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Carobbi A, Leo K, Di Nepi S, Bosis E, Salomon D, Sessa G. PIX is an N-terminal delivery domain that defines a class of polymorphic T6SS effectors in Enterobacterales. Cell Rep 2024; 43:114015. [PMID: 38568810 DOI: 10.1016/j.celrep.2024.114015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 02/13/2024] [Accepted: 03/14/2024] [Indexed: 04/05/2024] Open
Abstract
The type VI secretion system (T6SS), a widespread protein delivery apparatus, plays a role in bacterial competition by delivering toxic effectors into neighboring cells. Identifying new T6SS effectors and deciphering the mechanism that governs their secretion remain major challenges. Here, we report two orphan antibacterial T6SS effectors in the pathogen Pantoea agglomerans (Pa). These effectors share an N-terminal domain, Pantoea type six (PIX), that defines a widespread class of polymorphic T6SS effectors in Enterobacterales. We show that the PIX domain is necessary and sufficient for T6SS-mediated effector secretion and that PIX binds to a specialized Pa VgrG protein outside its C-terminal toxic domain. Our findings underline the importance of identifying and characterizing delivery domains in polymorphic toxin classes as a tool to reveal effectors and shed light on effector delivery mechanisms.
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Affiliation(s)
- Andrea Carobbi
- Department of Clinical Microbiology and Immunology, School of Medicine, Faculty of Medical and Health Sciences, Tel Aviv University, Tel Aviv, Israel; School of Plant Sciences and Food Security, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Ksenia Leo
- Department of Clinical Microbiology and Immunology, School of Medicine, Faculty of Medical and Health Sciences, Tel Aviv University, Tel Aviv, Israel; School of Plant Sciences and Food Security, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Simone Di Nepi
- School of Plant Sciences and Food Security, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Eran Bosis
- Department of Biotechnology Engineering, Braude College of Engineering, Karmiel, Israel
| | - Dor Salomon
- Department of Clinical Microbiology and Immunology, School of Medicine, Faculty of Medical and Health Sciences, Tel Aviv University, Tel Aviv, Israel.
| | - Guido Sessa
- School of Plant Sciences and Food Security, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
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2
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Mahata T, Molshanski-Mor S, Goren MG, Kohen-Manor M, Yosef I, Avram O, Salomon D, Qimron U. Inhibition of host cell division by T5 protein 008 (Hdi). Microbiol Spectr 2023; 11:e0169723. [PMID: 37888989 PMCID: PMC10714956 DOI: 10.1128/spectrum.01697-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 04/23/2023] [Accepted: 08/30/2023] [Indexed: 10/28/2023] Open
Abstract
IMPORTANCE We have identified a novel phage-encoded inhibitor of the major cytoskeletal protein in bacterial division, FtsZ. The inhibition is shown to confer T5 bacteriophage with a growth advantage in dividing hosts. Our studies demonstrate a strategy in bacteriophages to maximize their progeny number by inhibiting escape of one of the daughter cells of an infected bacterium. They further emphasize that FtsZ is a natural target for bacterial growth inhibition.
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Affiliation(s)
- Tridib Mahata
- Department of Clinical Microbiology and Immunology, School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Shahar Molshanski-Mor
- Department of Clinical Microbiology and Immunology, School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Moran G. Goren
- Department of Clinical Microbiology and Immunology, School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Miriam Kohen-Manor
- Department of Clinical Microbiology and Immunology, School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Ido Yosef
- Department of Clinical Microbiology and Immunology, School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Oren Avram
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Dor Salomon
- Department of Clinical Microbiology and Immunology, School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Udi Qimron
- Department of Clinical Microbiology and Immunology, School of Medicine, Tel Aviv University, Tel Aviv, Israel
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3
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Abstract
Bacteria belonging to the genus Vibrio include many known and emerging pathogens. Horizontal gene transfer of pathogenicity islands is a major contributor to the emergence of new pathogenic Vibrio strains. Here, we use the brine shrimp Artemia salina as a model and show that the marine bacterium Vibrio proteolyticus uses a horizontally shared type VI secretion system, T6SS3, to intoxicate a eukaryotic host. Two T6SS3 effectors, which were previously shown to induce inflammasome-mediated pyroptotic cell death in mammalian phagocytic cells, contribute to this toxicity. Furthermore, we find a novel T6SS3 effector that also contributes to the lethality mediated by this system against Artemia salina. Therefore, our results reveal a T6SS that is shared among diverse vibrios and mediates host lethality, indicating that it can lead to the emergence of new pathogenic strains. IMPORTANCE The rise in sea surface temperature has been linked to the spread of bacteria belonging to the genus Vibrio and the human illnesses associated with them. Since vibrios often share virulence traits horizontally, a better understanding of their virulence potential and determinants can prepare us for new emerging pathogens. In this work, we showed that a toxin delivery system found in various vibrios mediates lethality in an aquatic animal. Taken together with previous reports showing that the same system induces inflammasome-mediated cell death in mammalian phagocytic cells, our findings suggest that this delivery system and its associated toxins may contribute to the emergence of pathogenic strains.
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Affiliation(s)
- Hadar Cohen
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Chaya M. Fridman
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Motti Gerlic
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Dor Salomon
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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4
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Kanarek K, Fridman CM, Bosis E, Salomon D. The RIX domain defines a class of polymorphic T6SS effectors and secreted adaptors. Nat Commun 2023; 14:4983. [PMID: 37591831 PMCID: PMC10435454 DOI: 10.1038/s41467-023-40659-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [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: 11/17/2022] [Accepted: 08/01/2023] [Indexed: 08/19/2023] Open
Abstract
Bacteria use the type VI secretion system (T6SS) to deliver toxic effectors into bacterial or eukaryotic cells during interbacterial competition, host colonization, or when resisting predation. Identifying effectors is a challenging task, as they lack canonical secretion signals or universally conserved domains. Here, we identify a protein domain, RIX, that defines a class of polymorphic T6SS cargo effectors. RIX is widespread in the Vibrionaceae family and is located at N-termini of proteins containing diverse antibacterial and anti-eukaryotic toxic domains. We demonstrate that RIX-containing proteins are delivered via T6SS into neighboring cells and that RIX is necessary and sufficient for T6SS-mediated secretion. In addition, RIX-containing proteins can enable the T6SS-mediated delivery of other cargo effectors by a previously undescribed mechanism. The identification of RIX-containing proteins significantly enlarges the repertoire of known T6SS effectors, especially those with anti-eukaryotic activities. Furthermore, our findings also suggest that T6SSs may play an underappreciated role in the interactions between vibrios and eukaryotes.
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Affiliation(s)
- Katarzyna Kanarek
- Department of Clinical Microbiology and Immunology, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Chaya Mushka Fridman
- Department of Clinical Microbiology and Immunology, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Eran Bosis
- Department of Biotechnology Engineering, Braude College of Engineering, Karmiel, Israel.
| | - Dor Salomon
- Department of Clinical Microbiology and Immunology, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
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5
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Abstract
All strains of the marine bacterium Vibrio parahaemolyticus harbor a type VI secretion system (T6SS) named T6SS2, suggesting that this system plays an important role in the life cycle of this emerging pathogen. Although T6SS2 was recently shown to play a role in interbacterial competition, its effector repertoire remains unknown. Here, we employed proteomics to investigate the T6SS2 secretome of two V. parahaemolyticus strains, and we identified several antibacterial effectors encoded outside of the main T6SS2 gene cluster. We revealed two T6SS2-secreted proteins that are conserved in this species, indicating that they belong to the core secretome of T6SS2; other identified effectors are found only in subsets of strains, suggesting that they comprise an accessory effector arsenal of T6SS2. Remarkably, a conserved Rhs repeat-containing effector serves as a quality control checkpoint and is required for T6SS2 activity. Our results reveal effector repertoires of a conserved T6SS, including effectors that have no known activity and that have not been previously associated with T6SSs.
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Affiliation(s)
- Daniel Tchelet
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Kinga Keppel
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Eran Bosis
- Department of Biotechnology Engineering, Braude College of Engineering, Karmiel, Israel
| | - Dor Salomon
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel,CONTACT Dor Salomon Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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6
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Carobbi A, Di Nepi S, Fridman CM, Dar Y, Ben‐Yaakov R, Barash I, Salomon D, Sessa G. An antibacterial T6SS in Pantoea agglomerans pv. betae delivers a lysozyme-like effector to antagonize competitors. Environ Microbiol 2022; 24:4787-4802. [PMID: 35706135 PMCID: PMC9796082 DOI: 10.1111/1462-2920.16100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 12/02/2021] [Accepted: 06/10/2022] [Indexed: 12/30/2022]
Abstract
The type VI secretion system (T6SS) is deployed by numerous Gram-negative bacteria to deliver toxic effectors into neighbouring cells. The genome of Pantoea agglomerans pv. betae (Pab) phytopathogenic bacteria contains a gene cluster (T6SS1) predicted to encode a complete T6SS. Using secretion and competition assays, we found that T6SS1 in Pab is a functional antibacterial system that allows this pathogen to outcompete rival plant-associated bacteria found in its natural environment. Computational analysis of the T6SS1 gene cluster revealed that antibacterial effector and immunity proteins are encoded within three genomic islands that also harbour arrays of orphan immunity genes or toxin and immunity cassettes. Functional analyses indicated that VgrG, a specialized antibacterial effector, contains a C-terminal catalytically active glucosaminidase domain that is used to degrade prey peptidoglycan. Moreover, we confirmed that a bicistronic unit at the end of the T6SS1 cluster encodes a novel antibacterial T6SS effector and immunity pair. Together, these results demonstrate that Pab T6SS1 is an antibacterial system delivering a lysozyme-like effector to eliminate competitors, and indicate that this bacterium contains additional novel T6SS effectors.
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Affiliation(s)
- Andrea Carobbi
- School of Plant Sciences and Food Security, The George S. Wise Faculty of Life SciencesTel‐Aviv UniversityTel‐Aviv
| | - Simone Di Nepi
- School of Plant Sciences and Food Security, The George S. Wise Faculty of Life SciencesTel‐Aviv UniversityTel‐Aviv
| | - Chaya M. Fridman
- Department of Clinical Microbiology and Immunology, Sackler Faculty of MedicineTel Aviv UniversityTel Aviv
| | - Yasmin Dar
- Department of Clinical Microbiology and Immunology, Sackler Faculty of MedicineTel Aviv UniversityTel Aviv
| | - Rotem Ben‐Yaakov
- Department of Clinical Microbiology and Immunology, Sackler Faculty of MedicineTel Aviv UniversityTel Aviv
| | - Isaac Barash
- School of Plant Sciences and Food Security, The George S. Wise Faculty of Life SciencesTel‐Aviv UniversityTel‐Aviv
| | - Dor Salomon
- Department of Clinical Microbiology and Immunology, Sackler Faculty of MedicineTel Aviv UniversityTel Aviv
| | - Guido Sessa
- School of Plant Sciences and Food Security, The George S. Wise Faculty of Life SciencesTel‐Aviv UniversityTel‐Aviv
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7
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Cohen H, Baram N, Fridman CM, Edry-Botzer L, Salomon D, Gerlic M. Post-phagocytosis activation of NLRP3 inflammasome by two novel T6SS effectors. eLife 2022; 11:82766. [PMID: 36155655 PMCID: PMC9545535 DOI: 10.7554/elife.82766] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [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: 08/17/2022] [Accepted: 08/24/2022] [Indexed: 11/26/2022] Open
Abstract
The type VI secretion system (T6SS) is used by bacteria to deliver toxic effectors directly into target cells. Most T6SSs mediate antibacterial activities, whereas the potential anti-eukaryotic role of T6SS remains understudied. Here, we found a Vibrio T6SS that delivers two novel effectors into mammalian host immune cells. We showed that these effectors induce a pyroptotic cell death in a phagocytosis-dependent manner; we identified the NLRP3 inflammasome as being the underlying mechanism leading to the T6SS-induced pyroptosis. Moreover, we identified a compensatory T6SS-induced pathway that is activated upon inhibition of the canonical pyroptosis pathway. Genetic analyses revealed possible horizontal spread of this T6SS and its anti-eukaryotic effectors into emerging pathogens in the marine environment. Our findings reveal novel T6SS effectors that activate the host inflammasome and possibly contribute to virulence and to the emergence of bacterial pathogens.
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Affiliation(s)
- Hadar Cohen
- Department of Clinical Microbiology and Immunology, Tel Aviv University, Tel Aviv, Israel
| | - Noam Baram
- Department of Clinical Microbiology and Immunology, Tel Aviv University, Tel Aviv, Israel
| | - Chaya Mushka Fridman
- Department of Clinical Microbiology and Immunology, Tel Aviv University, Tel Aviv, Israel
| | - Liat Edry-Botzer
- Department of Clinical Microbiology and Immunology, Tel Aviv University, Tel Aviv, Israel
| | - Dor Salomon
- Department of Clinical Microbiology and Immunology, Tel Aviv University, Tel Aviv, Israel
| | - Motti Gerlic
- Department of Clinical Microbiology and Immunology, Tel Aviv University, Tel Aviv, Israel
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8
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Abstract
Gram-negative bacteria use type VI secretion systems (T6SSs) to deliver toxic effector proteins into neighboring cells. Cargo effectors are secreted by binding noncovalently to the T6SS apparatus. Occasionally, effector secretion is assisted by an adaptor protein, although the adaptor itself is not secreted. Here, we report a new T6SS secretion mechanism, in which an effector and a co-effector are secreted together. Specifically, we identify a novel periplasm-targeting effector that is secreted together with its co-effector, which contains a MIX (marker for type sIX effector) domain previously reported only in polymorphic toxins. The effector and co-effector directly interact, and they are dependent on each other for secretion. We term this new secretion mechanism "a binary effector module," and we show that it is widely distributed in marine bacteria.
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Affiliation(s)
- Yasmin Dar
- Department of Clinical Microbiology and ImmunologySackler Faculty of MedicineTel Aviv UniversityTel AvivIsrael
| | - Biswanath Jana
- Department of Clinical Microbiology and ImmunologySackler Faculty of MedicineTel Aviv UniversityTel AvivIsrael
| | - Eran Bosis
- Department of Biotechnology EngineeringORT Braude College of EngineeringKarmielIsrael
| | - Dor Salomon
- Department of Clinical Microbiology and ImmunologySackler Faculty of MedicineTel Aviv UniversityTel AvivIsrael
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9
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Tchelet D, Salomon D. A Rapid Fluorescence-Based Screen to Identify Regulators and Components of Interbacterial Competition Mechanisms in Bacteria. Methods Mol Biol 2022; 2427:11-24. [PMID: 35619021 DOI: 10.1007/978-1-0716-1971-1_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Contact-dependent antibacterial mechanisms enhance bacterial fitness as they enable bacteria to outcompete their rivals and thrive in diverse environments. Such systems also allow pathogenic bacteria to establish a niche inside a host, where they must compete with commensal microflora. In many cases, antibacterial systems are tightly regulated by complex sensor and signal transduction networks. Deciphering these regulatory networks, as well as identifying functional components of antibacterial mechanisms, are valuable objectives since essential regulators and components present possible targets for developing antivirulence therapies. Here we describe Bacterial Competition Fluorescence (BaCoF), a methodology that relies on a fluorescence signal to determine the outcome of bacterial competitions. This methodology enables screening of mutant libraries to identify genes that are essential for activating a contact-dependent antibacterial system of interest. Thus, this methodology can be applied to reveal essential regulators and components of antibacterial systems in bacterial pathogens.
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Affiliation(s)
- Daniel Tchelet
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Dor Salomon
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
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10
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Jana B, Keppel K, Salomon D. Engineering a customizable antibacterial T6SS-based platform in Vibrio natriegens. EMBO Rep 2021; 22:e53681. [PMID: 34494702 PMCID: PMC8567230 DOI: 10.15252/embr.202153681] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [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: 07/22/2021] [Revised: 08/19/2021] [Accepted: 08/20/2021] [Indexed: 01/22/2023] Open
Abstract
Bacterial pathogens are a major risk to human, animal, and plant health. To counteract the spread of antibiotic resistance, alternative antibacterial strategies are urgently needed. Here, we construct a proof‐of‐concept customizable, modular, and inducible antibacterial toxin delivery platform. By engineering a type VI secretion system (T6SS) that is controlled by an externally induced on/off switch, we transform the safe bacterium, Vibrio natriegens, into an effective antibacterial weapon. Furthermore, we demonstrate that the delivered effector repertoire, and thus the toxicity range of this platform, can be easily manipulated and tested. We believe that this platform can serve as a foundation for novel antibacterial bio‐treatments, as well as a unique tool to study antibacterial toxins.
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Affiliation(s)
- Biswanath Jana
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Kinga Keppel
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Dor Salomon
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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11
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Yurchenko A, Sartori A, Padioleau I, Rajabi F, Parmentier L, Salomon D, Dermitzakis E, Ongen H, Nikolaev S. Analyses intégratives de 100 génomes de carcinome baso-cellulaire dans le contexte des profils de transcription et de méthylation. Ann Dermatol Venereol 2020. [DOI: 10.1016/j.annder.2020.08.016] [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: 11/24/2022]
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12
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Abstract
During the COVID-19 pandemic, virtual conferences provide a much-needed alternative to cancelled meetings. Here are insights and lessons from organizing a virtual meeting.
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Affiliation(s)
- Dor Salomon
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Mario F Feldman
- Department of Molecular Microbiology, Washington University School of Medicine St Louis, St Louis, MO, USA
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13
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Abstract
Bacteroidetes are Gram-negative bacteria that are abundant in the environment as well as in the gut microbiota of animals. Many bacteroidetes encode large proteins containing an N-terminal domain of unknown function, named TANFOR. In this work, we show that TANFOR-containing proteins carry polymorphic C-terminal toxin domains with predicted antibacterial and anti-eukaryotic activities. We also show that a C-terminal domain that is prevalent in TANFOR-containing proteins represents a novel family of antibacterial DNase toxins, which we named BaCT (Bacteroidetes C-terminal Toxin). Finally, we discover that TANFOR-encoding gene neighborhoods are enriched with genes that encode substrates of the type IX secretion system (T9SS), which is involved in exporting proteins from the periplasm across the outer membrane. Based on these findings, we conclude that TANFOR-containing proteins are a new class of polymorphic toxins, and we hypothesize that they are T9SS substrates.
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Affiliation(s)
- Biswanath Jana
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Dor Salomon
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Eran Bosis
- Department of Biotechnology Engineering, ORT Braude College of Engineering, Karmiel, Israel
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14
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Abstract
Cell death mechanisms are central to combat infections and to drive inflammation. The inflammasome controls infection through activation of caspase-1 leading to either IL-1β dependent inflammation, or pyroptotic cell death in infected cells. Hemolysins, which are pore-forming toxins (PFTs), alter the permeability of the host target membrane, often leading to cell death. We previously discovered a leukocidin domain-containing PFT produced by the Gram-negative bacterium Vibrio proteolyticus, named VPRH. VPRH constitutes a distinct, understudied class within the leukocidin superfamily, which is distributed among several photogenic Vibrios. Since PFTs of other pathogens were shown to activate the inflammasome pathway, we hypothesized that VPRH-induced cell death is mediated by direct activation of the inflammasome in mammalian immune host cells. Indeed, we found that VPRH induced a two-step cell death in macrophages. The first, a rapid step, was mediated by activating the NLRP3 inflammasome, leading to caspase-1 activation that resulted in IL-1β secretion and pyroptosis. The second step was independent of the inflammasome; however, its mechanism remains unknown. This study sets the foundation for better understanding the immunological consequences of inflammasome activation by a new leukocidin class of toxins, which may be shared between marine bacteria and give rise to new pathogenic isolates.
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Affiliation(s)
- Hadar Cohen
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Noam Baram
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Liat Edry-Botzer
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Ariel Munitz
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Dor Salomon
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Motti Gerlic
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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15
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Abstract
Bacteria use toxin delivery systems, such as the type VI secretion system (T6SS), to antagonize competitors. The T6SS transports toxins, called effectors, directly into recipient cells. In the absence of cognate immunity proteins that protect against kin-intoxication, these effectors target conserved and essential cell components resulting in growth arrest or cell death. Here, we focus on antibacterial T6SS effectors and explore their different activities, modes of delivery, and the domains and proteins that are associated with them to provide a modular and dynamic toxin arsenal. We conclude that these natural machines present a lucrative pool and platform for future antibacterial treatments.
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Affiliation(s)
- Biswanath Jana
- Department of Clinical Microbiology & Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Dor Salomon
- Department of Clinical Microbiology & Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
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16
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Jana B, Fridman CM, Bosis E, Salomon D. A modular effector with a DNase domain and a marker for T6SS substrates. Nat Commun 2019; 10:3595. [PMID: 31399579 PMCID: PMC6688995 DOI: 10.1038/s41467-019-11546-6] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [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: 01/15/2019] [Accepted: 07/16/2019] [Indexed: 12/30/2022] Open
Abstract
Bacteria deliver toxic effectors via type VI secretion systems (T6SSs) to dominate competitors, but the identity and function of many effectors remain unknown. Here we identify a Vibrio antibacterial T6SS effector that contains a previously undescribed, widespread DNase toxin domain that we call PoNe (Polymorphic Nuclease effector). PoNe belongs to a diverse superfamily of PD-(D/E)xK phosphodiesterases, and is associated with several toxin delivery systems including type V, type VI, and type VII. PoNe toxicity is antagonized by cognate immunity proteins (PoNi) containing DUF1911 and DUF1910 domains. In addition to PoNe, the effector contains a domain of unknown function (FIX domain) that is also found N-terminal to known toxin domains and is genetically and functionally linked to T6SS. FIX sequences can be used to identify T6SS effector candidates with potentially novel toxin domains. Our findings underline the modular nature of bacterial effectors harboring delivery or marker domains, specific to a secretion system, fused to interchangeable toxins. Bacteria deliver toxic effectors via type VI secretion systems (T6SSs) to dominate competitors. Here, the authors identify a Vibrio antibacterial effector that contains a new DNase toxin domain and a domain of unknown function that can be used as a marker to identify new T6SS effectors.
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Affiliation(s)
- Biswanath Jana
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - Chaya M Fridman
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - Eran Bosis
- Department of Biotechnology Engineering, ORT Braude College of Engineering, 2161002, Karmiel, Israel.
| | - Dor Salomon
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, 6997801, Tel Aviv, Israel.
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17
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Ben-Yaakov R, Salomon D. The regulatory network of Vibrio parahaemolyticus type VI secretion system 1. Environ Microbiol 2019; 21:2248-2260. [PMID: 30882997 PMCID: PMC6618117 DOI: 10.1111/1462-2920.14594] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [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: 11/08/2018] [Revised: 02/13/2019] [Accepted: 03/14/2019] [Indexed: 12/15/2022]
Abstract
Type VI secretion systems (T6SSs) are widespread, tightly regulated, protein delivery apparatuses used by Gram‐negative bacteria to outcompete their neighbours. The pathogen, Vibrio parahaemolyticus, encodes two T6SSs. These T6SSs are differentially regulated by external conditions. T6SS1, an antibacterial system predominantly found in pathogenic isolates, requires warm marine‐like conditions and surface sensing for activation. The regulatory network that governs this activation is not well understood. In this work, we devised a screening methodology that allows us to easily monitor the outcome of bacterial competitions and thus to identify mutants that are defective in T6SS1‐mediated bacterial killing. The methodology, termed Bacterial Competition Fluorescence (BaCoF), relies on detection of a fluorescent signal as an indicator of the survival and growth of a T6SS‐sensitive, GFP‐expressing prey that has been co‐cultured with mutants derived from a T6SS+ attacker of interest. Using BaCoF, we screened a random transposon insertion mutant library and identified genes required for V. parahaemolyticus T6SS1 activation, among them TfoY and Tmk. We used epistasis experiments to determine the relationships between the newly identified components and other regulators that were previously described. Thus, we present here a detailed biological understanding of the T6SS1 regulatory network.
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Affiliation(s)
- Rotem Ben-Yaakov
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Dor Salomon
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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18
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Dar Y, Salomon D, Bosis E. The Antibacterial and Anti-Eukaryotic Type VI Secretion System MIX-Effector Repertoire in Vibrionaceae. Mar Drugs 2018; 16:md16110433. [PMID: 30400344 PMCID: PMC6267618 DOI: 10.3390/md16110433] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 10/31/2018] [Accepted: 11/01/2018] [Indexed: 12/12/2022] Open
Abstract
Vibrionaceae is a widespread family of aquatic bacteria that includes emerging pathogens and symbionts. Many Vibrionaceae harbor a type VI secretion system (T6SS), which is a secretion apparatus used to deliver toxins, termed effectors, into neighboring cells. T6SSs mediate both antibacterial and anti-eukaryotic activities. Notably, antibacterial effectors are encoded together with a gene that encodes a cognate immunity protein so as to antagonize the toxicity of the effector. The MIX (Marker for type sIX effectors) domain has been previously defined as a marker of T6SS effectors carrying polymorphic C-terminal toxins. Here, we set out to identify the Vibrionaceae MIX-effector repertoire and to analyze the various toxin domains they carry. We used a computational approach to search for the MIX-effectors in the Vibrionaceae genomes, and grouped them into clusters based on the C-terminal toxin domains. We classified MIX-effectors as either antibacterial or anti-eukaryotic, based on the presence or absence of adjacent putative immunity genes, respectively. Antibacterial MIX-effectors carrying pore-forming, phospholipase, nuclease, peptidoglycan hydrolase, and protease activities were found. Furthermore, we uncovered novel virulence MIX-effectors. These are encoded by “professional MIXologist” strains that employ a cocktail of antibacterial and anti-eukaryotic MIX-effectors. Our findings suggest that certain Vibrionaceae adapted their antibacterial T6SS to mediate interactions with eukaryotic hosts or predators.
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Affiliation(s)
- Yasmin Dar
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel.
| | - Dor Salomon
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel.
| | - Eran Bosis
- Department of Biotechnology Engineering, ORT Braude College of Engineering, Karmiel 2161002, Israel.
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19
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Ray A, Schwartz N, de Souza Santos M, Zhang J, Orth K, Salomon D. Type VI secretion system MIX-effectors carry both antibacterial and anti-eukaryotic activities. EMBO Rep 2017; 18:1978-1990. [PMID: 28912123 PMCID: PMC5666596 DOI: 10.15252/embr.201744226] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [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: 03/15/2017] [Revised: 08/14/2017] [Accepted: 08/16/2017] [Indexed: 12/12/2022] Open
Abstract
Most type VI secretion systems (T6SSs) described to date are protein delivery apparatuses that mediate bactericidal activities. Several T6SSs were also reported to mediate virulence activities, although only few anti‐eukaryotic effectors have been described. Here, we identify three T6SSs in the marine bacterium Vibrio proteolyticus and show that T6SS1 mediates bactericidal activities under warm marine‐like conditions. Using comparative proteomics, we find nine potential T6SS1 effectors, five of which belong to the polymorphic MIX‐effector class. Remarkably, in addition to six predicted bactericidal effectors, the T6SS1 secretome includes three putative anti‐eukaryotic effectors. One of these is a MIX‐effector containing a cytotoxic necrotizing factor 1 domain. We demonstrate that T6SS1 can use this MIX‐effector to target phagocytic cells, resulting in morphological changes and actin cytoskeleton rearrangements. In conclusion, the V. proteolyticus T6SS1, a system homologous to one found in pathogenic vibrios, uses a suite of polymorphic effectors that target both bacteria and eukaryotic neighbors.
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Affiliation(s)
- Ann Ray
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA.,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Nika Schwartz
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Marcela de Souza Santos
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Junmei Zhang
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA.,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Kim Orth
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA.,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Dor Salomon
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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20
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Abstract
The production of antimicrobial reactive oxygen species by the nicotinamide dinucleotide phosphate (NADPH) oxidase complex is an important mechanism for control of invading pathogens. Herein, we show that the gastrointestinal pathogen Vibrio parahaemolyticus counteracts reactive oxygen species (ROS) production using the Type III Secretion System 2 (T3SS2) effector VopL. In the absence of VopL, intracellular V. parahaemolyticus undergoes ROS-dependent filamentation, with concurrent limited growth. During infection, VopL assembles actin into non-functional filaments resulting in a dysfunctional actin cytoskeleton that can no longer mediate the assembly of the NADPH oxidase at the cell membrane, thereby limiting ROS production. This is the first example of how a T3SS2 effector contributes to the intracellular survival of V. parahaemolyticus, supporting the establishment of a protective intracellular replicative niche.
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Affiliation(s)
- Marcela de Souza Santos
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Dor Salomon
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Kim Orth
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- * E-mail:
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21
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Salomon D, Miloro M, Schlieve T, Kolokythas A. Increased Incidence and Severity of Odontogenic Infections With Escalation in Healthcare Costs After Public Dental Benefits Restriction in Illinois. J Oral Maxillofac Surg 2016. [DOI: 10.1016/j.joms.2016.06.069] [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: 11/24/2022]
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22
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23
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Li P, Rivera-Cancel G, Kinch LN, Salomon D, Tomchick DR, Grishin NV, Orth K. Bile salt receptor complex activates a pathogenic type III secretion system. eLife 2016; 5. [PMID: 27377244 PMCID: PMC4933562 DOI: 10.7554/elife.15718] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [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: 03/02/2016] [Accepted: 06/07/2016] [Indexed: 11/26/2022] Open
Abstract
Bile is an important component of the human gastrointestinal tract with an essential role in food absorption and antimicrobial activities. Enteric bacterial pathogens have developed strategies to sense bile as an environmental cue to regulate virulence genes during infection. We discovered that Vibrio parahaemolyticus VtrC, along with VtrA and VtrB, are required for activating the virulence type III secretion system 2 in response to bile salts. The VtrA/VtrC complex activates VtrB in the presence of bile salts. The crystal structure of the periplasmic domains of the VtrA/VtrC heterodimer reveals a β-barrel with a hydrophobic inner chamber. A co-crystal structure of VtrA/VtrC with bile salt, along with biophysical and mutational analysis, demonstrates that the hydrophobic chamber binds bile salts and activates the virulence network. As part of a family of conserved signaling receptors, VtrA/VtrC provides structural and functional insights into the evolutionarily conserved mechanism used by bacteria to sense their environment. DOI:http://dx.doi.org/10.7554/eLife.15718.001 When we eat a meal, bile salts in the intestine help the body to absorb molecules of fat. Certain bacteria that cause food poisoning in humans, such as Vibrio parahaemolyticus, can also detect bile salts and use them to sense that they have reached the intestine of a suitable host. The bacteria then produce toxins that inflame the intestine; this can result in days of diarrhea. However, it was not clear how the bacteria detect the bile salt signal and how this triggers them to produce the toxins. Li, Rivera-Cancel et al. now discover that not one, but two, genes are required for this process. The genes encode two proteins, called VtrA and VtrC, that interact to form protein ‘complex’ on the surface of the membrane that surrounds the bacterial cell. The two proteins create a barrel-like structure that can bind to bile salts and trigger the cell to produce the toxins. Future experiments will aim to understand how the binding of bile salts to this protein complex causes an increase toxin production. A future challenge is to find out how other disease-causing bacteria sense environmental cues to produce toxins. With this knowledge, researchers might be able to design new drugs that could prevent the production of toxins to relieve symptoms of food poisoning and other illnesses. DOI:http://dx.doi.org/10.7554/eLife.15718.002
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Affiliation(s)
- Peng Li
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Giomar Rivera-Cancel
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Lisa N Kinch
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, United States
| | - Dor Salomon
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Diana R Tomchick
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, United States
| | - Nick V Grishin
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, United States
| | - Kim Orth
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, United States.,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, United States
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24
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Teper D, Burstein D, Salomon D, Gershovitz M, Pupko T, Sessa G. Identification of novel Xanthomonas euvesicatoria type III effector proteins by a machine-learning approach. Mol Plant Pathol 2016; 17:398-411. [PMID: 26104875 PMCID: PMC6638362 DOI: 10.1111/mpp.12288] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The Gram-negative bacterium Xanthomonas euvesicatoria (Xcv) is the causal agent of bacterial spot disease in pepper and tomato. Xcv pathogenicity depends on a type III secretion (T3S) system that delivers effector proteins into host cells to suppress plant immunity and promote disease. The pool of known Xcv effectors includes approximately 30 proteins, most identified in the 85-10 strain by various experimental and computational techniques. To identify additional Xcv 85-10 effectors, we applied a genome-wide machine-learning approach, in which all open reading frames (ORFs) were scored according to their propensity to encode effectors. Scoring was based on a large set of features, including genomic organization, taxonomic dispersion, hypersensitive response and pathogenicity (hrp)-dependent expression, 5' regulatory sequences, amino acid composition bias and GC content. Thirty-six predicted effectors were tested for translocation into plant cells using the hypersensitive response (HR)-inducing domain of AvrBs2 as a reporter. Seven proteins (XopAU, XopAV, XopAW, XopAP, XopAX, XopAK and XopAD) harboured a functional translocation signal and their translocation relied on the HrpF translocon, indicating that they are bona fide T3S effectors. Remarkably, four belong to novel effector families. Inactivation of the xopAP gene reduced the severity of disease symptoms in infected plants. A decrease in cell death and chlorophyll content was observed in pepper leaves inoculated with the xopAP mutant when compared with the wild-type strain. However, populations of the xopAP mutant in infected leaves were similar in size to those of wild-type bacteria, suggesting that the reduction in virulence was not caused by impaired bacterial growth.
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Affiliation(s)
- Doron Teper
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv, 69978, Israel
| | - David Burstein
- Department of Cell Research and Immunology, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Dor Salomon
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Michael Gershovitz
- Department of Cell Research and Immunology, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Tal Pupko
- Department of Earth and Planetary Science, UC Berkeley, Berkeley, CA, 94720, USA
| | - Guido Sessa
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv, 69978, Israel
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25
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Abstract
Protein secretion systems that mediate interbacterial competition secret a wide repertoire of antibacterial toxins. A major player in these competitions is the newly discovered bacterial type VI secretion system (T6SS). We recently found that a subset of polymorphic MIX-effectors, which are a widespread class of effectors secreted by T6SSs, are horizontally shared between marine bacteria and are used to diversify their T6SS effector repertoires, thus enhancing their environmental fitness. In this commentary, I expand on the ideas that were introduced in the previous report, and further speculate on the possible mobility of other MIX-effectors. In addition, I discuss the possible role of horizontal gene transfer in the dissemination of MIX-effectors through bacterial genomes, as well as its possible role in diversifying the T6SS effector repertoire.
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Affiliation(s)
- Dor Salomon
- Department of Molecular Biology, University of Texas Southwestern Medical Center , Dallas, TX, USA
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26
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Abstract
Bacteria employ a variety of tools to survive in a competitive environment. Salomon and Orth describe one such tool-the Type 6 Secretion Systems used by bacteria to deliver a variety of toxins into competing cells.
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Affiliation(s)
- Dor Salomon
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148, USA.
| | - Kim Orth
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148, USA
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27
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Salomon D, Klimko JA, Trudgian DC, Kinch LN, Grishin NV, Mirzaei H, Orth K. Type VI Secretion System Toxins Horizontally Shared between Marine Bacteria. PLoS Pathog 2015; 11:e1005128. [PMID: 26305100 PMCID: PMC4549250 DOI: 10.1371/journal.ppat.1005128] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 08/04/2015] [Indexed: 11/19/2022] Open
Abstract
The type VI secretion system (T6SS) is a widespread protein secretion apparatus used by Gram-negative bacteria to deliver toxic effector proteins into adjacent bacterial or host cells. Here, we uncovered a role in interbacterial competition for the two T6SSs encoded by the marine pathogen Vibrio alginolyticus. Using comparative proteomics and genetics, we identified their effector repertoires. In addition to the previously described effector V12G01_02265, we identified three new effectors secreted by T6SS1, indicating that the T6SS1 secretes at least four antibacterial effectors, of which three are members of the MIX-effector class. We also showed that the T6SS2 secretes at least three antibacterial effectors. Our findings revealed that many MIX-effectors belonging to clan V are “orphan” effectors that neighbor mobile elements and are shared between marine bacteria via horizontal gene transfer. We demonstrated that a MIX V-effector from V. alginolyticus is a functional T6SS effector when ectopically expressed in another Vibrio species. We propose that mobile MIX V-effectors serve as an environmental reservoir of T6SS effectors that are shared and used to diversify antibacterial toxin repertoires in marine bacteria, resulting in enhanced competitive fitness. The bacterial type VI secretion system (T6SS) is a contact-dependent protein secretion apparatus that is emerging as a major component of interbacterial competition in the environment. The bacterium Vibrio alginolyticus is a pathogen of marine animals and a causal agent of wound infections, otitis, and gastroenteritis in humans. In this study, we provide a comprehensive characterization of the environmental regulation, antibacterial activities, and secreted effector repertoires of the two T6SSs found in this pathogen. We also identify a subset of T6SS effectors that appear to be mobile and shared between marine bacteria that can interact with each other in aquatic environments. Our findings suggest that bacteria can incorporate T6SS effectors from competitors in the environment. These newly acquired toxins may be used to expand and diversify T6SS effector repertoires and enhance bacterial fitness.
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Affiliation(s)
- Dor Salomon
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- * E-mail: (DS); (KO)
| | - John A. Klimko
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - David C. Trudgian
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Lisa N. Kinch
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Nick V. Grishin
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Hamid Mirzaei
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Kim Orth
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- * E-mail: (DS); (KO)
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28
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Niculescu AB, Levey D, Le-Niculescu H, Niculescu E, Kurian SM, Salomon D. Psychiatric blood biomarkers: avoiding jumping to premature negative or positive conclusions. Mol Psychiatry 2015; 20:286-8. [PMID: 25582618 PMCID: PMC4357859 DOI: 10.1038/mp.2014.180] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Revised: 11/12/2014] [Accepted: 11/14/2014] [Indexed: 01/26/2023]
Abstract
Blood biomarkers may provide a scientifically useful and clinically usable peripheral signal in psychiatry, as they have been doing for other fields of medicine. Jumping to premature conclusions, negative or positive, can create confusion in this field. Reproducibility is a hallmark of good science. We discuss some recent examples from this dynamic field, and show some new data in support of previously published biomarkers for suicidality (SAT1, MARCKS and SKA2). Methodological clarity and rigor in terms of biomarker discovery, validation and testing is needed. We propose a set of principles for what constitutes a good biomarker, similar in spirit to the Koch postulates used at the birth of the field of infectious diseases.
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Affiliation(s)
- A B Niculescu
- Department of Psychiatry and Medical Neuroscience, Indiana University School of Medicine, Indianapolis, IN, USA,Indianapolis VA Medical Center, Indianapolis, IN, USA,Department of Psychiatry, Indiana University School of Medicine, Neuroscience Research Building, Room 200B, 320 West 15th Street, Indianapolis, IN 46202, USA. E-mail:
| | - D Levey
- Department of Psychiatry and Medical Neuroscience, Indiana University School of Medicine, Indianapolis, IN, USA,Program in Medical Neuroscience, Paul and Carole Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - H Le-Niculescu
- Department of Psychiatry and Medical Neuroscience, Indiana University School of Medicine, Indianapolis, IN, USA
| | - E Niculescu
- Department of Psychiatry and Medical Neuroscience, Indiana University School of Medicine, Indianapolis, IN, USA
| | - S M Kurian
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - D Salomon
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, USA
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29
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Calder T, de Souza Santos M, Attah V, Klimko J, Fernandez J, Salomon D, Krachler AM, Orth K. Structural and regulatory mutations in Vibrio parahaemolyticus type III secretion systems display variable effects on virulence. FEMS Microbiol Lett 2014; 361:107-14. [PMID: 25288215 DOI: 10.1111/1574-6968.12619] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 09/30/2014] [Accepted: 10/03/2014] [Indexed: 12/31/2022] Open
Abstract
The Gram-negative bacterium, Vibrio parahaemolyticus, is a major cause of seafood-derived food poisoning throughout the world. The pathogenicity of V. parahaemolyticus is attributed to several virulence factors, including two type III secretion systems (T3SS), T3SS1 and T3SS2. Herein, we compare the virulence of V. parahaemolyticus POR strains, which harbor a mutation in the T3SS needle apparatus of either system, to V. parahaemolyticus CAB strains, which harbor mutations in positive transcriptional regulators of either system. These strains are derived from the clinical RIMD 2210633 strain. We demonstrate that each mutation affects the virulence of the bacterium in a different manner. POR and CAB strains exhibited similar levels of swarming motility and T3SS effector production and secretion, but the CAB3 and CAB4 strains, which harbor a mutation in the T3SS2 master regulator gene, formed reduced biofilm growth under T3SS2 inducing conditions. Additionally, while the cytotoxicity of the POR and CAB strains was similar, the CAB2 (T3SS1 regulatory mutant) strain was strikingly more invasive than the comparable POR2 (T3SS1 structural mutant) strain. In summary, creating structural or regulatory mutations in either T3SS1 or T3SS2 causes differential downstream effects on other virulence systems. Understanding the biological differences of strains created from a clinical isolate is critical for interpreting and understanding the pathogenic nature of V. parahaemolyticus.
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Affiliation(s)
- Thomas Calder
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
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30
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Karayannis T, Au E, Patel JC, Kruglikov I, Markx S, Delorme R, Héron D, Salomon D, Glessner J, Restituito S, Gordon A, Rodriguez-Murillo L, Roy NC, Gogos JA, Rudy B, Rice ME, Karayiorgou M, Hakonarson H, Keren B, Huguet G, Bourgeron T, Hoeffer C, Tsien RW, Peles E, Fishell G. Cntnap4 differentially contributes to GABAergic and dopaminergic synaptic transmission. Nature 2014; 511:236-40. [PMID: 24870235 PMCID: PMC4281262 DOI: 10.1038/nature13248] [Citation(s) in RCA: 125] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 03/11/2014] [Indexed: 01/08/2023]
Abstract
Although considerable evidence suggests that the chemical synapse is a lynchpin underlying affective disorders, how molecular insults differentially affect specific synaptic connections remains poorly understood. For instance, Neurexin 1a and 2 (NRXN1 and NRXN2) and CNTNAP2 (also known as CASPR2), all members of the neurexin superfamily of transmembrane molecules, have been implicated in neuropsychiatric disorders. However, their loss leads to deficits that have been best characterized with regard to their effect on excitatory cells. Notably, other disease-associated genes such as BDNF and ERBB4 implicate specific interneuron synapses in psychiatric disorders. Consistent with this, cortical interneuron dysfunction has been linked to epilepsy, schizophrenia and autism. Using a microarray screen that focused upon synapse-associated molecules, we identified Cntnap4 (contactin associated protein-like 4, also known as Caspr4) as highly enriched in developing murine interneurons. In this study we show that Cntnap4 is localized presynaptically and its loss leads to a reduction in the output of cortical parvalbumin (PV)-positive GABAergic (γ-aminobutyric acid producing) basket cells. Paradoxically, the loss of Cntnap4 augments midbrain dopaminergic release in the nucleus accumbens. In Cntnap4 mutant mice, synaptic defects in these disease-relevant neuronal populations are mirrored by sensory-motor gating and grooming endophenotypes; these symptoms could be pharmacologically reversed, providing promise for therapeutic intervention in psychiatric disorders.
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31
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Leventhal J, Mathew J, Salomon D, Kurian S, Friedewald J, Gallon L, Tambur A, Levitsky J, Kanwar Y, Abecassis M, Miller J. HLA Identical Renal Transplant Tolerance Using Donor Hematopoietic Stems Cells and Immunoregulation. Transplantation 2014. [DOI: 10.1097/00007890-201407151-00251] [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: 11/25/2022]
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32
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Abstract
The marine bacterium Vibrio parahaemolyticus, a major cause of food-borne gastroenteritis, employs a type VI secretion system 1 (T6SS1), a recently discovered protein secretion system, to combat competing bacteria. Environmental signals such as temperature, salinity, cell density and surface sensing, as well as the quorum-sensing master regulator OpaR, were previously reported to regulate T6SS1 activity and expression. In this work, we set out to identify additional transcription regulators that control the tightly regulated T6SS1 activity. To this end, we determined the effect of deletions in several known virulence regulators and in two regulators encoded within the T6SS1 gene cluster on expression and secretion of the core T6SS component Hcp1 and on T6SS1-mediated anti-bacterial activity. We report that VP1391 and VP1407, transcriptional regulators encoded within the T6SS1 gene cluster, are essential for T6SS1 activity. Moreover, we found that H-NS, a bacterial histone-like nucleoid structuring protein, which mediates transcription silencing of horizontally acquired genes, serves as a repressor of T6SS1. We also show that activation of surface sensing and high salt conditions alleviate the H-NS-mediated repression. Our results shed light on the complex network of environmental signals and transcription regulators that govern the tight regulation over T6SS1 activity.
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Affiliation(s)
- Dor Salomon
- Department of Molecular Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-8816, USA
| | - John A Klimko
- Department of Molecular Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-8816, USA
| | - Kim Orth
- Department of Molecular Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-8816, USA
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33
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Abstract
Pathogens use various mechanisms to manipulate host processes to promote infection. Decades of research on pathogens have revealed not only the molecular mechanisms that these microbes use to replicate and survive within host cells, but also seminal information on how host signaling machinery regulates cellular processes. Among these discoveries are mechanisms involving posttranslational modifications that alter the activity, localization, or interactions of the modified protein. Herein, we examine how pathogens have contributed to our basic understanding of three posttranslational modifications: phosphorylation, NMPylation, and ubiquitylation. Over the years, technologies, techniques and research tools have developed side by side with the study of pathogens, facilitating the discovery of protein modifications and furthering our understanding of how they contribute to both infection and cellular functions.
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Affiliation(s)
- Dor Salomon
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148, USA
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34
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Teper D, Salomon D, Sunitha S, Kim JG, Mudgett MB, Sessa G. Xanthomonas euvesicatoria type III effector XopQ interacts with tomato and pepper 14-3-3 isoforms to suppress effector-triggered immunity. Plant J 2014; 77:297-309. [PMID: 24279912 DOI: 10.1111/tpj.12391] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 11/12/2013] [Accepted: 11/15/2013] [Indexed: 05/09/2023]
Abstract
Effector-triggered immunity (ETI) to host-adapted pathogens is associated with rapid cell death at the infection site. The plant-pathogenic bacterium Xanthomonas euvesicatoria (Xcv) interferes with plant cellular processes by injecting effector proteins into host cells through the type III secretion system. Here, we show that the Xcv effector XopQ suppresses cell death induced by components of the ETI-associated MAP kinase cascade MAPKKKα MEK2/SIPK and by several R/avr gene pairs. Inactivation of xopQ by insertional mutagenesis revealed that this effector inhibits ETI-associated cell death induced by avirulent Xcv in resistant pepper (Capsicum annuum), and enhances bacterial growth in resistant pepper and tomato (Solanum lycopersicum). Using protein-protein interaction studies in yeast (Saccharomyces cerevisiae) and in planta, we identified the tomato 14-3-3 isoform SlTFT4 and homologs from other plant species as XopQ interactors. A mutation in the putative 14-3-3 binding site of XopQ impaired interaction of the effector with CaTFT4 in yeast and its virulence function in planta. Consistent with a role in ETI, TFT4 mRNA abundance increased during the incompatible interaction of tomato and pepper with Xcv. Silencing of NbTFT4 in Nicotiana benthamiana significantly reduced cell death induced by MAPKKKα. In addition, silencing of CaTFT4 in pepper delayed the appearance of ETI-associated cell death and enhanced growth of virulent and avirulent Xcv, demonstrating the requirement of TFT4 for plant immunity to Xcv. Our results suggest that the XopQ virulence function is to suppress ETI and immunity-associated cell death by interacting with TFT4, which is an important component of ETI and a bona fide target of XopQ.
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Affiliation(s)
- Doron Teper
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, 69978, Tel Aviv, Israel
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Salomon D, Orth K. Lost after translation: post-translational modifications by bacterial type III effectors. Curr Opin Microbiol 2013; 16:213-20. [PMID: 23466212 DOI: 10.1016/j.mib.2013.01.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Revised: 01/11/2013] [Accepted: 01/16/2013] [Indexed: 10/26/2022]
Abstract
Many Gram-negative bacterial pathogens use the type III secretion system to deliver effector proteins into host cells. These effectors use various mechanisms to exploit host processes to the advantage of the pathogen. A large group of effectors use post-translational modifications, either reversible or irreversible, to manipulate host proteins, and while most of these mechanisms mimic eukaryotic activities, others appear to be unique biochemical functions. Deciphering such mechanisms and identifying the host targets of these effectors sheds light on eukaryotic signaling pathways and immune responses.
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Affiliation(s)
- Dor Salomon
- Department of Molecular Biology, University of Texas Southwestern, Medical Center, Dallas, TX 75390-9148, USA
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Sreeramulu S, Mostizky Y, Sunitha S, Shani E, Nahum H, Salomon D, Hayun LB, Gruetter C, Rauh D, Ori N, Sessa G. BSKs are partially redundant positive regulators of brassinosteroid signaling in Arabidopsis. Plant J 2013; 74:905-19. [PMID: 23496207 DOI: 10.1111/tpj.12175] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 02/24/2013] [Accepted: 03/11/2013] [Indexed: 05/20/2023]
Abstract
Arabidopsis thaliana brassinosteroid signaling kinases (BSKs) constitute a receptor-like cytoplasmic kinase sub-family (RLCK-XII) with 12 members. Previous analysis demonstrated a positive role for BSK1 and BSK3 in the initial steps of brassinosteroid (BR) signal transduction. To investigate the function of BSKs in plant growth and BR signaling, we characterized T-DNA insertion lines for eight BSK genes (BSK1-BSK8) and multiple mutant combinations. Simultaneous elimination of three BSK genes caused alterations in growth and the BR response, and the most severe phenotypes were observed in the bsk3,4,7,8 quadruple and bsk3,4,6,7,8 pentuple mutants, which displayed reduced rosette size, leaf curling and enhanced leaf inclination. In addition, upon treatment with 24-epibrassinolide, these mutants showed reduced hypocotyl elongation, enhanced root growth and alteration in the expression of BR-responsive genes. Some mutant combinations also showed antagonistic interactions. In support of a redundant function in BR signaling, multiple BSKs interacted in vivo with the BR receptor BRI1, and served as its phosphorylation substrates in vitro. The BIN2 and BIL2 GSK3-like kinases, which are negative regulators of BR signaling, interacted in vivo with BSKs and phosphorylated them in vitro, probably at different sites to BRI1. This study demonstrates redundant biological functions for BSKs, and suggests the existence of a regulatory link between BSKs and GSK3-like kinases.
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Affiliation(s)
- Shivakumar Sreeramulu
- Department of Molecular Biology and Ecology of Plants, Tel-Aviv University, Tel-Aviv, 69978, Israel
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Le Pillouer-Prost A, Salomon D, Mordon S. Photothérapie dynamique : mise au point. Ann Dermatol Venereol 2013. [DOI: 10.1016/j.annder.2013.03.032] [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: 10/26/2022]
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Salomon D, Gonzalez H, Updegraff BL, Orth K. Vibrio parahaemolyticus type VI secretion system 1 is activated in marine conditions to target bacteria, and is differentially regulated from system 2. PLoS One 2013; 8:e61086. [PMID: 23613791 PMCID: PMC3628861 DOI: 10.1371/journal.pone.0061086] [Citation(s) in RCA: 147] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 03/06/2013] [Indexed: 12/21/2022] Open
Abstract
Vibrio parahaemolyticus is a marine bacterium that thrives in warm climates. It is a leading cause of gastroenteritis resulting from consumption of contaminated uncooked shellfish. This bacterium harbors two putative type VI secretion systems (T6SS). T6SSs are widespread protein secretion systems found in many Gram-negative bacteria, and are often tightly regulated. For many T6SSs studied to date, the conditions and cues, as well as the regulatory mechanisms that control T6SS activity are unknown. In this study, we characterized the environmental conditions and cues that activate both V. parahaemolyticus T6SSs, and identified regulatory mechanisms that control T6SS gene expression and activity. We monitored the expression and secretion of the signature T6SS secreted proteins Hcp1 and Hcp2, and found that both T6SSs are differentially regulated by quorum sensing and surface sensing. We also showed that T6SS1 and T6SS2 require different temperature and salinity conditions to be active. Interestingly, T6SS1, which is found predominantly in clinical isolates, was most active under warm marine-like conditions. Moreover, we found that T6SS1 has anti-bacterial activity under these conditions. In addition, we identified two transcription regulators in the T6SS1 gene cluster that regulate Hcp1 expression, but are not required for immunity against self-intoxication. Further examination of environmental isolates revealed a correlation between the presence of T6SS1 and virulence of V. parahaemolyticus against other bacteria, and we also showed that different V. parahaemolyticus isolates can outcompete each other. We propose that T6SS1 and T6SS2 play different roles in the V. parahaemolyticus lifestyles, and suggest a role for T6SS1 in enhancing environmental fitness of V. parahaemolyticus in marine environments when competing for a niche in the presence of other bacterial populations.
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Affiliation(s)
- Dor Salomon
- Department of Molecular Biology, University of Texas Southwestern, Medical Center, Dallas, Texas, United States of America
| | - Herman Gonzalez
- Department of Molecular Biology, University of Texas Southwestern, Medical Center, Dallas, Texas, United States of America
| | - Barrett L. Updegraff
- Department of Molecular Biology, University of Texas Southwestern, Medical Center, Dallas, Texas, United States of America
| | - Kim Orth
- Department of Molecular Biology, University of Texas Southwestern, Medical Center, Dallas, Texas, United States of America
- * E-mail:
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Dab W, Salomon D. L’impact sanitaire et humain du changement organisationnel, une nouvelle problématique de santé au travail. ARCH MAL PROF ENVIRO 2013. [DOI: 10.1016/j.admp.2012.12.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Sorg O, Kasraee B, Salomon D, Saurat JH. The Potential Depigmenting Activity of Retinaldehyde. Dermatology 2013; 227:231-7. [DOI: 10.1159/000354294] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 07/10/2013] [Indexed: 11/19/2022] Open
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Sorg O, Kasraee B, Salomon D, Saurat J. The Combination of a Retinoid, a Phenolic Agent and an Antioxidant Improves Tolerance while Retaining an Optimal Depigmenting Action in Reconstructed Epidermis. Dermatology 2013; 227:150-6. [DOI: 10.1159/000353578] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 06/06/2013] [Indexed: 11/19/2022] Open
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Saeki T, Takahashi T, Okabe M, Furuya A, Hanai N, Yamagami K, Mandai K, Moriwaki S, Doihara H, Takashima S, Salomon D. Immunohistochemical detection of ribonucleotide reductase in human breast-tumors. Int J Oncol 2012; 6:523-9. [PMID: 21556566 DOI: 10.3892/ijo.6.3.523] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ribonucleotide reductase (RNR) consists of two non-identical subunits, R1 and R2 and is one of the key enzymes involved in DNA biosynthesis. RNR activity is considerably higher in malignant tumors than in normal tissues in the rat suggesting that RNR may play an important role in the pathogenesis of human tumors. In order to obtain immunological reagents to study the localization and level of expression of RNR in various human tissues, a synthetic peptide containing sequences corresponding to the COOH-terminal region of the human R2 subunit was used to generate rat monoclonal antibodies. The generated rat monoclonal antibodies (IgG) inhibited RNR enzymatic activity purified from murine P388 leukemia cells. These antibodies were used to immunohistochemically examine the distribution of RNR in a small panel of 8 malignant and 4 benign human breast tumors. Positive immunostaining for RNR was observed in the cytoplasm of human breast carcinoma cells in which a specific 44 kDa specific band of R2 subunit was also detected by Western blot analysis. The immunostaining was blocked by preabsorption of the antibody with an excess amount of the synthetic peptide immunogen. In 8 of 8 breast carcinomas, positive immunostaining for the R2 subunit was observed whereas noninvolved, adjacent breast tissue showed no staining with this antibody. In addition, few of the benign breast lesions exhibited staining with this antibody. These data indicate that these antibodies can immunohistochemically detect RNR in frozen or formalin-fixed, paraffin- embedded tissues and that there is a differential expression of RNR between breast tumors and non-involved breast tissue. Immunohistochemical detection of RNR using these antibodies may therefore be useful for the diagnosis of human breast tumors.
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Affiliation(s)
- T Saeki
- NCI,TUMOR GROWTH FACTOR SECT,TUMOR IMMUNOL & BIOL LAB,BETHESDA,MD 20892. KYOWA HAKKO KOGYO CO LTD,TOKYO RES LABS,TOKYO,JAPAN. KYOWA HAKKO KOGYO CO LTD,PHARMATHEUT RES LABS,SHIZUOKA,JAPAN
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Saeki T, Salomon D, Normanno N, Johnson G, Gullick W, Mandai K, Moriwaki S, Takashima S, Kuniyasu M, Tahara E, Kawami H, Nishiyama M, Toge T. Immunohistochemical detection of cripto-1, amphiregulin and transforming growth-factor-alpha in human gastric carcinomas and intestinal metaplasias. Int J Oncol 2012; 5:215-23. [PMID: 21559578 DOI: 10.3892/ijo.5.2.215] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The expression and localization of cripto-1 (CR-1), amphiregulin (AR) and transforming growth factor alpha (TGFalpha) were assessed by immunocytochemistry in 37 primary human gastric tumors, 30 noninvolved gastric mucosa samples that were adjacent to carcinoma but exhibited intestinal metaplasia and 37 adjacent, noninvolved gastric mucosa samples. Seventeen (46%), nineteen (51%) and twenty-one (57%) carcinomas showed staining for CR-1, AR and TGFalpha, respectively; whereas sixteen (53%), eight (26%) and five (17%) intestinal metaplasias were reactive with the anti-CR-1, anti-AR and anti-TGFalpha antibodies, respectively. In contrast, none of the normal, noninvolved gastric mucosa samples reacted with the TGFalpha antibody and only 1 (3%) of these samples showed weak staining with the anti-CR-1 antibody. However, 8 (21%) of the normal gastric mucosa samples showed moderate levels of staining with the AR antibody. Within the carcinomas, there was a slight trend for association between TGFalpha and CR-1 expression (p<0.05), but no correlation was found between epidermal growth factor receptor and CR-1 expression. Staining for p53 was observed in 26 (70%) of the carcinomas, 3 (10%) intestinal metaplasias and none of the gastric mucosa samples. This data demonstrate that CR-1, like TGFalpha, may be a tumor marker for a subset of gastric carcinomas in addition to being an important factor in the early stages of gastric cancer development.
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Affiliation(s)
- T Saeki
- HAMMERSMITH HOSP,IMPERIAL CANC RES FUND,MOLEC ONCOL UNIT,LONDON W12 0HS,ENGLAND. HIROSHIMA UNIV,SCH MED,DEPT PATHOL,HIROSHIMA 730,JAPAN. HIROSHIMA UNIV,NUCL MED & BIOL RES INST,DEPT SURG,HIROSHIMA 730,JAPAN. US FDA,DIV CYTOKINE BIOL,BETHESDA,MD 20014. NCI,TUMOR IMMUNOL & BIOL LAB,TUMOR GROWTH FACTOR SECT,BETHESDA,MD 20892
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Salomon D, Bosis E, Dar D, Nachman I, Sessa G. Expression of Pseudomonas syringae type III effectors in yeast under stress conditions reveals that HopX1 attenuates activation of the high osmolarity glycerol MAP kinase pathway. Microbiology (Reading) 2012; 158:2859-2869. [PMID: 22977090 DOI: 10.1099/mic.0.062513-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The Gram-negative bacterium Pseudomonas syringae pv. tomato (Pst) is the causal agent of speck disease in tomato. Pst pathogenicity depends on a type III secretion system that delivers effector proteins into host cells, where they promote disease by manipulating processes to the advantage of the pathogen. Previous studies identified seven Pst effectors that inhibit growth when expressed in yeast under normal growth conditions, suggesting that they interfere with cellular processes conserved in yeast and plants. We hypothesized that effectors also target conserved cellular processes that are required for yeast growth only under stress conditions. We therefore examined phenotypes induced by expression of Pst effectors in yeast grown in the presence of various stressors. Out of 29 effectors tested, five (HopX1, HopG1, HopT1-1, HopH1 and AvrPtoB) displayed growth inhibition phenotypes only in combination with stress conditions. Viability assays revealed that the HopX1 effector caused loss of cell viability under prolonged osmotic stress. Using transcription reporters, we found that HopX1 attenuated the activation of the high osmolarity glycerol (HOG) mitogen-activated protein kinase (MAPK) pathway, which is responsible for yeast survival under osmotic stress, while other MAPK pathways were mildly affected by HopX1. Interestingly, HopX1-mediated phenotypes in yeast were dependent on the putative transglutaminase catalytic triad of the effector. This study enlarges the pool of phenotypes available for the functional analysis of Pst type III effectors in yeast, and exemplifies how analysis of phenotypes detected in yeast under stress conditions can lead to the identification of eukaryotic cellular processes affected by bacterial effectors.
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Affiliation(s)
- Dor Salomon
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Eran Bosis
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Daniel Dar
- Department of Biochemistry and Molecular Biology, Tel Aviv University, 69978 Tel Aviv, Israel
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Iftach Nachman
- Department of Biochemistry and Molecular Biology, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Guido Sessa
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, 69978 Tel Aviv, Israel
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Ayalew M, Le-Niculescu H, Levey DF, Jain N, Changala B, Patel SD, Winiger E, Breier A, Shekhar A, Amdur R, Koller D, Nurnberger JI, Corvin A, Geyer M, Tsuang MT, Salomon D, Schork NJ, Fanous AH, O'Donovan MC, Niculescu AB. Convergent functional genomics of schizophrenia: from comprehensive understanding to genetic risk prediction. Mol Psychiatry 2012; 17:887-905. [PMID: 22584867 PMCID: PMC3427857 DOI: 10.1038/mp.2012.37] [Citation(s) in RCA: 322] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Revised: 02/28/2012] [Accepted: 03/05/2012] [Indexed: 02/07/2023]
Abstract
We have used a translational convergent functional genomics (CFG) approach to identify and prioritize genes involved in schizophrenia, by gene-level integration of genome-wide association study data with other genetic and gene expression studies in humans and animal models. Using this polyevidence scoring and pathway analyses, we identify top genes (DISC1, TCF4, MBP, MOBP, NCAM1, NRCAM, NDUFV2, RAB18, as well as ADCYAP1, BDNF, CNR1, COMT, DRD2, DTNBP1, GAD1, GRIA1, GRIN2B, HTR2A, NRG1, RELN, SNAP-25, TNIK), brain development, myelination, cell adhesion, glutamate receptor signaling, G-protein-coupled receptor signaling and cAMP-mediated signaling as key to pathophysiology and as targets for therapeutic intervention. Overall, the data are consistent with a model of disrupted connectivity in schizophrenia, resulting from the effects of neurodevelopmental environmental stress on a background of genetic vulnerability. In addition, we show how the top candidate genes identified by CFG can be used to generate a genetic risk prediction score (GRPS) to aid schizophrenia diagnostics, with predictive ability in independent cohorts. The GRPS also differentiates classic age of onset schizophrenia from early onset and late-onset disease. We also show, in three independent cohorts, two European American and one African American, increasing overlap, reproducibility and consistency of findings from single-nucleotide polymorphisms to genes, then genes prioritized by CFG, and ultimately at the level of biological pathways and mechanisms. Finally, we compared our top candidate genes for schizophrenia from this analysis with top candidate genes for bipolar disorder and anxiety disorders from previous CFG analyses conducted by us, as well as findings from the fields of autism and Alzheimer. Overall, our work maps the genomic and biological landscape for schizophrenia, providing leads towards a better understanding of illness, diagnostics and therapeutics. It also reveals the significant genetic overlap with other major psychiatric disorder domains, suggesting the need for improved nosology.
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Affiliation(s)
- M Ayalew
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, USA
- Indianapolis VA Medical Center, Indianapolis, IN, USA
| | - H Le-Niculescu
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, USA
| | - D F Levey
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, USA
| | - N Jain
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, USA
| | - B Changala
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, USA
| | - S D Patel
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, USA
| | - E Winiger
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, USA
| | - A Breier
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, USA
| | - A Shekhar
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, USA
| | - R Amdur
- Washington DC VA Medical Center, Washington, DC, USA
| | - D Koller
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - J I Nurnberger
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, USA
| | - A Corvin
- Department of Psychiatry, Trinity College, Dublin, Ireland
| | - M Geyer
- Department of Psychiatry, University of California San Diego, La Jolla, CA, USA
| | - M T Tsuang
- Department of Psychiatry, University of California San Diego, La Jolla, CA, USA
| | - D Salomon
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - N J Schork
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - A H Fanous
- Washington DC VA Medical Center, Washington, DC, USA
| | - M C O'Donovan
- Department of Psychological Medicine, School of Medicine, Cardiff University, Cardiff, UK
| | - A B Niculescu
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, USA
- Indianapolis VA Medical Center, Indianapolis, IN, USA
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Dalimier E, Salomon D. Imagerie de la peau en profondeur à haute résolution avec la technologie FFOCT. Ann Dermatol Venereol 2012. [DOI: 10.1016/j.annder.2012.04.102] [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: 10/28/2022]
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Salomon D. La photothérapie dynamique (PDT), principes de base et questions de base non résolues. Ann Dermatol Venereol 2012. [DOI: 10.1016/j.annder.2012.04.163] [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: 10/28/2022]
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Bosis E, Salomon D, Sessa G. A simple yeast-based strategy to identify host cellular processes targeted by bacterial effector proteins. PLoS One 2011; 6:e27698. [PMID: 22110728 PMCID: PMC3216995 DOI: 10.1371/journal.pone.0027698] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 10/23/2011] [Indexed: 12/19/2022] Open
Abstract
Bacterial effector proteins, which are delivered into the host cell via the type III secretion system, play a key role in the pathogenicity of Gram-negative bacteria by modulating various host cellular processes to the benefit of the pathogen. To identify cellular processes targeted by bacterial effectors, we developed a simple strategy that uses an array of yeast deletion strains fitted into a single 96-well plate. The array is unique in that it was optimized computationally such that despite the small number of deletion strains, it covers the majority of genes in the yeast synthetic lethal interaction network. The deletion strains in the array are screened for hypersensitivity to the expression of a bacterial effector of interest. The hypersensitive deletion strains are then analyzed for their synthetic lethal interactions to identify potential targets of the bacterial effector. We describe the identification, using this approach, of a cellular process targeted by the Xanthomonas campestris type III effector XopE2. Interestingly, we discover that XopE2 affects the yeast cell wall and the endoplasmic reticulum stress response. More generally, the use of a single 96-well plate makes the screening process accessible to any laboratory and facilitates the analysis of a large number of bacterial effectors in a short period of time. It therefore provides a promising platform for studying the functions and cellular targets of bacterial effectors and other virulence proteins.
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Affiliation(s)
- Eran Bosis
- Department of Molecular Biology and Ecology of Plants, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Dor Salomon
- Department of Molecular Biology and Ecology of Plants, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Guido Sessa
- Department of Molecular Biology and Ecology of Plants, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
- * E-mail:
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Faucheux BA, Morain E, Diouron V, Brandel JP, Salomon D, Sazdovitch V, Privat N, Laplanche JL, Hauw JJ, Haïk S. Quantification of surviving cerebellar granule neurones and abnormal prion protein (PrPSc) deposition in sporadic Creutzfeldt-Jakob disease supports a pathogenic role for small PrPSc deposits common to the various molecular subtypes. Neuropathol Appl Neurobiol 2011; 37:500-12. [PMID: 21450052 DOI: 10.1111/j.1365-2990.2011.01179.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
AIMS Neuronal death is a major neuropathological hallmark in prion diseases. The association between the accumulation of the disease-related prion protein (PrP(Sc) ) and neuronal loss varies within the wide spectrum of prion diseases and their experimental models. In this study, we investigated the relationships between neuronal loss and PrP(Sc) deposition in the cerebellum from cases of the six subtypes of sporadic Creutzfeldt-Jakob disease (sCJD; n=100) that can be determined according to the M129V polymorphism of the human prion protein gene (PRNP) and PrP(Sc) molecular types. METHODS The numerical density of neurones was estimated with a computer-assisted image analysis system and the accumulation of PrP(Sc) deposits was scored. RESULTS The scores of PrP(Sc) immunoreactive deposits of the punctate type (synaptic type) were correlated with neurone counts - the higher the score the higher the neuronal loss - in all sCJD subtypes. Large 5- to 50-µm-wide deposits (focal type) were found in sCJD-MV2 and sCJD-VV2 subtypes, and occasionally in a few cases of the other studied groups. By contrast, the highest scores for 5- to 50-µm-wide deposits observed in sCJD-MV2 subtype were not associated with higher neuronal loss. In addition, these scores were inversely correlated with neuronal counts in the sCJD-VV2 subtype. CONCLUSIONS These results support a putative pathogenic role for small PrP(Sc) deposits common to the various sCJD subtypes. Furthermore, the observation of a lower loss of neurones associated with PrP(Sc) type-2 large deposits is consistent with a possible 'protective' role of aggregated deposits in both sCJD-MV2 and sCJD-VV2 subtypes.
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Affiliation(s)
- B A Faucheux
- Assistance Publique - Hôpitaux de Paris (AP-HP), Laboratoire de Neuropathologie, Hôpital de la Salpêtrière, 47 boulevard de l'Hôpital Centre de Recherche de l'Institut du Cerveau et de la Moelle, INSERM UMRS975, CNRS UMR7225, Paris, France.
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Le Gal FA, Toutous-Trellu L, Kaya G, Salomon D. [Lentigo maligna: a special melanoma]. Rev Med Suisse 2011; 7:765-771. [PMID: 21568099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Lentigo maligna (LM) and lentigo maligna melanoma (LMM) account for about 10% of all melanomas. They have distinct clinical and histological features as well as specific epidemiology, natural history, evolution, and genetics. Epidemiology of these tumors progressively concerns younger patients. Diagnostic and preparation of surgical removal of LM and LMM can now be optimized by new technologies of imaging, like dermoscopy or in vivo confocal reflectance microscopy. Surgery is the treatment of choice, but alternative options can be considered, especially for the elderly for whom the needs for efficiency and acceptability should be met.
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Affiliation(s)
- F-A Le Gal
- Clinique de dermatologie HUG, 1211 Geneve
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