examined biofilm formation with a signature-tagged mutagenesis library of S. sanguinis. Four genes that have not previously been associated with biofilm formation in any other bacterium, purB, purL, thrB, and pyrE, were putatively identified as contributing to in vitro biofilm formation in S. sanguinis. By examining 800 mutants for attenuation in the rabbit endocarditis model and for reduction in biofilm formation in vitro, we found some mutants that were both biofilm defective and attenuated for endocarditis. However, we also identified mutants with only reduced biofilm formation or with only attenuation in the endocarditis model. This result indicates that the ability to form biofilms in vitro is not associated with endocarditis virulence in vivo in S. sanguinis.
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Nobbs AH, Vajna RM, Johnson JR, Zhang Y, Erlandsen SL, Oli MW, Kreth J, Brady LJ, Herzberg MC. Consequences of a sortase A mutation in Streptococcus gordonii. MICROBIOLOGY-SGM 2008; 153:4088-4097. [PMID: 18048922 DOI: 10.1099/mic.0.2007/007252-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Sortase A (SrtA) is required for cell-wall anchoring of LPXTG-containing Gram-positive surface proteins. It was hypothesized, therefore, that disruption of the srtA gene would alter surface anchoring and functions of target LPXTG motif-bearing SspA and SspB proteins of Streptococcus gordonii. Mutant strains in srtA (V288srtA(-), DL1srtA(-)) were constructed in S. gordonii V288 (wtV288) and DL1 (wtDL1). When compared to wtV288, the V288srtA(-) mutant showed decreased biofilm formation on polystyrene, and reduced binding to immobilized purified salivary agglutinin (BIAcore analysis). The wtV288 and V288srtA(-) strains were similar in ultrastructure, but immunogold-labelled SspA/SspB surface expression was reduced on the V288srtA(-) mutant. DL1srtA(-) was also complemented to obtain DL1srtA(+). From the wild-type strains (wtV288, wtDL1), srtA(-) mutants (V288srtA(-), DL1srtA(-)), and the complemented mutant (DL1srtA(+)), cytoplasmic, cell-wall and released extracellular protein fractions were isolated. Each fraction was analysed by SDS-PAGE and immunoblotting with anti-P1. Spent medium from srtA(-) mutant cells contained over-represented proteins, including SspA/SspB (P1 antigen). Mutants showed less P1 on the cell surface than wild-types, as estimated using whole-cell ELISA, and no P1 appeared in the cytoplasmic fractions. Expression of several adhesin genes (sspA/B, cshA/B, fbpA) was generally upregulated in the mutants (V288srtA(-), DL1srtA(-)), but restored to wild-type levels in DL1srtA(+). These data therefore imply that in addition to its role in processing LPXTG-containing adhesins, sortase A has the novel function of contributing to transcriptional regulation of adhesin gene expression.
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Affiliation(s)
- Angela H Nobbs
- Department of Diagnostic and Biological Sciences, School of Dentistry, Medical School, University of Minnesota, Minneapolis, MN 55455, USA
| | - Reka M Vajna
- Department of Diagnostic and Biological Sciences, School of Dentistry, Medical School, University of Minnesota, Minneapolis, MN 55455, USA
| | - Jeremy R Johnson
- Department of Diagnostic and Biological Sciences, School of Dentistry, Medical School, University of Minnesota, Minneapolis, MN 55455, USA
| | - Yongshu Zhang
- Department of Diagnostic and Biological Sciences, School of Dentistry, Medical School, University of Minnesota, Minneapolis, MN 55455, USA
| | - Stanley L Erlandsen
- Department of Genetics, Cell Biology and Development, Medical School, University of Minnesota, Minneapolis, MN 55455, USA
| | - Monika W Oli
- Department of Oral Biology, Joint Health Science Center, University of Florida, Gainesville, FL 32611, USA
| | - Jens Kreth
- Department of Diagnostic and Biological Sciences, School of Dentistry, Medical School, University of Minnesota, Minneapolis, MN 55455, USA
| | - L Jeannine Brady
- Department of Oral Biology, Joint Health Science Center, University of Florida, Gainesville, FL 32611, USA
| | - Mark C Herzberg
- Mucosal and Vaccine Research Center, Minneapolis VA Medical Center, Minneapolis, MN 55417, USA.,Department of Diagnostic and Biological Sciences, School of Dentistry, Medical School, University of Minnesota, Minneapolis, MN 55455, USA
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15
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Shemesh M, Tam A, Steinberg D. Differential gene expression profiling of Streptococcus mutans cultured under biofilm and planktonic conditions. MICROBIOLOGY-SGM 2007; 153:1307-1317. [PMID: 17464045 DOI: 10.1099/mic.0.2006/002030-0] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Streptococcus mutans often adopts a sessile biofilm lifestyle that differs greatly from that of free-living cells. Biofilm formation represents a protected mode of growth that allows cells to survive in hostile environments. In this study, in vitro comparative transcriptome analysis was carried out to identify genes that are differentially expressed in biofilm of S. mutans compared with free-living cells. DNA-microarray analyses indicated that about 12 % of genes showed significant differential expression: 139 were activated and 104 were repressed in biofilm vs the planktonic environment. The differential expression of 20 selected genes was confirmed by real-time RT-PCR. In addition, regulation of expression of these genes during biofilm development was tested in 100 and 400 microm deep biofilms. Direct comparison of optical images consistently demonstrated that changes in biofilm thickness are accompanied by significant shifts in cell viability. From evaluation of gene expression patterns, it was shown that the majority of the genes tested were significantly down-regulated in 400 vs 100 microm deep biofilms. This study provides a genome-scale synopsis and adds important insights into gene expression in biofilm development processes of S. mutans, which are strongly associated with the pathogenesis of dental diseases.
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Affiliation(s)
- Moshe Shemesh
- Institute of Dental Sciences, Faculty of Dentistry, Hebrew University-Hadassah, POB 12272, Jerusalem 91120, Israel
| | - Avshalom Tam
- Institute of Dental Sciences, Faculty of Dentistry, Hebrew University-Hadassah, POB 12272, Jerusalem 91120, Israel
| | - Doron Steinberg
- Institute of Dental Sciences, Faculty of Dentistry, Hebrew University-Hadassah, POB 12272, Jerusalem 91120, Israel
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16
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Straume D, Kjos M, Nes IF, Diep DB. Quorum-sensing based bacteriocin production is down-regulated by N-terminally truncated species of gene activators. Mol Genet Genomics 2007; 278:283-93. [PMID: 17576598 DOI: 10.1007/s00438-007-0251-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Accepted: 05/17/2007] [Indexed: 10/23/2022]
Abstract
Down-regulation of quorum-sensing based pathways is an important but yet poorly understood process in bacterial gene regulation. In this study, we show that the gene regulator plnC not only acts as an activator gene in the quorum-sensing based bacteriocin production in Lactobacillus plantarum C11, but it also concurrently codes for truncated forms that were shown to repress bacteriocin production. By amino acid N-terminal sequencing and DNA sequence analysis, the truncated species of PlnC are believed to be translated from alternative start codons located in the so-called receiver domain of the regulator. To analyse the structure-function relationship of truncated species of PlnC, we performed a series of systematic truncation mutations: ten in the receiver domain, one in the hinge region and two in the C-terminal DNA-binding domain. It was revealed that any truncation mutation containing a disrupted receiver domain together with an intact DNA-binding domain displayed a repressive effect on bacteriocin production. Such a gene repression mechanism mediated by truncated regulators was also found in two other quorum-sensing based bacteriocin systems (spp in L. sakei LTH673 and NC8-pln in L. plantarum NC8), suggesting that this mode of repression might represent a common means applied by bacteria to down-regulate certain quorum-sensing based pathways.
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Affiliation(s)
- Daniel Straume
- Laboratory for Microbial Gene Technology, Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Science, PO Box 5003, 1432, As, Norway
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17
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Nobbs AH, Zhang Y, Khammanivong A, Herzberg MC. Streptococcus gordonii Hsa environmentally constrains competitive binding by Streptococcus sanguinis to saliva-coated hydroxyapatite. J Bacteriol 2007; 189:3106-14. [PMID: 17277052 PMCID: PMC1855861 DOI: 10.1128/jb.01535-06] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Competition between pioneer colonizing bacteria may determine polymicrobial succession during dental plaque development, but the ecological constraints are poorly understood. For example, more Streptococcus sanguinis than Streptococcus gordonii organisms are consistently isolated from the same intraoral sites, yet S. gordonii fails to be excluded and survives as a species over time. To explain this observation, we hypothesized that S. gordonii could compete with S. sanguinis to adhere to saliva-coated hydroxyapatite (sHA), an in vitro model of the tooth surface. Both species bound similarly to sHA, yet 10- to 50-fold excess S. gordonii DL1 reduced binding of S. sanguinis SK36 by 85 to >95%. S. sanguinis, by contrast, did not significantly compete with S. gordonii to adhere. S. gordonii competed with S. sanguinis more effectively than other species of oral streptococci and depended upon the salivary film on HA. Next, putative S. gordonii adhesins were analyzed for contributions to interspecies competitive binding. Like wild-type S. gordonii, isogenic mutants with mutations in antigen I/II polypeptides (sspAB), amylase-binding proteins (abpAB), and Csh adhesins (cshAB) competed effectively against S. sanguinis. By contrast, an hsa-deficient mutant of S. gordonii showed significantly reduced binding and competitive capabilities, while these properties were restored in an hsa-complemented strain. Thus, Hsa confers a selective advantage to S. gordonii over S. sanguinis in competitive binding to sHA. Hsa expression may, therefore, serve as an environmental constraint against S. sanguinis, enabling S. gordonii to persist within the oral cavity, despite the greater natural prevalence of S. sanguinis in plaque and saliva.
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Affiliation(s)
- Angela H Nobbs
- Department of Diagnostic and Biological Sciences, University of Minnesota, 17-164 Moos Tower, 515 Delaware Street, S.E., Minneapolis, MN 55455, USA
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18
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Kuboniwa M, Tribble GD, James CE, Kilic AO, Tao L, Herzberg MC, Shizukuishi S, Lamont RJ. Streptococcus gordonii utilizes several distinct gene functions to recruit Porphyromonas gingivalis into a mixed community. Mol Microbiol 2006; 60:121-39. [PMID: 16556225 DOI: 10.1111/j.1365-2958.2006.05099.x] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Dental plaque biofilm formation proceeds through a developmental pathway initiated by the attachment of pioneer organisms, such as Streptococcus gordonii, to tooth surfaces. Through a variety of synergistic interactions, pioneer organisms facilitate the colonization of later arrivals including Porphyromonas gingivalis, a potential periodontal pathogen. We have investigated genes of S. gordonii required to support a heterotypic biofilm community with P. gingivalis. By screening a plasmid integration library of S. gordonii, genes were identified that are crucial for the accumulation of planktonic P. gingivalis cells into a multispecies biofilm. These genes were further investigated by specific mutation and complementation analyses. The biofilm-associated genes can be grouped into broad categories based on putative function as follows: (i) intercellular or intracellular signalling (cbe and spxB), (ii) cell wall integrity and maintenance of adhesive proteins (murE, msrA and atf), (iii) extracellular capsule biosynthesis (pgsA and atf), and (iv) physiology (gdhA, ccmA and ntpB). In addition, a gene for a hypothetical protein was identified. Biofilm visualization and quantification by confocal microscopy confirmed the role of these genes in the maturation of the multispecies community, including biofilm architectural development. The results suggest that S. gordonii governs the development of heterotypic oral biofilms through multiple genetic pathways.
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Affiliation(s)
- Masae Kuboniwa
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA
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19
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Jenkinson HF, Lamont RJ. Oral microbial communities in sickness and in health. Trends Microbiol 2005; 13:589-95. [PMID: 16214341 DOI: 10.1016/j.tim.2005.09.006] [Citation(s) in RCA: 347] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2005] [Revised: 09/06/2005] [Accepted: 09/22/2005] [Indexed: 10/25/2022]
Abstract
The relationship between humans and their oral microflora begins shortly after birth and lasts a lifetime. Up until fairly recently, the associations between the host and oral bacteria were considered in terms of a multiplicity of single species interactions. However, it is becoming more apparent that the oral microbes comprise a complex community, and that oral health or disease depends on the interface between the host and the microbial community as a whole. Although it is important to continue studies of the pathogenic properties of specific microbes, these are relevant only in the context of the properties of the community within which they reside. Understanding the microbial communities that drive sickness or health is a key to combating human oral diseases.
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Affiliation(s)
- Howard F Jenkinson
- Department of Oral and Dental Sciences, University of Bristol, Bristol BS1 2LY, UK.
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20
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Abstract
The production of biofilms by bacteria is a lifestyle that is thought to require or involve a differential gene expression compared with that of planktonic bacteria. Recently, we have witnessed a change of focus from the simple hunt for hypothetical essential biofilm genes to the identification of late and more complex biofilm functions. However, finding common bacterial biofilm gene-expression patterns through global expression analysis remains difficult. Owing to the apparently minimal overlap between functions involved in biofilm formation by different bacteria, exploring the biofilm lifestyle could prove to be a case-by-case task for which global approaches show their limits.
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Affiliation(s)
- Christophe Beloin
- Groupe de Génétique des Biofilms, Institut Pasteur, CNRS URA 2172, 25 rue du Dr. Roux, 75724 Paris CEDEX 15, France
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21
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Zhang Y, Lei Y, Nobbs A, Khammanivong A, Herzberg MC. Inactivation of Streptococcus gordonii SspAB alters expression of multiple adhesin genes. Infect Immun 2005; 73:3351-7. [PMID: 15908361 PMCID: PMC1111841 DOI: 10.1128/iai.73.6.3351-3357.2005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
SspA and SspB (antigen I/II family proteins) can bind Streptococcus gordonii to other oral bacteria and also to salivary agglutinin glycoprotein, a constituent of the salivary film or pellicle that coats the tooth. To learn if SspA and SspB are essential for adhesion and initial biofilm formation on teeth, S. gordonii DL1 was incubated with saliva-coated hydroxyapatite (sHA) for 2 h in Todd-Hewitt broth with 20% saliva to develop initial biofilms. Sessile cells attached to sHA, surrounding planktonic cells, and free-growing cells were recovered separately. Free-growing cells expressed more sspA-specific mRNA and sspB-specific mRNA than sessile cells. Free-growing cells expressed the same levels of sspA and sspB as planktonic cells. Surprisingly, an SspA(-) SspB(-) mutant strain showed 2.2-fold greater biofilm formation on sHA than wild-type S. gordonii DL1. To explain this observation, we tested the hypothesis that inactivation of sspA and sspB genes altered the expression of other adhesin genes during initial biofilm formation in vitro. When compared to wild-type cells, expression of scaA and abpB was significantly up-regulated in the SspA(-) SspB(-) strain in sessile, planktonic, and free-growing cells. Consistent with this finding, ScaA antigen was also overexpressed in planktonic and free-growing SspA(-) SspB(-) cells compared to the wild type. SspA/B adhesins, therefore, were strongly suggested to be involved in the regulation of multiple adhesin genes.
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Affiliation(s)
- Yongshu Zhang
- Department of Oral Sciences and Mucosal and Vaccine Research Center, University of Minnesota, 17-164 Moos Tower, 515 Delaware Street SE, Minneapolis, MN 55455, USA
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22
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Rediers H, Rainey PB, Vanderleyden J, De Mot R. Unraveling the secret lives of bacteria: use of in vivo expression technology and differential fluorescence induction promoter traps as tools for exploring niche-specific gene expression. Microbiol Mol Biol Rev 2005; 69:217-61. [PMID: 15944455 PMCID: PMC1197422 DOI: 10.1128/mmbr.69.2.217-261.2005] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A major challenge for microbiologists is to elucidate the strategies deployed by microorganisms to adapt to and thrive in highly complex and dynamic environments. In vitro studies, including those monitoring genomewide changes, have proven their value, but they can, at best, mimic only a subset of the ensemble of abiotic and biotic stimuli that microorganisms experience in their natural habitats. The widely used gene-to-phenotype approach involves the identification of altered niche-related phenotypes on the basis of gene inactivation. However, many traits contributing to ecological performance that, upon inactivation, result in only subtle or difficult to score phenotypic changes are likely to be overlooked by this otherwise powerful approach. Based on the premise that many, if not most, of the corresponding genes will be induced or upregulated in the environment under study, ecologically significant genes can alternatively be traced using the promoter trap techniques differential fluorescence induction and in vivo expression technology (IVET). The potential and limitations are discussed for the different IVET selection strategies and system-specific variants thereof. Based on a compendium of genes that have emerged from these promoter-trapping studies, several functional groups have been distinguished, and their physiological relevance is illustrated with follow-up studies of selected genes. In addition to confirming results from largely complementary approaches such as signature-tagged mutagenesis, some unexpected parallels as well as distinguishing features of microbial phenotypic acclimation in diverse environmental niches have surfaced. On the other hand, by the identification of a large proportion of genes with unknown function, these promoter-trapping studies underscore how little we know about the secret lives of bacteria and other microorganisms.
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Affiliation(s)
- Hans Rediers
- Centre of Microbial and Plant Genetics, Heverlee, Belgium
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Loo CY, Mitrakul K, Jaafar S, Gyurko C, Hughes CV, Ganeshkumar N. Role of a nosX homolog in Streptococcus gordonii in aerobic growth and biofilm formation. J Bacteriol 2005; 186:8193-206. [PMID: 15576767 PMCID: PMC532431 DOI: 10.1128/jb.186.24.8193-8206.2004] [Citation(s) in RCA: 14] [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
Oral streptococci such as Streptococcus gordonii are facultative anaerobes that initiate biofilm formation on tooth surfaces. An isolated S. gordonii::Tn917-lac biofilm-defective mutant contained a transposon insertion in an open reading frame (ORF) encoding a homolog of NosX of Ralstonia eutropha, a putative maturation factor of nitrous oxide reductase. Located downstream are two genes, qor1 and qor2, predicted to encode two putative NADPH quinone oxidoreductases. These three genes are cotranscribed, forming a putative oxidative stress response (osr) operon in S. gordonii. Inactivation of nosX, qor1, or qor2 resulted in biofilm-defective phenotypes. Expression of nosX, measured by the beta-galactosidase activity of the nosX::Tn917-lac mutant, was growth-phase dependent and enhanced when grown under aerobic conditions or in the presence of paraquat. Real-time reverse transcription-PCR revealed that nosX-specific mRNA levels were increased approximately 8.4 and 3.5 fold in biofilm-derived cells grown on plastic and glass, respectively, when compared to planktonic cells. Expression of nosX increased 19.9 fold in cells grown under aerated aerobic conditions and 4.7 fold in cells grown under static aerobic conditions. Two ORFs immediately adjacent to the osr operon encode a putative NADH oxidase (Nox) and a putative thiol-specific antioxidant enzyme (AhpC, for alkyl hydroperoxide peroxidase C). Expression of nox and ahpC was also significantly increased in cells grown under aerated and static aerobic conditions when compared to anaerobic conditions. In addition, nox expression was increased in biofilm cells compared to planktonic cells. These genes may be part of an island that deals with oxidoreductive response, some of which may be important in S. gordonii biofilm formation.
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Affiliation(s)
- C Y Loo
- Department of Pediatric Dentistry, Goldman School of Dental Medicine, Boston University, 801 Albany St., Room 215, Boston, MA 02118, USA
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Kiliç AO, Tao L, Zhang Y, Lei Y, Khammanivong A, Herzberg MC. Involvement of Streptococcus gordonii beta-glucoside metabolism systems in adhesion, biofilm formation, and in vivo gene expression. J Bacteriol 2004; 186:4246-53. [PMID: 15205427 PMCID: PMC421613 DOI: 10.1128/jb.186.13.4246-4253.2004] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus gordonii genes involved in beta-glucoside metabolism are induced in vivo on infected heart valves during experimental endocarditis and in vitro during biofilm formation on saliva-coated hydroxyapatite (sHA). To determine the roles of beta-glucoside metabolism systems in biofilm formation, the loci of these induced genes were analyzed. To confirm the function of genes in each locus, strains were constructed with gene inactivation, deletion, and/or reporter gene fusions. Four novel systems responsible for beta-glucoside metabolism were identified, including three phosphoenolpyruvate-dependent phosphotransferase systems (PTS) and a binding protein-dependent sugar uptake system for metabolizing multiple sugars, including beta-glucosides. Utilization of arbutin and esculin, aryl-beta-glucosides, was defective in some mutants. Esculin and oligochitosaccharides induced genes in one of the three beta-glucoside metabolism PTS and in four other genetic loci. Mutation of genes in any of the four systems affected in vitro adhesion to sHA, biofilm formation on plastic surfaces, and/or growth rate in liquid medium. Therefore, genes associated with beta-glucoside metabolism may regulate S. gordonii in vitro adhesion, biofilm formation, growth, and in vivo colonization.
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Affiliation(s)
- Ali O Kiliç
- Department of Oral Biology, College of Dentistry, University of Illinois at Chicago, Chicago, Illinois 60612, USA
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