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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.
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Affiliation(s)
| | - Daniel E. Hammers
- Biology Department, Houghton University, Houghton, NY, United States
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2
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Vogel V, Fuchs M, Jachmann M, Bitzer A, Mauerer S, Münch J, Spellerberg B. The Role of SilX in Bacteriocin Production of Streptococcus anginosus. Front Microbiol 2022; 13:904318. [PMID: 35875552 PMCID: PMC9298176 DOI: 10.3389/fmicb.2022.904318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 06/07/2022] [Indexed: 12/03/2022] Open
Abstract
Streptococcus anginosus produces the novel antimicrobial peptide Angicin, which inhibits Gram positive microorganisms and is classified as a group IId bacteriocin. Production of Angicin is regulated by the quorum sensing system Sil (Streptococcus invasion locus), which is located adjacent to the bacteriocin gene cluster. Within this genetic region a typical CAAX protease is encoded, which was designated SilX. Nelfinavir, a HIV protease inhibitor, led to a concentration dependent reduction in antimicrobial activity, presumably through the inhibition of SilX. Concentrations exceeding 25 μM Nelfinavir caused a complete abolishment of bacteriocin activity against Listeria monocytogenes. These results are supported by the observation, that a SilX deletion mutant of S. anginosus strain BSU 1211 no longer inhibits the growth of L. monocytogenes. Antimicrobial activity could be restored by addition of synthetically synthesized mature SilCR, implying that SilX may be involved in the export and processing of the signal peptide SilCR. Some CAAX proteases have been reported to provide immunity against bacteriocins. However, in a radial diffusion assay the deletion mutant S. anginosus BSU 1211ΔSilX showed no sensitivity toward Angicin arguing against a role of SilX in the immunity of S. anginosus. The putative processing of the signal peptide SilCR indicates a novel function of the CAAX protease SilX, in the context of S. anginosus bacteriocin production.
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Affiliation(s)
- Verena Vogel
- Institute of Medical Microbiology and Hygiene, Ulm University Medical Center, Ulm, Germany
| | - Miki Fuchs
- Institute of Medical Microbiology and Hygiene, Ulm University Medical Center, Ulm, Germany
| | - Marie Jachmann
- Institute of Medical Microbiology and Hygiene, Ulm University Medical Center, Ulm, Germany
| | - Alina Bitzer
- Institute of Medical Microbiology and Hygiene, Ulm University Medical Center, Ulm, Germany
| | - Stefanie Mauerer
- Institute of Medical Microbiology and Hygiene, Ulm University Medical Center, Ulm, Germany
| | - Jan Münch
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | - Barbara Spellerberg
- Institute of Medical Microbiology and Hygiene, Ulm University Medical Center, Ulm, Germany
- *Correspondence: Barbara Spellerberg,
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Vogel V, Bauer R, Mauerer S, Schiffelholz N, Haupt C, Seibold GM, Fändrich M, Walther P, Spellerberg B. Angicin, a novel bacteriocin of Streptococcus anginosus. Sci Rep 2021; 11:24377. [PMID: 34934110 PMCID: PMC8692603 DOI: 10.1038/s41598-021-03797-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 12/01/2021] [Indexed: 11/09/2022] Open
Abstract
As a conserved defense mechanism, many bacteria produce antimicrobial peptides, called bacteriocins, which provide a colonization advantage in a multispecies environment. Here the first bacteriocin of Streptococcus anginosus, designated Angicin, is described. S. anginosus is commonly described as a commensal, however it also possesses a high pathogenic potential. Therefore, understanding factors contributing to its host colonization and persistence are important. A radial diffusion assay was used to identify S. anginosus BSU 1211 as a potent bacteriocin producer. By genetic mutagenesis the background of bacteriocin production and the bacteriocin gene itself were identified. Synthetic Angicin shows high activity against closely related streptococci, listeria and vancomycin resistant enterococci. It has a fast mechanism of action and causes a membrane disruption in target cells. Angicin, present in cell free supernatant, is insensitive to changes in temperature from - 70 to 90 °C and pH values from 2 to 10, suggesting that it represents an interesting compound for potential applications in food preservation or clinical settings.
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Affiliation(s)
- Verena Vogel
- Institute of Medical Microbiology and Hygiene, Ulm University Medical Center, Ulm, Germany
| | - Richard Bauer
- Institute of Medical Microbiology and Hygiene, Ulm University Medical Center, Ulm, Germany
| | - Stefanie Mauerer
- Institute of Medical Microbiology and Hygiene, Ulm University Medical Center, Ulm, Germany
| | | | - Christian Haupt
- Institute of Protein Biochemistry, Ulm University, Ulm, Germany
| | - Gerd M Seibold
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Marcus Fändrich
- Institute of Protein Biochemistry, Ulm University, Ulm, Germany
| | - Paul Walther
- Central Facility for Electron Microscopy, Ulm University, Ulm, Germany
| | - Barbara Spellerberg
- Institute of Medical Microbiology and Hygiene, Ulm University Medical Center, Ulm, Germany.
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Issa E, Salloum T, Tokajian S. From Normal Flora to Brain Abscesses: A Review of Streptococcus intermedius. Front Microbiol 2020; 11:826. [PMID: 32457718 PMCID: PMC7221147 DOI: 10.3389/fmicb.2020.00826] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Accepted: 04/07/2020] [Indexed: 11/13/2022] Open
Abstract
Streptococcus intermedius is a β-hemolytic Gram-positive member of the Streptococcus anginosus group (SAG). Despite being a part of the normal microbiota, it is one of the most common pathogens associated with brain and liver abscesses and thoracic empyema, increasing as a result the morbidity and mortality rates in affected patients. Though there are numerous published case reports on S. intermedius infections, it is still understudied compared to other SAG members. Our knowledge of the genomic factors contributing to its dissemination to the brain and abscess development is also limited to few characterized genes. In this review, we summarize our current knowledge on S. intermedius identification methods, virulence factors, and insight provided by the whole-genome and correlate patients’ metadata, symptoms, and disease outcome with S. intermedius infections in 101 recent case reports obtained from PubMed. This combined information highlights the gaps in our understanding of S. intermedius pathogenesis, suggesting future research directions to unveil the factors contributing to abscess development.
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Affiliation(s)
- Elio Issa
- Department of Natural Sciences, School of Arts and Sciences, Lebanese American University, Byblos, Lebanon
| | - Tamara Salloum
- Department of Natural Sciences, School of Arts and Sciences, Lebanese American University, Byblos, Lebanon
| | - Sima Tokajian
- Department of Natural Sciences, School of Arts and Sciences, Lebanese American University, Byblos, Lebanon
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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: 14] [Impact Index Per Article: 3.5] [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.
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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
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Issa E, Salloum T, Panossian B, Ayoub D, Abboud E, Tokajian S. Genome Mining and Comparative Analysis of Streptococcus intermedius Causing Brain Abscess in a Child. Pathogens 2019; 8:pathogens8010022. [PMID: 30781742 PMCID: PMC6471051 DOI: 10.3390/pathogens8010022] [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: 12/12/2018] [Revised: 01/18/2019] [Accepted: 01/30/2019] [Indexed: 01/09/2023] Open
Abstract
Streptococcus intermedius (SI) is associated with prolonged hospitalization and low survival rates. The genetic mechanisms involved in brain abscess development and genome evolution in comparison to other members of the Streptococcus anginosus group are understudied. We performed a whole-genome comparative analysis of an SI isolate, LAU_SINT, associated with brain abscess following sinusitis with all SI genomes in addition to S. constellatus and S. anginosus. Selective pressure on virulence factors, phages, pan-genome evolution and single-nucleotide polymorphism analysis were assessed. The structural details of the type seven secretion system (T7SS) was elucidated and compared with different organisms. ily and nanA were both abundant and conserved. Nisin resistance determinants were found in 47% of the isolates. Pan-genome and SNPs-based analysis didn’t reveal significant geo-patterns. Our results showed that two SC isolates were misidentified as SI. We propose the presence of four T7SS modules (I–IV) located on various genomic islands. We detected a variety of factors linked to metal ions binding on the GIs carrying T7SS. This is the first detailed report characterizing the T7SS and its link to nisin resistance and metal ions binding in SI. These and yet uncharacterized T7SS transmembrane proteins merit further studies and could represent potential therapeutic targets.
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Affiliation(s)
- Elio Issa
- Department of Natural Sciences, School of Arts and Sciences, Lebanese American University, Byblos 36, Lebanon.
| | - Tamara Salloum
- Department of Natural Sciences, School of Arts and Sciences, Lebanese American University, Byblos 36, Lebanon.
| | - Balig Panossian
- Department of Natural Sciences, School of Arts and Sciences, Lebanese American University, Byblos 36, Lebanon.
| | - David Ayoub
- Department of Neurosurgery, the Middle East Institute of Health University Hospital, Beirut 60-387, Lebanon.
| | - Edmond Abboud
- Laboratory Department, the Middle East Institute of Health University Hospital, Beirut 60-387, Lebanon.
| | - Sima Tokajian
- Department of Natural Sciences, School of Arts and Sciences, Lebanese American University, Byblos 36, Lebanon.
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ABC transporter content diversity in Streptococcus pneumoniae impacts competence regulation and bacteriocin production. Proc Natl Acad Sci U S A 2018; 115:E5776-E5785. [PMID: 29866828 PMCID: PMC6016807 DOI: 10.1073/pnas.1804668115] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The opportunistic pathogen Streptococcus pneumoniae (pneumococcus) participates in horizontal gene transfer through genetic competence and produces antimicrobial peptides called “bacteriocins.” Here, we show that the competence and bacteriocin-related ABC transporters ComAB and BlpAB share the same substrate pool, resulting in bidirectional crosstalk between competence and bacteriocin regulation. We also clarify the role of each transporter in bacteriocin secretion and show that, based on their transporter content, pneumococcal strains can be separated into a majority opportunist group that uses bacteriocins only to support competence and a minority aggressor group that uses bacteriocins in broader contexts. Our findings will impact how bacteriocin regulation and production is modeled in the many other bacterial species that use ComAB/BlpAB-type transporters. The opportunistic pathogen Streptococcus pneumoniae (pneumococcus) uses natural genetic competence to increase its adaptability through horizontal gene transfer. One method of acquiring DNA is through predation of neighboring strains with antimicrobial peptides called “bacteriocins.” Competence and production of the major family of pneumococcal bacteriocins, pneumocins, are regulated by the quorum-sensing systems com and blp, respectively. In the classical paradigm, the ABC transporters ComAB and BlpAB each secretes its own system’s signaling pheromone and in the case of BlpAB also secretes the pneumocins. While ComAB is found in all pneumococci, only 25% of strains encode an intact version of BlpAB [BlpAB(+)] while the rest do not [BlpAB(−)]. Contrary to the classical paradigm, it was previously shown that BlpAB(−) strains can activate blp through ComAB-mediated secretion of the blp pheromone during brief periods of competence. To better understand the full extent of com-blp crosstalk, we examined the contribution of each transporter to competence development and pneumocin secretion. We found that BlpAB(+) strains have a greater capacity for competence activation through BlpAB-mediated secretion of the com pheromone. Similarly, we show that ComAB and BlpAB are promiscuous and both can secrete pneumocins. Consequently, differences in pneumocin secretion between BlpAB(+) and BlpAB(−) strains derive from the regulation and kinetics of transporter expression rather than substrate specificity. We speculate that BlpAB(−) strains (opportunists) use pneumocins mainly in a narrowly tailored role for DNA acquisition and defense during competence while BlpAB(+) strains (aggressors) expand their use for the general inhibition of rival strains.
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Streptococcus intermedius: An Unusual Case of Purulent Pericarditis. Case Rep Infect Dis 2017; 2017:5864694. [PMID: 28932608 PMCID: PMC5592407 DOI: 10.1155/2017/5864694] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 08/02/2017] [Indexed: 11/18/2022] Open
Abstract
Purulent pericarditis is a rare diagnosis with life-threatening implications due to the rapid accumulation of pericardial material, swiftly progressing to tamponade physiology. The nature of its quickly evolving and severe implications demands a low threshold for diagnostic consideration where appropriate. We present an unusual case of purulent pericarditis secondary to Streptococcus intermedius in a previously healthy male adolescent without traditional risk factors, which raises the question of whether emergent S. intermedius species may have acquired novel molecular mechanisms.
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