1
|
Mueller Brown K, Eutsey R, Gazioglu O, Wang D, Vallon A, Rosch JW, Yesilkaya H, Hiller NL. Peptide maturation molecules act as molecular gatekeepers to coordinate cell-cell communication in Streptococcus pneumoniae. Cell Rep 2024; 43:114432. [PMID: 38963762 DOI: 10.1016/j.celrep.2024.114432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 05/14/2024] [Accepted: 06/19/2024] [Indexed: 07/06/2024] Open
Abstract
The human pathogen Streptococcus pneumoniae (Spn) encodes several cell-cell communication systems, notably multiple members of the Rgg/SHP and the Tpr/Phr families. Until now, members of these diverse communication systems were thought to work independently. Our study reveals that the ABC transporter PptAB and the transmembrane enzyme Eep act as a molecular link between Rgg/SHP and TprA/PhrA systems. We demonstrate that PptAB/Eep activates the Rgg/SHP systems and represses the TprA/PhrA system. Specifically, they regulate the respective precursor peptides (SHP and PhrA) before these leave the cell. This dual mode of action leads to temporal coordination of these systems, producing an overlap between their respective regulons during host cell infection. Thus, we have identified a single molecular mechanism that targets diverse cell-cell communication systems in Spn. Moreover, these molecular components are encoded by many gram-positive bacteria, suggesting that this mechanism may be broadly conserved.
Collapse
Affiliation(s)
- Karina Mueller Brown
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Rory Eutsey
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Ozcan Gazioglu
- Department of Respiratory Sciences, University of Leicester, Leicester, UK
| | - Derek Wang
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Amanda Vallon
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Jason W Rosch
- Department of Host-Microbe Interactions, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Hasan Yesilkaya
- Department of Respiratory Sciences, University of Leicester, Leicester, UK
| | - N Luisa Hiller
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA.
| |
Collapse
|
2
|
Hiller NL, Orihuela CJ. Biological puzzles solved by using Streptococcus pneumoniae: a historical review of the pneumococcal studies that have impacted medicine and shaped molecular bacteriology. J Bacteriol 2024; 206:e0005924. [PMID: 38809015 DOI: 10.1128/jb.00059-24] [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: 05/30/2024] Open
Abstract
The major human pathogen Streptococcus pneumoniae has been the subject of intensive clinical and basic scientific study for over 140 years. In multiple instances, these efforts have resulted in major breakthroughs in our understanding of basic biological principles as well as fundamental tenets of bacterial pathogenesis, immunology, vaccinology, and genetics. Discoveries made with S. pneumoniae have led to multiple major public health victories that have saved the lives of millions. Studies on S. pneumoniae continue today, where this bacterium is being used to dissect the impact of the host on disease processes, as a powerful cell biology model, and to better understand the consequence of human actions on commensal bacteria at the population level. Herein we review the major findings, i.e., puzzle pieces, made with S. pneumoniae and how, over the years, they have come together to shape our understanding of this bacterium's biology and the practice of medicine and modern molecular biology.
Collapse
Affiliation(s)
- N Luisa Hiller
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
| | - Carlos J Orihuela
- Department of Microbiology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| |
Collapse
|
3
|
Wahlenmayer ER, Hammers DE. Streptococcal peptides and their roles in host-microbe interactions. Front Cell Infect Microbiol 2023; 13:1282622. [PMID: 37915845 PMCID: PMC10617681 DOI: 10.3389/fcimb.2023.1282622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 10/02/2023] [Indexed: 11/03/2023] Open
Abstract
The genus Streptococcus encompasses many bacterial species that are associated with hosts, ranging from asymptomatic colonizers and commensals to pathogens with a significant global health burden. Streptococci produce numerous factors that enable them to occupy their host-associated niches, many of which alter their host environment to the benefit of the bacteria. The ability to manipulate host immune systems to either evade detection and clearance or induce a hyperinflammatory state influences whether bacteria are able to survive and persist in a given environment, while also influencing the propensity of the bacteria to cause disease. Several bacterial factors that contribute to this inter-species interaction have been identified. Recently, small peptides have become increasingly appreciated as factors that contribute to Streptococcal relationships with their hosts. Peptides are utilized by streptococci to modulate their host environment in several ways, including by directly interacting with host factors to disrupt immune system function and signaling to other bacteria to control the expression of genes that contribute to immune modulation. In this review, we discuss the many contributions of Streptococcal peptides in terms of their ability to contribute to pathogenesis and disruption of host immunity. This discussion will highlight the importance of continuing to elucidate the functions of these Streptococcal peptides and pursuing the identification of new peptides that contribute to modulation of host environments. Developing a greater understanding of how bacteria interact with their hosts has the potential to enable the development of techniques to inhibit these peptides as therapeutic approaches against Streptococcal infections.
Collapse
Affiliation(s)
| | - Daniel E. Hammers
- Biology Department, Houghton University, Houghton, NY, United States
| |
Collapse
|
4
|
Hu D, Laczkovich I, Federle MJ, Morrison DA. Identification and Characterization of Negative Regulators of Rgg1518 Quorum Sensing in Streptococcus pneumoniae. J Bacteriol 2023; 205:e0008723. [PMID: 37341600 PMCID: PMC10367586 DOI: 10.1128/jb.00087-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 06/02/2023] [Indexed: 06/22/2023] Open
Abstract
Streptococcus pneumoniae is an agent of otitis media, septicemia, and meningitis and remains the leading cause of community-acquired pneumonia regardless of vaccine use. Of the various strategies that S. pneumoniae takes to enhance its potential to colonize the human host, quorum sensing (QS) is an intercellular communication process that provides coordination of gene expression at a community level. Numerous putative QS systems are identifiable in the S. pneumoniae genome, but their gene-regulatory activities and contributions to fitness have yet to be fully evaluated. To contribute to assessing regulatory activities of rgg paralogs present in the D39 genome, we conducted transcriptomic analysis of mutants of six QS regulators. Our results find evidence that at least four QS regulators impact the expression of a polycistronic operon (encompassing genes spd_1517 to spd_1513) that is directly controlled by the Rgg/SHP1518 QS system. As an approach to unravel the convergent regulation placed on the spd_1513-1517 operon, we deployed transposon mutagenesis screening in search of upstream regulators of the Rgg/SHP1518 QS system. The screen identified two types of insertion mutants that result in increased activity of Rgg1518-dependent transcription, one type being where the transposon inserted into pepO, an annotated endopeptidase, and the other type being insertions in spxB, a pyruvate oxidase. We demonstrate that pneumococcal PepO degrades SHP1518 to prevent activation of Rgg/SHP1518 QS. Moreover, the glutamic acid residue in the conserved "HExxH" domain is indispensable for the catalytic function of PepO. Finally, we confirmed the metalloendopeptidase property of PepO, which requires zinc ions, but not other ions, to facilitate peptidyl hydrolysis. IMPORTANCE Streptococcus pneumoniae uses quorum sensing to communicate and regulate virulence. In our study, we focused on one Rgg quorum sensing system (Rgg/SHP1518) and found that multiple other Rgg regulators also control it. We further identified two enzymes that inhibit Rgg/SHP1518 signaling and revealed and validated one enzyme's mechanisms for breaking down quorum sensing signaling molecules. Our findings shed light on the complex regulatory network of quorum sensing in Streptococcus pneumoniae.
Collapse
Affiliation(s)
- Duoyi Hu
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Irina Laczkovich
- Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Michael J. Federle
- Department of Pharmaceutical Sciences, University of Illinois at Chicago, Chicago, Illinois, USA
- Center for Biomolecular Science, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Donald A. Morrison
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, USA
| |
Collapse
|
5
|
Brennan AA, Mehrani M, Tal-Gan Y. Modulating streptococcal phenotypes using signal peptide analogues. Open Biol 2022; 12:220143. [PMID: 35920042 PMCID: PMC9346555 DOI: 10.1098/rsob.220143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Understanding bacterial communication mechanisms is imperative to improve our current understanding of bacterial infectivity and find alternatives to current modes of antibacterial therapeutics. Both Gram-positive and Gram-negative bacteria use quorum sensing (QS) to regulate group behaviours and associated phenotypes in a cell-density-dependent manner. Group behaviours, phenotypic expression and resultant infection and disease can largely be attributed to efficient bacterial communication. Of particular interest are the communication mechanisms of Gram-positive bacteria known as streptococci. This group has demonstrated marked resistance to traditional antibiotic treatment, resulting in increased morbidity and mortality of infected hosts and an ever-increasing burden on the healthcare system. Modulating circuits and mechanisms involved in streptococcal communication has proven to be a promising anti-virulence therapeutic approach that allows managing bacterial phenotypic response but does not affect bacterial viability. Targeting the chemical signals bacteria use for communication is a promising starting point, as manipulation of these signals can dramatically affect resultant bacterial phenotypes, minimizing associated morbidity and mortality. This review will focus on the use of modified peptide signals in modulating the development of proliferative phenotypes in different streptococcal species, specifically regarding how such modification can attenuate bacterial infectivity and aid in developing future alternative therapeutic agents.
Collapse
Affiliation(s)
- Alec A Brennan
- Department of Chemistry, University of Nevada, Reno, 1664 N. Virginia St., Reno, NV 89557, USA
| | - Mona Mehrani
- Department of Chemistry, University of Nevada, Reno, 1664 N. Virginia St., Reno, NV 89557, USA
| | - Yftah Tal-Gan
- Department of Chemistry, University of Nevada, Reno, 1664 N. Virginia St., Reno, NV 89557, USA
| |
Collapse
|
6
|
Discovery of Unannotated Small Open Reading Frames in Streptococcus pneumoniae D39 Involved in Quorum Sensing and Virulence Using Ribosome Profiling. mBio 2022; 13:e0124722. [PMID: 35852327 PMCID: PMC9426450 DOI: 10.1128/mbio.01247-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus pneumoniae, an opportunistic human pathogen, is the leading cause of community-acquired pneumonia and an agent of otitis media, septicemia, and meningitis. Although genomic and transcriptomic studies of S. pneumoniae have provided detailed perspectives on gene content and expression programs, they have lacked information pertaining to the translational landscape, particularly at a resolution that identifies commonly overlooked small open reading frames (sORFs), whose importance is increasingly realized in metabolism, regulation, and virulence. To identify protein-coding sORFs in S. pneumoniae, antibiotic-enhanced ribosome profiling was conducted. Using translation inhibitors, 114 novel sORFs were detected, and the expression of a subset of them was experimentally validated. Two loci associated with virulence and quorum sensing were examined in deeper detail. One such sORF, rio3, overlaps with the noncoding RNA srf-02 that was previously implicated in pathogenesis. Targeted mutagenesis parsing rio3 from srf-02 revealed that rio3 is responsible for the fitness defect seen in a murine nasopharyngeal colonization model. Additionally, two novel sORFs located adjacent to the quorum sensing receptor rgg1518 were found to impact regulatory activity. Our findings emphasize the importance of sORFs present in the genomes of pathogenic bacteria and underscore the utility of ribosome profiling for identifying the bacterial translatome.
Collapse
|
7
|
Lella M, Oh MW, Kuo SH, Lau GW, Tal-Gan Y. Attenuating the Streptococcus pneumoniae Competence Regulon Using Urea-Bridged Cyclic Dominant-Negative Competence-Stimulating Peptide Analogs. J Med Chem 2022; 65:6826-6839. [PMID: 35452241 PMCID: PMC9106926 DOI: 10.1021/acs.jmedchem.2c00148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Streptococcus pneumoniae (pneumococcus) is a prevalent human pathogen that utilizes the competence regulon quorum sensing circuitry to acquire antibiotic resistance and initiate its attack on the human host. Therefore, targeting the competence regulon can be applied as an anti-infective approach with minimal pressure for resistance development. Herein, we report the construction of a library of urea-bridged cyclic dominant-negative competence-stimulating peptide (dnCSP) derivatives and their evaluation as competitive inhibitors of the competence regulon. Our results reveal the first pneumococcus dual-action CSPs that inhibit the group 1 pneumococcus competence regulon while activating the group 2 pneumococcus competence regulon. Structural analysis indicates that the urea-bridge cyclization stabilizes the bioactive α-helix conformation, while in vivo studies using a mouse model of infection exhibit that the lead dual-action dnCSP, CSP1-E1A-cyc(Dab6Dab10), attenuates group 1-mediated mortality without significantly reducing the bacterial burden. Overall, our results pave the way for developing novel therapeutics against this notorious pathogen.
Collapse
Affiliation(s)
- Muralikrishna Lella
- Department of Chemistry, University of Nevada, Reno, 1664 North Virginia Street, Reno, Nevada 89557, United States
| | - Myung Whan Oh
- Department of Pathobiology, University of Illinois at Urbana-Champaign, 2001 South Lincoln Avenue, Urbana, Illinois 61802, United States
| | - Shanny Hsuan Kuo
- Department of Pathobiology, University of Illinois at Urbana-Champaign, 2001 South Lincoln Avenue, Urbana, Illinois 61802, United States
| | - Gee W Lau
- Department of Pathobiology, University of Illinois at Urbana-Champaign, 2001 South Lincoln Avenue, Urbana, Illinois 61802, United States
| | - Yftah Tal-Gan
- Department of Chemistry, University of Nevada, Reno, 1664 North Virginia Street, Reno, Nevada 89557, United States
| |
Collapse
|
8
|
Janoušková M, Straw ML, Su YC, Riesbeck K. Gene Expression Regulation in Airway Pathogens: Importance for Otitis Media. Front Cell Infect Microbiol 2022; 12:826018. [PMID: 35252035 PMCID: PMC8895709 DOI: 10.3389/fcimb.2022.826018] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 01/19/2022] [Indexed: 11/13/2022] Open
Abstract
Otitis media (OM) is an inflammatory disorder in the middle ear. It is mainly caused by viruses or bacteria associated with the airways. Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis are the three main pathogens in infection-related OM, especially in younger children. In this review, we will focus upon the multifaceted gene regulation mechanisms that are well-orchestrated in S. pneumoniae, H. influenzae, and M. catarrhalis during the course of infection in the middle ear either in experimental OM or in clinical settings. The sophisticated findings from the past 10 years on how the othopathogens govern their virulence phenotypes for survival and host adaptation via phase variation- and quorum sensing-dependent gene regulation, will be systematically discussed. Comprehensive understanding of gene expression regulation mechanisms employed by pathogens during the onset of OM may provide new insights for the design of a new generation of antimicrobial agents in the fight against bacterial pathogens while combating the serious emergence of antimicrobial resistance.
Collapse
|
9
|
Kono M, Umar NK, Takeda S, Ohtani M, Murakami D, Sakatani H, Kaneko F, Nanushaj D, Hotomi M. Novel Antimicrobial Treatment Strategy Based on Drug Delivery Systems for Acute Otitis Media. Front Pharmacol 2021; 12:640514. [PMID: 34421583 PMCID: PMC8371970 DOI: 10.3389/fphar.2021.640514] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 07/22/2021] [Indexed: 12/27/2022] Open
Abstract
Despite tremendous success of pneumococcal conjugated vaccine and antimicrobial treatment by amoxicillin, acute otitis media (AOM) still remains as a great medical concern. Failure of antimicrobial treatment includes several factors. The middle ear cavity is surrounded by bone tissue, which makes it difficult to maintain sufficient concentration of antibiotics. Tympanic membrane of AOM patients thickens and actually becomes a barrier for topical therapy. This review discusses novel antimicrobial treatment strategies based on drug delivery systems (DDS) for AOM. To deliver drugs enough to kill the pathogenic bacteria without systemic side effects, the development of new antimicrobial treatment strategy applying innovative drug DDS has been expected. The sustained-release DDS can achieve sufficient time for antimicrobial concentrations to exceed minimum inhibitory concentration (MIC) for time-dependent antibiotics as well as enough maximum concentration for dose-dependent antibiotics to eradicate causative pathogens in the middle ear. The development of trans-tympanic membranes of DDS, such as hydrogels with chemical permeation enhancers (CPEs), is another attractive strategy. Phage is a promising strategy for developing DDS-based therapies. The DDS formulations enable antimicrobial treatment of AOM by a single dose and thus, an attractive future antimicrobial treatment for AOM.
Collapse
Affiliation(s)
- Masamitsu Kono
- Department of Otorhinolaryngology-Head and Neck Surgery, Wakayama Medical University, Wakayama, Japan
| | - Nafisa K Umar
- Department of Otorhinolaryngology-Head and Neck Surgery, Wakayama Medical University, Wakayama, Japan
| | - Saori Takeda
- Department of Otorhinolaryngology-Head and Neck Surgery, Wakayama Medical University, Wakayama, Japan
| | - Makiko Ohtani
- Department of Otorhinolaryngology-Head and Neck Surgery, Wakayama Medical University, Wakayama, Japan
| | - Daichi Murakami
- Department of Otorhinolaryngology-Head and Neck Surgery, Wakayama Medical University, Wakayama, Japan
| | - Hideki Sakatani
- Department of Otorhinolaryngology-Head and Neck Surgery, Wakayama Medical University, Wakayama, Japan
| | - Fumie Kaneko
- Department of Otorhinolaryngology-Head and Neck Surgery, Wakayama Medical University, Wakayama, Japan.,Department of Otorhinolaryngology, Tokyo Women's Medical University Medical Center East, Tokyo, Japan
| | - Denisa Nanushaj
- Department of Otorhinolaryngology-Head and Neck Surgery, Wakayama Medical University, Wakayama, Japan
| | - Muneki Hotomi
- Department of Otorhinolaryngology-Head and Neck Surgery, Wakayama Medical University, Wakayama, Japan
| |
Collapse
|
10
|
Shlla B, Gazioglu O, Shafeeq S, Manzoor I, Kuipers OP, Ulijasz A, Hiller NL, Andrew PW, Yesilkaya H. The Rgg1518 transcriptional regulator is a necessary facet of sugar metabolism and virulence in Streptococcus pneumoniae. Mol Microbiol 2021; 116:996-1008. [PMID: 34328238 DOI: 10.1111/mmi.14788] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Revised: 07/22/2021] [Accepted: 07/26/2021] [Indexed: 10/20/2022]
Abstract
Rggs are a group of transcriptional regulators with diverse roles in metabolism and virulence. Here, we present work on the Rgg1518/SHP1518 quorum sensing system of Streptococcus pneumoniae. The activity of Rgg1518 is induced by its cognate peptide, SHP1518. In vitro analysis showed that the Rgg1518 system is active in conditions rich in galactose and mannose, key nutrients during nasopharyngeal colonization. Rgg1518 expression is highly induced in the presence of these sugars and its isogenic mutant is attenuated in growth on galactose and mannose. When compared with other Rgg systems, Rgg1518 has the largest regulon on galactose. On galactose it controls up- or downregulation of a functionally diverse set of genes involved in galactose metabolism, capsule biosynthesis, iron metabolism, protein translation, as well as other metabolic functions, acting mainly as a repressor of gene expression. Rgg1518 is a repressor of capsule biosynthesis, and binds directly to the capsule regulatory region. Comparison with other Rggs revealed inter-regulatory interactions among Rggs. Finally, the rgg1518 mutant is attenuated in colonization and virulence in a mouse model of colonization and pneumonia. We conclude that Rgg1518 is a virulence determinant that contributes to a regulatory network composed of multiple Rgg systems.
Collapse
Affiliation(s)
- Bushra Shlla
- Department of Respiratory Sciences, University of Leicester, Leicester, UK.,Department of Biology, College of Science, University of Mosul, Mosul, Iraq
| | - Ozcan Gazioglu
- Department of Respiratory Sciences, University of Leicester, Leicester, UK
| | - Sulman Shafeeq
- Molecular Genetics, University of Groningen, Groningen, The Netherlands
| | - Irfan Manzoor
- Molecular Genetics, University of Groningen, Groningen, The Netherlands
| | - Oscar P Kuipers
- Molecular Genetics, University of Groningen, Groningen, The Netherlands
| | - Andrew Ulijasz
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois, USA
| | - N Luisa Hiller
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
| | - Peter W Andrew
- Department of Respiratory Sciences, University of Leicester, Leicester, UK
| | - Hasan Yesilkaya
- Department of Respiratory Sciences, University of Leicester, Leicester, UK
| |
Collapse
|
11
|
Lella M, Tal-Gan Y. Strategies to Attenuate the Competence Regulon in Streptococcus pneumoniae. Pept Sci (Hoboken) 2021; 113:e24222. [PMID: 34337308 PMCID: PMC8323945 DOI: 10.1002/pep2.24222] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 01/19/2021] [Indexed: 12/18/2022]
Abstract
Streptococcus pneumoniae is an opportunistic respiratory human pathogen that poses a continuing threat to human health. Natural competence for genetic transformation in S. pneumoniae plays an important role in aiding pathogenicity and it is the best-characterized feature to acquire antimicrobial resistance genes by a frequent process of recombination. In S. pneumoniae, competence, along with virulence factor production, is controlled by a cell-density communication mechanism termed the competence regulon. In this review, we present the recent advances in the development of alternative methods to attenuate the pathogenicity of S. pneumoniae by targeting the various stages of the non-essential competence regulon communication system. We mainly focus on new developments related to competitively intercepting the competence regulon signaling through the introduction of promising dominant-negative Competence Stimulating Peptide (dnCSP) scaffolds. We also discuss recent reports on antibiotics that can block CSP export by disturbing the proton motive force (PMF) across the membrane and various ways to control the pneumococcal pathogenicity by activating the counter signaling circuit and targeting the pneumococcal proteome.
Collapse
Affiliation(s)
- Muralikrishna Lella
- Department of Chemistry, University of Nevada, Reno, 1664 North Virginia Street, Reno, NV 89557 (USA)
| | - Yftah Tal-Gan
- Department of Chemistry, University of Nevada, Reno, 1664 North Virginia Street, Reno, NV 89557 (USA)
| |
Collapse
|
12
|
García-Curiel L, Del Rocío López-Cuellar M, Rodríguez-Hernández AI, Chavarría-Hernández N. Toward understanding the signals of bacteriocin production by Streptococcus spp. and their importance in current applications. World J Microbiol Biotechnol 2021; 37:15. [PMID: 33394178 DOI: 10.1007/s11274-020-02973-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Accepted: 12/01/2020] [Indexed: 12/25/2022]
Abstract
Microorganisms have developed quorum sensing (QS) systems to detect small signaling molecules that help to control access to additional nutrients and space in highly competitive polymicrobial niches. Many bacterial processes are QS-regulated; two examples are the highly related traits of the natural genetic competence state and the production of antimicrobial peptides such as bacteriocins. The Streptococcus genus is widely studied for its competence and for its ability to produce bacteriocins, as these antimicrobial peptides have significant potential in the treatment of infections caused by multiple-resistant pathogens, a severe public health issue. The transduction of a two-component system controls competence in streptococci: (1) ComD/E, which controls the competence in the Mitis and Anginosus groups, and (2) ComR/S, which performs the same function in the Bovis, Mutans, Salivarius, and Pyogenic groups. The cell-to-cell communication required for bacteriocin production in the Streptococcus groups is controlled mainly by a paralog of the ComD/E system. The relationships between pheromone signals and induction pathways are related to the bacteriocin production systems. In this review, we discuss the recent advances in the understanding of signaling and the induction of bacteriocin biosynthesis by QS regulation in streptococci. This information could aid in the design of better methods for the development and production of these antimicrobial peptides. It could also contribute to the analysis and emerging applications of bacteriocins in terms of their safety, quality, and human health benefits.
Collapse
Affiliation(s)
- Laura García-Curiel
- Cuerpo Académico de Biotecnología Agroalimentaria, Instituto de Ciencias Agropecuarias-Universidad Autónoma del Estado de Hidalgo, Tulancingo de Bravo, México
| | - Ma Del Rocío López-Cuellar
- Cuerpo Académico de Biotecnología Agroalimentaria, Instituto de Ciencias Agropecuarias-Universidad Autónoma del Estado de Hidalgo, Tulancingo de Bravo, México.
| | - Adriana Inés Rodríguez-Hernández
- Cuerpo Académico de Biotecnología Agroalimentaria, Instituto de Ciencias Agropecuarias-Universidad Autónoma del Estado de Hidalgo, Tulancingo de Bravo, México
| | - Norberto Chavarría-Hernández
- Cuerpo Académico de Biotecnología Agroalimentaria, Instituto de Ciencias Agropecuarias-Universidad Autónoma del Estado de Hidalgo, Tulancingo de Bravo, México
| |
Collapse
|
13
|
Deciphering Streptococcal Biofilms. Microorganisms 2020; 8:microorganisms8111835. [PMID: 33233415 PMCID: PMC7700319 DOI: 10.3390/microorganisms8111835] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 11/10/2020] [Accepted: 11/17/2020] [Indexed: 12/19/2022] Open
Abstract
Streptococci are a diverse group of bacteria, which are mostly commensals but also cause a considerable proportion of life-threatening infections. They colonize many different host niches such as the oral cavity, the respiratory, gastrointestinal, and urogenital tract. While these host compartments impose different environmental conditions, many streptococci form biofilms on mucosal membranes facilitating their prolonged survival. In response to environmental conditions or stimuli, bacteria experience profound physiologic and metabolic changes during biofilm formation. While investigating bacterial cells under planktonic and biofilm conditions, various genes have been identified that are important for the initial step of biofilm formation. Expression patterns of these genes during the transition from planktonic to biofilm growth suggest a highly regulated and complex process. Biofilms as a bacterial survival strategy allow evasion of host immunity and protection against antibiotic therapy. However, the exact mechanisms by which biofilm-associated bacteria cause disease are poorly understood. Therefore, advanced molecular techniques are employed to identify gene(s) or protein(s) as targets for the development of antibiofilm therapeutic approaches. We review our current understanding of biofilm formation in different streptococci and how biofilm production may alter virulence-associated characteristics of these species. In addition, we have summarized the role of surface proteins especially pili proteins in biofilm formation. This review will provide an overview of strategies which may be exploited for developing novel approaches against biofilm-related streptococcal infections.
Collapse
|
14
|
Abstract
Gram-positive bacteria employ an array of secreted peptides to control population-level behaviors in response to environmental cues. We review mechanistic and functional features of secreted peptides produced by the human pathogen Streptococcus pneumoniae. We discuss sequence features, mechanisms of transport, and receptors for 3 major categories of small peptides: the double-glycine peptides, the Rap, Rgg, NprR, PlcR, and PrgX (RRNPP)-binding peptides, and the lanthionine-containing peptides. We highlight the impact of factors that contribute to carriage and pathogenesis, specifically genetic diversity, microbial competition, biofilm development, and environmental adaptation. A recent expansion in pneumococcal peptide studies reveals a complex network of interacting signaling systems where multiple peptides are integrated into the same signaling pathway, allowing multiple points of entry into the pathway and extending information content in new directions. In addition, since peptides are present in the extracellular milieu, there are opportunities for crosstalk, quorum sensing (QS), as well as intra- and interstrain and species interactions. Knowledge on the manner that population-level behaviors contribute to disease provides an avenue for the design and development of anti-infective strategies.
Collapse
|
15
|
Thornton RB, Hakansson A, Hood DW, Nokso-Koivisto J, Preciado D, Riesbeck K, Richmond PC, Su YC, Swords WE, Brockman KL. Panel 7 - Pathogenesis of otitis media - a review of the literature between 2015 and 2019. Int J Pediatr Otorhinolaryngol 2020; 130 Suppl 1:109838. [PMID: 31879085 PMCID: PMC7062565 DOI: 10.1016/j.ijporl.2019.109838] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
OBJECTIVE To perform a comprehensive review of the literature from July 2015 to June 2019 on the pathogenesis of otitis media. Bacteria, viruses and the role of the microbiome as well as the host response are discussed. Directions for future research are also suggested. DATA SOURCES PubMed database of the National Library of Medicine. REVIEW METHODS PubMed was searched for any papers pertaining to OM pathogenesis between July 2015 and June 2019. If in English, abstracts were assessed individually for their relevance and included in the report. Members of the panel drafted the report based on these searches and on new data presented at the 20th International Symposium on Recent Advances in Otitis Media. CONCLUSIONS The main themes that arose in OM pathogenesis were around the need for symptomatic viral infections to develop disease. Different populations potentially having different mechanisms of pathogenesis. Novel bacterial otopathogens are emerging and need to be monitored. Animal models need to continue to be developed and used to understand disease pathogenesis. IMPLICATIONS FOR PRACTICE The findings in the pathogenesis panel have several implications for both research and clinical practice. The most urgent areas appear to be to continue monitoring the emergence of novel otopathogens, and the need to develop prevention and preventative therapies that do not rely on antibiotics and protect against the development of the initial OM episode.
Collapse
Affiliation(s)
- R B Thornton
- Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, Perth, Western Australia, Australia; School of Biomedical Sciences, Faculty Health and Medical Science, University of Western Australia, Perth, Western Australia, Australia
| | - A Hakansson
- Experimental Infection Medicine, Dept. of Translational Medicine, Faculty of Medicine, Lund University, Malmö, Sweden
| | - D W Hood
- MRC Harwell Institute, Mammalian Genetics Unit, Harwell Campus, Oxfordshire, OX11 0RD, UK
| | - J Nokso-Koivisto
- Department of Otorhinolaryngology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - D Preciado
- Sheikh Zayed Center for Pediatric Surgical Innovation, Children's National Health System, Washington, DC, USA; Division of Pediatric Otolaryngology, Children's National Health System, Washington, DC, USA
| | - K Riesbeck
- Clinical Microbiology, Dept. of Translational Medicine, Faculty of Medicine, Lund University, Malmö, Sweden
| | - P C Richmond
- School of Medicine, Division of Paediatrics, Faculty Health and Medical Science, University of Western Australia, Perth, Western Australia, Australia; Perth Children's Hospital, Perth, Western Australia, Australia
| | - Y C Su
- Clinical Microbiology, Dept. of Translational Medicine, Faculty of Medicine, Lund University, Malmö, Sweden
| | - W E Swords
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - K L Brockman
- Department of Microbiology & Immunology, Medical College of Wisconsin, Milwaukee, WI, USA.
| |
Collapse
|
16
|
Gisselsson-Solén M, Tähtinen PA, Ryan AF, Mulay A, Kariya S, Schilder AG, Valdez TA, Brown S, Nolan RM, Hermansson A, van Ingen G, Marom T. Panel 1: Biotechnology, biomedical engineering and new models of otitis media. Int J Pediatr Otorhinolaryngol 2020; 130 Suppl 1:109833. [PMID: 31901291 PMCID: PMC7176743 DOI: 10.1016/j.ijporl.2019.109833] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To summarize recently published key articles on the topics of biomedical engineering, biotechnology and new models in relation to otitis media (OM). DATA SOURCES Electronic databases: PubMed, Ovid Medline, Cochrane Library and Clinical Evidence (BMJ Publishing). REVIEW METHODS Articles on biomedical engineering, biotechnology, material science, mechanical and animal models in OM published between May 2015 and May 2019 were identified and subjected to review. A total of 132 articles were ultimately included. RESULTS New imaging technologies for the tympanic membrane (TM) and the middle ear cavity are being developed to assess TM thickness, identify biofilms and differentiate types of middle ear effusions. Artificial intelligence (AI) has been applied to train software programs to diagnose OM with a high degree of certainty. Genetically modified mice models for OM have further investigated what predisposes some individuals to OM and consequent hearing loss. New vaccine candidates protecting against major otopathogens are being explored and developed, especially combined vaccines, targeting more than one pathogen. Transcutaneous vaccination against non-typeable Haemophilus influenzae has been successfully tried in a chinchilla model. In terms of treatment, novel technologies for trans-tympanic drug delivery are entering the clinical domain. Various growth factors and grafting materials aimed at improving healing of TM perforations show promising results in animal models. CONCLUSION New technologies and AI applications to improve the diagnosis of OM have shown promise in pre-clinical models and are gradually entering the clinical domain. So are novel vaccines and drug delivery approaches that may allow local treatment of OM. IMPLICATIONS FOR PRACTICE New diagnostic methods, potential vaccine candidates and the novel trans-tympanic drug delivery show promising results, but are not yet adapted to clinical use.
Collapse
Affiliation(s)
- Marie Gisselsson-Solén
- Department of Clinical Sciences, Division of Otorhinolaryngology, Head and Neck Surgery, Lund University Hospital, Lund, Sweden
| | - Paula A. Tähtinen
- Department of Pediatrics and Adolescent Medicine, Turku University Hospital and University of Turku, Turku, Finland
| | - Allen F. Ryan
- Division of Otolaryngology, Department of Surgery, University of California, San Diego, La Jolla, CA, USA,San Diego Veterans Affairs Healthcare System, Research Department, San Diego, CA, USA
| | - Apoorva Mulay
- The Stripp Lab, Pulmonary Department, Cedars Sinai Medical Center, Los Angeles, CA, USA
| | - Shin Kariya
- Department of Otolaryngology-Head and Neck Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Anne G.M. Schilder
- EvidENT, Ear Institute, University College London, London, UK,National Institute for Health Research University College London Biomedical Research Centre, London, UK,Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Tulio A. Valdez
- Department of Otolaryngology Head & Neck Surgery, Stanford University, Palo Alto, CA, USA
| | - Steve Brown
- MRC Harwell Institute, Mammalian Genetics Unit, Harwell Campus, Oxfordshire, UK
| | | | - Ann Hermansson
- Department of Clinical Sciences, Division of Otorhinolaryngology, Head and Neck Surgery, Lund University Hospital, Lund, Sweden
| | - Gijs van Ingen
- Department of Otolaryngology, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Tal Marom
- Department of Otolaryngology-Head and Neck Surgery, Samson Assuta Ashdod University Hospital, Faculty of Health Sciences Ben Gurion University, Ashdod, Israel.
| |
Collapse
|
17
|
Wang CY, Medlin JS, Nguyen DR, Disbennett WM, Dawid S. Molecular Determinants of Substrate Selectivity of a Pneumococcal Rgg-Regulated Peptidase-Containing ABC Transporter. mBio 2020; 11:e02502-19. [PMID: 32047125 PMCID: PMC7018657 DOI: 10.1128/mbio.02502-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 12/23/2019] [Indexed: 01/31/2023] Open
Abstract
Peptidase-containing ABC transporters (PCATs) are a widely distributed family of transporters which secrete double-glycine (GG) peptides. In the opportunistic pathogen Streptococcus pneumoniae (pneumococcus), the PCATs ComAB and BlpAB have been shown to secrete quorum-sensing pheromones and bacteriocins related to the competence and pneumocin pathways. Here, we describe another pneumococcal PCAT, RtgAB, encoded by the rtg locus and found intact in 17% of strains. The Rgg/SHP-like quorum-sensing system RtgR/S, which uses a peptide pheromone with a distinctive Trp-X-Trp motif, regulates expression of the rtg locus and provides a competitive fitness advantage in a mouse model of nasopharyngeal colonization. RtgAB secretes a set of coregulated rtg GG peptides. ComAB and BlpAB, which share a substrate pool, do not secrete the rtg GG peptides. Similarly, RtgAB does not efficiently secrete ComAB/BlpAB substrates. We examined the molecular determinants of substrate selectivity between ComAB, BlpAB, and RtgAB and found that the GG peptide signal sequences contain all the information necessary to direct secretion through specific transporters. Secretion through ComAB and BlpAB depends largely on the identity of four conserved hydrophobic signal sequence residues previously implicated in substrate recognition by PCATs. In contrast, a motif situated at the N-terminal end of the signal sequence, found only in rtg GG peptides, directs secretion through RtgAB. These findings illustrate the complexity in predicting substrate-PCAT pairings by demonstrating specificity that is not dictated solely by signal sequence residues previously implicated in substrate recognition.IMPORTANCE The export of peptides from the cell is a fundamental process carried out by all bacteria. One method of bacterial peptide export relies on a family of transporters called peptidase-containing ABC transporters (PCATs). PCATs export so-called GG peptides which carry out diverse functions, including cell-to-cell communication and interbacterial competition. In this work, we describe a PCAT-encoding genetic locus, rtg, in the pathogen Streptococcus pneumoniae (pneumococcus). The rtg locus is linked to increased competitive fitness advantage in a mouse model of nasopharyngeal colonization. We also describe how the rtg PCAT preferentially secretes a set of coregulated GG peptides but not GG peptides secreted by other pneumococcal PCATs. These findings illuminate a relatively understudied part of PCAT biology: how these transporters discriminate between different subsets of GG peptides. Ultimately, expanding our knowledge of PCATs will advance our understanding of the many microbial processes dependent on these transporters.
Collapse
Affiliation(s)
- Charles Y Wang
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, USA
| | - Jennifer S Medlin
- Department of Pediatrics, University of Michigan, Ann Arbor, Michigan, USA
| | - Don R Nguyen
- Department of Pediatrics, University of Michigan, Ann Arbor, Michigan, USA
| | | | - Suzanne Dawid
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, USA
- Department of Pediatrics, University of Michigan, Ann Arbor, Michigan, USA
| |
Collapse
|
18
|
Motib AS, Al-Bayati FAY, Manzoor I, Shafeeq S, Kadam A, Kuipers OP, Hiller NL, Andrew PW, Yesilkaya H. TprA/PhrA Quorum Sensing System Has a Major Effect on Pneumococcal Survival in Respiratory Tract and Blood, and Its Activity Is Controlled by CcpA and GlnR. Front Cell Infect Microbiol 2019; 9:326. [PMID: 31572692 PMCID: PMC6753895 DOI: 10.3389/fcimb.2019.00326] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 08/29/2019] [Indexed: 12/25/2022] Open
Abstract
Streptococcus pneumoniae is able to cause deadly diseases by infecting different tissues, each with distinct environmental and nutritional compositions. We hypothesize that the adaptive capabilities of the microbe is an important facet of pneumococcal survival in fluctuating host environments. Quorum-sensing (QS) mechanisms are pivotal for microbial host adaptation. We previously demonstrated that the TprA/PhrA QS system is required for pneumococcal utilization of galactose and mannose, neuraminidase activity, and virulence. We also showed that the system can be modulated by using linear molecularly imprinted polymers. Due to being a drugable target, we further studied the operation of this QS system in S. pneumoniae. We found that TprA controls the expression of nine different operons on galactose and mannose. Our data revealed that TprA expression is modulated by a complex regulatory network, where the master regulators CcpA and GlnR are involved in a sugar dependent manner. Mutants in the TprA/PhrA system are highly attenuated in their survival in nasopharynx and lungs after intranasal infection, and growth in blood after intravenous infection.
Collapse
Affiliation(s)
- Anfal Shakir Motib
- Department of Infection, Immunity & Inflammation, University of Leicester, Leicester, United Kingdom.,Department of Microbiology, College of Medicine, University of Diyala, Baqubah, Iraq
| | - Firas A Y Al-Bayati
- Department of Infection, Immunity & Inflammation, University of Leicester, Leicester, United Kingdom.,College of Pharmacy, University of Kirkuk, Kirkuk, Iraq
| | - Irfan Manzoor
- Molecular Genetics, University of Groningen, Groningen, Netherlands
| | - Sulman Shafeeq
- Molecular Genetics, University of Groningen, Groningen, Netherlands
| | - Anagha Kadam
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Oscar P Kuipers
- Molecular Genetics, University of Groningen, Groningen, Netherlands
| | - N Luisa Hiller
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Peter W Andrew
- Department of Infection, Immunity & Inflammation, University of Leicester, Leicester, United Kingdom
| | - Hasan Yesilkaya
- Department of Infection, Immunity & Inflammation, University of Leicester, Leicester, United Kingdom
| |
Collapse
|
19
|
Takeuchi N, Ohkusu M, Wada N, Kurosawa S, Miyabe A, Yamaguchi M, Nahm MH, Ishiwada N. Molecular typing, antibiotic susceptibility, and biofilm production in nonencapsulated Streptococcus pneumoniae isolated from children in Japan. J Infect Chemother 2019; 25:750-757. [PMID: 31235348 DOI: 10.1016/j.jiac.2019.02.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 02/04/2019] [Accepted: 02/10/2019] [Indexed: 10/26/2022]
Abstract
The prevalence of nonencapsulated Streptococcus pneumoniae (NESp) has increased with the introduction of pneumococcal conjugate vaccines in children; however, the bacteriological characteristics of NESp have not been sufficiently clarified. In this study, NESp strains isolated from the nasopharyngeal carriage of children from four nursery schools in Japan were analyzed for molecular type, antibiotic susceptibility, and biofilm productivity. A total of 152 putative S. pneumoniae strains were identified by optochin-susceptibility analysis, of which 21 were not serotypeable by slide agglutination, quellung reaction, or multiplex PCR. Among these 21 strains, three were lytA-negative and, therefore, not S. pneumoniae. The remaining 18 strains were positive for lytA, ply, pspK, and bile solubility and were confirmed as NESp. Therefore, the isolation rate of NESp in the S. pneumoniae strains in this study was 12.0% (18/149). Molecular-typing analyses classified five strains as two existing sequence types (STs; ST7502 and ST7786), and 13 strains formed four novel STs. Horizontal spread was suspected, because strains with the same ST were often isolated from the same nursery school. The NESp isolates were generally susceptible to most antimicrobials, with the exception of macrolides; however, all isolates possessed more than one abnormal penicillin-binding protein gene. Furthermore, NESp strains were more effective than encapsulated counterparts at forming biofilms, which showed obvious differences in morphology. These data indicated that NESp strains should be continuously monitored as emerging respiratory pathogens.
Collapse
Affiliation(s)
- Noriko Takeuchi
- Department of Infectious Diseases, Medical Mycology Research Center, Chiba University, Chiba, Japan.
| | - Misako Ohkusu
- Department of Infectious Diseases, Medical Mycology Research Center, Chiba University, Chiba, Japan
| | | | - Satoko Kurosawa
- Kurosawa Children's and Internal Medicine Clinic, Tokyo, Japan
| | - Akiko Miyabe
- Division of Laboratory Medicine and Clinical Genetics, Chiba University Hospital, Chiba, Japan
| | | | - Moon H Nahm
- Division of Pulmonary, Allergy & Critical Care Medicine, Department of Medicine, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Naruhiko Ishiwada
- Department of Infectious Diseases, Medical Mycology Research Center, Chiba University, Chiba, Japan
| |
Collapse
|
20
|
Parrish JM, Soni M, Mittal R. Subversion of host immune responses by otopathogens during otitis media. J Leukoc Biol 2019; 106:943-956. [PMID: 31075181 PMCID: PMC7166519 DOI: 10.1002/jlb.4ru0119-003r] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 03/11/2019] [Accepted: 04/05/2019] [Indexed: 12/26/2022] Open
Abstract
Otitis media (OM) is one of the most common ear diseases affecting humans. Children are at greater risk and suffer most frequently from OM, which can cause serious deterioration in the quality of life. OM is generally classified into two main types: acute and chronic OM (AOM and COM). AOM is characterized by tympanic membrane swelling or otorrhea and is accompanied by signs or symptoms of ear infection. In COM, there is a tympanic membrane perforation and purulent discharge. The most common pathogens that cause AOM are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis whereas Pseudomonas aeruginosa and Staphylococcus aureus are commonly associated with COM. Innate and adaptive immune responses provide protection against OM. However, pathogens employ a wide arsenal of weapons to evade potent immune responses and these mechanisms likely contribute to AOM and COM. Immunologic evasion is multifactorial, and involves damage to host mucociliary tract, genetic polymorphisms within otopathogens, the number and variety of different otopathogens in the nasopharynx as well as the interaction between the host's innate and adaptive immune responses. Otopathogens utilize host mucin production, phase variation, biofilm production, glycans, as well as neutrophil and eosinophilic extracellular traps to induce OM. The objective of this review article is to discuss our current understanding about the mechanisms through which otopathogens escape host immunity to induce OM. A better knowledge about the molecular mechanisms leading to subversion of host immune responses will provide novel clues to develop effective treatment modalities for OM.
Collapse
Affiliation(s)
- James M Parrish
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Manasi Soni
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Rahul Mittal
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida, USA
| |
Collapse
|
21
|
Junges R, Salvadori G, Chen T, Morrison DA, Petersen FC. Hidden Gems in the Transcriptome Maps of Competent Streptococci. Front Mol Biosci 2019; 5:116. [PMID: 30662898 PMCID: PMC6328492 DOI: 10.3389/fmolb.2018.00116] [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: 10/28/2018] [Accepted: 12/11/2018] [Indexed: 11/22/2022] Open
Abstract
Natural transformation is regarded as an important mechanism in bacteria that allows for adaptation to different environmental stressors by ensuring genome plasticity. Since the discovery of this phenomenon in Streptococcus pneumoniae, remarkable progress has been made in the understanding of the molecular mechanisms and pathways coordinating this process. Recently, the advent of high-throughput sequencing allows the posing of questions that address the system at a larger scale but also allow for the creation of high-resolution maps of transcription. Thus, while much is already known about genetic competence in streptococci, recent studies continue to reveal intricate novel regulation pathways and components. In this perspective article, we highlight the use of transcriptional profiling and mapping as a valuable resource in the identification and characterization of “hidden gems” pertinent to the natural transformation system. Such strategies have recently been employed in a variety of different species. In S. mutans, for example, genome editing combined with the power of promoter mapping and RNA-Seq allowed for the identification of a link between the ComCDE and the ComRS systems, a ComR positive feedback loop mediated by SigX, and the XrpA peptide, encoded within sigX, which inhibits competence. In S. pneumoniae, a novel member of the competence regulon termed BriC was found to be directly under control of ComE and to promote biofilm formation and nasopharyngeal colonization but not competence. Together these new technologies enable us to discover new links and to revisit old pathways in the compelling study of natural genetic transformation.
Collapse
Affiliation(s)
- Roger Junges
- Faculty of Dentistry, Institute of Oral Biology, University of Oslo, Oslo, Norway
| | - Gabriela Salvadori
- Faculty of Dentistry, Institute of Oral Biology, University of Oslo, Oslo, Norway
| | - Tsute Chen
- Department of Microbiology, The Forsyth Institute, Cambridge, MA, United States
| | - Donald A Morrison
- Department of Biological Sciences, College of Liberal Arts and Sciences, University of Illinois at Chicago, Chicago, IL, United States
| | - Fernanda C Petersen
- Faculty of Dentistry, Institute of Oral Biology, University of Oslo, Oslo, Norway
| |
Collapse
|
22
|
Eutsey RA, Woolford CA, Aggarwal SD, Cuevas RA, Hiller NL. Gene Expression Analysis in the Pneumococcus. Methods Mol Biol 2019; 1968:79-88. [PMID: 30929207 DOI: 10.1007/978-1-4939-9199-0_7] [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: 06/09/2023]
Abstract
Bacterial cells modify their gene expression profiles throughout different stages of growth and in response to environmental cues. Analyses of gene expression across conditions reveal both conserved and condition-specific gene responses of bacteria to adapt to these dynamic conditions. In this chapter, we present a guide to pneumococcal RNA extraction for use in the NanoString nCounter platform. The nCounter is a highly effective method to measure gene expression of bacteria not only in a planktonic mode of growth but also in the presence of host cells where the RNA of interest represents only a small portion of the total material.
Collapse
Affiliation(s)
- Rory A Eutsey
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Carol A Woolford
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Surya D Aggarwal
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Rolando A Cuevas
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA
| | - N Luisa Hiller
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA.
| |
Collapse
|
23
|
Bravo A, Ruiz-Cruz S, Alkorta I, Espinosa M. When Humans Met Superbugs: Strategies to Tackle Bacterial Resistances to Antibiotics. Biomol Concepts 2018; 9:216-226. [PMID: 30811343 DOI: 10.1515/bmc-2018-0021] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 12/17/2018] [Indexed: 12/25/2022] Open
Abstract
Bacterial resistance to antibiotics poses enormous health and economic burdens to our society, and it is of the essence to explore old and new ways to deal with these problems. Here we review the current status of multi-resistance genes and how they spread among bacteria. We discuss strategies to deal with resistant bacteria, namely the search for new targets and the use of inhibitors of protein-protein interactions, fragment-based methods, or modified antisense RNAs. Finally, we discuss integrated approaches that consider bacterial populations and their niches, as well as the role of global regulators that activate and/or repress the expression of multiple genes in fluctuating environments and, therefore, enable resistant bacteria to colonize new niches. Understanding how the global regulatory circuits work is, probably, the best way to tackle bacterial resistance.
Collapse
Affiliation(s)
- Alicia Bravo
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu, 9, 28040 Madrid, Spain
| | - Sofia Ruiz-Cruz
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu, 9, 28040 Madrid, Spain
| | - Itziar Alkorta
- Instituto BIOFISIKA (CSIC, UPV/EHU), Departamento de Bioquímica y Biología Molecular, Universidad del Pais Vasco, P.O. Box 644, 48080 Bilbao, Spain
| | - Manuel Espinosa
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu, 9, 28040 Madrid, Spain
| |
Collapse
|
24
|
Hiller NL, Sá-Leão R. Puzzling Over the Pneumococcal Pangenome. Front Microbiol 2018; 9:2580. [PMID: 30425695 PMCID: PMC6218428 DOI: 10.3389/fmicb.2018.02580] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 10/09/2018] [Indexed: 12/11/2022] Open
Abstract
The Gram positive bacterium Streptococcus pneumoniae (pneumococcus) is a major human pathogen. It is a common colonizer of the human host, and in the nasopharynx, sinus, and middle ear it survives as a biofilm. This mode of growth is optimal for multi-strain colonization and genetic exchange. Over the last decades, the far-reaching use of antibiotics and the widespread implementation of pneumococcal multivalent conjugate vaccines have posed considerable selective pressure on pneumococci. This scenario provides an exceptional opportunity to study the evolution of the pangenome of a clinically important bacterium, and has the potential to serve as a case study for other species. The goal of this review is to highlight key findings in the studies of pneumococcal genomic diversity and plasticity.
Collapse
Affiliation(s)
- N. Luisa Hiller
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, United States
- Center of Excellence in Biofilm Research, Allegheny Health Network, Pittsburgh, PA, United States
| | - Raquel Sá-Leão
- Laboratory of Molecular Microbiology of Human Pathogens, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB NOVA), Oeiras, Portugal
- Departamento de Biologia Vegetal, Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal
| |
Collapse
|
25
|
Function of BriC peptide in the pneumococcal competence and virulence portfolio. PLoS Pathog 2018; 14:e1007328. [PMID: 30308062 PMCID: PMC6181422 DOI: 10.1371/journal.ppat.1007328] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 09/10/2018] [Indexed: 02/07/2023] Open
Abstract
Streptococcus pneumoniae (pneumococcus) is an opportunistic pathogen that causes otitis media, sinusitis, pneumonia, meningitis and sepsis. The progression to this pathogenic lifestyle is preceded by asymptomatic colonization of the nasopharynx. This colonization is associated with biofilm formation; the competence pathway influences the structure and stability of biofilms. However, the molecules that link the competence pathway to biofilm formation are unknown. Here, we describe a new competence-induced gene, called briC, and demonstrate that its product promotes biofilm development and stimulates colonization in a murine model. We show that expression of briC is induced by the master regulator of competence, ComE. Whereas briC does not substantially influence early biofilm development on abiotic surfaces, it significantly impacts later stages of biofilm development. Specifically, briC expression leads to increases in biofilm biomass and thickness at 72h. Consistent with the role of biofilms in colonization, briC promotes nasopharyngeal colonization in the murine model. The function of BriC appears to be conserved across pneumococci, as comparative genomics reveal that briC is widespread across isolates. Surprisingly, many isolates, including strains from clinically important PMEN1 and PMEN14 lineages, which are widely associated with colonization, encode a long briC promoter. This long form captures an instance of genomic plasticity and functions as a competence-independent expression enhancer that may serve as a precocious point of entry into this otherwise competence-regulated pathway. Moreover, overexpression of briC by the long promoter fully rescues the comE-deletion induced biofilm defect in vitro, and partially in vivo. These findings indicate that BriC may bypass the influence of competence in biofilm development and that such a pathway may be active in a subset of pneumococcal lineages. In conclusion, BriC is a part of the complex molecular network that connects signaling of the competence pathway to biofilm development and colonization. Pneumococcal biofilms occur in chronic otitis media, chronic rhinosinusitis, and nasopharyngeal colonization. These biofilms are an important component of pneumococcal epidemiology, particularly in influencing transmission, maintenance of asymptomatic colonization, and development of disease. The transcriptional program initiated via signaling of the competence pathway is critical for productive biofilm formation and is a strong contributor of pneumococcal infection and adaptation. In this study, we have identified BriC, a previously uncharacterized peptide that serves as a bridge between the competence pathway and biofilm development. We show that briC is induced by ComE, the master regulator of competence, and promotes biofilm development. Moreover, our studies in the murine model demonstrate that BriC is a novel colonization enhancer. Our studies of briC regulation capture an instance of genomic plasticity, where natural variation in the briC promoter sequence reveals the existence of an additional competence-independent regulatory unit. This natural variation may be able to modify the extent to which competence contributes to biofilm development and to nasopharyngeal colonization across different pneumococcal lineages. In summary, this study introduces a colonization factor and reveals a molecular link between competence and biofilm development.
Collapse
|
26
|
Rezaei Javan R, van Tonder AJ, King JP, Harrold CL, Brueggemann AB. Genome Sequencing Reveals a Large and Diverse Repertoire of Antimicrobial Peptides. Front Microbiol 2018; 9:2012. [PMID: 30210481 PMCID: PMC6120550 DOI: 10.3389/fmicb.2018.02012] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 08/09/2018] [Indexed: 12/14/2022] Open
Abstract
Competition among bacterial members of the same ecological niche is mediated by bacteriocins: antimicrobial peptides produced by bacterial species to kill other bacteria. Bacteriocins are also promising candidates for novel antimicrobials. Streptococcus pneumoniae (the “pneumococcus”) is a leading cause of morbidity and mortality worldwide and a frequent colonizer of the human nasopharynx. Here, 14 newly discovered bacteriocin gene clusters were identified among >6,200 pneumococcal genomes. The molecular epidemiology of the bacteriocin clusters was investigated using a large global and historical pneumococcal dataset dating from 1916. These analyses revealed extraordinary bacteriocin diversity among pneumococci and the majority of bacteriocin clusters were also found in other streptococcal species. Genomic hotspots for the integration of different bacteriocin gene clusters were discovered. Experimentally, bacteriocin genes were transcriptionally active when the pneumococcus was under stress and when two strains were co-cultured in broth. These findings reveal much more diversity among bacterial defense mechanisms than previously appreciated, which fundamentally broaden our understanding of bacteriocins relative to intraspecies and interspecies nasopharyngeal competition and bacterial population structure.
Collapse
Affiliation(s)
- Reza Rezaei Javan
- Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | | | - James P King
- Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Caroline L Harrold
- Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Angela B Brueggemann
- Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom.,Department of Medicine, Imperial College London, London, United Kingdom
| |
Collapse
|
27
|
Mittal R, Parrish JM, Soni M, Mittal J, Mathee K. Microbial otitis media: recent advancements in treatment, current challenges and opportunities. J Med Microbiol 2018; 67:1417-1425. [PMID: 30084766 DOI: 10.1099/jmm.0.000810] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Otitis media (OM) is a common disease affecting humans, especially paediatric populations. OM refers to inflammation of the middle ear and can be broadly classified into two types, acute and chronic. Bacterial infection is one of the most common causes of OM. Despite the introduction of vaccines, the incidence of OM remains significantly high worldwide. In this mini-review article, we discuss the recent treatment modalities for OM, such as suspension gel, transcutaneous immunization, and intranasal and transtympanic drug delivery, including therapies that are currently undergoing clinical trials. We provide an overview of how these recent advancements in therapeutic strategies can facilitate the circumvention of current treatment challenges involving preadolescence soft palate dysfunction, biofilm formation, tympanic membrane (ear drum) barrier and the attainment of efficacious drug concentrations in the middle ear. While traditional first-line immunization strategies are generally not very efficacious against biofilms, new technologies that use transdermal or intranasal drug delivery via chitosan-PsaA nanoparticles have shown promising results in experimental animal models of OM. Sustained drug delivery systems such as penta-block copolymer poloxamer 407-polybutylphosphoester (P407-PBP) or poloxamer 407 (e.g. OTO-201, with the brand name 'OTIPRIO') have demonstrated that treatments can be reduced to a single topical application. The emergence of effective new treatment modalities opens up promising new avenues for the treatment of OM that could lead to improved quality of life for many children and their families.
Collapse
Affiliation(s)
- Rahul Mittal
- 1Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - James M Parrish
- 1Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Manasi Soni
- 1Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Jeenu Mittal
- 1Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Kalai Mathee
- 2Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA.,3Biomolecular Sciences Institute, Florida International University, Miami, FL, USA
| |
Collapse
|
28
|
Zhi X, Abdullah IT, Gazioglu O, Manzoor I, Shafeeq S, Kuipers OP, Hiller NL, Andrew PW, Yesilkaya H. Rgg-Shp regulators are important for pneumococcal colonization and invasion through their effect on mannose utilization and capsule synthesis. Sci Rep 2018; 8:6369. [PMID: 29686372 PMCID: PMC5913232 DOI: 10.1038/s41598-018-24910-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 04/05/2018] [Indexed: 01/18/2023] Open
Abstract
Microbes communicate with each other by using quorum sensing (QS) systems and modulate their collective 'behavior' for in-host colonization and virulence, biofilm formation, and environmental adaptation. The recent increase in genome data availability reveals the presence of several putative QS sensing circuits in microbial pathogens, but many of these have not been functionally characterized yet, despite their possible utility as drug targets. To increase the repertoire of functionally characterized QS systems in bacteria, we studied Rgg144/Shp144 and Rgg939/Shp939, two putative QS systems in the important human pathogen Streptococcus pneumoniae. We find that both of these QS circuits are induced by short hydrophobic peptides (Shp) upon sensing sugars found in the respiratory tract, such as galactose and mannose. Microarray analyses using cultures grown on mannose and galactose revealed that the expression of a large number of genes is controlled by these QS systems, especially those encoding for essential physiological functions and virulence-related genes such as the capsular locus. Moreover, the array data revealed evidence for cross-talk between these systems. Finally, these Rgg systems play a key role in colonization and virulence, as deletion mutants of these QS systems are attenuated in the mouse models of colonization and pneumonia.
Collapse
Affiliation(s)
- Xiangyun Zhi
- Department of Infection, Immunity & Inflammation, University of Leicester, Leicester, LE1 9HN, UK
| | - Iman Tajer Abdullah
- Department of Infection, Immunity & Inflammation, University of Leicester, Leicester, LE1 9HN, UK
- Department of Biology, College of Science, University of Kirkuk, Kirkuk, Iraq
| | - Ozcan Gazioglu
- Department of Infection, Immunity & Inflammation, University of Leicester, Leicester, LE1 9HN, UK
| | - Irfan Manzoor
- Molecular Genetics, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands
| | - Sulman Shafeeq
- Molecular Genetics, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands
| | - Oscar P Kuipers
- Molecular Genetics, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands
| | - N Luisa Hiller
- Department of Biological Sciences, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA, 15213, USA
| | - Peter W Andrew
- Department of Infection, Immunity & Inflammation, University of Leicester, Leicester, LE1 9HN, UK
| | - Hasan Yesilkaya
- Department of Infection, Immunity & Inflammation, University of Leicester, Leicester, LE1 9HN, UK.
| |
Collapse
|
29
|
Nasher F, Förster S, Yildirim EC, Grandgirard D, Leib SL, Heller M, Hathaway LJ. Foreign peptide triggers boost in pneumococcal metabolism and growth. BMC Microbiol 2018; 18:23. [PMID: 29580217 PMCID: PMC5870813 DOI: 10.1186/s12866-018-1167-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 03/15/2018] [Indexed: 01/19/2023] Open
Abstract
Background Nonencapsulated Streptococcus pneumoniae bacteria are successful colonizers of the human nasopharynx and often possess genes aliB-like ORF 1 and 2 in place of capsule genes. AliB-like ORF 2 binds peptide FPPQSV, found in Prevotella species, resulting in enhanced colonization. How this response is mediated is so far unknown. Results Here we show that the peptide increases expression of genes involved in release of host carbohydrates, carbohydrate uptake and carbohydrate metabolism. In particular, the peptide increased expression of 1,5-anhydro-D-fructose reductase, a metabolic enzyme of an alternative starch and glycogen degrading pathway found in many organisms, in both transcriptomic and proteomic data. The peptide enhanced pneumococcal growth giving a competitive advantage to a strain with aliB-like ORF 2, over its mutant lacking the gene. Possession of aliB-like ORF 2 did not affect release of inflammatory cytokine CXCL8 from epithelial cells in culture and the nonencapsulated wild type strain was not able to establish disease or inflammation in an infant rat model of meningitis. Conclusions We propose that AliB-like ORF 2 confers an advantage in colonization by enhancing carbohydrate metabolism resulting in a boost in growth. This may explain the widespread presence of aliB-like ORF 2 in the nonencapsulated pneumococcal population in the human nasopharynx. Electronic supplementary material The online version of this article (10.1186/s12866-018-1167-y) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Fauzy Nasher
- Institute for Infectious Diseases, Faculty of Medicine, University of Bern, Friedbühlstrasse 51, CH-3001, Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Sunniva Förster
- Institute for Infectious Diseases, Faculty of Medicine, University of Bern, Friedbühlstrasse 51, CH-3001, Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland.,Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland
| | - Efe C Yildirim
- Institute for Infectious Diseases, Faculty of Medicine, University of Bern, Friedbühlstrasse 51, CH-3001, Bern, Switzerland
| | - Denis Grandgirard
- Institute for Infectious Diseases, Faculty of Medicine, University of Bern, Friedbühlstrasse 51, CH-3001, Bern, Switzerland
| | - Stephen L Leib
- Institute for Infectious Diseases, Faculty of Medicine, University of Bern, Friedbühlstrasse 51, CH-3001, Bern, Switzerland
| | - Manfred Heller
- Proteomics and Mass Spectrometry Core Facility, Department for BioMedical Research, University of Bern, CH-3010, Bern, Switzerland
| | - Lucy J Hathaway
- Institute for Infectious Diseases, Faculty of Medicine, University of Bern, Friedbühlstrasse 51, CH-3001, Bern, Switzerland.
| |
Collapse
|