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Zhang T, Tamman H, Coppieters 't Wallant K, Kurata T, LeRoux M, Srikant S, Brodiazhenko T, Cepauskas A, Talavera A, Martens C, Atkinson GC, Hauryliuk V, Garcia-Pino A, Laub MT. Direct activation of a bacterial innate immune system by a viral capsid protein. Nature 2022; 612:132-140. [PMID: 36385533 PMCID: PMC9712102 DOI: 10.1038/s41586-022-05444-z] [Citation(s) in RCA: 47] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 10/13/2022] [Indexed: 11/17/2022]
Abstract
Bacteria have evolved diverse immunity mechanisms to protect themselves against the constant onslaught of bacteriophages1-3. Similar to how eukaryotic innate immune systems sense foreign invaders through pathogen-associated molecular patterns4 (PAMPs), many bacterial immune systems that respond to bacteriophage infection require phage-specific triggers to be activated. However, the identities of such triggers and the sensing mechanisms remain largely unknown. Here we identify and investigate the anti-phage function of CapRelSJ46, a fused toxin-antitoxin system that protects Escherichia coli against diverse phages. Using genetic, biochemical and structural analyses, we demonstrate that the C-terminal domain of CapRelSJ46 regulates the toxic N-terminal region, serving as both antitoxin and phage infection sensor. Following infection by certain phages, newly synthesized major capsid protein binds directly to the C-terminal domain of CapRelSJ46 to relieve autoinhibition, enabling the toxin domain to pyrophosphorylate tRNAs, which blocks translation to restrict viral infection. Collectively, our results reveal the molecular mechanism by which a bacterial immune system directly senses a conserved, essential component of phages, suggesting a PAMP-like sensing model for toxin-antitoxin-mediated innate immunity in bacteria. We provide evidence that CapRels and their phage-encoded triggers are engaged in a 'Red Queen conflict'5, revealing a new front in the intense coevolutionary battle between phages and bacteria. Given that capsid proteins of some eukaryotic viruses are known to stimulate innate immune signalling in mammalian hosts6-10, our results reveal a deeply conserved facet of immunity.
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Affiliation(s)
- Tong Zhang
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Hedvig Tamman
- Cellular and Molecular Microbiology, Faculté des Sciences, Université Libre de Bruxelles, (ULB), Brussels, Belgium
| | - Kyo Coppieters 't Wallant
- Centre for Structural Biology and Bioinformatics, Université Libre de Bruxelles (ULB), Bruxelles, Belgium
| | - Tatsuaki Kurata
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Michele LeRoux
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Sriram Srikant
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | - Albinas Cepauskas
- Cellular and Molecular Microbiology, Faculté des Sciences, Université Libre de Bruxelles, (ULB), Brussels, Belgium
| | - Ariel Talavera
- Cellular and Molecular Microbiology, Faculté des Sciences, Université Libre de Bruxelles, (ULB), Brussels, Belgium
| | - Chloe Martens
- Centre for Structural Biology and Bioinformatics, Université Libre de Bruxelles (ULB), Bruxelles, Belgium
| | - Gemma C Atkinson
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Vasili Hauryliuk
- Department of Experimental Medical Science, Lund University, Lund, Sweden.
- Institute of Technology, University of Tartu, Tartu, Estonia.
| | - Abel Garcia-Pino
- Cellular and Molecular Microbiology, Faculté des Sciences, Université Libre de Bruxelles, (ULB), Brussels, Belgium.
- WELBIO, Brussels, Belgium.
| | - Michael T Laub
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, USA.
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LeRoux M, Srikant S, Teodoro GIC, Zhang T, Littlehale ML, Doron S, Badiee M, Leung AKL, Sorek R, Laub MT. The DarTG toxin-antitoxin system provides phage defence by ADP-ribosylating viral DNA. Nat Microbiol 2022; 7:1028-1040. [PMID: 35725776 PMCID: PMC9250638 DOI: 10.1038/s41564-022-01153-5] [Citation(s) in RCA: 56] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 05/18/2022] [Indexed: 01/03/2023]
Abstract
Toxin-antitoxin (TA) systems are broadly distributed, yet poorly conserved, genetic elements whose biological functions are unclear and controversial. Some TA systems may provide bacteria with immunity to infection by their ubiquitous viral predators, bacteriophages. To identify such TA systems, we searched bioinformatically for those frequently encoded near known phage defence genes in bacterial genomes. This search identified homologues of DarTG, a recently discovered family of TA systems whose biological functions and natural activating conditions were unclear. Representatives from two different subfamilies, DarTG1 and DarTG2, strongly protected E. coli MG1655 against different phages. We demonstrate that for each system, infection with either RB69 or T5 phage, respectively, triggers release of the DarT toxin, a DNA ADP-ribosyltransferase, that then modifies viral DNA and prevents replication, thereby blocking the production of mature virions. Further, we isolated phages that have evolved to overcome DarTG defence either through mutations to their DNA polymerase or to an anti-DarT factor, gp61.2, encoded by many T-even phages. Collectively, our results indicate that phage defence may be a common function for TA systems and reveal the mechanism by which DarTG systems inhibit phage infection.
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Affiliation(s)
- Michele LeRoux
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Sriram Srikant
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | - Tong Zhang
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Megan L Littlehale
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Shany Doron
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Mohsen Badiee
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Anthony K L Leung
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
- Department of Molecular Biology and Genetics, Department of Genetic Medicine, Department of Oncology, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Rotem Sorek
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Michael T Laub
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, USA.
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Abstract
Toxin-antitoxin (TA) systems are ubiquitous genetic elements in bacteria that consist of a growth-inhibiting toxin and its cognate antitoxin. These systems are prevalent in bacterial chromosomes, plasmids, and phage genomes, but individual systems are not highly conserved, even among closely related strains. The biological functions of TA systems have been controversial and enigmatic, although a handful of these systems have been shown to defend bacteria against their viral predators, bacteriophages. Additionally, their patterns of conservation-ubiquitous, but rapidly acquired and lost from genomes-as well as the co-occurrence of some TA systems with known phage defense elements are suggestive of a broader role in mediating phage defense. Here, we review the existing evidence for phage defense mediated by TA systems, highlighting how toxins are activated by phage infection and how toxins disrupt phage replication. We also discuss phage-encoded systems that counteract TA systems, underscoring the ongoing coevolutionary battle between bacteria and phage. We anticipate that TA systems will continue to emerge as central players in the innate immunity of bacteria against phage. Expected final online publication date for the Annual Review of Microbiology, Volume 76 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Michele LeRoux
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA;
| | - Michael T Laub
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA; .,Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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4
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LeRoux M, Culviner PH, Liu YJ, Littlehale ML, Laub MT. Stress Can Induce Transcription of Toxin-Antitoxin Systems without Activating Toxin. Mol Cell 2020; 79:280-292.e8. [PMID: 32533919 PMCID: PMC7368831 DOI: 10.1016/j.molcel.2020.05.028] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 04/02/2020] [Accepted: 05/20/2020] [Indexed: 12/14/2022]
Abstract
Toxin-antitoxin (TA) systems are ubiquitous genetic elements in bacterial genomes, but their functions are controversial. Although they are frequently postulated to regulate cell growth following stress, few null phenotypes for TA systems have been reported. Here, we show that TA transcript levels can increase substantially in response to stress, but toxin is not liberated. We find that the growth of an Escherichia coli strain lacking ten TA systems encoding endoribonuclease toxins is not affected following exposure to six stresses that each trigger TA transcription. Additionally, using RNA sequencing, we find no evidence of mRNA cleavage following stress. Stress-induced transcription arises from antitoxin degradation and relief of transcriptional autoregulation. Importantly, although free antitoxin is readily degraded in vivo, antitoxin bound to toxin is protected from proteolysis, preventing release of active toxin. Thus, transcription is not a reliable marker of TA activity, and TA systems do not strongly promote survival following individual stresses.
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Affiliation(s)
- Michele LeRoux
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Peter H Culviner
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Yue J Liu
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Megan L Littlehale
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Michael T Laub
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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5
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Whitney JC, Quentin D, Sawai S, LeRoux M, Harding BN, Ledvina HE, Tran BQ, Robinson H, Goo YA, Goodlett DR, Raunser S, Mougous JD. An interbacterial NAD(P)(+) glycohydrolase toxin requires elongation factor Tu for delivery to target cells. Cell 2015; 163:607-19. [PMID: 26456113 DOI: 10.1016/j.cell.2015.09.027] [Citation(s) in RCA: 156] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 07/15/2015] [Accepted: 08/19/2015] [Indexed: 11/17/2022]
Abstract
Type VI secretion (T6S) influences the composition of microbial communities by catalyzing the delivery of toxins between adjacent bacterial cells. Here, we demonstrate that a T6S integral membrane toxin from Pseudomonas aeruginosa, Tse6, acts on target cells by degrading the universally essential dinucleotides NAD(+) and NADP(+). Structural analyses of Tse6 show that it resembles mono-ADP-ribosyltransferase proteins, such as diphtheria toxin, with the exception of a unique loop that both excludes proteinaceous ADP-ribose acceptors and contributes to hydrolysis. We find that entry of Tse6 into target cells requires its binding to an essential housekeeping protein, translation elongation factor Tu (EF-Tu). These proteins participate in a larger assembly that additionally directs toxin export and provides chaperone activity. Visualization of this complex by electron microscopy defines the architecture of a toxin-loaded T6S apparatus and provides mechanistic insight into intercellular membrane protein delivery between bacteria.
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Affiliation(s)
- John C Whitney
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
| | - Dennis Quentin
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
| | - Shin Sawai
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
| | - Michele LeRoux
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
| | - Brittany N Harding
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
| | - Hannah E Ledvina
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
| | - Bao Q Tran
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD 21201, USA
| | - Howard Robinson
- Biology Department, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Young Ah Goo
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD 21201, USA
| | - David R Goodlett
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD 21201, USA
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
| | - Joseph D Mougous
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA; Howard Hughes Medical Institute, Seattle, WA 98195, USA.
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Abstract
Here we propose that bacteria detect and respond to threats posed by other bacteria via an innate immune-like process that we term danger sensing. We find support for this contention by reexamining existing literature from the perspective that intermicrobial antagonism, not opportunistic pathogenesis, is the major evolutionary force shaping the defensive behaviors of most bacteria. We conclude that many bacteria possess danger sensing pathways composed of a danger signal receptor and corresponding signal transduction mechanism that regulate pathways important for survival in the presence of the perceived competitor.
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Affiliation(s)
- Michele LeRoux
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA; Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98195, USA
| | - S Brook Peterson
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
| | - Joseph D Mougous
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA; Howard Hughes Medical Institute, Seattle, WA 98195, USA.
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7
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LeRoux M, Kirkpatrick RL, Montauti EI, Tran BQ, Peterson SB, Harding BN, Whitney JC, Russell AB, Traxler B, Goo YA, Goodlett DR, Wiggins PA, Mougous JD. Kin cell lysis is a danger signal that activates antibacterial pathways of Pseudomonas aeruginosa. eLife 2015; 4. [PMID: 25643398 PMCID: PMC4348357 DOI: 10.7554/elife.05701] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 01/30/2015] [Indexed: 12/21/2022] Open
Abstract
The perception and response to cellular death is an important aspect of multicellular eukaryotic life. For example, damage-associated molecular patterns activate an inflammatory cascade that leads to removal of cellular debris and promotion of healing. We demonstrate that lysis of Pseudomonas aeruginosa cells triggers a program in the remaining population that confers fitness in interspecies co-culture. We find that this program, termed P. aeruginosa response to antagonism (PARA), involves rapid deployment of antibacterial factors and is mediated by the Gac/Rsm global regulatory pathway. Type VI secretion, and, unexpectedly, conjugative type IV secretion within competing bacteria, induce P. aeruginosa lysis and activate PARA, thus providing a mechanism for the enhanced capacity of P. aeruginosa to target bacteria that elaborate these factors. Our finding that bacteria sense damaged kin and respond via a widely distributed pathway to mount a complex response raises the possibility that danger sensing is an evolutionarily conserved process. DOI:http://dx.doi.org/10.7554/eLife.05701.001 Bacteria live in diverse and changing environments where resources such as nutrients and space are often limited. They have thus evolved many survival strategies, including competitive and cooperative behaviors. In the first case, bacteria antagonize or prevent the growth of other microorganisms competing with them for resources, such as by generating antibiotics that specifically target rivals. During cooperation, bacteria may coordinate the production of compounds that have a shared benefit for members of their community. In multicellular organisms, some cell types sense harmful microorganisms by the injury they cause in neighboring cells. This triggers a process that can lead to the production of molecules that kill the invaders and factors that promote the repair of cellular damage. An equivalent process has so far not been described for single-celled organisms such as bacteria. However, bacteria often live in structured groups containing many different species. In this type of growth environment, the ability of bacteria to sense when others of their species are attacked and to respond by taking measures to defend themselves could improve their chances of survival. Now, LeRoux et al. reveal that the bacterium Pseudomonas aeruginosa is able to detect ‘danger signals’ released when neighboring P. aeruginosa cells are killed by other bacteria. These signals trigger a response in surviving cells by turning on a pathway that controls a number of antibacterial factors. These include the production of the so-called ‘type VI secretion system’, a molecular machine that delivers a potent cocktail of antibacterial toxins directly into nearby bacteria. This process, which LeRoux et al. have named ‘P. aeruginosa response to antagonism’, or PARA for short, enables P. aeruginosa to thrive when grown with competing bacterial species. P. aeruginosa is notorious for infecting the lungs of people with the genetic disease cystic fibrosis, as well as chronic wounds often found in people with diabetes. In both cases, when P. aeruginosa is present, the numbers of other, often less harmful organisms, tend to decrease. PARA may be one reason for the success of P. aeruginosa in these multi-species infections. DOI:http://dx.doi.org/10.7554/eLife.05701.002
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Affiliation(s)
- Michele LeRoux
- Department of Microbiology, University of Washington, Seattle, United States
| | - Robin L Kirkpatrick
- Department of Microbiology, University of Washington, Seattle, United States
| | - Elena I Montauti
- Department of Microbiology, University of Washington, Seattle, United States
| | - Bao Q Tran
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, United States
| | - S Brook Peterson
- Department of Microbiology, University of Washington, Seattle, United States
| | - Brittany N Harding
- Department of Microbiology, University of Washington, Seattle, United States
| | - John C Whitney
- Department of Microbiology, University of Washington, Seattle, United States
| | - Alistair B Russell
- Department of Microbiology, University of Washington, Seattle, United States
| | - Beth Traxler
- Department of Microbiology, University of Washington, Seattle, United States
| | - Young Ah Goo
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, United States
| | - David R Goodlett
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, United States
| | - Paul A Wiggins
- Department of Physics, University of Washington, Seattle, United States
| | - Joseph D Mougous
- Department of Microbiology, University of Washington, Seattle, United States
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Corbitt J, LeRoux M, Kirkpatrick R, Mougous J, Wiggins PA. Dissecting the Mechanism of Type VI Secretion System Effector Delivery by Fluorescence Cross-Correlation Microscopy. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.3267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Russell AB, LeRoux M, Hathazi K, Agnello DM, Ishikawa T, Wiggins PA, Wai SN, Mougous JD. Diverse type VI secretion phospholipases are functionally plastic antibacterial effectors. Nature 2013; 496:508-12. [PMID: 23552891 PMCID: PMC3652678 DOI: 10.1038/nature12074] [Citation(s) in RCA: 268] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 03/15/2013] [Indexed: 11/17/2022]
Abstract
Membranes allow the compartmentalization of biochemical processes and are therefore fundamental to life. The conservation of the cellular membrane, combined with its accessibility to secreted proteins, has made it a common target of factors mediating antagonistic interactions between diverse organisms. Here we report the discovery of a diverse superfamily of bacterial phospholipase enzymes. Within this superfamily, we defined enzymes with phospholipase A1 (PLA1) and A2 (PLA2) activity, which are common in host cell-targeting bacterial toxins and the venoms of certain insects and reptiles1,2. However, we find that the fundamental role of the superfamily is to mediate antagonistic bacterial interactions as effectors of the type VI secretion system (T6SS) translocation apparatus; accordingly, we name these proteins type VI lipase effectors (Tle). Our analyses indicate that PldA of Pseudomonas aeruginosa, a eukaryotic-like phospholipase D (PLD)3, is a member of the Tle superfamily and the founding substrate of the haemolysin co-regulated protein secretion island II T6SS (H2-T6SS). While prior studies have specifically implicated PldA and the H2-T6SS in pathogenesis3–5, we uncovered a specific role for the effector and its secretory machinery in intra- and inter-species bacterial interactions. Furthermore we find that this effector achieves its antibacterial activity by degrading phosphatidylethanolamine (PE), the major component of bacterial membranes. The surprising finding that virulence-associated phospholipases can serve as specific antibacterial effectors suggests that interbacterial interactions are a relevant factor driving the ongoing evolution of pathogenesis.
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Affiliation(s)
- Alistair B Russell
- Department of Microbiology, University of Washington, Seattle, Washington 98195, USA
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Chou S, Bui NK, Russell AB, Lexa KW, Gardiner TE, LeRoux M, Vollmer W, Mougous JD. Structure of a peptidoglycan amidase effector targeted to Gram-negative bacteria by the type VI secretion system. Cell Rep 2012; 1:656-64. [PMID: 22813741 DOI: 10.1016/j.celrep.2012.05.016] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 05/11/2012] [Accepted: 05/21/2012] [Indexed: 12/21/2022] Open
Abstract
The target range of a bacterial secretion system can be defined by effector substrate specificity or by the efficacy of effector delivery. Here, we report the crystal structure of Tse1, a type VI secretion (T6S) bacteriolytic amidase effector from Pseudomonas aeruginosa. Consistent with its role as a toxin, Tse1 has a more accessible active site than related housekeeping enzymes. The activity of Tse1 against isolated peptidoglycan shows its capacity to act broadly against Gram-negative bacteria and even certain Gram-positive species. Studies with intact cells indicate that Gram-positive bacteria can remain vulnerable to Tse1 despite cell wall modifications. However, interbacterial competition studies demonstrate that Tse1-dependent lysis is restricted to Gram-negative targets. We propose that the previously observed specificity for T6S against Gram-negative bacteria is a consequence of high local effector concentration achieved by T6S-dependent targeting to its site of action rather than inherent effector substrate specificity.
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Affiliation(s)
- Seemay Chou
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
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Ndiaye D, Patel V, Demas A, LeRoux M, Ndir O, Mboup S, Clardy J, Lakshmanan V, Daily JP, Wirth DF. A non-radioactive DAPI-based high-throughput in vitro assay to assess Plasmodium falciparum responsiveness to antimalarials--increased sensitivity of P. falciparum to chloroquine in Senegal. Am J Trop Med Hyg 2010; 82:228-30. [PMID: 20133997 DOI: 10.4269/ajtmh.2010.09-0470] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The spread of Plasmodium falciparum drug resistance is outpacing new antimalarial development and compromising effective malaria treatment. Combination therapy is widely implemented to prolong the effectiveness of currently approved antimalarials. To maximize utility of available drugs, periodic monitoring of drug efficacy and gathering of accurate information regarding parasite-sensitivity changes are essential. We describe a high-throughput, non-radioactive, field-based assay to evaluate in vitro antimalarial drug sensitivity of P. falciparum isolates from 40 Senegalese patients. Compared with earlier years, we found a significant decrease in chloroquine in vitro and in genotypic resistances (> 50% and > 65%, respectively, in previous studies) with only 23% of isolates showing resistance. This is possibly caused by a withdrawal of chloroquine from Senegal in 2002. We also found a range of artemisinin responses. Prevalence of drug resistance is dynamic and varies by region. Therefore, the implementation of non-radioactive, robust, high-throughput antimalarial sensitivity assays is critical for defining region-specific prophylaxis and treatment guidelines.
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Affiliation(s)
- Daouda Ndiaye
- Faculty of Medicine and Pharmacy, Cheikh Anta Diop University, Dakar, Senegal.
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LeRoux M. Auditing helps cut hospitalization costs. Bus Insur 1985; 19:54-6. [PMID: 10270039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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LeRoux M. Employers hope for savings from home care. Bus Insur 1984; 18:19-20. [PMID: 10269298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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14
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LeRoux M. Grants help communities attack health costs. Bus Insur 1984; 18:36-8. [PMID: 10267145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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15
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LeRoux M. Employers ambivalent about big PPO push. Bus Insur 1983; 17:36. [PMID: 10262653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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LeRoux M. Not many PPOs actually providing care. Bus Insur 1983; 17:38-40. [PMID: 10262654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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LeRoux M. Outpatient benefits need right incentive. Bus Insur 1983; 17:44-5. [PMID: 10325186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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18
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LeRoux M. Du Pont builds cost containment into optional self-insured health plan. Bus Insur 1983; 17:3, 25. [PMID: 10257824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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LeRoux M. Employee assistance programs well worth their cost, employers say. Bus Insur 1982; 16:3, 16, 20. [PMID: 10257822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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LeRoux M. Risk management, 'healthy' hospital-insurers grapple with commercial firms. Mod Healthc 1982; 12:83-5. [PMID: 10256759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/13/2023]
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LeRoux M. North Carolina Memorial looks at moving into self-insurance. Mod Healthc 1981; 11:108, 110, 112. [PMID: 10252858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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LeRoux M. Medical malpractice crisis: Part 2. Bus Insur 1981; 15:1, 25. [PMID: 10251267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/13/2023]
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23
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LeRoux M. Health plan would pay the non-user. Bus Insur 1980; 14:20. [PMID: 10246626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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24
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LeRoux M. Kaiser marks $300 million for HMOs. Bus Insur 1980; 14:86-7. [PMID: 10246625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/13/2023]
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25
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LeRoux M. Pump $300 million into Kaiser growth. Mod Healthc 1980; 10:52-4. [PMID: 10247339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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26
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LeRoux M. CHA negotiates a 21% primary layer reduction. Mod Healthc 1978; 8:48. [PMID: 152398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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27
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LeRoux M. $80 million program to cover 450 hospitals. Bus Insur 1978; 12:20. [PMID: 10238667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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28
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LeRoux M. Surplus softens Proposition 13 blow. Mod Healthc 1978; 8:16, 18. [PMID: 150517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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29
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LeRoux M. San Francisco eyes smaller contribution to benefit program. Bus Insur 1978; 12:47-8. [PMID: 10304680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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30
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LeRoux M. Our reporter finds Kaiser HMO a good place for medical care. Bus Insur 1978; 12:73. [PMID: 10304681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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