101
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Rampioni G, Leoni L, Williams P. The art of antibacterial warfare: Deception through interference with quorum sensing–mediated communication. Bioorg Chem 2014; 55:60-8. [DOI: 10.1016/j.bioorg.2014.04.005] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 04/09/2014] [Accepted: 04/11/2014] [Indexed: 01/02/2023]
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102
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Staphylococcus epidermidis agr quorum-sensing system: signal identification, cross talk, and importance in colonization. J Bacteriol 2014; 196:3482-93. [PMID: 25070736 DOI: 10.1128/jb.01882-14] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Staphylococcus epidermidis is an opportunistic pathogen that is one of the leading causes of medical device infections. Global regulators like the agr quorum-sensing system in this pathogen have received a limited amount of attention, leaving important questions unanswered. There are three agr types in S. epidermidis strains, but only one of the autoinducing peptide (AIP) signals has been identified (AIP-I), and cross talk between agr systems has not been tested. We structurally characterized all three AIP types using mass spectrometry and discovered that the AIP-II and AIP-III signals are 12 residues in length, making them the largest staphylococcal AIPs identified to date. S. epidermidis agr reporter strains were developed for each system, and we determined that cross-inhibitory interactions occur between the agr type I and II systems and between the agr type I and III systems. In contrast, no cross talk was observed between the type II and III systems. To further understand the outputs of the S. epidermidis agr system, an RNAIII mutant was constructed, and microarray studies revealed that exoenzymes (Ecp protease and Geh lipase) and low-molecular-weight toxins were downregulated in the mutant. Follow-up analysis of Ecp confirmed the RNAIII is required to induce protease activity and that agr cross talk modulates Ecp activity in a manner that mirrors the agr reporter results. Finally, we demonstrated that the agr system enhances skin colonization by S. epidermidis using a porcine model. This work expands our knowledge of S. epidermidis agr system function and will aid future studies on cell-cell communication in this important opportunistic pathogen.
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103
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Cech NB, Horswill AR. Small-molecule quorum quenchers to prevent Staphylococcus aureus infection. Future Microbiol 2014; 8:1511-4. [PMID: 24266350 DOI: 10.2217/fmb.13.134] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Affiliation(s)
- Nadja B Cech
- Department of Chemistry/Biochemistry, The University of North Carolina at Greensboro, 435 Sullivan Building, Greensboro, NC 27402, USA
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104
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Figueroa M, Jarmusch AK, Raja H, El-Elimat T, Kavanaugh JS, Horswill AR, Cooks RG, Cech NB, Oberlies NH. Polyhydroxyanthraquinones as quorum sensing inhibitors from the guttates of Penicillium restrictum and their analysis by desorption electrospray ionization mass spectrometry. JOURNAL OF NATURAL PRODUCTS 2014; 77:1351-8. [PMID: 24911880 PMCID: PMC4073659 DOI: 10.1021/np5000704] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Indexed: 05/22/2023]
Abstract
The endophytic fungus Penicillium restrictum was isolated from the stems of a milk thistle (Silybum marianum) plant. In culture, the fungus produced distinct red guttates, which have been virtually uninvestigated, particularly from the standpoint of chemistry. Hence, this study examined the chemical mycology of P. restrictum and, in doing so, uncovered a series of both known and new polyhydroxyanthraquinones (1-9). These compounds were quorum sensing inhibitors in a clinical isolate of methicillin-resistant Staphylococcus aureus (MRSA), with IC50 values ranging from 8 to 120 μM, suggesting antivirulence potential for the compounds. Moreover, the spatial and temporal distribution of the polyhydroxyanthraquinones was examined in situ via desorption electrospray ionization-mass spectrometry (DESI-MS) imaging, demonstrating the first application of this technique to a guttate-forming fungus and revealing both the concentration of secondary metabolites at the ventral surface of the fungus and their variance in colonies of differing ages.
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Affiliation(s)
- Mario Figueroa
- Department
of Chemistry and Biochemistry, University
of North Carolina at Greensboro, Greensboro, North Carolina 27402, United States
| | - Alan K. Jarmusch
- Department
of Chemistry and Center for Analytical Instrumentation Development, Purdue University, West Lafayette, Indiana 47907, United States
| | - Huzefa
A. Raja
- Department
of Chemistry and Biochemistry, University
of North Carolina at Greensboro, Greensboro, North Carolina 27402, United States
| | - Tamam El-Elimat
- Department
of Chemistry and Biochemistry, University
of North Carolina at Greensboro, Greensboro, North Carolina 27402, United States
| | - Jeffrey S. Kavanaugh
- Department
of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, United States
| | - Alexander R. Horswill
- Department
of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, United States
| | - R. Graham Cooks
- Department
of Chemistry and Center for Analytical Instrumentation Development, Purdue University, West Lafayette, Indiana 47907, United States
| | - Nadja B. Cech
- Department
of Chemistry and Biochemistry, University
of North Carolina at Greensboro, Greensboro, North Carolina 27402, United States
| | - Nicholas H. Oberlies
- Department
of Chemistry and Biochemistry, University
of North Carolina at Greensboro, Greensboro, North Carolina 27402, United States
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105
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Sully EK, Malachowa N, Elmore BO, Alexander SM, Femling JK, Gray BM, DeLeo FR, Otto M, Cheung AL, Edwards BS, Sklar LA, Horswill AR, Hall PR, Gresham HD. Selective chemical inhibition of agr quorum sensing in Staphylococcus aureus promotes host defense with minimal impact on resistance. PLoS Pathog 2014; 10:e1004174. [PMID: 24945495 PMCID: PMC4055767 DOI: 10.1371/journal.ppat.1004174] [Citation(s) in RCA: 245] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 04/23/2014] [Indexed: 12/31/2022] Open
Abstract
Bacterial signaling systems are prime drug targets for combating the global health threat of antibiotic resistant bacterial infections including those caused by Staphylococcus aureus. S. aureus is the primary cause of acute bacterial skin and soft tissue infections (SSTIs) and the quorum sensing operon agr is causally associated with these. Whether efficacious chemical inhibitors of agr signaling can be developed that promote host defense against SSTIs while sparing the normal microbiota of the skin is unknown. In a high throughput screen, we identified a small molecule inhibitor (SMI), savirin (S. aureusvirulence inhibitor) that disrupted agr-mediated quorum sensing in this pathogen but not in the important skin commensal Staphylococcus epidermidis. Mechanistic studies employing electrophoretic mobility shift assays and a novel AgrA activation reporter strain revealed the transcriptional regulator AgrA as the target of inhibition within the pathogen, preventing virulence gene upregulation. Consistent with its minimal impact on exponential phase growth, including skin microbiota members, savirin did not provoke stress responses or membrane dysfunction induced by conventional antibiotics as determined by transcriptional profiling and membrane potential and integrity studies. Importantly, savirin was efficacious in two murine skin infection models, abating tissue injury and selectively promoting clearance of agr+ but not Δagr bacteria when administered at the time of infection or delayed until maximal abscess development. The mechanism of enhanced host defense involved in part enhanced intracellular killing of agr+ but not Δagr in macrophages and by low pH. Notably, resistance or tolerance to savirin inhibition of agr was not observed after multiple passages either in vivo or in vitro where under the same conditions resistance to growth inhibition was induced after passage with conventional antibiotics. Therefore, chemical inhibitors can selectively target AgrA in S. aureus to promote host defense while sparing agr signaling in S. epidermidis and limiting resistance development. New approaches are needed to lessen the burden of antibiotic resistant bacterial infections. One strategy is to develop therapies that target virulence which rely on host defense elements to clear the bacteria rather than direct antimicrobial killing. Quorum sensing is a bacterial signaling mechanism that often regulates virulence in medically relevant bacterial pathogens. Therefore, drugs that inhibit quorum sensing can promote host defense by rendering the pathogenic bacteria avirulent and/or less fit for survival within the host. Our work addressed this strategy in the pathogen Staphylococcus aureus which is the major cause of acute bacterial skin and soft tissue infections. We conducted a high throughput screen to identify compounds that could inhibit signaling by the quorum sensing operon, agr. We found a compound that we termed savirin (S. aureusvirulence inhibitor) that could inhibit signaling by this operon. The drug helped the innate immune system in animals to clear bacteria that express this operon without affecting clearance of bacteria that do not have this operon. We addressed the mechanism of action of this compound and whether resistance or tolerance to this compound would likely develop. Our data indicate for the first time that host defense against S. aureus skin infections can be enhanced by chemical inhibition of agr-mediated quorum sensing.
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Affiliation(s)
- Erin K. Sully
- Research Service, New Mexico Veterans Affairs Medical Center, Albuquerque, New Mexico, United States of America
- Division of Infectious Diseases, Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, New Mexico, United States of America
| | - Natalia Malachowa
- Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Bradley O. Elmore
- College of Pharmacy, University of New Mexico, Albuquerque, New Mexico, United States of America
| | - Susan M. Alexander
- Research Service, New Mexico Veterans Affairs Medical Center, Albuquerque, New Mexico, United States of America
| | - Jon K. Femling
- Department of Emergency Medicine, University of New Mexico, Albuquerque, New Mexico, United States of America
| | - Brian M. Gray
- Research Service, New Mexico Veterans Affairs Medical Center, Albuquerque, New Mexico, United States of America
- College of Pharmacy, University of New Mexico, Albuquerque, New Mexico, United States of America
| | - Frank R. DeLeo
- Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Michael Otto
- Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Ambrose L. Cheung
- Department of Microbiology, Dartmouth Medical School, Hanover, New Hampshire, United States of America
| | - Bruce S. Edwards
- Center for Molecular Discovery and Department of Pathology, University of New Mexico School of Medicine, Albuquerque, New Mexico, United States of America
| | - Larry A. Sklar
- Center for Molecular Discovery and Department of Pathology, University of New Mexico School of Medicine, Albuquerque, New Mexico, United States of America
| | - Alexander R. Horswill
- Department of Microbiology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Pamela R. Hall
- College of Pharmacy, University of New Mexico, Albuquerque, New Mexico, United States of America
- * E-mail:
| | - Hattie D. Gresham
- Research Service, New Mexico Veterans Affairs Medical Center, Albuquerque, New Mexico, United States of America
- Division of Infectious Diseases, Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, New Mexico, United States of America
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106
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Christiaen SEA, O'Connell Motherway M, Bottacini F, Lanigan N, Casey PG, Huys G, Nelis HJ, van Sinderen D, Coenye T. Autoinducer-2 plays a crucial role in gut colonization and probiotic functionality of Bifidobacterium breve UCC2003. PLoS One 2014; 9:e98111. [PMID: 24871429 PMCID: PMC4037206 DOI: 10.1371/journal.pone.0098111] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 04/29/2014] [Indexed: 01/13/2023] Open
Abstract
In the present study we show that luxS of Bifidobacterium breve UCC2003 is involved in the production of the interspecies signaling molecule autoinducer-2 (AI-2), and that this gene is essential for gastrointestinal colonization of a murine host, while it is also involved in providing protection against Salmonella infection in Caenorhabditis elegans. We demonstrate that a B. breve luxS-insertion mutant is significantly more susceptible to iron chelators than the WT strain and that this sensitivity can be partially reverted in the presence of the AI-2 precursor DPD. Furthermore, we show that several genes of an iron starvation-induced gene cluster, which are downregulated in the luxS-insertion mutant and which encodes a presumed iron-uptake system, are transcriptionally upregulated under in vivo conditions. Mutation of two genes of this cluster in B. breve UCC2003 renders the derived mutant strains sensitive to iron chelators while deficient in their ability to confer gut pathogen protection to Salmonella-infected nematodes. Since a functional luxS gene is present in all tested members of the genus Bifidobacterium, we conclude that bifidobacteria operate a LuxS-mediated system for gut colonization and pathogen protection that is correlated with iron acquisition.
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Affiliation(s)
| | - Mary O'Connell Motherway
- Alimentary Pharmabiotic Centre and School of Microbiology, University College Cork, Western Road, Cork, Ireland
| | - Francesca Bottacini
- Alimentary Pharmabiotic Centre and School of Microbiology, University College Cork, Western Road, Cork, Ireland
| | - Noreen Lanigan
- Alimentary Pharmabiotic Centre and School of Microbiology, University College Cork, Western Road, Cork, Ireland
| | - Pat G. Casey
- Alimentary Pharmabiotic Centre and School of Microbiology, University College Cork, Western Road, Cork, Ireland
| | - Geert Huys
- Laboratory of Microbiology & BCCM/LMG Bacteria Collection, Ghent University, Ghent, Belgium
| | - Hans J. Nelis
- Laboratory of Pharmaceutical Microbiology, Ghent University, Ghent, Belgium
| | - Douwe van Sinderen
- Alimentary Pharmabiotic Centre and School of Microbiology, University College Cork, Western Road, Cork, Ireland
| | - Tom Coenye
- Laboratory of Pharmaceutical Microbiology, Ghent University, Ghent, Belgium
- * E-mail:
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107
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Murray EJ, Crowley RC, Truman A, Clarke SR, Cottam JA, Jadhav GP, Steele VR, O'Shea P, Lindholm C, Cockayne A, Chhabra SR, Chan WC, Williams P. Targeting Staphylococcus aureus quorum sensing with nonpeptidic small molecule inhibitors. J Med Chem 2014; 57:2813-9. [PMID: 24592914 PMCID: PMC4010551 DOI: 10.1021/jm500215s] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
A series of 3-oxo-C12-HSL,
tetramic acid, and tetronic
acid analogues were synthesized to gain insights into the structural
requirements for quorum sensing inhibition in Staphylococcus
aureus. Compounds active against agr were
noncompetitive inhibitors of the autoinducing peptide (AIP) activated
AgrC receptor, by altering the activation efficacy of the cognate
AIP-1. They appeared to act as negative allosteric modulators and
are exemplified by 3-tetradecanoyltetronic acid 17, which
reduced nasal cell colonization and arthritis in a murine infection
model.
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Affiliation(s)
- Ewan J Murray
- School of Life Sciences, Centre for Biomolecular Sciences, University of Nottingham , Nottingham, NG7 2RD, U.K
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108
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Scutera S, Zucca M, Savoia D. Novel approaches for the design and discovery of quorum-sensing inhibitors. Expert Opin Drug Discov 2014; 9:353-66. [DOI: 10.1517/17460441.2014.894974] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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109
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Herrmann M. Antimicrobial Effects Promoting Biofilm Formation and Persistent Disease: The Role of a DNA-Binding Regulator, SarA, in Staphylococcal Endocarditis. J Infect Dis 2014; 209:1153-5. [DOI: 10.1093/infdis/jiu008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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110
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Wang L, Quan C, Liu B, Wang J, Xiong W, Zhao P, Fan S. Functional reconstitution of Staphylococcus aureus truncated AgrC histidine kinase in a model membrane system. PLoS One 2013; 8:e80400. [PMID: 24303011 PMCID: PMC3841183 DOI: 10.1371/journal.pone.0080400] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 10/03/2013] [Indexed: 11/18/2022] Open
Abstract
The integral membrane protein AgrC is a histidine kinase whose sensor domains interact with an autoinducing peptide, resulting in a series of downstream responses. In this study, truncated AgrCTM5-6C and AgrCTM5-6C-GFP with GFP as a reporter gene were produced using a bacterial system. Purified AgrCTM5-6C and AgrCTM5-6C-GFP were reconstituted into liposomes by a detergent-mediated method. To achieve high-yield protein incorporation, we investigated the effect of different detergents on protein reconstitution efficiency. The highest incorporation was found with N,N-dimethyldode-cylamine N-oxide during complete liposome solubilization, which resulted in a yield of 85±5%. The COOH-terminus of the protein AgrCTM5-6C was almost exclusively oriented towards the inside of the vesicles. AgrCTM5-6C in proteoliposomes exhibited approximately a 6-fold increase in constitutive activity compared with AgrCTM5-6C in detergent micelles. The reconstitution of AgrCTM5-6C or AgrCTM5-6C-GFP was characterized using dynamic light scattering, fluorescence microscopy, and transmission electron microscopy. Based on the results, the optimal conditions for protein incorporation were defined. These findings contribute to the study of membrane protein structure and function in vitro using a reconstitution system.
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Affiliation(s)
- Lina Wang
- Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
| | - Chunshan Quan
- Department of Life Science, Dalian Nationalities University, Dalian, China
- The State Ethnic Affairs Commission-Ministry of Education, Dalian, China
- * E-mail:
| | - Baoquan Liu
- Department of Life Science, Dalian Nationalities University, Dalian, China
- The State Ethnic Affairs Commission-Ministry of Education, Dalian, China
| | - Jianfeng Wang
- Department of Life Science, Dalian Nationalities University, Dalian, China
- The State Ethnic Affairs Commission-Ministry of Education, Dalian, China
| | - Wen Xiong
- Department of Life Science, Dalian Nationalities University, Dalian, China
- The State Ethnic Affairs Commission-Ministry of Education, Dalian, China
| | - Pengchao Zhao
- Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
| | - Shengdi Fan
- Department of Life Science, Dalian Nationalities University, Dalian, China
- The State Ethnic Affairs Commission-Ministry of Education, Dalian, China
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111
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Tal-Gan Y, Ivancic M, Cornilescu G, Cornilescu CC, Blackwell HE. Structural characterization of native autoinducing peptides and abiotic analogues reveals key features essential for activation and inhibition of an AgrC quorum sensing receptor in Staphylococcus aureus. J Am Chem Soc 2013; 135:18436-44. [PMID: 24219181 DOI: 10.1021/ja407533e] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Staphylococcus aureus is a major human pathogen that uses quorum sensing (QS) to control virulence. Its QS system is regulated by macrocyclic peptide signals (or autoinducing peptides (AIPs)) and their cognate transmembrane receptors (AgrCs). Four different specificity groups of S. aureus have been identified to date (groups I-IV), each of which uses a different AIP:AgrC pair. Non-native ligands capable of intercepting AIP:AgrC binding, and thereby QS, in S. aureus have attracted considerable interest as chemical tools to study QS pathways and as possible antivirulence strategies for the treatment of infection. We recently reported a set of analogues of the group-III AIP that are capable of strongly modulating the activity of all four AgrC receptors. Critical to the further development of such ligands is a detailed understanding of the structural features of both native AIPs and non-native analogues that are essential for activity. Herein, we report the first three-dimensional structural analysis of the known native AIP signals (AIPs-I-IV) and several AIP-III analogues with varied biological activities using NMR spectroscopy. Integration of these NMR studies with the known agonism and antagonism profiles of these peptides in AgrC-III revealed two key structural elements that control AIP-III (and non-native peptide) activity: (1) a tri-residue hydrophobic "knob" essential for both activation and inhibition and (2) a fourth anchor point on the exocyclic tail needed for receptor activation. These results provide strong structural support for a mechanism of AIP-mediated AgrC activation and inhibition in S. aureus , and should facilitate the design of new AgrC ligands with enhanced activities (as agonists or antagonists) and simplified chemical structures.
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Affiliation(s)
- Yftah Tal-Gan
- Department of Chemistry, University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53706, United States
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112
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James EH, Edwards AM, Wigneshweraraj S. Transcriptional downregulation of agr expression in Staphylococcus aureus during growth in human serum can be overcome by constitutively active mutant forms of the sensor kinase AgrC. FEMS Microbiol Lett 2013; 349:153-62. [PMID: 24164684 PMCID: PMC4274972 DOI: 10.1111/1574-6968.12309] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 10/11/2013] [Accepted: 10/17/2013] [Indexed: 01/05/2023] Open
Abstract
The temporal and cell density-dependent regulation of expression of virtually all the Staphylococcus aureus virulon is under the control of the agr (accessory gene regulatory) operon. The expression of the agr operon is subject to transcriptional regulation by the AgrA/C two-component response regulator/sensor kinase pair. During bacteraemia, a frequent syndrome caused by methicillin-resistant S. aureus (MRSA), the transcriptional downregulation of agr expression has been attributed to the sequestration of the quorum-signalling molecule auto-inducing peptide (AIP) by the human serum component apolipoprotein B as part of an innate immune response to infection. However, it is not known whether transcriptional downregulation of agr expression during growth in human serum is additionally subjected to regulation by transcription regulatory proteins that either directly or indirectly affect transcription from the agr operon promoters. Here, using chromosomal fluorescence reporters of agr expression in S. aureus, we show that the transcriptional downregulation of agr expression in human serum can be overcome using constitutive active mutant forms of AgrC. Therefore, it seems that the sequestration of the AIP is likely to be the only mechanism by which the host innate immune response limits agr expression at the transcriptional level to maintain the host-pathogen balance towards a noninvasive outcome.
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Affiliation(s)
- Ellen H James
- Faculty of Medicine, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, UK
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113
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Fleuchot B, Guillot A, Mézange C, Besset C, Chambellon E, Monnet V, Gardan R. Rgg-associated SHP signaling peptides mediate cross-talk in Streptococci. PLoS One 2013; 8:e66042. [PMID: 23776602 PMCID: PMC3679016 DOI: 10.1371/journal.pone.0066042] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 05/01/2013] [Indexed: 01/01/2023] Open
Abstract
We described a quorum-sensing mechanism in the streptococci genus involving a short hydrophobic peptide (SHP), which acts as a pheromone, and a transcriptional regulator belonging to the Rgg family. The shp/rgg genes, found in nearly all streptococcal genomes and in several copies in some, have been classified into three groups. We used a genetic approach to evaluate the functionality of the SHP/Rgg quorum-sensing mechanism, encoded by three selected shp/rgg loci, in pathogenic and non-pathogenic streptococci. We characterized the mature form of each SHP pheromone by mass-spectrometry. We produced synthetic peptides corresponding to these mature forms, and used them to study functional complementation and cross-talk between these different SHP/Rgg systems. We demonstrate that a SHP pheromone of one system can influence the activity of a different system. Interestingly, this does not seem to be dependent on the SHP/Rgg group and cross-talk between pathogenic and non-pathogenic streptococci is observed.
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Affiliation(s)
- Betty Fleuchot
- INRA, UMR1319 MICALIS, Jouy en Josas, France ; AgroParistech, UMR MICALIS, Jouy en Josas, France.
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114
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Tal-Gan Y, Stacy DM, Foegen MK, Koenig DW, Blackwell HE. Highly potent inhibitors of quorum sensing in Staphylococcus aureus revealed through a systematic synthetic study of the group-III autoinducing peptide. J Am Chem Soc 2013; 135:7869-82. [PMID: 23647400 DOI: 10.1021/ja3112115] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Methods to intercept bacterial quorum sensing (QS) have attracted significant attention as potential anti-infective therapies. Staphylococcus aureus is a major human pathogen that utilizes autoinducing peptide (AIP) signals to mediate QS and thereby regulate virulence. S. aureus strains are categorized into four groups (I-IV) according to their AIP signal and cognate extracellular receptor, AgrC. Each group is associated with a certain disease profile, and S. aureus group-III strains are responsible for toxic shock syndrome and have been underestimated in other infections to date. A limited set of non-native AIP analogs have been shown to inhibit AgrC receptors; such compounds represent promising tools to study QS pathways in S. aureus . We seek to expand this set of chemical probes and report herein the first design, synthesis, and biological testing of AIP-III mimetics. A set of non-native peptides was identified that can inhibit all four of the AgrC receptors (I-IV) with picomolar IC50 values in reporter strains. These analogs also blocked hemolysis by wild-type S. aureus group I-IV strains-a virulence trait under the control of QS-at picomolar concentrations. Moreover, four of the lead AgrC inhibitors were capable of attenuating the production of toxic shock syndrome toxin-1 (also under the control of QS) by over 80% at nanomolar concentrations in a wild-type S. aureus group-III strain. These peptides represent, to our knowledge, the most potent synthetic inhibitors of QS in S. aureus known, and constitute new and readily accessible chemical tools for the study of the AgrC system and virulence in this deadly pathogen.
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Affiliation(s)
- Yftah Tal-Gan
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA
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115
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Gray B, Hall P, Gresham H. Targeting agr- and agr-Like quorum sensing systems for development of common therapeutics to treat multiple gram-positive bacterial infections. SENSORS 2013; 13:5130-66. [PMID: 23598501 PMCID: PMC3673130 DOI: 10.3390/s130405130] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 04/06/2013] [Accepted: 04/12/2013] [Indexed: 12/13/2022]
Abstract
Invasive infection by the Gram-positive pathogen Staphylococcus aureus is controlled by a four gene operon, agr that encodes a quorum sensing system for the regulation of virulence. While agr has been well studied in S. aureus, the contribution of agr homologues and analogues in other Gram-positive pathogens is just beginning to be understood. Intriguingly, other significant human pathogens, including Clostridium perfringens, Listeria monocytogenes, and Enterococcus faecalis contain agr or analogues linked to virulence. Moreover, other significant human Gram-positive pathogens use peptide based quorum sensing systems to establish or maintain infection. The potential for commonality in aspects of these signaling systems across different species raises the prospect of identifying therapeutics that could target multiple pathogens. Here, we review the status of research into these agr homologues, analogues, and other peptide based quorum sensing systems in Gram-positive pathogens as well as the potential for identifying common pathways and signaling mechanisms for therapeutic discovery.
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Affiliation(s)
- Brian Gray
- Department of Pharmaceutical Sciences, College of Pharmacy/MRF 208, MSC09 5360, University of New Mexico, Albuquerque, NM 87131-0001, USA; E-Mail:
- Research Service, New Mexico Veterans Affairs Medical Center, Albuquerque, NM 87108, USA
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-505-265-1711 (ext. 2841)
| | - Pamela Hall
- Department of Pharmaceutical Sciences, College of Pharmacy/MRF 208, MSC09 5360, University of New Mexico, Albuquerque, NM 87131-0001, USA; E-Mail:
- Research Service, New Mexico Veterans Affairs Medical Center, Albuquerque, NM 87108, USA
| | - Hattie Gresham
- Research Service, New Mexico Veterans Affairs Medical Center, Albuquerque, NM 87108, USA
- Department of Internal Medicine, Division of Infectious Diseases, University of New Mexico, Albuquerque, NM 87131, USA; E-Mail:
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