Publications
236 results found
Ramos JL, Goldberg JB, Filloux A, 2015, Pseudomonas: Volume 7: New aspects of pseudomonas biology, ISBN: 9789401795548
Pseudomonas volume 7 collects some of the most relevant and emerging issues in the biology of these microorganisms, and a number of other important issues that were not collected in the previous volumes. The first six volumes of the Pseudomonas series covered the biology of pseudomonads in a wide range of contexts, including the niches they inhabit, the taxonomic relations among its members of this group, the molecular biology of gene expression in different niches and under different environmental conditions, the analysis of virulence in plants, animal and human pathogens, as well as the determinants that make some of these strains of interesting for biotechnological applications. This seventh volume covers the following topics: The history of the biology of Pseudomonas The use of Pseudomonas as biological agents New trends in the molecular biology of these microorganisms Pseudomonas and the immune system of insects and animals This book will be of use to researchers working on these bacteria, particularly those studying medical aspects of Pseudomonas, and their use as a means to control pathogens or to stimulate plant growth. This volume is also interesting for those studying the physiology, genetics, molecular biology of Pseudomonas and those using novel-omics approaches to understand bacteria of the genus Pseudomonas.
Filloux A, Ramos JL, 2015, Preface, Methods in Molecular Biology, Vol: 1149, Pages: 5-6, ISSN: 1064-3745
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Filloux A, 2015, Untitled, FEMS MICROBIOLOGY REVIEWS, Vol: 39, Pages: 1-1, ISSN: 0168-6445
Filloux A, Sagfors A, 2015, News and views on protein secretion systems, COMPREHENSIVE SOURCEBOOK OF BACTERIAL PROTEIN TOXINS, 4TH EDITION, Editors: Alouf, Ladant, Popoff, Publisher: ELSEVIER SCIENCE BV, Pages: 77-108, ISBN: 978-0-12-800188-2
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- Citations: 4
Foerster A, Planamente S, Manoli E, et al., 2014, Coevolution of the ATPase ClpV, the Sheath Proteins TssB and TssC, and the Accessory Protein TagJ/HsiE1 Distinguishes Type VI Secretion Classes, JOURNAL OF BIOLOGICAL CHEMISTRY, Vol: 289
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- Citations: 43
Fajardo A, Hernando-Amado S, Oliver A, et al., 2014, Characterization of a novel Zn<SUP>2+</SUP>-dependent intrinsic imipenemase from <i>Pseudomonas aeruginosa</i>, JOURNAL OF ANTIMICROBIAL CHEMOTHERAPY, Vol: 69, Pages: 2972-2978, ISSN: 0305-7453
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- Citations: 21
Moscoso JA, Jaeger T, Valentini M, et al., 2014, The Diguanylate Cyclase SadC Is a Central Player in Gac/Rsm-Mediated Biofilm Formation in Pseudomonas aeruginosa, Journal of Bacteriology, Vol: 196, Pages: 4081-4088, ISSN: 1098-5530
Pseudomonas aeruginosa is a Gram-negative opportunistic human pathogen and a threat for immunocompromised and cysticfibrosis patients. It is responsible for acute and chronic infections and can switch between these lifestyles upon taking an informeddecision involving complex regulatory networks. The RetS/LadS/Gac/Rsm network and the cyclic-di-GMP (c-di-GMP)signaling pathways are both central to this phenomenon redirecting the P. aeruginosa population toward a biofilm mode ofgrowth, which is associated with chronic infections. While these two pathways were traditionally studied independently fromeach other, we recently showed that cellular levels of c-di-GMP are increased in the hyperbiofilm retS mutant. Here, we have formallyestablished the link between the two networks by showing that the SadC diguanylate cyclase is central to the Gac/Rsmassociatedphenotypes, notably, biofilm formation. Importantly, SadC is involved in the signaling that converges onto the RsmAtranslational repressor either via RetS/LadS or via HptB/HsbR. Although the level of expression of the sadC gene does not seemto be impacted by the regulatory cascade, the production of the SadC protein is tightly repressed by RsmA. This adds to thegrowing complexity of the signaling network associated with c-di-GMP in P. aeruginosa. While this organism possesses morethan 40 c-di-GMP-related enzymes, it remains unclear how signaling specificity is maintained within the c-di-GMP network. Thefinding that SadC but no other diguanylate cyclase is related to the formation of biofilm governed by the Gac/Rsm pathway furthercontributes to understanding of this insulation mechanism.
Ma L-S, Hachani A, Lin J-S, et al., 2014, Agrobacterium tumefaciens Deploys a Superfamily of Type VI Secretion DNase Effectors as Weapons for Interbacterial Competition In Planta, Cell Host & Microbe, Vol: 16, Pages: 94-104, ISSN: 1934-6069
The type VI secretion system (T6SS) is a widespread molecular weapon deployed by many Proteobacteria to target effectors/toxins into both eukaryotic and prokaryotic cells. We report that Agrobacterium tumefaciens, a soil bacterium that triggers tumorigenesis in plants, produces a family of type VI DNase effectors (Tde) that are distinct from previously known polymorphic toxins and nucleases. Tde exhibits an antibacterial DNase activity that relies on a conserved HxxD motif and can be counteracted by a cognate immunity protein, Tdi. In vitro, A. tumefaciens T6SS could kill Escherichia coli but triggered a lethal counterattack by Pseudomonas aeruginosa upon injection of the Tde toxins. However, in an in planta coinfection assay, A. tumefaciens used Tde effectors to attack both siblings cells and P. aeruginosa to ultimately gain a competitive advantage. Such acquired T6SS-dependent fitness in vivo and conservation of Tde-Tdi couples in bacteria highlights a widespread antibacterial weapon beneficial for niche colonization.
Hachani A, Allsopp LP, Oduko Y, et al., 2014, The VgrG Proteins Are "à la Carte" Delivery Systems for Bacterial Type VI Effectors, Journal of Biological Chemistry, Vol: 289, Pages: 17872-17884, ISSN: 1083-351X
The bacterial type VI secretion system (T6SS) is a supra-molecular complex akin to bacteriophage tails, with VgrG proteins acting as a puncturing device. The Pseudomonas aeruginosa H1-T6SS has been extensively characterized. It is involved in bacterial killing and in the delivery of three toxins, Tse1–3. Here, we demonstrate the independent contribution of the three H1-T6SS co-regulated vgrG genes, vgrG1abc, to bacterial killing. A putative toxin is encoded in the vicinity of each vgrG gene, supporting the concept of specific VgrG/toxin couples. In this respect, VgrG1c is involved in the delivery of an Rhs protein, RhsP1. The RhsP1 C terminus carries a toxic activity, from which the producing bacterium is protected by a cognate immunity. Similarly, VgrG1a-dependent toxicity is associated with the PA0093 gene encoding a two-domain protein with a putative toxin domain (Toxin_61) at the C terminus. Finally, VgrG1b-dependent killing is detectable upon complementation of a triple vgrG1abc mutant. The VgrG1b-dependent killing is mediated by PA0099, which presents the characteristics of the superfamily nuclease 2 toxin members. Overall, these data develop the concept that VgrGs are indispensable components for the specific delivery of effectors. Several additional vgrG genes are encoded on the P. aeruginosa genome and are not linked genetically to other T6SS genes. A closer inspection of these clusters reveals that they also encode putative toxins. Overall, these associations further support the notion of an original form of secretion system, in which VgrG acts as the carrier.
Ball G, Filloux A, Voulhoux R, 2014, A method to capture large DNA fragments from genomic DNA., Methods Mol Biol, Vol: 1149, Pages: 491-500
The gene capture technique is a powerful tool that allows the cloning of large DNA regions (up to 80 kb), such as entire genomic islands, without using restriction enzymes or DNA amplification. This technique takes advantage of the high recombinant capacity of the yeast. A "capture" vector containing both ends of the target DNA region must first be constructed. The target region is then captured by co-transformation and recombination in yeast between the "capture" vector and appropriate genomic DNA. The selected recombinant plasmid can be verified by sequencing and transferred in the bacteria for multiple applications. This chapter describes a protocol specifically adapted for Pseudomonas aeruginosa genomic DNA capture.
Muhl D, Filloux A, 2014, Site-Directed Mutagenesis and Gene Deletion Using Reverse Genetics, PSEUDOMONAS: METHODS AND PROTOCOLS, Vol: 1149, Pages: 521-539, ISSN: 1064-3745
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- Citations: 13
Barraud N, Moscoso JA, Ghigo J-M, et al., 2014, Methods for Studying Biofilm Dispersal in <i>Pseudomonas aeruginosa</i>, PSEUDOMONAS: METHODS AND PROTOCOLS, Vol: 1149, Pages: 643-651, ISSN: 1064-3745
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- Citations: 26
Jones C, Filloux A, 2014, Gene Amplification and qRT-PCR, PSEUDOMONAS: METHODS AND PROTOCOLS, Vol: 1149, Pages: 457-468, ISSN: 1064-3745
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- Citations: 1
Filloux A, Ramos J-L, 2014, Pseudomonas Methods and Protocols Preface, PSEUDOMONAS: METHODS AND PROTOCOLS, Vol: 1149, Pages: V-V, ISSN: 1064-3745
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- Citations: 5
Filloux A, 2013, Fit and resistant is a worst case scenario with bacterial pathogens, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, Vol: 110, Pages: 20360-20361, ISSN: 0027-8424
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- Citations: 1
Jones C, Hachani A, Manoli E, et al., 2013, An rhs Gene Linked to the Second Type VI Secretion Cluster Is a Feature of the Pseudomonas aeruginosa Strain PA14, Journal of Bacteriology, Vol: 196, Pages: 800-810, ISSN: 1098-5530
The type VI secretion system (T6SS) of Gram-negative bacteria has been involved in various processes, notably bacterial competition and eukaryotic cell subversion. Most Pseudomonas aeruginosa strains possess three T6SS gene clusters, but only the function of the first T6SS (H1-T6SS) has been clearly elucidated. It is involved in the secretion of three toxins (Tse1 to -3) that target bacterial competitors. In the case of the H2- and H3-T6SS, no clear function has been assigned, and only one effector has been associated with these systems. Yet the H2-T6SS was proposed to promote P. aeruginosa internalization in nonphagocytic epithelial cells. Although the H2-T6SS genetic organization is conserved across P. aeruginosa isolates, one feature is the presence of an additional transcriptional unit in the PA14 strain H2-T6SS cluster, which is divergent from the core H2-T6SS genes. A specific set of four genes encodes an Hcp protein (Hcp2), a VgrG protein (VgrG14), an Rhs element (PA14_43100 or RhsP2), and a protein with no homologies with previously characterized proteins (PA14_43090). In this study, we engineered a P. aeruginosa PA14 strain carrying an arabinose-inducible H2-T6SS on the chromosome. We showed that arabinose induction readily promotes assembly of the H2-T6SS, as seen by monitoring Hcp2 secretion. We further studied the secretion fate of VgrG14 and RhsP2, but these were not detectable in the extracellular medium. We finally investigated whether activation of the PA14 H2-T6SS gene cluster could influence phenotypic traits such as internalization in eukaryotic cells, and we reported noteworthy differences compared to strain PAO1, which may be accounted for by the described genetic differences.
Filloux A, 2013, The rise of the Type VI secretion system, F1000prime reports, Vol: 5, ISSN: 2051-7599
Bacterial cells have developed multiple strategies to communicate with their surrounding environment. The intracellular compartment is separated from the milieu by a relatively impermeable cell envelope through which small molecules can passively diffuse, while larger macromolecules, such as proteins, can be actively transported. In Gram-negative bacteria, the cell envelope is a double membrane, which houses several supramolecular protein complexes that facilitate the trafficking of molecules. For example, bacterial pathogens use these types of machines to deliver toxins into target eukaryotic host cells, thus subverting host cellular functions. Six different types of nanomachines, called Type I - Type VI secretion systems (T1SS - T6SS), can be readily identified by their composition and mode of action. A remarkable feature of these protein secretion systems is their similarity to systems with other biological functions, such as motility or the exchange of genetic material. The T6SS has provided a refreshing view on this concept since it shares similarity with the puncturing device of bacteriophages, which is used by these viruses to inject their DNA into bacterial target cells. In contrast, the bacterial T6SS transports toxins into other bacteria, engaging a ferocious competition for the colonization of their environment. Moreover, as with few other secretion systems, the T6SS is capable of injecting toxins into eukaryotic cells, which contributes to a successful infection. This highlights the multifunctional aspects of the T6SS, and our understanding of its mechanistic details is an intense field of investigation with significant implications for ecology, agriculture and medicine.
Jones C, Allsopp L, Horlick J, et al., 2013, Subinhibitory concentration of kanamycin induces the pseudomonas aeruginosa type VI secretion system, PLoS ONE, Vol: 8, ISSN: 1932-6203
Pseudomonas aeruginosa is a Gram-negative bacterium found in natural environments including plants, soils and warm moist surfaces. This organism is also in the top ten of nosocomial pathogens, and prevalent in cystic fibrosis (CF) lung infections. The ability of P. aeruginosa to colonize a wide variety of environments in a lasting manner is associated with the formation of a resistant biofilm and the capacity to efficiently outcompete other microorganisms. Here we demonstrate that sub-inhibitory concentration of kanamycin not only induces biofilm formation but also induces expression of the type VI secretion genes in the H1-T6SS cluster. The H1-T6SS is known for its role in toxin production and bacterial competition. We show that the antibiotic induction of the H1-T6SS only occurs when a functional Gac/Rsm pathway is present. These observations may contribute to understand how P. aeruginosa responds to antibiotic producing competitors. It also suggests that improper antibiotic therapy may enhance P. aeruginosa colonization, including in the airways of CF patients.
Filloux A, 2013, MICROBIOLOGY A weapon for bacterial warfare, NATURE, Vol: 500, Pages: 284-285, ISSN: 0028-0836
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- Citations: 7
Mikkelsen H, Hui K, Barraud N, et al., 2013, The pathogenicity island encoded PvrSR/RcsCB regulatory network controls biofilm formation and dispersal in Pseudomonas aeruginosa PA14, Molecular Microbiology, Vol: 89, Pages: 450-463, ISSN: 0950-382X
Pseudomonas aeruginosa biofilm formation is linked to persistent infections in humans. Biofilm formation is facilitated by extracellular appendages, some of which are assembled by the Chaperone Usher Pathway (Cup). The cupD gene cluster is located on the PAPI‐1 pathogenicity island of strain PA14 and has probably been acquired together with four genes encoding two‐component signal transduction proteins. We have previously showed that the RcsB response regulator activates expression of the cupD genes, which leads to the production of CupD fimbriae and increased attachment. Here we show that RcsB activity is tightly modulated by two sensors, RcsC and PvrS. While PvrS acts as a kinase that enhances RcsB activity, RcsC has a dual function, first as a phosphorelay, and second as a phosphatase. We found that, under certain growth conditions, overexpression of RcsB readily induces biofilm dispersal. Microarray analysis shows that RcsB positively controls expression of pvrR that encodes the phosphodiesterase required for this dispersal process. Finally, in addition to the PAPI‐1 encoded cupD genes, RcsB controls several genes on the core genome, some of which encode orphan response regulators. We thus discovered that RcsB is central to a large regulatory network that fine‐tunes the switch between biofilm formation and dispersal.
Aksoy E, Taboubi S, Torres D, et al., 2013, The p110δ isoform of the kinase PI(3)K controls the subcellular compartmentalization of TLR4 signaling and protects from endotoxic shock (vol 13, pg 1045, 2012), NATURE IMMUNOLOGY, Vol: 14, Pages: 877-877, ISSN: 1529-2908
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- Citations: 2
Hachani A, Lossi NS, Filloux A, 2013, A visual assay to monitor T6SS-mediated bacterial competition, Jove-Journal of Visualized Experiments, ISSN: 1940-087X
Type VI secretion systems (T6SSs) are molecular nanomachines allowing Gram-negative bacteria to transport and inject proteins into a wide variety of target cells1,2. The T6SS is composed of 13 core components and displays structural similarities with the tail-tube of bacteriophages3. The phage uses a tube and a puncturing device to penetrate the cell envelope of target bacteria and inject DNA. It is proposed that the T6SS is an inverted bacteriophage device creating a specific path in the bacterial cell envelope to drive effectors and toxins to the surface. The process could be taken further and the T6SS device could perforate other cells with which the bacterium is in contact, thus injecting the effectors into these targets. The tail tube and puncturing device parts of the T6SS are made with Hcp and VgrG proteins, respectively4,5.The versatility of the T6SS has been demonstrated through studies using various bacterial pathogens. The Vibrio cholerae T6SS can remodel the cytoskeleton of eukaryotic host cells by injecting an "evolved" VgrG carrying a C-terminal actin cross-linking domain6,7. Another striking example was recently documented using Pseudomonas aeruginosa which is able to target and kill bacteria in a T6SS-dependent manner, therefore promoting the establishment of bacteria in specific microbial niches and competitive environment8,9,10.In the latter case, three T6SS-secreted proteins, namely Tse1, Tse2 and Tse3 have been identified as the toxins injected in the target bacteria (Figure 1). The donor cell is protected from the deleterious effect of these effectors via an anti-toxin mechanism, mediated by the Tsi1, Tsi2 and Tsi3 immunity proteins8,9,10. This antimicrobial activity can be monitored when T6SS-proficient bacteria are co-cultivated on solid surfaces in competition with other bacterial species or with T6SS-inactive bacteria of the same species8,11,12,13.The data available emphasized a numerical approach to the bacterial competition assay
Filloux A, 2013, Untitled, FEMS MICROBIOLOGY REVIEWS, Vol: 37, Pages: 111-111, ISSN: 0168-6445
Aksoy E, Taboubi S, Torres D, et al., 2012, The p110δ isoform of the kinase PI(3)K controls the subcellular compartmentalization of TLR4 signaling and protects from endotoxic shock, NATURE IMMUNOLOGY, Vol: 13, Pages: 1045-1054, ISSN: 1529-2908
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- Citations: 138
Lossi NS, Manoli E, Simpson P, et al., 2012, The archetype Pseudomonas aeruginosa proteins TssB and TagJ form a novel subcomplex in the bacterial type VI secretion system, MOLECULAR MICROBIOLOGY, Vol: 86, Pages: 437-456, ISSN: 0950-382X
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- Citations: 20
Ball G, Viarre V, Garvis S, et al., 2012, Type II-dependent secretion of a <i>Pseudomonas aeruginosa</i> DING protein, RESEARCH IN MICROBIOLOGY, Vol: 163, Pages: 457-469, ISSN: 0923-2508
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- Citations: 16
Sana TG, Hachani A, Bucior I, et al., 2012, The Second Type VI Secretion System of Pseudomonas aeruginosa Strain PAO1 Is Regulated by Quorum Sensing and Fur and Modulates Internalization in Epithelial Cells, Journal of Biological Chemistry, Vol: 287, Pages: 27095-27105, ISSN: 1083-351X
The genome of Pseudomonas aeruginosa PAO1 contains three type VI secretion systems (T6SSs) called H1-, H2-, and H3-T6SS. The H1-T6SS secretes three identified toxins that target other bacteria, providing a fitness advantage for P. aeruginosa, and likely contributes to bacterial pathogenesis in chronic infections. However, no specific substrates or defined roles have been described for the two other systems. Here, we demonstrate that the expression of H2-T6SS genes of strain PAO1 is up-regulated during the transition from exponential to stationary phase growth and regulated by the Las and Rhl quorum sensing systems. In addition, we identify two putative Fur boxes in the promoter region and find that H2-T6SS transcription is negatively regulated by iron. We also show that the H2-T6SS system enhances bacterial uptake into HeLa cells (75% decrease in internalization with a H2-T6SS mutant) and into lung epithelial cells through a phosphatidylinositol 3-kinase-dependent pathway that induces Akt activation in the host cell (50% decrease in Akt phosphorylation). Finally, we show that H2-T6SS plays a role in P. aeruginosa virulence in the worm model. Thus, in contrast to H1-T6SS, H2-T6SS modulates interaction with eukaryotic host cells. Together, T6SS can carry out different functions that may be important in establishing chronic P. aeruginosa infections in the human host.
Hengge R, Wigneshweraraj S, Llamas MA, et al., 2012, Bacterial regulatory Networks, Publisher: Caister Academic Press
Douzi B, Filloux A, Voulhoux R, 2012, On the path to uncover the bacterial type II secretion system, PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES, Vol: 367, Pages: 1059-1072, ISSN: 0962-8436
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- Citations: 89
Moscoso JA, Mikkelsen H, Heeb S, et al., 2012, The <i>Pseudomonas aeruginosa</i> sensor RetS switches Type III and Type VI secretion via c-di-GMP signalling (vol 13, pg 3128, 2011), ENVIRONMENTAL MICROBIOLOGY, Vol: 14, Pages: 1088-1089, ISSN: 1462-2912
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