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Mårli MT, Oppegaard O, Porcellato D, Straume D, Kjos M. Genetic modification of Streptococcus dysgalactiae by natural transformation. mSphere 2024; 9:e0021424. [PMID: 38904369 PMCID: PMC11288034 DOI: 10.1128/msphere.00214-24] [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: 03/18/2024] [Accepted: 05/13/2024] [Indexed: 06/22/2024] Open
Abstract
Streptococcus dysgalactiae is an emerging human and animal pathogen. Functional studies of genes involved in virulence of S. dysgalactiae and other pyogenic group streptococci are often hampered by limited genetic tractability. It is known that pyogenic streptococci carry genes required for competence for natural transformation; however, in contrast to other streptococcal subgroups, there is limited evidence for gene transfer by natural transformation in these bacteria. In this study, we systematically assessed the genomes of 179 S. dysgalactiae strains of both human and animal origins (subsp. equisimilis and dysgalactiae, respectively) for the presence of genes required for natural transformation. While a considerable fraction of the strains contained inactive genes, the majority (64.2%) of the strains had an intact gene set. In selected strains, we examined the dynamics of competence activation after addition of competence-inducing pheromones using transcriptional reporter assays and exploratory RNA-seq. Based on these findings, we were able to establish a protocol allowing us to utilize natural transformation to construct deletion mutants by allelic exchange in several S. dysgalactiae strains of both subspecies. As part of the work, we deleted putative lactose utilization genes to study their role in growth on lactose. The data presented here provide new knowledge on the potential of horizonal gene transfer by natural transformation in S. dysgalactiae and, importantly, demonstrates the possibility to exploit natural transformation for genetic engineering in these bacteria. IMPORTANCE Numerous Streptococcus spp. exchange genes horizontally through natural transformation, which also facilitates efficient genetic engineering in these organisms. However, for the pyogenic group of streptococci, including the emerging pathogen Streptococcus dysgalactiae, there is limited experimental evidence for natural transformation. In this study, we demonstrate that natural transformation in vitro indeed is possible in S. dysgalactiae strains under optimal conditions. We utilized this method to perform gene deletion through allelic exchange in several strains, thereby paving the way for more efficient gene engineering methods in pyogenic streptococci.
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Affiliation(s)
- Marita Torrissen Mårli
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Oddvar Oppegaard
- Haukeland University Hospital, University of Bergen, Bergen, Norway
| | - Davide Porcellato
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Daniel Straume
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Morten Kjos
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
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2
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Sheriff EK, Salvato F, Andersen SE, Chatterjee A, Kleiner M, Duerkop BA. Enterococcal quorum-controlled protease alters phage infection. FEMS MICROBES 2024; 5:xtae022. [PMID: 39156124 PMCID: PMC11328733 DOI: 10.1093/femsmc/xtae022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2024] [Revised: 06/21/2024] [Accepted: 07/25/2024] [Indexed: 08/20/2024] Open
Abstract
Increased prevalence of multidrug-resistant bacterial infections has sparked interest in alternative antimicrobials, including bacteriophages (phages). Limited understanding of the phage infection process hampers our ability to utilize phages to their full therapeutic potential. To understand phage infection dynamics, we performed proteomics on Enterococcus faecalis infected with the phage VPE25. We discovered that numerous uncharacterized phage proteins are produced during phage infection of E. faecalis. Additionally, we identified hundreds of changes in bacterial protein abundances during infection. One such protein, enterococcal gelatinase (GelE), an fsr quorum-sensing-regulated protease involved in biofilm formation and virulence, was reduced during VPE25 infection. Plaque assays showed that mutation of either the quorum-sensing regulator fsrA or gelE resulted in plaques with a "halo" morphology and significantly larger diameters, suggesting decreased protection from phage infection. GelE-associated protection during phage infection is dependent on the putative murein hydrolase regulator LrgA and antiholin-like protein LrgB, whose expression have been shown to be regulated by GelE. Our work may be leveraged in the development of phage therapies that can modulate the production of GelE thereby altering biofilm formation and decreasing E. faecalis virulence.
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Affiliation(s)
- Emma K Sheriff
- Department of Immunology and Microbiology, School of Medicine, University of Colorado – Anschutz Medical Campus, 12800 E. 19th Ave., Aurora, CO 80045, United States
| | - Fernanda Salvato
- Department of Plant and Microbial Biology, North Carolina State University, 112 Derieux Pl., Raleigh, NC 27695, United States
| | - Shelby E Andersen
- Department of Immunology and Microbiology, School of Medicine, University of Colorado – Anschutz Medical Campus, 12800 E. 19th Ave., Aurora, CO 80045, United States
| | - Anushila Chatterjee
- Department of Immunology and Microbiology, School of Medicine, University of Colorado – Anschutz Medical Campus, 12800 E. 19th Ave., Aurora, CO 80045, United States
| | - Manuel Kleiner
- Department of Plant and Microbial Biology, North Carolina State University, 112 Derieux Pl., Raleigh, NC 27695, United States
| | - Breck A Duerkop
- Department of Immunology and Microbiology, School of Medicine, University of Colorado – Anschutz Medical Campus, 12800 E. 19th Ave., Aurora, CO 80045, United States
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3
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Kim H, Marraffini LA. Cas9 interaction with the tracrRNA nexus modulates the repression of type II-A CRISPR-cas genes. Nucleic Acids Res 2024:gkae597. [PMID: 38994567 DOI: 10.1093/nar/gkae597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Revised: 06/22/2024] [Accepted: 07/10/2024] [Indexed: 07/13/2024] Open
Abstract
Immune responses need to be regulated to prevent autoimmunity. CRISPR-Cas systems provide adaptive immunity in prokaryotes through the acquisition of short DNA sequences from invading viruses (bacteriophages), known as spacers. Spacers are inserted into the CRISPR locus and serve as templates for the transcription of guides used by RNA-guided nucleases to recognize complementary nucleic acids of the invaders and start the CRISPR immune response. In type II-A CRISPR systems, Cas9 uses the guide RNA to cleave target DNA sequences in the genome of infecting phages, and the tracrRNA to bind the promoter of cas genes and repress their transcription. We previously isolated a Cas9 mutant carrying the I473F substitution that increased the frequency of spacer acquisition by 2-3 orders of magnitude, leading to a fitness cost due to higher levels of autoimmunity. Here, we investigated the molecular basis underlying these findings. We found that the I473F mutation decreases the association of Cas9 to tracrRNA, limiting its repressor function, leading to high levels of expression of cas genes, which in turn increase the strength of the type II-A CRISPR-Cas immune response. We obtained similar results for a related type II-A system, and therefore our findings highlight the importance of the interaction between Cas9 and its tracrRNA cofactor in tuning the immune response to balanced levels that enable phage defense but avoid autoimmunity.
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Affiliation(s)
- Hyejin Kim
- Laboratory of Bacteriology, The Rockefeller University, 1230 York Ave, New York, NY 10065, USA
- Weill Cornell/Rockefeller/Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY, USA
| | - Luciano A Marraffini
- Laboratory of Bacteriology, The Rockefeller University, 1230 York Ave, New York, NY 10065, USA
- Howard Hughes Medical Institute, The Rockefeller University, 1230 York Ave, New York, NY 10065, USA
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4
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Chen YYM, Yang YC, Shieh HR, Lin YJ, Ke WJ, Chiu CH. Functional Analysis of the Major Pilin Proteins of Type IV Pili in Streptococcus sanguinis CGMH010. Int J Mol Sci 2024; 25:5402. [PMID: 38791440 PMCID: PMC11121087 DOI: 10.3390/ijms25105402] [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: 03/29/2024] [Revised: 05/02/2024] [Accepted: 05/03/2024] [Indexed: 05/26/2024] Open
Abstract
The pil gene cluster for Type IV pilus (Tfp) biosynthesis is commonly present and highly conserved in Streptococcus sanguinis. Nevertheless, Tfp-mediated twitching motility is less common among strains, and the factors determining twitching activity are not fully understood. Here, we analyzed the functions of three major pilin proteins (PilA1, PilA2, and PilA3) in the assembly and activity of Tfp in motile S. sanguinis CGMH010. Using various recombinant pilA deletion strains, we found that Tfp composed of different PilA proteins varied morphologically and functionally. Among the three PilA proteins, PilA1 was most critical in the assembly of twitching-active Tfp, and recombinant strains expressing motility generated more structured biofilms under constant shearing forces compared to the non-motile recombinant strains. Although PilA1 and PilA3 shared 94% identity, PilA3 could not compensate for the loss of PilA1, suggesting that the nature of PilA proteins plays an essential role in twitching activity. The single deletion of individual pilA genes had little effect on the invasion of host endothelia by S. sanguinis CGMH010. In contrast, the deletion of all three pilA genes or pilT, encoding the retraction ATPase, abolished Tfp-mediated invasion. Tfp- and PilT-dependent invasion were also detected in the non-motile S. sanguinis SK36, and thus, the retraction of Tfp, but not active twitching, was found to be essential for invasion.
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Affiliation(s)
- Yi-Ywan M. Chen
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan; (H.-R.S.); (Y.-J.L.); (W.-J.K.)
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan;
- Molecular Infectious Disease Research Center, Chang Gung Memorial Hospital, Linkou 333, Taiwan;
| | - Yuan-Chen Yang
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan;
| | - Hui-Ru Shieh
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan; (H.-R.S.); (Y.-J.L.); (W.-J.K.)
| | - Yu-Juan Lin
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan; (H.-R.S.); (Y.-J.L.); (W.-J.K.)
| | - Wan-Ju Ke
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan; (H.-R.S.); (Y.-J.L.); (W.-J.K.)
| | - Cheng-Hsun Chiu
- Molecular Infectious Disease Research Center, Chang Gung Memorial Hospital, Linkou 333, Taiwan;
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5
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Sheriff EK, Salvato F, Andersen SE, Chatterjee A, Kleiner M, Duerkop BA. Enterococcal quorum-controlled protease alters phage infection. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.10.593607. [PMID: 38766208 PMCID: PMC11100838 DOI: 10.1101/2024.05.10.593607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Increased prevalence of multidrug resistant bacterial infections has sparked interest in alternative antimicrobials, including bacteriophages (phages). Limited understanding of the phage infection process hampers our ability to utilize phages to their full therapeutic potential. To understand phage infection dynamics we performed proteomics on Enterococcus faecalis infected with the phage VPE25. We discovered numerous uncharacterized phage proteins are produced during phage infection of Enterococcus faecalis. Additionally, we identified hundreds of changes in bacterial protein abundances during infection. One such protein, enterococcal gelatinase (GelE), an fsr quorum sensing regulated protease involved in biofilm formation and virulence, was reduced during VPE25 infection. Plaque assays showed that mutation of either the fsrA or gelE resulted in plaques with a "halo" morphology and significantly larger diameters, suggesting decreased protection from phage infection. GelE-associated protection during phage infection is dependent on the murein hydrolase regulator LrgA and antiholin-like protein LrgB, whose expression have been shown to be regulated by GelE. Our work may be leveraged in the development of phage therapies that can modulate the production of GelE thereby altering biofilm formation and decreasing E. faecalis virulence.
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Affiliation(s)
- Emma K. Sheriff
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Fernanda Salvato
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695
| | - Shelby E. Andersen
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Anushila Chatterjee
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Manuel Kleiner
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695
| | - Breck A. Duerkop
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
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6
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Aviram N, Shilton AK, Lyn NG, Reis BS, Brivanlou A, Marraffini LA. The Cas10 nuclease activity relieves host dormancy to facilitate spacer acquisition and retention during type III-A CRISPR immunity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.11.579731. [PMID: 38405743 PMCID: PMC10888962 DOI: 10.1101/2024.02.11.579731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
A hallmark of CRISPR immunity is the acquisition of short viral DNA sequences, known as spacers, that are transcribed into guide RNAs to recognize complementary sequences. The staphylococcal type III-A CRISPR-Cas system uses guide RNAs to locate viral transcripts and start a response that displays two mechanisms of immunity. When immunity is triggered by an early-expressed phage RNA, degradation of viral ssDNA can cure the host from infection. In contrast, when the RNA guide targets a late-expressed transcript, defense requires the activity of Csm6, a non-specific RNase. Here we show that Csm6 triggers a growth arrest of the host that provides immunity at the population level which hinders viral propagation to allow the replication of non-infected cells. We demonstrate that this mechanism leads to defense against not only the target phage but also other viruses present in the population that fail to replicate in the arrested cells. On the other hand, dormancy limits the acquisition and retention of spacers that trigger it. We found that the ssDNase activity of type III-A systems is required for the re-growth of a subset of the arrested cells, presumably through the degradation of the phage DNA, ending target transcription and inactivating the immune response. Altogether, our work reveals a built-in mechanism within type III-A CRISPR-Cas systems that allows the exit from dormancy needed for the subsistence of spacers that provide broad-spectrum immunity.
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Affiliation(s)
- Naama Aviram
- Laboratory of Bacteriology, the Rockefeller University, 1230 York Ave, New York, NY 10065, USA
| | - Amanda K Shilton
- Laboratory of Bacteriology, the Rockefeller University, 1230 York Ave, New York, NY 10065, USA
| | - Nia G Lyn
- Laboratory of Bacteriology, the Rockefeller University, 1230 York Ave, New York, NY 10065, USA
| | - Bernardo S Reis
- Laboratory of Mucosal Immunology, the Rockefeller University, 1230 York Ave, New York, NY 10065, USA
| | - Amir Brivanlou
- Laboratory of Bacteriology, the Rockefeller University, 1230 York Ave, New York, NY 10065, USA
| | - Luciano A Marraffini
- Laboratory of Bacteriology, the Rockefeller University, 1230 York Ave, New York, NY 10065, USA
- Howard Hughes Medical Institute, The Rockefeller University, 1230 York Ave, New York, NY 10065, USA
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7
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Huo W, Price VJ, Sharifi A, Zhang MQ, Palmer KL. Enterococcus faecalis Strains with Compromised CRISPR-Cas Defense Emerge under Antibiotic Selection for a CRISPR-Targeted Plasmid. Appl Environ Microbiol 2023; 89:e0012423. [PMID: 37278656 PMCID: PMC10304774 DOI: 10.1128/aem.00124-23] [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: 01/31/2023] [Accepted: 05/12/2023] [Indexed: 06/07/2023] Open
Abstract
Enterococcus faecalis is a Gram-positive bacterium that natively colonizes the human gastrointestinal tract and opportunistically causes life-threatening infections. Multidrug-resistant (MDR) E. faecalis strains have emerged that are replete with mobile genetic elements (MGEs). Non-MDR E. faecalis strains frequently possess CRISPR-Cas systems, which reduce the frequency of MGE acquisition. We demonstrated in previous studies that E. faecalis populations can transiently maintain both a functional CRISPR-Cas system and a CRISPR-Cas target. In this study, we used serial passage and deep sequencing to analyze these populations. In the presence of antibiotic selection for the plasmid, mutants with compromised CRISPR-Cas defense and enhanced ability to acquire a second antibiotic resistance plasmid emerged. Conversely, in the absence of selection, the plasmid was lost from wild-type E. faecalis populations but not E. faecalis populations that lacked the cas9 gene. Our results indicate that E. faecalis CRISPR-Cas can become compromised under antibiotic selection, generating populations with enhanced abilities to undergo horizontal gene transfer. IMPORTANCE Enterococcus faecalis is a leading cause of hospital-acquired infections and disseminator of antibiotic resistance plasmids among Gram-positive bacteria. We have previously shown that E. faecalis strains with an active CRISPR-Cas system can prevent plasmid acquisition and thus limit the transmission of antibiotic resistance determinants. However, CRISPR-Cas is not a perfect barrier. In this study, we observed populations of E. faecalis with transient coexistence of CRISPR-Cas and one of its plasmid targets. Our experimental data demonstrate that antibiotic selection results in compromised E. faecalis CRISPR-Cas function, thereby facilitating the acquisition of additional resistance plasmids by E. faecalis.
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Affiliation(s)
- Wenwen Huo
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Valerie J. Price
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Ardalan Sharifi
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Michael Q. Zhang
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Kelli L. Palmer
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
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8
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Kirsch JM, Ely S, Stellfox ME, Hullahalli K, Luong P, Palmer KL, Van Tyne D, Duerkop BA. Targeted IS-element sequencing uncovers transposition dynamics during selective pressure in enterococci. PLoS Pathog 2023; 19:e1011424. [PMID: 37267422 PMCID: PMC10266640 DOI: 10.1371/journal.ppat.1011424] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 06/14/2023] [Accepted: 05/15/2023] [Indexed: 06/04/2023] Open
Abstract
Insertion sequences (IS) are simple transposons implicated in the genome evolution of diverse pathogenic bacterial species. Enterococci have emerged as important human intestinal pathogens with newly adapted virulence potential and antibiotic resistance. These genetic features arose in tandem with large-scale genome evolution mediated by mobile elements. Pathoadaptation in enterococci is thought to be mediated in part by the IS element IS256 through gene inactivation and recombination events. However, the regulation of IS256 and the mechanisms controlling its activation are not well understood. Here, we adapt an IS256-specfic deep sequencing method to describe how chronic lytic phage infection drives widespread diversification of IS256 in E. faecalis and how antibiotic exposure is associated with IS256 diversification in E. faecium during a clinical human infection. We show through comparative genomics that IS256 is primarily found in hospital-adapted enterococcal isolates. Analyses of IS256 transposase gene levels reveal that IS256 mobility is regulated at the transcriptional level by multiple mechanisms in E. faecalis, indicating tight control of IS256 activation in the absence of selective pressure. Our findings reveal that stressors such as phages and antibiotic exposure drives rapid genome-scale transposition in the enterococci. IS256 diversification can therefore explain how selective pressures mediate evolution of the enterococcal genome, ultimately leading to the emergence of dominant nosocomial lineages that threaten human health.
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Affiliation(s)
- Joshua M. Kirsch
- Department of Immunology and Microbiology, University of Colorado–Anschutz Medical Campus, School of Medicine, Aurora, Colorado, United States of America
| | - Shannon Ely
- Department of Immunology and Microbiology, University of Colorado–Anschutz Medical Campus, School of Medicine, Aurora, Colorado, United States of America
| | - Madison E. Stellfox
- Department of Medicine, Division of Infectious Diseases, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Karthik Hullahalli
- Department of Biological Sciences, University of Texas at Dallas, Richardson, Texas, United States of America
| | - Phat Luong
- Department of Immunology and Microbiology, University of Colorado–Anschutz Medical Campus, School of Medicine, Aurora, Colorado, United States of America
| | - Kelli L. Palmer
- Department of Biological Sciences, University of Texas at Dallas, Richardson, Texas, United States of America
| | - Daria Van Tyne
- Department of Medicine, Division of Infectious Diseases, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Breck A. Duerkop
- Department of Immunology and Microbiology, University of Colorado–Anschutz Medical Campus, School of Medicine, Aurora, Colorado, United States of America
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9
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Sugiyama Y, Mori Y, Nara M, Kotani Y, Nagai E, Kawada H, Kitamura M, Hirano R, Shimokawa H, Nakagawa A, Minami H, Gotoh A, Sakanaka M, Iida N, Koyanagi T, Katayama T, Okamoto S, Kurihara S. Gut bacterial aromatic amine production: aromatic amino acid decarboxylase and its effects on peripheral serotonin production. Gut Microbes 2022; 14:2128605. [PMID: 36217238 PMCID: PMC9553188 DOI: 10.1080/19490976.2022.2128605] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Colonic luminal aromatic amines have been historically considered to be derived from dietary source, especially fermented foods; however, recent studies indicate that the gut microbiota serves as an alternative source of these amines. Herein, we show that five prominent genera of Firmicutes (Blautia, Clostridium, Enterococcus, Ruminococcus, and Tyzzerella) have the ability to abundantly produce aromatic amines through the action of aromatic amino acid decarboxylase (AADC). In vitro cultivation of human fecal samples revealed that a significant positive correlation between aadc copy number of Ruminococcus gnavus and phenylethylamine (PEA) production. Furthermore, using genetically engineered Enterococcus faecalis-colonized BALB/cCrSlc mouse model, we showed that the gut bacterial aadc stimulates the production of colonic serotonin, which is reportedly involved in osteoporosis and irritable bowel syndrome. Finally, we showed that human AADC inhibitors carbidopa and benserazide inhibit PEA production in En. faecalis.
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Affiliation(s)
- Yuta Sugiyama
- Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, Nonoichi, 921-8836, Japan,Gunma University Center for Food Science and Wellness, Gunma University, Maebashi, Japan
| | - Yumiko Mori
- Department of Clinical Laboratory Sciences, Faculty of Health Sciences, Institute of Medical, Pharmaceutical, and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Misaki Nara
- Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, Nonoichi, 921-8836, Japan
| | - Yusuke Kotani
- Department of Clinical Laboratory Sciences, Faculty of Health Sciences, Institute of Medical, Pharmaceutical, and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Emiko Nagai
- Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, Nonoichi, 921-8836, Japan,Department of Biotechnology, Graduate School of Agricultural and Life Sciences, the University of Tokyo, Bunkyo-ku, Japan
| | - Hiroki Kawada
- Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, Nonoichi, 921-8836, Japan
| | - Mayu Kitamura
- Department of Clinical Laboratory Sciences, Faculty of Health Sciences, Institute of Medical, Pharmaceutical, and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Rika Hirano
- Faculty of Biology-Oriented Science and Technology, Kindai University, Kinokawa, Japan
| | - Hiromi Shimokawa
- Faculty of Biology-Oriented Science and Technology, Kindai University, Kinokawa, Japan
| | - Akira Nakagawa
- Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, Nonoichi, 921-8836, Japan
| | - Hiromichi Minami
- Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, Nonoichi, 921-8836, Japan
| | - Aina Gotoh
- Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Mikiyasu Sakanaka
- Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, Nonoichi, 921-8836, Japan
| | - Noriho Iida
- Department of Gastroenterology, Graduate School of Medicine, Kanazawa University, Kanazawa, Japan
| | - Takashi Koyanagi
- Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, Nonoichi, 921-8836, Japan
| | - Takane Katayama
- Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, Nonoichi, 921-8836, Japan,Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Shigefumi Okamoto
- Department of Clinical Laboratory Sciences, Faculty of Health Sciences, Institute of Medical, Pharmaceutical, and Health Sciences, Kanazawa University, Kanazawa, Japan,Advanced Health Care Science Research Unit, Innovative Integrated Bio-Research Core, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Japan
| | - Shin Kurihara
- Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, Nonoichi, 921-8836, Japan,Faculty of Biology-Oriented Science and Technology, Kindai University, Kinokawa, Japan,CONTACT Shin Kurihara Faculty of Biology-Oriented Science and Technology, Kindai University, Kinokawa, Wakayama649-6493, Japan
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10
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Maguin P, Varble A, Modell JW, Marraffini LA. Cleavage of viral DNA by restriction endonucleases stimulates the type II CRISPR-Cas immune response. Mol Cell 2022; 82:907-919.e7. [PMID: 35134339 PMCID: PMC8900293 DOI: 10.1016/j.molcel.2022.01.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 12/03/2021] [Accepted: 01/14/2022] [Indexed: 12/26/2022]
Abstract
Prokaryotic organisms have developed multiple defense systems against phages; however, little is known about whether and how these interact with each other. Here, we studied the connection between two of the most prominent prokaryotic immune systems: restriction-modification and CRISPR. While both systems employ enzymes that cleave a specific DNA sequence of the invader, CRISPR nucleases are programmed with phage-derived spacer sequences, which are integrated into the CRISPR locus upon infection. We found that restriction endonucleases provide a short-term defense, which is rapidly overcome through methylation of the phage genome. In a small fraction of the cells, however, restriction results in the acquisition of spacer sequences from the cleavage site, which mediates a robust type II-A CRISPR-Cas immune response against the methylated phage. This mechanism is reminiscent of eukaryotic immunity in which the innate response offers a first temporary line of defense and also activates a second and more robust adaptive response.
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Affiliation(s)
- Pascal Maguin
- Laboratory of Bacteriology, The Rockefeller University, 1230 York Ave, New York, NY 10065, USA
| | - Andrew Varble
- Laboratory of Bacteriology, The Rockefeller University, 1230 York Ave, New York, NY 10065, USA
| | - Joshua W. Modell
- Laboratory of Bacteriology, The Rockefeller University, 1230 York Ave, New York, NY 10065, USA.,Present address: Department of Molecular Biology & Genetics, Johns Hopkins University School of Medicine, 725 N. Wolfe St., PCTB 803, Baltimore, MD 21205, USA
| | - Luciano A. Marraffini
- Laboratory of Bacteriology, The Rockefeller University, 1230 York Ave, New York, NY 10065, USA.,Howard Hughes Medical Institute, The Rockefeller University, 1230 York Ave, New York, NY 10065, USA.,Correspondence to:
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11
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Prophage integration into CRISPR loci enables evasion of antiviral immunity in Streptococcus pyogenes. Nat Microbiol 2021; 6:1516-1525. [PMID: 34819640 DOI: 10.1038/s41564-021-00996-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 10/15/2021] [Indexed: 12/26/2022]
Abstract
CRISPR loci are composed of short DNA repeats separated by sequences, known as spacers, that match the genomes of invaders such as phages and plasmids. Spacers are transcribed and processed to generate RNA guides used by CRISPR-associated nucleases to recognize and destroy the complementary nucleic acids of invaders. To counteract this defence, phages can produce small proteins that inhibit these nucleases, termed anti-CRISPRs (Acrs). Here we demonstrate that the ΦAP1.1 temperate phage utilizes an alternative approach to antagonize the type II-A CRISPR response in Streptococcus pyogenes. Immediately after infection, this phage expresses a small anti-CRISPR protein, AcrIIA23, that prevents Cas9 function, allowing ΦAP1.1 to integrate into the direct repeats of the CRISPR locus, neutralizing immunity. However, acrIIA23 is not transcribed during lysogeny and phage integration/excision cycles can result in the deletion and/or transduction of spacers, enabling a complex modulation of the type II-A CRISPR immune response. A bioinformatic search identified prophages integrated not only in the CRISPR repeats, but also the cas genes, of diverse bacterial species, suggesting that prophage disruption of the CRISPR-cas locus is a recurrent mechanism to counteract immunity.
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Chen V, Griffin ME, Maguin P, Varble A, Hang HC. RecT Recombinase Expression Enables Efficient Gene Editing in Enterococcus spp. Appl Environ Microbiol 2021; 87:e0084421. [PMID: 34232061 PMCID: PMC8388837 DOI: 10.1128/aem.00844-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 06/25/2021] [Indexed: 12/24/2022] Open
Abstract
Enterococcus faecium is a ubiquitous Gram-positive bacterium that has been recovered from the environment, food, and microbiota of mammals. Commensal strains of E. faecium can confer beneficial effects on host physiology and immunity, but antibiotic usage has afforded antibiotic-resistant and pathogenic isolates from livestock and humans. However, the dissection of E. faecium functions and mechanisms has been restricted by inefficient gene-editing methods. To address these limitations, here, we report that the expression of E. faecium RecT recombinase significantly improves the efficiency of recombineering technologies in both commensal and antibiotic-resistant strains of E. faecium and other Enterococcus species such as E. durans and E. hirae. Notably, the expression of RecT in combination with clustered regularly interspaced short palindromic repeat (CRISPR)-Cas9 and guide RNAs (gRNAs) enabled highly efficient scarless single-stranded DNA recombineering to generate specific gene-editing mutants in E. faecium. Moreover, we demonstrate that E. faecium RecT expression facilitated chromosomal insertions of double-stranded DNA templates encoding antibiotic-selectable markers to generate gene deletion mutants. As a further proof of principle, we use CRISPR-Cas9-mediated recombineering to knock out both sortase A genes in E. faecium for downstream functional characterization. The general RecT-mediated recombineering methods described here should significantly enhance genetic studies of E. faecium and other closely related species for functional and mechanistic studies. IMPORTANCE Enterococcus faecium is widely recognized as an emerging public health threat with the rise of drug resistance and nosocomial infections. Nevertheless, commensal Enterococcus strains possess beneficial health functions in mammals to upregulate host immunity and prevent microbial infections. This functional dichotomy of Enterococcus species and strains highlights the need for in-depth studies to discover and characterize the genetic components underlying its diverse activities. However, current genetic engineering methods in E. faecium still require passive homologous recombination from plasmid DNA. This involves the successful cloning of multiple homologous fragments into a plasmid, introducing the plasmid into E. faecium, and screening for double-crossover events that can collectively take up to multiple weeks to perform. To alleviate these challenges, we show that RecT recombinase enables the rapid and efficient integration of mutagenic DNA templates to generate substitutions, deletions, and insertions in the genomic DNA of E. faecium. These improved recombineering methods should facilitate functional and mechanistic studies of Enterococcus.
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Affiliation(s)
- Victor Chen
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University, New York, New York, USA
| | - Matthew E. Griffin
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University, New York, New York, USA
| | - Pascal Maguin
- Laboratory of Bacteriology, The Rockefeller University, New York, New York, USA
| | - Andrew Varble
- Laboratory of Bacteriology, The Rockefeller University, New York, New York, USA
| | - Howard C. Hang
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University, New York, New York, USA
- Department of Immunology and Microbiology, Scripps Research, La Jolla, California, USA
- Department of Chemistry, Scripps Research, La Jolla, California, USA
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The Streptococcus pyogenes signaling peptide SpoV regulates streptolysin O and enhances survival in murine blood. J Bacteriol 2021; 203:JB.00586-20. [PMID: 33722844 PMCID: PMC8117530 DOI: 10.1128/jb.00586-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus pyogenes (Group A Streptococcus, GAS) is a human pathogen that causes a wide range of diseases. For successful colonization within a variety of host niches, GAS must sense and respond to environmental changes. Intercellular communication mediated by peptides is one way GAS coordinates gene expression in response to diverse environmental stressors, which enhances bacterial survival and contributes to virulence. Using peptidomics we identified SpoV (Streptococcal peptide controlling virulence) in culture supernatant fluids. SpoV is a secreted peptide encoded near the gene encoding the extracellular cholesterol-dependent cytolysin streptolysin O (slo) The addition of synthetic SpoV peptide derivatives, but not control peptides, increased slo transcript abundance in an M49 isolate but not in an M3 isolate. Deletion of spoV decreased slo transcript abundance, extracellular SLO protein levels, and SLO-specific hemolytic activity. Complementation of the spoV mutant increased slo transcript abundance. Lastly, a spoV mutant was deficient in the ability to survive in murine blood compared to the parental strain. Moreover, pre-incubation of the spoV mutant with synthetic SpoV peptide derivatives increased GAS survival. Our findings show that slo expression is regulated, in part, by the GAS-specific signaling peptide SpoV.IMPORTANCEGAS secretes signaling peptides that can alter gene expression and impact virulence. We used peptidomics to identify a signaling peptide designated SpoV. Further, we showed that SpoV altered the expression of the cholesterol-dependent cytolysin SLO. Peptide signaling plays an important regulatory role during disease progression among several bacterial pathogens, including GAS. The therapeutic potential of manipulating peptide-controlled regulatory networks is an attractive option for the development of novel therapeutic strategies that disrupt virulence gene expression.
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Lytic bacteriophages facilitate antibiotic sensitization of Enterococcus faecium. Antimicrob Agents Chemother 2021; 65:AAC.00143-21. [PMID: 33649110 PMCID: PMC8092871 DOI: 10.1128/aac.00143-21] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Enterococcus faecium, a commensal of the human intestine, has emerged as a hospital-adapted, multi-drug resistant (MDR) pathogen. Bacteriophages (phages), natural predators of bacteria, have regained attention as therapeutics to stem the rise of MDR bacteria. Despite their potential to curtail MDR E. faecium infections, the molecular events governing E. faecium-phage interactions remain largely unknown. Such interactions are important to delineate because phage selective pressure imposed on E. faecium will undoubtedly result in phage resistance phenotypes that could threaten the efficacy of phage therapy. In an effort to understand the emergence of phage resistance in E. faecium, three newly isolated lytic phages were used to demonstrate that E. faecium phage resistance is conferred through an array of cell wall-associated molecules, including secreted antigen A (SagA), enterococcal polysaccharide antigen (Epa), wall teichoic acids, capsule, and an arginine-aspartate-aspartate (RDD) protein of unknown function. We find that capsule and Epa are important for robust phage adsorption and that phage resistance mutations in sagA, epaR, and epaX enhance E. faecium susceptibility to ceftriaxone, an antibiotic normally ineffective due to its low affinity for enterococcal penicillin binding proteins. Consistent with these findings, we provide evidence that phages potently synergize with cell wall (ceftriaxone and ampicillin) and membrane-acting (daptomycin) antimicrobials to slow or completely inhibit the growth of E. faecium Our work demonstrates that the evolution of phage resistance comes with fitness defects resulting in drug sensitization and that lytic phages could serve as effective antimicrobials for the treatment of E. faecium infections.
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Using Lactococcus lactis as Surrogate Organism to Study Group A Streptococcus Surface Proteins. Methods Mol Biol 2021. [PMID: 32430819 DOI: 10.1007/978-1-0716-0467-0_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/06/2023]
Abstract
The isolation of a single Group A Streptococcus (GAS) virulence determinant in functional investigations is challenging, as GAS employs a multitude of virulence factors. The redundancy between many surface proteins such as adhesins also adds complexity and difficulty. Lactococcus lactis is a non-pathogenic Gram-positive species related to GAS that can be an ideal surrogate organism to circumvent this problem. Genetic manipulation in L. lactis is easy, and the mechanisms for processing and cell wall-anchoring of surface proteins are similar to GAS. Lactococci have been extensively used to express heterologous surface proteins from other bacterial species, and modern molecular cloning tools and protocols have been developed. This chapter describes the workflow of generating recombinant L. lactis strains expressing GAS surface proteins and the validation and quantification of their surface expression.
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Abstract
Streptococcus parasanguinis is a dominant isolate of dental plaque and an opportunistic pathogen associated with subacute endocarditis. As the expression of collagen binding proteins (CBPs) could promote the establishment of S. parasanguinis in the host, the functions of three putative CBP-encoding loci, Spaf_0420, Spaf_1570, and Spaf_1573, were analyzed using isogenic mutant strains. It was revealed that S. parasanguinis FW213 bound effectively to fibronectin and type I collagen, but the strain's affinity for laminin and type IV collagen was quite low. By using various deletion derivatives, it was found that these three loci mediated the binding of S. parasanguinis to multiple extracellular matrix molecules, with type I collagen as the common substrate. Derivative strains with a deletion in any of the three loci expressed reduced binding to trypsin-treated swine heart valves. The deletion of these loci also reduced the viable count of S. parasanguinis bacteria within macrophages, especially the loss of Spaf_0420, but only strains with deletions in Spaf_0420 and Spaf_1570 expressed reduced virulence in the Galleria mellonella larva model. The deletion of Spaf_1570 and Spaf_1573 affected mainly the structure, but not the overall mass, of biofilm cultures in a flow cell system. Thus, CBPs are likely to be more critical for the initial colonization of S. parasanguinis on host tissues during the development of endocarditis.IMPORTANCE Bacteria generally can utilize multiple adhesins to establish themselves in the host. We found that Streptococcus parasanguinis, a dominant oral commensal and an opportunistic pathogen for subacute endocarditis, possesses at least three collagen-binding proteins that enable S. parasanguinis to successfully colonize damaged heart tissues and escape innate immune clearance. The binding specificities of these three proteins for extracellular matrix molecules differ, although all three proteins participate in biofilm formation by S. parasanguinis The "multiligand for multisubstrate" feature of these adhesins may explain the high adaptability of this microbe to different tissue sites.
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Zhu L, Olsen RJ, Beres SB, Saavedra MO, Kubiak SL, Cantu CC, Jenkins L, Waller AS, Sun Z, Palzkill T, Porter AR, DeLeo FR, Musser JM. Streptococcus pyogenes genes that promote pharyngitis in primates. JCI Insight 2020; 5:137686. [PMID: 32493846 DOI: 10.1172/jci.insight.137686] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 04/30/2020] [Indexed: 02/02/2023] Open
Abstract
Streptococcus pyogenes (group A streptococcus; GAS) causes 600 million cases of pharyngitis annually worldwide. There is no licensed human GAS vaccine despite a century of research. Although the human oropharynx is the primary site of GAS infection, the pathogenic genes and molecular processes used to colonize, cause disease, and persist in the upper respiratory tract are poorly understood. Using dense transposon mutant libraries made with serotype M1 and M28 GAS strains and transposon-directed insertion sequencing, we performed genome-wide screens in the nonhuman primate (NHP) oropharynx. We identified many potentially novel GAS fitness genes, including a common set of 115 genes that contribute to fitness in both genetically distinct GAS strains during experimental NHP pharyngitis. Targeted deletion of 4 identified fitness genes/operons confirmed that our newly identified targets are critical for GAS virulence during experimental pharyngitis. Our screens discovered many surface-exposed or secreted proteins - substrates for vaccine research - that potentially contribute to GAS pharyngitis, including lipoprotein HitA. Pooled human immune globulin reacted with purified HitA, suggesting that humans produce antibodies against this lipoprotein. Our findings provide new information about GAS fitness in the upper respiratory tract that may assist in translational research, including developing novel vaccines.
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Affiliation(s)
- Luchang Zhu
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, and Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, Texas, USA
| | - Randall J Olsen
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, and Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, Texas, USA.,Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, New York, USA
| | - Stephen B Beres
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, and Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, Texas, USA
| | - Matthew Ojeda Saavedra
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, and Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, Texas, USA
| | - Samantha L Kubiak
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, and Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, Texas, USA
| | - Concepcion C Cantu
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, and Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, Texas, USA
| | - Leslie Jenkins
- Department of Comparative Medicine, Houston Methodist Research Institute, Houston, Texas, USA
| | - Andrew S Waller
- Animal Health Trust, Lanwades Park, Newmarket, United Kingdom
| | - Zhizeng Sun
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Timothy Palzkill
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Adeline R Porter
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, NIH, Hamilton, Montana, USA
| | - Frank R DeLeo
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, NIH, Hamilton, Montana, USA
| | - James M Musser
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, and Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, Texas, USA.,Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, New York, USA
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Depardieu F, Bikard D. Gene silencing with CRISPRi in bacteria and optimization of dCas9 expression levels. Methods 2020; 172:61-75. [PMID: 31377338 DOI: 10.1016/j.ymeth.2019.07.024] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 07/25/2019] [Accepted: 07/29/2019] [Indexed: 12/15/2022] Open
Abstract
The catalytic null mutant of the Cas9 endonuclease from the bacterial CRISPR immune system, known as dCas9, can be guided by a small RNA to bind DNA sequences of interest and block gene transcription in a strategy known as CRISPRi. This powerful gene silencing method has already been used in a large number of species and in high throughput screens. Here we provide detailed design rules, methods and novel vectors to perform CRISPRi experiments in S. aureus and in E. coli, using the well characterized dCas9 protein from S. pyogenes. In particular, we describe a vector based on plasmid pC194 which is broadly used in Firmicutes, as well as a vector based on the very broad host-range rolling circle plasmid pLZ12, reported to replicate in both Firmicutes and Proteobacteria. A potential caveat of adapting dCas9 tools to various bacterial species is that dCas9 was shown to be toxic when expressed too strongly. We describe a method to optimize the expression level of dCas9 in order to avoid toxicity while ensuring strong on-target repression activity. We demonstrate this method by optimizing a pLZ12 based vector originally developed for S. aureus so that it can work in E. coli. This article should provide all the resources required to perform CRISPRi experiments in a broad range of bacterial species.
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Affiliation(s)
| | - David Bikard
- Groupe de Biologie de Synthèse, Institut Pasteur, Paris 75015, France.
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19
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Abstract
Streptococcus pyogenes (group A streptococcus) is remarkable in terms of the large number of diseases it can cause in humans and for the large number of streptococcal factors that have been identified as potential virulence determinants for these diseases. A challenge is to link the function of potential virulence factors to the pathogenesis of specific diseases. An exciting advance has been the development of sophisticated genetic systems for the construction of loss-of-function, conditional, hypomorphic, and gain-of-function mutations in targeted S. pyogenes genes that can be used to test specific hypotheses regarding these genes in pathogenesis. This will facilitate a mechanistic understanding of how a specific gene function contributes to the pathogenesis of each streptococcal disease. Since the first S. pyogenes genome was completed in 2001, hundreds of complete and draft genome sequences have been deposited. We now know that the average S. pyogenes genome is approximately 1.85 Mb and encodes ∼1,800 genes and that the function of most of those genes in pathogenesis remains to be elucidated. However, advances in the development of a variety of genetic tools for manipulation of the S. pyogenes genome now provide a platform for the interrogation of gene/phenotype relationships for individual S. pyogenes diseases, which may lead to the development of more sophisticated and targeted therapeutic interventions. This article presents an overview of these genetic tools, including the methods of genetic modification and their applications.
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Molecular and Functional Analysis of the Type IV Pilus Gene Cluster in Streptococcus sanguinis SK36. Appl Environ Microbiol 2019; 85:AEM.02788-18. [PMID: 30635384 DOI: 10.1128/aem.02788-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 01/04/2019] [Indexed: 12/11/2022] Open
Abstract
Streptococcus sanguinis, dominant in the oral microbiome, is the only known streptococcal species possessing a pil gene cluster for the biosynthesis of type IV pili (Tfp). Although this cluster is commonly present in the genome of S. sanguinis, most of the strains do not express Tfp-mediated twitching motility. Thus, this study was designed to investigate the biological functions encoded by the cluster in the twitching-negative strain S. sanguinis SK36. We found that the cluster was transcribed as an operon, with three promoters located 5' to the cluster and one in the intergenic region between SSA_2307 and SSA_2305. Studies using promoter-cat fusion strains revealed that the transcription of the cluster was mainly driven by the distal 5' promoter, which is located more than 800 bases 5' to the first gene of the cluster, SSA_2318. Optimal expression of the cluster occurred at the early stationary growth phase in a CcpA-dependent manner, although a CcpA-binding consensus is absent in the promoter region. Expression of the cluster resulted in a short hairlike surface structure under transmission electron microscopy. Deletion of the putative pilin genes (SSA_2313 to SSA_2315) abolished the biosynthesis of this structure and significantly reduced the adherence of SK36 to HeLa and SCC-4 cells. Mutations in the pil genes downregulated biofilm formation by S. sanguinis SK36. Taken together, the results demonstrate that Tfp of SK36 are important for host cell adherence, but not for motility, and that expression of the pil cluster is subject to complex regulation.IMPORTANCE The proteins and assembly machinery of the type IV pili (Tfp) are conserved throughout bacteria and archaea, and yet the function of this surface structure differs from species to species and even from strain to strain. As seen in Streptococcus sanguinis SK36, the expression of the Tfp gene cluster results in a hairlike surface structure that is much shorter than the typical Tfp. This pilus is essential for the adherence of SK36 but is not involved in motility. Being a member of the highly diverse dental biofilm, perhaps S. sanguinis could more effectively utilize this structure to adhere to host cells and to interact with other microbes within the same niche.
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21
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Wessels MR. Capsular Polysaccharide of Group A Streptococcus. Microbiol Spectr 2019; 7:10.1128/microbiolspec.GPP3-0050-2018. [PMID: 30632480 PMCID: PMC6342470 DOI: 10.1128/microbiolspec.gpp3-0050-2018] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Indexed: 01/02/2023] Open
Abstract
Most clinical isolates of Streptococcus pyogenes elaborate a capsular polysaccharide, which is composed of hyaluronic acid, a high-molecular-mass polymer of alternating residues of N-acetyl glucosamine and glucuronic acid. Certain strains, particularly those of the M18 serotype, produce abundant amounts of capsule, resulting in formation of large, wet-appearing, translucent or "mucoid" colonies on solid media, whereas strains of M-types 4 and 22 produce none. Studies of acapsular mutant strains have provided evidence that the capsule enhances virulence in animal models of infection, an effect attributable, at least in part, to resistance to complement-mediated opsonophagocytic killing by leukocytes. The presence of the hyaluronic acid capsule may mask adhesins on the bacterial cell wall. However, the capsule itself can mediate bacterial attachment to host cells by binding to the hyaluronic-acid binding protein, CD44. Furthermore, binding of the S. pyogenes capsule to CD44 on host epithelial cells can trigger signaling events that disrupt cell-cell junctions and facilitate bacterial invasion into deep tissues. This article summarizes the biochemistry, genetics, regulation, and role in pathogenesis of this important virulence determinant.
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Affiliation(s)
- Michael R Wessels
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, MA
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Hertzog BB, Kaufman Y, Biswas D, Ravins M, Ambalavanan P, Wiener R, Angeli V, Chen SL, Hanski E. A Sub-population of Group A Streptococcus Elicits a Population-wide Production of Bacteriocins to Establish Dominance in the Host. Cell Host Microbe 2018; 23:312-323.e6. [PMID: 29544095 DOI: 10.1016/j.chom.2018.02.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 12/26/2017] [Accepted: 02/07/2018] [Indexed: 11/30/2022]
Abstract
Bacteria use quorum sensing (QS) to regulate gene expression. We identified a group A Streptococcus (GAS) strain possessing the QS system sil, which produces functional bacteriocins, through a sequential signaling pathway integrating host and bacterial signals. Host cells infected by GAS release asparagine (ASN), which is sensed by the bacteria to alter its gene expression and rate of proliferation. We show that upon ASN sensing, GAS upregulates expression of the QS autoinducer peptide SilCR. Initial SilCR expression activates the autoinduction cycle for further SilCR production. The autoinduction process propagates throughout the GAS population, resulting in bacteriocin production. Subcutaneous co-injection of mice with a bacteriocin-producing strain and the globally disseminated M1T1 GAS clone results in M1T1 killing within soft tissue. Thus, by sensing host signals, a fraction of a bacterial population can trigger an autoinduction mechanism mediated by QS, which acts on the entire bacterial community to outcompete other bacteria within the infection.
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Affiliation(s)
- Baruch B Hertzog
- Department of Microbiology and Molecular Genetics, The Institute for Medical Research, Israel-Canada (IMRIC), The Hebrew University of Jerusalem, Faculty of Medicine, Jerusalem 9112102, Israel
| | - Yael Kaufman
- Department of Microbiology and Molecular Genetics, The Institute for Medical Research, Israel-Canada (IMRIC), The Hebrew University of Jerusalem, Faculty of Medicine, Jerusalem 9112102, Israel
| | - Debabrata Biswas
- NUS-HUJ-CREATE Programme for Inflammation Research, Center for Research Excellence & Technological Enterprise (CREATE), Department of Microbiology and Immunology, National University of Singapore, Singapore 138602, Singapore
| | - Miriam Ravins
- Department of Microbiology and Molecular Genetics, The Institute for Medical Research, Israel-Canada (IMRIC), The Hebrew University of Jerusalem, Faculty of Medicine, Jerusalem 9112102, Israel
| | - Poornima Ambalavanan
- NUS-HUJ-CREATE Programme for Inflammation Research, Center for Research Excellence & Technological Enterprise (CREATE), Department of Microbiology and Immunology, National University of Singapore, Singapore 138602, Singapore
| | - Reuven Wiener
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research, Israel-Canada (IMRIC), The Hebrew University of Jerusalem, Faculty of Medicine, Jerusalem 9112102, Israel
| | - Veronique Angeli
- Department of Microbiology and Immunology, National University of Singapore; LSI Immunology Programme, National University of Singapore, Singapore 117456, Singapore
| | - Swaine L Chen
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, and Infectious Diseases Group, Genome Institute of Singapore, Singapore 119074, Singapore
| | - Emanuel Hanski
- Department of Microbiology and Molecular Genetics, The Institute for Medical Research, Israel-Canada (IMRIC), The Hebrew University of Jerusalem, Faculty of Medicine, Jerusalem 9112102, Israel; NUS-HUJ-CREATE Programme for Inflammation Research, Center for Research Excellence & Technological Enterprise (CREATE), Department of Microbiology and Immunology, National University of Singapore, Singapore 138602, Singapore.
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Stable Expression of Modified Green Fluorescent Protein in Group B Streptococci To Enable Visualization in Experimental Systems. Appl Environ Microbiol 2018; 84:AEM.01262-18. [PMID: 30006391 DOI: 10.1128/aem.01262-18] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 07/04/2018] [Indexed: 12/17/2022] Open
Abstract
Group B streptococcus (GBS) is a Gram-positive bacterium associated with various diseases in humans and animals. Many studies have examined GBS physiology, virulence, and microbe-host interactions using diverse imaging approaches, including fluorescence microscopy. Strategies to label and visualize GBS using fluorescence biomarkers have been limited to antibody-based methods or nonspecific stains that bind DNA or protein; an effective plasmid-based system to label GBS with a fluorescence biomarker would represent a useful visualization tool. In this study, we developed and validated a green fluorescent protein (GFP)-variant-expressing plasmid, pGU2664, which can be applied as a marker to visualize GBS in experimental studies. The synthetic constitutively active CP25 promoter drives strong and stable expression of the GFPmut3 biomarker in GBS strains carrying pGU2664. GBS maintains GFPmut3 activity at different phases of growth. The application of fluorescence polarization enables easy discrimination of GBS GFPmut3 activity from the autofluorescence of culture media commonly used to grow GBS. Differential interference contrast microscopy, in combination with epifluorescence microscopy to detect GFPmut3 in GBS, enabled visualization of bacterial attachment to live human epithelial cells in real time. Plasmid pGU2664 was also used to visualize phenotypic differences in the adherence of wild-type GBS and an isogenic gene-deficient mutant strain lacking CovR (the control of virulence regulator) in adhesion assays. The system for GFPmut3 expression in GBS described in this study provides a new tool for the visualization of this organism in diverse research applications. We discuss the advantages and consider the limitations of this fluorescent biomarker system developed for GBS.IMPORTANCE Group B streptococcus (GBS) is a bacterium associated with various diseases in humans and animals. This study describes the development of a strategy to label and visualize GBS using a fluorescence biomarker, termed GFPmut3. We show that this biomarker can be successfully applied to track the growth of bacteria in liquid medium, and it enables the detailed visualization of GBS in the context of live human cells in real-time microscopic analysis. The system for GFPmut3 expression in GBS described in this study provides a new tool for the visualization of this organism in diverse research applications.
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Kitada Y, Muramatsu K, Toju H, Kibe R, Benno Y, Kurihara S, Matsumoto M. Bioactive polyamine production by a novel hybrid system comprising multiple indigenous gut bacterial strategies. SCIENCE ADVANCES 2018; 4:eaat0062. [PMID: 29963630 PMCID: PMC6021145 DOI: 10.1126/sciadv.aat0062] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 05/18/2018] [Indexed: 05/15/2023]
Abstract
Metabolites of the intestinal microbiota are thought to be generated through metabolic pathways spanning multiple taxa of intestinal bacteria. We have previously shown that the level of putrescine, a polyamine found abundantly in the human intestinal lumen, is increased in the colonic lumen following administration of arginine and the probiotic Bifidobacterium sp.; however, the underlying mechanism remained poorly understood. We report a novel pathway for putrescine production from arginine through agmatine involving the collaboration of two bacterial groups, and triggered by environmental acidification (drop in pH to below 6.5 from neutral). This pathway comprises the acid tolerance system of Escherichia coli, representing bacteria that have an arginine-dependent acid resistance system; the energy production system of Enterococcus faecalis, representing bacteria that have an agmatine deiminase system; and the acid production system of the acid-producing bacteria, represented by Bifidobacterium spp. This pathway is unique in that it represents a relationship between the independent survival strategies of multiple bacteria.
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Affiliation(s)
- Yusuke Kitada
- Dairy Science and Technology Institute, Kyodo Milk Industry Co. Ltd., Hinode-machi, Nishitama-gun, Tokyo 190-0182, Japan
| | - Koji Muramatsu
- Dairy Science and Technology Institute, Kyodo Milk Industry Co. Ltd., Hinode-machi, Nishitama-gun, Tokyo 190-0182, Japan
| | - Hirokazu Toju
- Center for Ecological Research, Kyoto University, Otsu, Shiga 520-2113, Japan
| | - Ryoko Kibe
- Benno Laboratory, RIKEN Innovation Center, Wako, Saitama 351-0198, Japan
| | - Yoshimi Benno
- Benno Laboratory, RIKEN Innovation Center, Wako, Saitama 351-0198, Japan
| | - Shin Kurihara
- Host-Microbe Interaction Research Laboratory, Ishikawa Prefectural University, Nonoich, Ishikawa 921-8836, Japan
| | - Mitsuharu Matsumoto
- Dairy Science and Technology Institute, Kyodo Milk Industry Co. Ltd., Hinode-machi, Nishitama-gun, Tokyo 190-0182, Japan
- Benno Laboratory, RIKEN Innovation Center, Wako, Saitama 351-0198, Japan
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Impact of growth pH and glucose concentrations on the CodY regulatory network in Streptococcus salivarius. BMC Genomics 2018; 19:386. [PMID: 29792173 PMCID: PMC5966866 DOI: 10.1186/s12864-018-4781-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 05/10/2018] [Indexed: 11/10/2022] Open
Abstract
Background Streptococcus salivarius is an abundant isolate of the human oral microbiota. Since both pH and glucose availability fluctuate frequently in the oral cavity, the goal of this study was to investigate regulation by CodY, a conserved pleiotropic regulator of Gram positive bacteria, in response to these two signals. The chemostat culture system was employed to precisely control the growth parameters, and the transcriptomes of wild-type S. salivarius 57.I and its CodY-null derivative (ΔcodY) grown at pH 7 and 5.5, with limited and excessive glucose supply were determined. Results The transcriptomic analysis revealed that CodY was most active at pH 7 under conditions of glucose limitation. Based on whether a CodY binding consensus could be located in the 5′ flanking region of the identified target, the transcriptomic analysis also found that CodY shaped the transcriptome via both direct and indirect regulation. Inactivation of codY reduced the glycolytic capacity and the viability of S. salivarius at pH 5.5 or in the presence of H2O2. Studies using the Galleria mellonella larva model showed that CodY was essential for the toxicity generated from S. salivarius infection, suggesting that CodY regulation was critical for immune evasion and systemic infections. Furthermore, the CodY-null mutant strain exhibited a clumping phenotype and reduced attachment in biofilm assays, suggesting that CodY also modulates cell wall metabolism. Finally, the expression of genes belonging to the CovR regulon was affected by codY inactivation, but CodY and CovR regulated these genes in opposite directions. Conclusions Metabolic adaptation in response to nutrient availability and growth pH is tightly linked to stress responses and virulence expression in S. salivarius. The regulation of metabolism by CodY allows for the maximal utilization of available nutrients and ATP production. The counteractive regulation of the CovR regulon could fine tune the transcriptomes in response to environmental changes. Electronic supplementary material The online version of this article (10.1186/s12864-018-4781-z) contains supplementary material, which is available to authorized users.
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Kiran MD, Bala S, Hirshberg M, Balaban N. YhgC protects Bacillus anthracis from oxidative stress. Int J Artif Organs 2018. [DOI: 10.1177/039139881003300905] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Bacillus anthracis can cause lethal inhalational anthrax and can be used as a bioweapon due to its ability to form spores and to survive under various environmental stress conditions. YhgC in bacilli are structural homologues of TRAP, a protein involved in stress response in staphylococci. To test the role of YhgC in B. anthracis, YhgC gene was deleted in B. anthracis strain Sterne and parent and mutant strains tested. Immunolocalization studies indicated that YhgC is clustered both on the cell surface and within the cytoplasm. Phenotypic analyses indicated that YhgC is an important factor for oxidative stress tolerance and for macrophage infection in vitro. Accordingly, transcriptomics studies indicated that yhgC has a profound effect on genes encoding for stress response regulatory proteins where it negatively regulates the expression of genes encoding for Class I and Class III stress response proteins belonging to the regulons hrcA (hrcA, grpE, dnaK, dnaJ, groEL and groES) and ctsR (ctsR, mcsA, mcsB, clpC/mecB, clpP1). Proteomics studies also indicated that YhgC positively regulates the expression of ClpP-2 and camelysin, which are proteins involved in adaptive responses and pathogenesis in various Gram-positive bacteria. Put together, these results suggest that YhgC is important for the survival of B. anthracis under oxidative stress conditions and thus inhibition of YhgC may compromise the ability of the bacteria to survive within the host.
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Affiliation(s)
- Madanahally D. Kiran
- Tufts University, Cummings School of Veterinary Medicine, North Grafton, MA - USA
- IQUUM Inc, Marlborough MA - USA
| | - Shashi Bala
- University of Massachusetts Medical School, Worcester, MA - USA
| | - Miriam Hirshberg
- EMBL Outstation – Hinxton, European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge - United Kingdom
| | - Naomi Balaban
- Tufts University, Cummings School of Veterinary Medicine, North Grafton, MA - USA
- Yale University, Department of Chemical Engineering, New Haven, CT - USA
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Gibson Assembly facilitates bacterial allelic exchange mutagenesis. J Microbiol Methods 2018; 144:157-163. [PMID: 29196271 DOI: 10.1016/j.mimet.2017.11.023] [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: 10/22/2017] [Revised: 11/27/2017] [Accepted: 11/27/2017] [Indexed: 02/01/2023]
Abstract
Allelic exchange mutagenesis that relies on RecA-mediated homologous recombination up- and downstream from the targeted gene is a generalizable method of site-specific bacterial gene knock-out and knock-in. However, generation of a mutagenic DNA construct (alternative allele flanked by regions surrounding the gene target) and subsequent mutant selection are laborious procedures. Here we demonstrate allelic exchange knock-out facilitated by Gibson Assembly in Streptococcus iniae. Gibson Assembly allows rapid construction of a large allelic exchange cassette simultaneous with cloning, as well as rapid reconstruction of complete recombinant vector sequence when required. Additionally, we show that during two-step mutant selection, absence of recombination at one of the homologous regions (single cross-over) might be rapidly detected by colony PCR of meroploid clones and resolved by extension/shifting of corresponding sequence in DNA construct. The combination of Gibson Assembly for mutagenic DNA construction/redesign with colony PCR screening of meroploids to detect recombination at both sides of the exchange target may significantly accelerate generation of chromosomal mutants in a wide range of bacterial taxa.
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Reduced Chlorhexidine and Daptomycin Susceptibility in Vancomycin-Resistant Enterococcus faecium after Serial Chlorhexidine Exposure. Antimicrob Agents Chemother 2017; 62:AAC.01235-17. [PMID: 29038276 PMCID: PMC5740357 DOI: 10.1128/aac.01235-17] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 10/10/2017] [Indexed: 12/22/2022] Open
Abstract
Vancomycin-resistant Enterococcus faecium strains (VREfm) are critical public health concerns because they are among the leading causes of hospital-acquired bloodstream infections. Chlorhexidine (CHX) is a bisbiguanide cationic antiseptic that is routinely used for patient bathing and other infection control practices. VREfm are likely frequently exposed to CHX; however, the long-term effects of CHX exposure have not been studied in enterococci. In this study, we serially exposed VREfm to increasing concentrations of CHX for a period of 21 days in two independent experimental evolution trials. Reduced CHX susceptibility emerged (4-fold shift in CHX MIC). Subpopulations with reduced daptomycin (DAP) susceptibility were detected, which were further analyzed by genome sequencing and lipidomic analysis. Across the trials, we identified adaptive changes in genes with predicted or experimentally confirmed roles in chlorhexidine susceptibility (efrE), global nutritional stress response (relA), nucleotide metabolism (cmk), phosphate acquisition (phoU), and glycolipid biosynthesis (bgsB), among others. Moreover, significant alterations in membrane phospholipids were identified for some populations with reduced DAP susceptibility. Our results are clinically significant because they identify a link between serial subinhibitory CHX exposure and reduced DAP susceptibility. In addition, the CHX-induced genetic and lipidomic changes described in this study offer new insights into the mechanisms underlying the emergence of antibiotic resistance in VREfm.
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Broad Targeting Specificity during Bacterial Type III CRISPR-Cas Immunity Constrains Viral Escape. Cell Host Microbe 2017; 22:343-353.e3. [PMID: 28826839 DOI: 10.1016/j.chom.2017.07.016] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 06/28/2017] [Accepted: 07/27/2017] [Indexed: 12/26/2022]
Abstract
CRISPR loci are a cluster of repeats separated by short "spacer" sequences derived from prokaryotic viruses and plasmids that determine the targets of the host's CRISPR-Cas immune response against its invaders. For type I and II CRISPR-Cas systems, single-nucleotide mutations in the seed or protospacer adjacent motif (PAM) of the target sequence cause immune failure and allow viral escape. This is overcome by the acquisition of multiple spacers that target the same invader. Here we show that targeting by the Staphylococcus epidermidis type III-A CRISPR-Cas system does not require PAM or seed sequences, and thus prevents viral escape via single-nucleotide substitutions. Instead, viral escapers can only arise through complete target deletion. Our work shows that, as opposed to type I and II systems, the relaxed specificity of type III CRISPR-Cas targeting provides robust immune responses that can lead to viral extinction with a single spacer targeting an essential phage sequence.
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Hullahalli K, Rodrigues M, Palmer KL. Exploiting CRISPR-Cas to manipulate Enterococcus faecalis populations. eLife 2017; 6:e26664. [PMID: 28644125 PMCID: PMC5491264 DOI: 10.7554/elife.26664] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 06/15/2017] [Indexed: 12/21/2022] Open
Abstract
CRISPR-Cas provides a barrier to horizontal gene transfer in prokaryotes. It was previously observed that functional CRISPR-Cas systems are absent from multidrug-resistant (MDR) Enterococcus faecalis, which only possess an orphan CRISPR locus, termed CRISPR2, lacking cas genes. Here, we investigate how the interplay between CRISPR-Cas genome defense and antibiotic selection for mobile genetic elements shapes in vitro E. faecalis populations. We demonstrate that CRISPR2 can be reactivated for genome defense in MDR strains. Interestingly, we observe that E. faecalis transiently maintains CRISPR targets despite active CRISPR-Cas systems. Subsequently, if selection for the CRISPR target is present, toxic CRISPR spacers are lost over time, while in the absence of selection, CRISPR targets are lost over time. We find that forced maintenance of CRISPR targets induces a fitness cost that can be exploited to alter heterogeneous E. faecalis populations.
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Affiliation(s)
- Karthik Hullahalli
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, United States
| | - Marinelle Rodrigues
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, United States
| | - Kelli L Palmer
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, United States
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YMC-2011, a Temperate Phage of Streptococcus salivarius 57.I. Appl Environ Microbiol 2017; 83:AEM.03186-16. [PMID: 28062463 DOI: 10.1128/aem.03186-16] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 01/04/2017] [Indexed: 11/20/2022] Open
Abstract
Streptococcus salivarius is an abundant isolate of the oral cavity. The genome of S. salivarius 57.I consists of a 2-Mb chromosome and a 40,758-bp circular molecule, designated YMC-2011. Annotation of YMC-2011 revealed 55 open reading frames, most of them associated with phage production, although plaque formation is not observed in S. salivarius 57.I after lytic induction using mitomycin C. Results from Southern hybridization and quantitative real-time PCR confirmed that YMC-2011 exists extrachromosomally, with an estimated copy number of 3 to 4. Phage particles were isolated from the supernatant of mitomycin C-treated S. salivarius 57.I cultures, and transmission electron microscopic examination indicated that YMC-2011 belongs to the Siphoviridae family. Phylogenetic analysis suggests that phage YMC-2011 and the cos-type phages of Streptococcus thermophilus originated from a common ancestor. An extended -10 element (p L ) and a σ70-like promoter (p R ) were mapped 5' to Ssal_phage00013 (encoding a CI-like repressor) and Ssal_phage00014 (encoding a hypothetical protein), respectively, using 5' rapid amplification of cDNA ends, indicating that YMC-2011 transcribes at least two mRNAs in opposite orientations. Studies using promoter-chloramphenicol acetyltransferase reporter gene fusions revealed that p R , but not p L , was sensitive to mitomycin C induction, suggesting that the switch from lysogenic growth to lytic growth was controlled mainly by the activity of these two promoters. In conclusion, a lysogenic state is maintained in S. salivarius 57.I, presumably by the repression of genes encoding proteins for lytic growth.IMPORTANCE The movement of mobile genetic elements such as bacteriophages and the establishment of lysogens may have profound effects on the balance of microbial ecology where lysogenic bacteria reside. The discovery of phage YMC-2011 from Streptococcus salivarius 57.I suggests that YMC-2011 and Streptococcus thermophilus-infecting phages share an ancestor. Although S. salivarius and S. thermophilus are close phylogenetically, S. salivarius is a natural inhabitant of the human mouth, whereas S. thermophilus is commonly found in the mammary mucosa of bovine species. Thus, the identification of YMC-2011 suggests that horizontal gene transfer via phage infection could take place between species from different ecological niches.
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Shanker E, Morrison DA, Talagas A, Nessler S, Federle MJ, Prehna G. Pheromone Recognition and Selectivity by ComR Proteins among Streptococcus Species. PLoS Pathog 2016; 12:e1005979. [PMID: 27907154 PMCID: PMC5131902 DOI: 10.1371/journal.ppat.1005979] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 10/04/2016] [Indexed: 12/11/2022] Open
Abstract
Natural transformation, or competence, is an ability inherent to bacteria for the uptake of extracellular DNA. This process is central to bacterial evolution and allows for the rapid acquirement of new traits, such as antibiotic resistance in pathogenic microorganisms. For the Gram-positive bacteria genus Streptococcus, genes required for competence are under the regulation of quorum sensing (QS) mediated by peptide pheromones. One such system, ComRS, consists of a peptide (ComS) that is processed (XIP), secreted, and later imported into the cytoplasm, where it binds and activates the transcription factor ComR. ComR then engages in a positive feedback loop for the expression of ComS and the alternative sigma-factor SigX. Although ComRS are present in the majority of Streptococcus species, the sequence of both ComS/XIP and ComR diverge significantly, suggesting a mechanism for species-specific communication. To study possible cross-talk between streptococcal species in the regulation of competence, and to explore in detail the molecular interaction between ComR and XIP we undertook an interdisciplinary approach. We developed a 'test-bed' assay to measure the activity of different ComR proteins in response to cognate and heterologous XIP peptides in vivo, revealing distinct ComR classes of strict, intermediate, and promiscuous specificity among species. We then solved an X-ray crystal structure of ComR from S. suis to further understand the interaction with XIP and to search for structural features in ComR proteins that may explain XIP recognition. Using the structure as a guide, we probed the apo conformation of the XIP-binding pocket by site-directed mutagenesis, both in test-bed cultures and biochemically in vitro. In alignments with ComR proteins from other species, we find that the pocket is lined by a variable and a conserved face, where residues of the conserved face contribute to ligand binding and the variable face discriminate among XIP peptides. Together, our results not only provide a model for XIP recognition and specificity, but also allow for the prediction of novel XIP peptides that induce ComR activity.
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Affiliation(s)
- Erin Shanker
- Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, IL, United States of America
- Center for Biomolecular Science, University of Illinois at Chicago, Chicago, IL, United States of America
| | - Donald A. Morrison
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, United States of America
| | - Antoine Talagas
- Institute of Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, France
| | - Sylvie Nessler
- Institute of Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, France
| | - Michael J. Federle
- Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, IL, United States of America
- Center for Biomolecular Science, University of Illinois at Chicago, Chicago, IL, United States of America
| | - Gerd Prehna
- Center for Structural Biology, Research Resources Center, University of Illinois at Chicago, Chicago, IL, United States of America
- Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, IL, United States of America
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McGinn J, Marraffini LA. CRISPR-Cas Systems Optimize Their Immune Response by Specifying the Site of Spacer Integration. Mol Cell 2016; 64:616-623. [PMID: 27618488 DOI: 10.1016/j.molcel.2016.08.038] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 08/25/2016] [Accepted: 08/30/2016] [Indexed: 12/26/2022]
Abstract
CRISPR-Cas systems defend prokaryotes against viruses and plasmids. Short DNA segments of the invader, known as spacers, are stored in the CRISPR array as immunological memories. New spacers are added invariably to the 5' end of the array; therefore, the first spacer matches the latest foreign threat. Whether this highly polarized order of spacer insertion influences CRISPR-Cas immunity has not been explored. Here we show that a conserved sequence located immediately upstream of the CRISPR array specifies the site of new spacer integration. Mutation of this sequence results in erroneous incorporation of new spacers into the middle of the array. We show that spacers added through polarized acquisition give rise to more robust CRISPR-Cas immunity than spacers added to the middle of the array. This study demonstrates that the CRISPR-Cas system specifies the site of spacer integration to optimize the immune response against the most immediate threat to the host.
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Affiliation(s)
- Jon McGinn
- Laboratory of Bacteriology, The Rockefeller University, New York, NY 10065, USA
| | - Luciano A Marraffini
- Laboratory of Bacteriology, The Rockefeller University, New York, NY 10065, USA.
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Chen YYM, Chen YY, Hung JL, Chen PM, Chia JS. The GlnR Regulon in Streptococcus mutans Is Differentially Regulated by GlnR and PmrA. PLoS One 2016; 11:e0159599. [PMID: 27454482 PMCID: PMC4959772 DOI: 10.1371/journal.pone.0159599] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 05/30/2016] [Indexed: 12/13/2022] Open
Abstract
GlnR-mediated repression of the GlnR regulon at acidic pH is required for optimal acid tolerance in Streptococcus mutans, the etiologic agent for dental caries. Unlike most streptococci, the GlnR regulon is also regulated by newly identified PmrA (SMUGS5_RS05810) at the transcriptional level in S. mutans GS5. Results from gel mobility shift assays confirmed that both GlnR and PmrA recognized the putative GlnR box in the promoter regions of the GlnR regulon genes. By using a chemostat culture system, we found that PmrA activated the expression of the GlnR regulon at pH 7, and that this activation was enhanced by excess glucose. Deletion of pmrA (strain ΔPmrA) reduced the survival rate of S. mutans GS5 at pH 3 moderately, whereas the GlnR mutant (strain ΔGlnR) exhibited an acid-sensitive phenotype in the acid killing experiments. Elevated biofilm formation in both ΔGlnR and ΔPmrA mutant strains is likely a result of indirect regulation of the GlnR regulon since GlnR and PmrA regulate the regulon differently. Taken together, it is suggested that activation of the GlnR regulon by PmrA at pH 7 ensures adequate biosynthesis of amino acid precursor, whereas repression by GlnR at acidic pH allows greater ATP generation for acid tolerance. The tight regulation of the GlnR regulon in response to pH provides an advantage for S. mutans to better survive in its primary niche, the oral cavity.
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Affiliation(s)
- Yi-Ywan M. Chen
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Molecular Infectious Disease Research Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan
- * E-mail:
| | - Yueh-Ying Chen
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Jui-Lung Hung
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Pei-Min Chen
- Department and Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Jean-San Chia
- Department and Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
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Ipe DS, Ben Zakour NL, Sullivan MJ, Beatson SA, Ulett KB, Benjamin WH, Davies MR, Dando SJ, King NP, Cripps AW, Schembri MA, Dougan G, Ulett GC. Discovery and Characterization of Human-Urine Utilization by Asymptomatic-Bacteriuria-Causing Streptococcus agalactiae. Infect Immun 2016; 84:307-19. [PMID: 26553467 PMCID: PMC4694007 DOI: 10.1128/iai.00938-15] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 11/01/2015] [Indexed: 12/27/2022] Open
Abstract
Streptococcus agalactiae causes both symptomatic cystitis and asymptomatic bacteriuria (ABU); however, growth characteristics of S. agalactiae in human urine have not previously been reported. Here, we describe a phenotype of robust growth in human urine observed in ABU-causing S. agalactiae (ABSA) that was not seen among uropathogenic S. agalactiae (UPSA) strains isolated from patients with acute cystitis. In direct competition assays using pooled human urine inoculated with equal numbers of a prototype ABSA strain, designated ABSA 1014, and any one of several UPSA strains, measurement of the percentage of each strain recovered over time showed a markedly superior fitness of ABSA 1014 for urine growth. Comparative phenotype profiling of ABSA 1014 and UPSA strain 807, isolated from a patient with acute cystitis, using metabolic arrays of >2,500 substrates and conditions revealed unique and specific l-malic acid catabolism in ABSA 1014 that was absent in UPSA 807. Whole-genome sequencing also revealed divergence in malic enzyme-encoding genes between the strains predicted to impact the activity of the malate metabolic pathway. Comparative growth assays in urine comparing wild-type ABSA and gene-deficient mutants that were functionally inactivated for the malic enzyme metabolic pathway by targeted disruption of the maeE or maeK gene in ABSA demonstrated attenuated growth of the mutants in normal human urine as well as synthetic human urine containing malic acid. We conclude that some S. agalactiae strains can grow in human urine, and this relates in part to malic acid metabolism, which may affect the persistence or progression of S. agalactiae ABU.
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Affiliation(s)
- Deepak S Ipe
- School of Medical Sciences, Menzies Health Institute Queensland, Griffith University, Gold Coast Campus, QLD, Australia
| | - Nouri L Ben Zakour
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia
| | - Matthew J Sullivan
- School of Medical Sciences, Menzies Health Institute Queensland, Griffith University, Gold Coast Campus, QLD, Australia
| | - Scott A Beatson
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia
| | - Kimberly B Ulett
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - William H Benjamin
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Mark R Davies
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - Samantha J Dando
- Institute for Glycomics, Griffith University, Gold Coast Campus, QLD, Australia
| | - Nathan P King
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Allan W Cripps
- School of Medical Sciences, Menzies Health Institute Queensland, Griffith University, Gold Coast Campus, QLD, Australia
| | - Mark A Schembri
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia
| | - Gordon Dougan
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - Glen C Ulett
- School of Medical Sciences, Menzies Health Institute Queensland, Griffith University, Gold Coast Campus, QLD, Australia Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
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Complete Genome Sequences of emm6 Streptococcus pyogenes JRS4 and Parental Strain D471. GENOME ANNOUNCEMENTS 2015; 3:3/4/e00725-15. [PMID: 26139722 PMCID: PMC4490850 DOI: 10.1128/genomea.00725-15] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report the complete genome assemblies of the group A Streptococcus pyogenes serotype emm6 strain D471 and its streptomycin-resistant derivative JRS4. Both of these well-studied laboratory strains have been extensively characterized over the past three decades and have been instrumental in the discovery of multiple aspects of streptococcal pathogenesis.
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Genome Modification in Enterococcus faecalis OG1RF Assessed by Bisulfite Sequencing and Single-Molecule Real-Time Sequencing. J Bacteriol 2015; 197:1939-51. [PMID: 25825433 DOI: 10.1128/jb.00130-15] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Accepted: 03/23/2015] [Indexed: 12/25/2022] Open
Abstract
UNLABELLED Enterococcus faecalis is a Gram-positive bacterium that natively colonizes the human gastrointestinal tract and opportunistically causes life-threatening infections. Multidrug-resistant (MDR) E. faecalis strains have emerged, reducing treatment options for these infections. MDR E. faecalis strains have large genomes containing mobile genetic elements (MGEs) that harbor genes for antibiotic resistance and virulence determinants. Bacteria commonly possess genome defense mechanisms to block MGE acquisition, and we hypothesize that these mechanisms have been compromised in MDR E. faecalis. In restriction-modification (R-M) defense, the bacterial genome is methylated at cytosine (C) or adenine (A) residues by a methyltransferase (MTase), such that nonself DNA can be distinguished from self DNA. A cognate restriction endonuclease digests improperly modified nonself DNA. Little is known about R-M in E. faecalis. Here, we use genome resequencing to identify DNA modifications occurring in the oral isolate OG1RF. OG1RF has one of the smallest E. faecalis genomes sequenced to date and possesses few MGEs. Single-molecule real-time (SMRT) and bisulfite sequencing revealed that OG1RF has global 5-methylcytosine (m5C) methylation at 5'-GCWGC-3' motifs. A type II R-M system confers the m5C modification, and disruption of this system impacts OG1RF electrotransformability and conjugative transfer of an antibiotic resistance plasmid. A second DNA MTase was poorly expressed under laboratory conditions but conferred global N(4)-methylcytosine (m4C) methylation at 5'-CCGG-3' motifs when expressed in Escherichia coli. Based on our results, we conclude that R-M can act as a barrier to MGE acquisition and likely influences antibiotic resistance gene dissemination in the E. faecalis species. IMPORTANCE The horizontal transfer of antibiotic resistance genes among bacteria is a critical public health concern. Enterococcus faecalis is an opportunistic pathogen that causes life-threatening infections in humans. Multidrug resistance acquired by horizontal gene transfer limits treatment options for these infections. In this study, we used innovative DNA sequencing methodologies to investigate how a model strain of E. faecalis discriminates its own DNA from foreign DNA, i.e., self versus nonself discrimination. We also assess the role of an E. faecalis genome modification system in modulating conjugative transfer of an antibiotic resistance plasmid. These results are significant because they demonstrate that differential genome modification impacts horizontal gene transfer frequencies in E. faecalis.
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Unique genomic arrangements in an invasive serotype M23 strain of Streptococcus pyogenes identify genes that induce hypervirulence. J Bacteriol 2014; 196:4089-102. [PMID: 25225265 DOI: 10.1128/jb.02131-14] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The first genome sequence of a group A Streptococcus pyogenes serotype M23 (emm23) strain (M23ND), isolated from an invasive human infection, has been completed. The genome of this opacity factor-negative (SOF(-)) strain is composed of a circular chromosome of 1,846,477 bp. Gene profiling showed that this strain contained six phage-encoded and 24 chromosomally inherited well-known virulence factors, as well as 11 pseudogenes. The bacterium has acquired four large prophage elements, ΦM23ND.1 to ΦM23ND.4, harboring genes encoding streptococcal superantigen (ssa), streptococcal pyrogenic exotoxins (speC, speH, and speI), and DNases (spd1 and spd3), with phage integrase genes being present at one flank of each phage insertion, suggesting that the phages were integrated by horizontal gene transfer. Comparative analyses revealed unique large-scale genomic rearrangements that result in genomic rearrangements that differ from those of previously sequenced GAS strains. These rearrangements resulted in an imbalanced genomic architecture and translocations of chromosomal virulence genes. The covS sensor in M23ND was identified as a pseudogene, resulting in the attenuation of speB function and increased expression of the genes for the chromosomal virulence factors multiple-gene activator (mga), M protein (emm23), C5a peptidase (scpA), fibronectin-binding proteins (sfbI and fbp54), streptolysin O (slo), hyaluronic acid capsule (hasA), streptokinase (ska), and DNases (spd and spd3), which were verified by PCR. These genes are responsible for facilitating host epithelial cell binding and and/or immune evasion, thus further contributing to the virulence of M23ND. In conclusion, strain M23ND has become highly pathogenic as the result of a combination of multiple genetic factors, particularly gene composition and mutations, prophage integrations, unique genomic rearrangements, and regulated expression of critical virulence factors.
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Baruch M, Belotserkovsky I, Hertzog BB, Ravins M, Dov E, McIver KS, Le Breton YS, Zhou Y, Cheng CY, Chen CY, Hanski E. An extracellular bacterial pathogen modulates host metabolism to regulate its own sensing and proliferation. Cell 2014; 156:97-108. [PMID: 24439371 DOI: 10.1016/j.cell.2013.12.007] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 09/16/2013] [Accepted: 11/15/2013] [Indexed: 01/10/2023]
Abstract
Successful infection depends on the ability of the pathogen to gain nutrients from the host. The extracellular pathogenic bacterium group A Streptococcus (GAS) causes a vast array of human diseases. By using the quorum-sensing sil system as a reporter, we found that, during adherence to host cells, GAS delivers streptolysin toxins, creating endoplasmic reticulum stress. This, in turn, increases asparagine (ASN) synthetase expression and the production of ASN. The released ASN is sensed by the bacteria, altering the expression of ∼17% of GAS genes of which about one-third are dependent on the two-component system TrxSR. The expression of the streptolysin toxins is strongly upregulated, whereas genes linked to proliferation are downregulated in ASN absence. Asparaginase, a widely used chemotherapeutic agent, arrests GAS growth in human blood and blocks GAS proliferation in a mouse model of human bacteremia. These results delineate a pathogenic pathway and propose a therapeutic strategy against GAS infections.
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Affiliation(s)
- Moshe Baruch
- Department of Microbiology and Molecular Genetics, The Hebrew University of Jerusalem, Faculty of Medicine, Jerusalem 91120, Israel
| | - Ilia Belotserkovsky
- Department of Microbiology and Molecular Genetics, The Hebrew University of Jerusalem, Faculty of Medicine, Jerusalem 91120, Israel
| | - Baruch B Hertzog
- Department of Microbiology and Molecular Genetics, The Hebrew University of Jerusalem, Faculty of Medicine, Jerusalem 91120, Israel
| | - Miriam Ravins
- Department of Microbiology and Molecular Genetics, The Hebrew University of Jerusalem, Faculty of Medicine, Jerusalem 91120, Israel
| | - Eran Dov
- Department of Microbiology and Molecular Genetics, The Hebrew University of Jerusalem, Faculty of Medicine, Jerusalem 91120, Israel
| | - Kevin S McIver
- Department of Cell Biology & Molecular Genetics and Maryland Pathogen Research Institut, University of Maryland, College Park, MD 20742, USA
| | - Yoann S Le Breton
- Department of Cell Biology & Molecular Genetics and Maryland Pathogen Research Institut, University of Maryland, College Park, MD 20742, USA
| | - Yiting Zhou
- Mechanism of Inflammation Program, Center for Research Excellence & Technological Enterprise (CREATE), National University of Singapore and The Hebrew University of Jerusalem (HUJI), Singapore 138602, Singapore
| | - Catherine Youting Cheng
- Mechanism of Inflammation Program, Center for Research Excellence & Technological Enterprise (CREATE), National University of Singapore and The Hebrew University of Jerusalem (HUJI), Singapore 138602, Singapore
| | | | - Emanuel Hanski
- Department of Microbiology and Molecular Genetics, The Hebrew University of Jerusalem, Faculty of Medicine, Jerusalem 91120, Israel; Mechanism of Inflammation Program, Center for Research Excellence & Technological Enterprise (CREATE), National University of Singapore and The Hebrew University of Jerusalem (HUJI), Singapore 138602, Singapore.
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Le Breton Y, Mistry P, Valdes KM, Quigley J, Kumar N, Tettelin H, McIver KS. Genome-wide identification of genes required for fitness of group A Streptococcus in human blood. Infect Immun 2013; 81:862-75. [PMID: 23297387 PMCID: PMC3584890 DOI: 10.1128/iai.00837-12] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Accepted: 12/15/2012] [Indexed: 12/27/2022] Open
Abstract
The group A streptococcus (GAS) is a strict human pathogen responsible for a wide spectrum of diseases. Although GAS genome sequences are available, functional genomic analyses have been limited. We developed a mariner-based transposon, osKaR, designed to perform Transposon-Site Hybridization (TraSH) in GAS and successfully tested its use in several invasive serotypes. A complex osKaR mutant library in M1T1 GAS strain 5448 was subjected to negative selection in human blood to identify genes important for GAS fitness in this clinically relevant environment. Mutants underrepresented after growth in blood (output pool) compared to growth in rich media (input pool) were identified using DNA microarray hybridization of transposon-specific tags en masse. Using blood from three different donors, we identified 81 genes that met our criteria for reduced fitness in blood from at least two individuals. Genes known to play a role in survival of GAS in blood were found, including those encoding the virulence regulator Mga (mga), the peroxide response regulator PerR (perR), and the RofA-like regulator Ralp-3 (ralp3). We also identified genes previously reported for their contribution to sepsis in other pathogens, such as de novo nucleotide synthesis (purD, purA, pyrB, carA, carB, guaB), sugar metabolism (scrB, fruA), zinc uptake (adcC), and transcriptional regulation (cpsY). To validate our findings, independent mutants with mutations in 10 different genes identified in our screen were confirmed to be defective for survival in blood bactericidal assays. Overall, this work represents the first use of TraSH in GAS to identify potential virulence genes.
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Affiliation(s)
- Yoann Le Breton
- Department of Cell Biology & Molecular Genetics and Maryland Pathogen Research Institute, University of Maryland, College Park, Maryland, USA
| | - Pragnesh Mistry
- Department of Cell Biology & Molecular Genetics and Maryland Pathogen Research Institute, University of Maryland, College Park, Maryland, USA
| | - Kayla M. Valdes
- Department of Cell Biology & Molecular Genetics and Maryland Pathogen Research Institute, University of Maryland, College Park, Maryland, USA
| | - Jeffrey Quigley
- Department of Cell Biology & Molecular Genetics and Maryland Pathogen Research Institute, University of Maryland, College Park, Maryland, USA
| | - Nikhil Kumar
- Institute for Genome Sciences and Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Hervé Tettelin
- Institute for Genome Sciences and Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Kevin S. McIver
- Department of Cell Biology & Molecular Genetics and Maryland Pathogen Research Institute, University of Maryland, College Park, Maryland, USA
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Liang Z, Zhang Y, Agrahari G, Chandrahas V, Glinton K, Donahue DL, Balsara RD, Ploplis VA, Castellino FJ. A natural inactivating mutation in the CovS component of the CovRS regulatory operon in a pattern D Streptococcal pyogenes strain influences virulence-associated genes. J Biol Chem 2013; 288:6561-73. [PMID: 23316057 PMCID: PMC3585089 DOI: 10.1074/jbc.m112.442657] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 12/28/2012] [Indexed: 11/06/2022] Open
Abstract
A skin-tropic invasive group A Streptococcus pyogenes (GAS) strain, AP53, contains a natural inactivating mutation in the covS gene (covS(M)) of the two-component responder (CovR)/sensor (CovS) gene regulatory system. The effects of this mutation on specific GAS virulence determinants have been assessed, with emphasis on expression of the extracellular protease, streptococcal pyrogenic exotoxin B (SpeB), capsular hyaluronic acid, and proteins that allow host plasmin assembly on the bacterial surface, viz. a high affinity plasminogen (Pg)/plasmin receptor, Pg-binding group A streptococcal M protein (PAM), and the human Pg activator streptokinase. To further illuminate mechanisms of the functioning of CovRS in the virulence of AP53, two AP53 isogenic strains were generated, one in which the natural covS(M) gene was mutated to WT-covS (AP53/covS(WT)) and a strain that contained an inactivated covR gene (AP53/ΔcovR). Two additional strains that do not contain PAM, viz. WT-NS931 and NS931/covS(M), were also employed. SpeB was not measurably expressed in strains containing covR(WT)/covS(M), whereas in strains with natural or engineered covR(WT)/covS(WT), SpeB expression was highly up-regulated. Alternatively, capsule synthesis via the hasABC operon was enhanced in strain AP53/covS(M), whereas streptokinase expression was only slightly affected by the covS inactivation. PAM expression was not substantially influenced by the covS mutation, suggesting that covRS had minimal effects on the mga regulon that controls PAM expression. These results demonstrate that a covS inactivation results in virulence gene alterations and also suggest that the CovR phosphorylation needed for gene up- or down-regulation can occur by alternative pathways to CovS kinase.
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Affiliation(s)
- Zhong Liang
- From the W. M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Yueling Zhang
- From the W. M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Garima Agrahari
- From the W. M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Vishwanatha Chandrahas
- From the W. M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Kristofor Glinton
- From the W. M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Deborah L. Donahue
- From the W. M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Rashna D. Balsara
- From the W. M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Victoria A. Ploplis
- From the W. M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Francis J. Castellino
- From the W. M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
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Heffron JD, Jenkins AL, Bozue JA, Kaatz LK, Cote CK, Welkos SL. Phenotypic changes in spores and vegetative cells of Bacillus anthracis associated with BenK. Microb Pathog 2012. [PMID: 23178382 DOI: 10.1016/j.micpath.2012.11.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
A transposon insertional mutagenesis spore library of the pathogen Bacillus anthracis was screened to identify mutants altered in germination kinetics. One mutant exhibited an accelerated rate of germination in association with disruption of benK. This gene encodes a putative protein with high homology to membrane transporters that facilitate benzoate transport. We hypothesized that BenK may not be only spore associated, but also have a vegetative cell role. A reporter strain with a translational fusion of benK to green fluorescent protein demonstrated that full-length BenK was present in vegetative cells and that a BenK degradation product was present in spores by detecting the reporter using fluorescence and Western blot analysis. A minimum inhibitory concentration assay indicated that vegetative cells of a benK::Kan mutant were more susceptible to the antimicrobial effects of Na-benzoate. The mutant spores germinated to a greater extent within 1 h than the wild type in an in vitro fluorescence assay. The disruption of benK also resulted in spores that were less readily phagocytosed in a macrophage assay. Despite these altered in vitro phenotypes, no apparent effect of the BenK protein on virulence in the intranasal mouse model or the guinea pig competitive assay was observed. This work shows that, although the BenK protein does not impact fitness or virulence in an infection model, it is involved in other aspects of both the spore and vegetative forms of the organism.
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Affiliation(s)
- Jared D Heffron
- United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Bacteriology Division, 1425 Porter Street, Fort Detrick, Frederick, MD 21702-5011, USA
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Hossain MS, Biswas I. An extracelluar protease, SepM, generates functional competence-stimulating peptide in Streptococcus mutans UA159. J Bacteriol 2012; 194:5886-96. [PMID: 22923597 PMCID: PMC3486099 DOI: 10.1128/jb.01381-12] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 08/21/2012] [Indexed: 02/04/2023] Open
Abstract
Cell-cell communication in Gram-positive bacteria often depends on the production of extracellular peptides. The cariogenic bacterium Streptococcus mutans employs so-called competence-stimulating peptide (CSP) to stimulate mutacin (bacteriocin) production and competence development through the activation of the ComDE two-component pathway. In S. mutans, CSP is secreted as a 21-residue peptide; however, mass spectrometric analysis of culture supernatant indicates the presence of an 18-residue proteolytically cleaved species. In this study, using a transposon mutagenesis screening, we identified a cell surface protease that is involved in the processing of 21-residue CSP to generate the 18-residue CSP. We named this protease SepM for streptococcal extracellular protease required for mutacin production. We showed that the truncated 18-residue peptide is the biologically active form and that the specific postexport cleavage is a prerequisite to activate the ComDE two-component signal transduction pathway. We also showed that the CSP and the mutacins are exported outside the cell by the same ABC transporter, NlmTE. Our study further confirmed that the ComDE two-component system is absolutely necessary for mutacin production in S. mutans.
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Hondorp ER, Hou SC, Hempstead AD, Hause LL, Beckett DM, McIver KS. Characterization of the Group A Streptococcus Mga virulence regulator reveals a role for the C-terminal region in oligomerization and transcriptional activation. Mol Microbiol 2012; 83:953-67. [PMID: 22468267 DOI: 10.1111/j.1365-2958.2012.07980.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The Group A Streptococcus (GAS) is a strict human pathogen that causes a broad spectrum of illnesses. One of the key regulators of virulence in GAS is the transcriptional activator Mga, which co-ordinates the early stages of infection. Although the targets of Mga have been well characterized, basic biochemical analyses have been limited due to difficulties in obtaining purified protein. In this study, high-level purification of soluble Mga was achieved, enabling the first detailed characterization of the protein. Fluorescence titrations coupled with filter-binding assays indicate that Mga binds cognate DNA with nanomolar affinity. Gel filtration analyses, analytical ultracentrifugation and co-immunoprecipitation experiments demonstrate that Mga forms oligomers in solution.Moreover, the ability of the protein to oligomerize in solution was found to correlate with transcriptional activation; DNA binding appears to be necessary but insufficient for full activity. Truncation analyses reveal that the uncharacterized C-terminal region of Mga, possessing similarity to phosphotransferase system EIIB proteins, plays a critical role in oligomerization and in vivo activity. Mga from a divergent serotype was found to behave similarly, suggesting that this study describes a general mechanism for Mga regulation of target virulence genes within GAS and provides insight into related regulators in other Gram-positive pathogens.
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Affiliation(s)
- Elise R Hondorp
- Department of Cell Biology & Molecular Genetics andMaryland Pathogen Research Institute, University of Maryland, College Park, MD 20742, USA
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45
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Kang SO, Wright JO, Tesorero RA, Lee H, Beall B, Cho KH. Thermoregulation of capsule production by Streptococcus pyogenes. PLoS One 2012; 7:e37367. [PMID: 22615992 PMCID: PMC3355187 DOI: 10.1371/journal.pone.0037367] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Accepted: 04/20/2012] [Indexed: 11/18/2022] Open
Abstract
The capsule of Streptococcus pyogenes serves as an adhesin as well as an anti-phagocytic factor by binding to CD44 on keratinocytes of the pharyngeal mucosa and the skin, the main entry sites of the pathogen. We discovered that S. pyogenes HSC5 and MGAS315 strains are further thermoregulated for capsule production at a post-transcriptional level in addition to the transcriptional regulation by the CovRS two-component regulatory system. When the transcription of the hasABC capsular biosynthetic locus was de-repressed through mutation of the covRS system, the two strains, which have been used for pathogenesis studies in the laboratory, exhibited markedly increased capsule production at sub-body temperature. Employing transposon mutagenesis, we found that CvfA, a previously identified membrane-associated endoribonuclease, is required for the thermoregulation of capsule synthesis. The mutation of the cvfA gene conferred increased capsule production regardless of temperature. However, the amount of the capsule transcript was not changed by the mutation, indicating that a post-transcriptional regulator mediates between CvfA and thermoregulated capsule production. When we tested naturally occurring invasive mucoid strains, a high percentage (11/53, 21%) of the strains exhibited thermoregulated capsule production. As expected, the mucoid phenotype of these strains at sub-body temperature was due to mutations within the chromosomal covRS genes. Capsule thermoregulation that exhibits high capsule production at lower temperatures that occur on the skin or mucosal surface potentially confers better capability of adhesion and invasion when S. pyogenes penetrates the epithelial surface.
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Affiliation(s)
- Song Ok Kang
- Department of Microbiology, Southern Illinois University Carbondale, Carbondale, Illinois, United States of America
| | - Jordan O. Wright
- Department of Microbiology, Southern Illinois University Carbondale, Carbondale, Illinois, United States of America
| | - Rafael A. Tesorero
- Department of Microbiology, Southern Illinois University Carbondale, Carbondale, Illinois, United States of America
| | - Hyunwoo Lee
- Center for Pharmaceutical Biotechnology, University of Illinois, Chicago, Illinois, United States of America
| | - Bernard Beall
- Streptococcus Laboratory, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Kyu Hong Cho
- Department of Microbiology, Southern Illinois University Carbondale, Carbondale, Illinois, United States of America
- * E-mail:
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Raz A, Talay SR, Fischetti VA. Cellular aspects of the distinct M protein and SfbI anchoring pathways in Streptococcus pyogenes. Mol Microbiol 2012; 84:631-47. [PMID: 22512736 DOI: 10.1111/j.1365-2958.2012.08047.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Wall-anchored surface proteins are critical for the in vivo survival of Streptococcus pyogenes. Cues in the signal sequence direct the membrane translocation of surface proteins: M protein to the septum, and SfbI to the poles. Both proteins are subsequently anchored to the wall by the membrane bound enzyme sortase A. However, the cellular features of these pathways are not fully understood. Here we show that M protein and SfbI are anchored simultaneously throughout the cell cycle. M protein is rapidly anchored at the septum, and in part of the cell cycle, is anchored simultaneously at the mother and daughter septa. Conversely, SfbI accumulates gradually on peripheral peptidoglycan, resulting in a polar distribution. Sortase is not required for translocation of M protein or SfbI at their respective locations. Methicillin-induced unbalanced peptidoglycan synthesis diminishes surface M protein but not SfbI. Furthermore, overexpression of the division regulator DivIVA also diminishes surface M protein but increases SfbI. These results demonstrate a close connection between the regulation of cell division and protein anchoring. Better understanding of the spatial regulation of surface anchoring may lead to the identification of novel targets for the development of anti-infective agents, given the importance of surface molecules for pathogenesis.
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Affiliation(s)
- Assaf Raz
- Bacterial Pathogenesis and Immunology, Rockefeller University, New York, USA.
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Egan SA, Ward PN, Watson M, Field TR, Leigh JA. Vru (Sub0144) controls expression of proven and putative virulence determinants and alters the ability of Streptococcus uberis to cause disease in dairy cattle. MICROBIOLOGY-SGM 2012; 158:1581-1592. [PMID: 22383474 PMCID: PMC3541772 DOI: 10.1099/mic.0.055863-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The regulation and control of gene expression in response to differing environmental stimuli is crucial for successful pathogen adaptation and persistence. The regulatory gene vru of Streptococcus uberis encodes a stand-alone response regulator with similarity to the Mga of group A Streptococcus. Mga controls expression of a number of important virulence determinants. Experimental intramammary challenge of dairy cattle with a mutant of S. uberis carrying an inactivating lesion in vru showed reduced ability to colonize the mammary gland and an inability to induce clinical signs of mastitis compared with the wild-type strain. Analysis of transcriptional differences of gene expression in the mutant, determined by microarray analysis, identified a number of coding sequences with altered expression in the absence of Vru. These consisted of known and putative virulence determinants, including Lbp (Sub0145), SclB (Sub1095), PauA (Sub1785) and hasA (Sub1696).
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Affiliation(s)
- Sharon A Egan
- The School of Veterinary Medicine and Science, The University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Leicestershire LE12 5RD, UK
| | - Philip N Ward
- Nuffield Department of Clinical Laboratory Sciences, Oxford University, John Radcliffe Hospital, Headington, Oxfordshire OX3 9DU, UK
| | - Michael Watson
- Institute for Animal Health, Compton, Berkshire RG20 7NN, UK.,ARK-Genomics, The Roslin Institute, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
| | - Terence R Field
- Institute for Animal Health, Compton, Berkshire RG20 7NN, UK
| | - James A Leigh
- The School of Veterinary Medicine and Science, The University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Leicestershire LE12 5RD, UK
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Inhibitor of streptokinase gene expression improves survival after group A streptococcus infection in mice. Proc Natl Acad Sci U S A 2012; 109:3469-74. [PMID: 22331877 DOI: 10.1073/pnas.1201031109] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The widespread occurrence of antibiotic resistance among human pathogens is a major public health problem. Conventional antibiotics typically target bacterial killing or growth inhibition, resulting in strong selection for the development of antibiotic resistance. Alternative therapeutic approaches targeting microbial pathogenicity without inhibiting growth might minimize selection for resistant organisms. Compounds inhibiting gene expression of streptokinase (SK), a critical group A streptococcal (GAS) virulence factor, were identified through a high-throughput, growth-based screen on a library of 55,000 small molecules. The lead compound [Center for Chemical Genomics 2979 (CCG-2979)] and an analog (CCG-102487) were confirmed to also inhibit the production of active SK protein. Microarray analysis of GAS grown in the presence of CCG-102487 showed down-regulation of a number of important virulence factors in addition to SK, suggesting disruption of a general virulence gene regulatory network. CCG-2979 and CCG-102487 both enhanced granulocyte phagocytosis and killing of GAS in an in vitro assay, and CCG-2979 also protected mice from GAS-induced mortality in vivo. These data suggest that the class of compounds represented by CCG-2979 may be of therapeutic value for the treatment of GAS and potentially other gram-positive infections in humans.
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49
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Biological roles of nontypeable Haemophilus influenzae type IV pilus proteins encoded by the pil and com operons. J Bacteriol 2012; 194:1927-33. [PMID: 22328674 DOI: 10.1128/jb.06540-11] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
We previously demonstrated that one or more products of the genes in the pil and com gene clusters of the opportunistic human respiratory pathogen nontypeable Haemophilus influenzae (NTHI) are required for type IV pilus (Tfp) biogenesis and function. Here, we have now demonstrated that the pilABCD and comABCDEF gene clusters are operons and that the product of each gene is essential for normal pilus function. Mutants with nonpolar deletions in each of the 10 pil and com genes had an adherence defect when primary human airway cells were used as the target. These mutants were also diminished in their ability to form a biofilm in vitro and, additionally, were deficient in natural transformation. Collectively, our data demonstrate that the product of each gene within these operons is required for the normal biogenesis and/or function of NTHI Tfp. Based on the similarity of PilA to other type IV pilins, we further predicted that the product of the pilA gene would be the major pilin subunit. Toward that end, we also demonstrated by immunogold labeling and mass spectrometry that PilA is indeed the majority type IV pilin protein expressed by NTHI. These new observations set the stage for experiments designed to dissect the function of each of the proteins encoded by genes within the pil and com gene clusters. The ability to characterize individual proteins with vital roles in NTHI colonization or pathogenesis has the potential to reduce the burden of NTHI-induced diseases through development of a Tfp-derived vaccine or a pilus-directed therapeutic.
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50
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BrpA is involved in regulation of cell envelope stress responses in Streptococcus mutans. Appl Environ Microbiol 2012; 78:2914-22. [PMID: 22327589 DOI: 10.1128/aem.07823-11] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previous studies have shown that BrpA plays a major role in acid and oxidative stress tolerance and biofilm formation by Streptococcus mutans. Mutant strains lacking BrpA also display increased autolysis and decreased viability, suggesting a role for BrpA in cell envelope integrity. In this study, we examined the impact of BrpA deficiency on cell envelope stresses induced by envelope-active antimicrobials. Compared to the wild-type strain UA159, the BrpA-deficient mutant (TW14D) was significantly more susceptible to antimicrobial agents, especially lipid II inhibitors. Several genes involved in peptidoglycan synthesis were identified by DNA microarray analysis as downregulated in TW14D. Luciferase reporter gene fusion assays also revealed that expression of brpA is regulated in response to environmental conditions and stresses induced by exposure to subinhibitory concentrations of cell envelope antimicrobials. In a Galleria mellonella (wax worm) model, BrpA deficiency was shown to diminish the virulence of S. mutans OMZ175, which, unlike S. mutans UA159, efficiently kills the worms. Collectively, these results suggest that BrpA plays a role in the regulation of cell envelope integrity and that deficiency of BrpA adversely affects the fitness and diminishes the virulence of OMZ175, a highly invasive strain of S. mutans.
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