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Karimova G, Ladant D. Defining Membrane Protein Topology Using pho-lac Reporter Fusions. Methods Mol Biol 2024; 2715:181-195. [PMID: 37930528 DOI: 10.1007/978-1-0716-3445-5_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2023]
Abstract
Experimental determination of membrane protein topology can be achieved using various techniques. Here, we present the pho-lac dual reporter system, a simple, convenient, and reliable tool to analyze the topology of membrane protein in vivo. The system is based on the use of two topological markers with complementary properties: The Escherichia coli β-galactosidase, LacZ, which is active in the cytoplasm, and the E. coli alkaline phosphatase, PhoA, which is active in the bacterial periplasm. Specifically, in this pho-lac gene system, the reporter molecule is a chimera composed of the mature PhoA that is in-frame with the β-galactosidase α-peptide (LacZα). Hence, when targeted to the periplasm, the PhoA-LacZα dual reporter displays high alkaline phosphatase activity but no β-galactosidase activity. Conversely, when located in the cytoplasm, PhoA-LacZα has no phosphatase activity but exhibits high β-galactosidase activity in E. coli cells expressing the α-fragment of LacZ, LacZα (via the α-complementation phenomenon). The dual nature of the PhoA-LacZα reporter allows a simple way to normalize both enzymatic activities to obtain readily interpretable information about the subcellular location of the fusion site between the membrane protein under study and the reporter. In addition, the PhoA-LacZα reporter permits the utilization of dual indicator agar plates to easily discriminate between colonies bearing cytoplasmic fusions, periplasmic fusions, or out-of-frame fusions. In total, the phoA-lacZα fusion reporter approach is a direct and rather inexpensive method to characterize the topology of membrane proteins in vivo.
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Affiliation(s)
- Gouzel Karimova
- Unité de Biochimie des Interactions Macromoléculaires, Département de Biologie Structurale et Chimie, Institut Pasteur, CNRS, UMR 3528, Université Paris Cité, Paris, France.
| | - Daniel Ladant
- Unité de Biochimie des Interactions Macromoléculaires, Département de Biologie Structurale et Chimie, Institut Pasteur, CNRS, UMR 3528, Université Paris Cité, Paris, France
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Exploiting Conserved Quorum Sensing Signals in Streptococcus mutans and Streptococcus pneumoniae. Microorganisms 2022; 10:microorganisms10122386. [PMID: 36557639 PMCID: PMC9785397 DOI: 10.3390/microorganisms10122386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 11/27/2022] [Accepted: 11/29/2022] [Indexed: 12/03/2022] Open
Abstract
Bacterial species of the Streptococcus genera are considered either commensal bacteria or potential pathogens, according to their metabolic evolution and production of quorum sensing (QS)-controlled virulence factors. S. mutans, in particular, has become one of the best-studied examples of bacteria that are able to get along or cheat commensal species, even of the same genera. S. mutans and S. pneumoniae share homolog QS pathways and a competence stimulating peptide (CSP) for regulating bacteriocin production. Intriguingly, the abundance of S. pneumoniae and S. mutans alternates in complex microbial communities, thus opening the role for the fratricide communication of homolog QS systems. Since the inhibition of the QS has been proposed in treating bacterial infections, in this study, we designed and synthesized analogs of S. pneumoniae CSP with precise residual modifications. We reported that S. pneumoniae CSP analogs reduced the expression of genes involved in the QS of S. mutans and biofilm formation without affecting bacterial growth. The CSP analogs inhibited bacteriocin production in S. mutans, as reported by co-cultures with commensal bacteria of the oral cavity. The peptide CSP1AA, bearing substitutions in the residues involved in QS receptor recognition and activation, reported the most significant quorum-quenching activities. Our findings provide new insights into specific chemical drivers in the CSP sequences controlling the interconnection between S. mutans and S. pneumoniae. We think that the results reported in this study open the way for new therapeutic interventions in controlling the virulence factors in complex microbial communities such as the oral microbiota.
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Zhang Z, Zeng J, Zhou X, Xu Q, Li C, Liu Y, Zhang C, Wang L, Zeng W, Li Y. Activity of Ligustrum robustum (Roxb.) Blume extract against the biofilm formation and exopolysaccharide synthesis of Streptococcus mutans. Mol Oral Microbiol 2020; 36:67-79. [PMID: 33316854 DOI: 10.1111/omi.12328] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 12/09/2020] [Accepted: 12/10/2020] [Indexed: 12/01/2022]
Abstract
Ligustrum robustum (Roxb.) Blume is utilized as a traditional Chinese herbal tea with various health benefits and protective effects. Streptococcus mutans is an important cariogenic oral bacteria species. The present study aimed to assess the influence of Ligustrum robustum extract (LRE) on the biofilm formation of S. mutans and the mechanism of its action, as well as to identify its chemical components. For chemical identification, HPLC-MS and nuclear magnetic resonance were applied and four identified phytochemicals were reported (Ligurobustoside B, Ligurobustoside N, Ligurobustoside J, and Ligurobustoside C). The dose-dependent (0.5 to 2.0 μg/μL) antimicrobial toxicity of LRE against S. mutans biofilm formation and exopolysaccharide (EPS) synthesis was evaluated by confocal laser scanning microscopy (CLSM), Crystal violet stain, and CFU counting. The microstructure of S. mutans biofilm treated with LRE was investigated both on glass coverslips and ex vivo bovine dental enamel by scanning electron microscopy (SEM). Moreover, LRE downregulated the expression of S. mutans glucosyltransferase-encoding genes gtfB, gtfC, and gtfD, and the quorum sensing (QS) factors comD and comE, suggesting its toxic mechanism. In addition, the result of CCK-8 test on human oral cells revealed an acceptable biocompatibility of LRE. These findings indicated the possible application of this daily consumed herbal tea for caries prevention.
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Affiliation(s)
- Zhong Zhang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, School of Stomatology, Sichuan University, Chengdu, PR China
| | - Jumei Zeng
- West China School of Public Health, Sichuan University, Chengdu, PR China
| | - Xuedong Zhou
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, School of Stomatology, Sichuan University, Chengdu, PR China
| | - Qianda Xu
- Department of Food Engineering, Sichuan University, Chengdu, PR China
| | - Chenghui Li
- Analytical and Testing Center, Sichuan University, Chengdu, PR China
| | - Yiduo Liu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, School of Stomatology, Sichuan University, Chengdu, PR China
| | - Chaoliang Zhang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, School of Stomatology, Sichuan University, Chengdu, PR China
| | - Liu Wang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, School of Stomatology, Sichuan University, Chengdu, PR China
| | - Weicai Zeng
- Department of Food Engineering, Sichuan University, Chengdu, PR China
| | - Yuqing Li
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, School of Stomatology, Sichuan University, Chengdu, PR China
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Khan F, Javaid A, Kim YM. Functional Diversity of Quorum Sensing Receptors in Pathogenic Bacteria: Interspecies, Intraspecies and Interkingdom Level. Curr Drug Targets 2020; 20:655-667. [PMID: 30468123 DOI: 10.2174/1389450120666181123123333] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 11/16/2018] [Accepted: 11/16/2018] [Indexed: 01/17/2023]
Abstract
The formation of biofilm by pathogenic bacteria is considered as one of the most powerful mechanisms/modes of resistance against the action of several antibiotics. Biofilm is formed as a structural adherent over the surfaces of host, food and equipments etc. and is further functionally coordinated by certain chemicals produced itself. These chemicals are known as quorum sensing (QS) signaling molecules and are involved in the cross talk at interspecies, intraspecies and interkingdom levels thus resulting in the production of virulence factors leading to pathogenesis. Bacteria possess receptors to sense these chemicals, which interact with the incoming QS molecules. It is followed by the secretion of virulence molecules, regulation of bioluminescence, biofilm formation, antibiotic resistance development and motility behavioral responses. In the natural environment, different bacterial species (Gram-positive and Gram-negative) produce QS signaling molecules that are structurally and functionally different. Recent and past research shows that various antagonistic molecules (naturally and chemically synthesized) are characterized to inhibit the formation of biofilm and attenuation of bacterial virulence by blocking the QS receptors. This review article describes about the diverse QS receptors at their structural, functional and production levels. Thus, by blocking these receptors with inhibitory molecules can be a potential therapeutic approach to control pathogenesis. Furthermore, these receptors can also be used as a structural platform to screen the most potent inhibitors with the help of bioinformatics approaches.
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Affiliation(s)
- Fazlurrahman Khan
- Marine-Integrated Bionics Research Center, Pukyong National University, Busan 48513, South Korea.,Department of Biotechnology, School of Engineering and Technology, Sharda University, Greater Noida 201306, U.P, India
| | - Aqib Javaid
- Department of Biotechnology, School of Engineering and Technology, Sharda University, Greater Noida 201306, U.P, India
| | - Young-Mog Kim
- Marine-Integrated Bionics Research Center, Pukyong National University, Busan 48513, South Korea.,Department of Food Science and Technology, Pukyong National University, Busan 48513, South Korea
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McBrayer DN, Cameron CD, Tal-Gan Y. Development and utilization of peptide-based quorum sensing modulators in Gram-positive bacteria. Org Biomol Chem 2020; 18:7273-7290. [PMID: 32914160 DOI: 10.1039/d0ob01421d] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Quorum sensing (QS) is a mechanism by which bacteria regulate cell density-dependent group behaviors. Gram-positive bacteria generally rely on auto-inducing peptide (AIP)-based QS signaling to regulate their group behaviors. To develop synthetic modulators of these behaviors, the natural peptide needs to be identified and its structure-activity relationships (SARs) with its cognate receptor (either membrane-bound or cytosolic) need to be understood. SAR information allows for the rational design of peptides or peptide mimics with enhanced characteristics, which in turn can be utilized in studies to understand species-specific QS mechanisms and as lead scaffolds for the development of therapeutic candidates that target QS. In this review, we discuss recent work associated with the approaches used towards forwarding each of these steps in Gram-positive bacteria, with a focus on species that have received less attention.
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Affiliation(s)
- Dominic N McBrayer
- Department of Chemistry, SUNY New Paltz, 1 Hawk Drive, New Paltz, NY 12561, USA. and Department of Chemistry, University of Nevada, Reno, 1664 N. Virginia Street, Reno, NV 89557, USA.
| | - Crissey D Cameron
- Department of Chemistry, University of Nevada, Reno, 1664 N. Virginia Street, Reno, NV 89557, USA.
| | - Yftah Tal-Gan
- Department of Chemistry, University of Nevada, Reno, 1664 N. Virginia Street, Reno, NV 89557, USA.
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Tian XL, Li M, Scinocca Z, Rutherford H, Li YH. ClpP is required for proteolytic regulation of type II toxin-antitoxin systems and persister cell formation in Streptococcus mutans. Access Microbiol 2019; 1:e000054. [PMID: 32974554 PMCID: PMC7470404 DOI: 10.1099/acmi.0.000054] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 07/25/2019] [Indexed: 11/18/2022] Open
Abstract
The type II toxin-antitoxin (TA) modules, mazEF and relBE, in Streptococcus mutans have been implicated in stress response, antibiotic tolerance and persister cell formation. However, how S. mutans regulates these systems to prevent unwanted toxin activation and persister cell formation is unclear. In this study, we provide evidence that ClpP is required for the proteolytic regulation of these TA systems and persister cell formation in S. mutans following antibiotic challenge. A persister viability assay showed that S. mutans UA159 (WT) formed a larger quantity of persister cells than its isogenic mutant ΔclpP following antibiotic challenge. However, the lux reporter assay revealed that clpP deletion did not affect the transcriptional levels of mazEF and relBE, since no significant differences (P>0.05) in the reporter activities were detected between the wild-type and ΔclpP background. Instead, all antibiotics tested at a sub-minimum inhibitory concentration (sub-MIC) induced transcriptional levels of mazEF and relBE operons. We then examined the protein profiles of His-tagged MazE and RelB proteins in the UA159 and ΔclpP backgrounds by Western blotting analysis. The results showed that S. mutans strains grown under non-stress conditions expressed very low but detectable levels of MazE and RelB antitoxin proteins. Antibiotics at sub-MICs induced the levels of the MazE and RelB proteins, but the protein levels decreased rapidly in the wild-type background. In contrast, a stable level of MazE and RelB proteins could be detected in the ΔclpP mutant background, suggesting that both proteins accumulated in the ΔclpP mutant. We conclude that ClpP is required for the proteolytic regulation of cellular levels of the MazE and RelB antitoxins in S. mutans , which may play a critical role in modulating the TA activities and persister cell formation of this organism following antibiotic challenge.
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Affiliation(s)
- Xiao-Lin Tian
- Department of Applied Oral Sciences, Dalhousie Universit, Halifax, NS, Canada
| | - Miao Li
- Department of Applied Oral Sciences, Dalhousie Universit, Halifax, NS, Canada.,Lanzhou University, Gansu, PR China
| | - Zachariah Scinocca
- Department of Applied Oral Sciences, Dalhousie Universit, Halifax, NS, Canada
| | - Heather Rutherford
- Department of Applied Oral Sciences, Dalhousie Universit, Halifax, NS, Canada
| | - Yung-Hua Li
- Department of Applied Oral Sciences, Dalhousie Universit, Halifax, NS, Canada.,Department of Microbiology and Immunology, Dalhousie University, Halifax, NS, Canada
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Kaspar JR, Walker AR. Expanding the Vocabulary of Peptide Signals in Streptococcus mutans. Front Cell Infect Microbiol 2019; 9:194. [PMID: 31245303 PMCID: PMC6563777 DOI: 10.3389/fcimb.2019.00194] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 05/21/2019] [Indexed: 12/18/2022] Open
Abstract
Streptococci, including the dental pathogen Streptococcus mutans, undergo cell-to-cell signaling that is mediated by small peptides to control critical physiological functions such as adaptation to the environment, control of subpopulation behaviors and regulation of virulence factors. One such model pathway is the regulation of genetic competence, controlled by the ComRS signaling system and the peptide XIP. However, recent research in the characterization of this pathway has uncovered novel operons and peptides that are intertwined into its regulation. These discoveries, such as cell lysis playing a critical role in XIP release and importance of bacterial self-sensing during the signaling process, have caused us to reevaluate previous paradigms and shift our views on the true purpose of these signaling systems. The finding of new peptides such as the ComRS inhibitor XrpA and the peptides of the RcrRPQ operon also suggests there may be more peptides hidden in the genomes of streptococci that could play critical roles in the physiology of these organisms. In this review, we summarize the recent findings in S. mutans regarding the integration of other circuits into the ComRS signaling pathway, the true mode of XIP export, and how the RcrRPQ operon controls competence activation. We also look at how new technologies can be used to re-annotate the genome to find new open reading frames that encode peptide signals. Together, this summary of research will allow us to reconsider how we perceive these systems to behave and lead us to expand our vocabulary of peptide signals within the genus Streptococcus.
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Affiliation(s)
- Justin R. Kaspar
- Department of Oral Biology, University of Florida, Gainesville, FL, United States
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