1
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Hajjar H, Berry L, Wu Y, Touqui L, Vergunst AC, Blanc-Potard AB. Contribution of intramacrophage stages to Pseudomonas aeruginosa infection outcome in zebrafish embryos: insights from mgtC and oprF mutants. Sci Rep 2024; 14:6297. [PMID: 38491095 PMCID: PMC10943088 DOI: 10.1038/s41598-024-56725-8] [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: 10/02/2023] [Accepted: 03/10/2024] [Indexed: 03/18/2024] Open
Abstract
Pseudomonas aeruginosa often colonizes immunocompromised patients, causing acute and chronic infections. This bacterium can reside transiently inside cultured macrophages, but the contribution of the intramacrophic stage during infection remains unclear. MgtC and OprF have been identified as important bacterial factors when P. aeruginosa resides inside cultured macrophages. In this study, we showed that P. aeruginosa mgtC and oprF mutants, particular the latter one, had attenuated virulence in both mouse and zebrafish animal models of acute infection. To further investigate P. aeruginosa pathogenesis in zebrafish at a stage different from acute infection, we monitored bacterial load and visualized fluorescent bacteria in live larvae up to 4 days after infection. Whereas the attenuated phenotype of the oprF mutant was associated with a rapid elimination of bacteria, the mgtC mutant was able to persist at low level, a feature also observed with the wild-type strain in surviving larvae. Interestingly, these persistent bacteria can be visualized in macrophages of zebrafish. In a short-time infection model using a macrophage cell line, electron microscopy revealed that internalized P. aeruginosa wild-type bacteria were either released after macrophage lysis or remained intracellularly, where they were localized in vacuoles or in the cytoplasm. The mgtC mutant could also be detected inside macrophages, but without causing cell damage, whereas the oprF mutant was almost completely eliminated after phagocytosis, or localized in phagolysosomes. Taken together, our results show that the main role of OprF for intramacrophage survival impacts both acute and persistent infection by this bacterium. On the other hand, MgtC plays a clear role in acute infection but is not essential for bacterial persistence, in relation with the finding that the mgtC mutant is not completely eliminated by macrophages.
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Affiliation(s)
- Hélène Hajjar
- Laboratory of Pathogens and Host Immunity (LPHI), Université de Montpellier, CNRS-UMR5294, INSERM, Montpellier, France
| | - Laurence Berry
- Laboratory of Pathogens and Host Immunity (LPHI), Université de Montpellier, CNRS-UMR5294, INSERM, Montpellier, France
| | - Yongzheng Wu
- Institut Pasteur, Université Paris Cité, CNRS UMR3691, Cellular Biology and Microbial Infection Unit, Paris, France
| | - Lhousseine Touqui
- Sorbonne Université, Inserm U938, Centre de Recherche Saint-Antoine (CRSA), Paris, France
- Institut Pasteur, Université de Paris Cité, Mucoviscidose et Bronchopathies Chroniques, Paris, France
| | - Annette C Vergunst
- Bacterial Virulence and Chronic Infections (VBIC), Université de Montpellier, INSERM, U1047, Nîmes, France.
| | - Anne-Béatrice Blanc-Potard
- Laboratory of Pathogens and Host Immunity (LPHI), Université de Montpellier, CNRS-UMR5294, INSERM, Montpellier, France.
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2
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Rahimova R, Nogaret P, Huteau V, Gelin M, Clément DA, Labesse G, Pochet S, Blanc-Potard AB, Lionne C. Structure-based design, synthesis and biological evaluation of a NAD + analogue targeting Pseudomonas aeruginosa NAD kinase. FEBS J 2023; 290:482-501. [PMID: 36036789 PMCID: PMC10087438 DOI: 10.1111/febs.16604] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 07/20/2022] [Accepted: 07/27/2022] [Indexed: 02/05/2023]
Abstract
Multidrug resistance is a major public health problem that requires the urgent development of new antibiotics and therefore the identification of novel bacterial targets. The activity of nicotinamide adenine dinucleotide kinase, NADK, is essential in all bacteria tested so far, including many human pathogens that display antibiotic resistance leading to the failure of current treatments. Inhibiting NADK is therefore a promising and innovative antibacterial strategy since there is currently no drug on the market targeting this enzyme. Through a fragment-based drug design approach, we have recently developed a NAD+ -competitive inhibitor of NADKs, which displayed in vivo activity against Staphylococcus aureus. Here, we show that this compound, a di-adenosine derivative, is inactive against the NADK enzyme from the Gram-negative bacteria Pseudomonas aeruginosa (PaNADK). This lack of activity can be explained by the crystal structure of PaNADK, which was determined in complex with NADP+ in this study. Structural analysis led us to design and synthesize a benzamide adenine dinucleoside analogue, active against PaNADK. This novel compound efficiently inhibited PaNADK enzymatic activity in vitro with a Ki of 4.6 μm. Moreover, this compound reduced P. aeruginosa infection in vivo in a zebrafish model.
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Affiliation(s)
- Rahila Rahimova
- Centre de Biologie Structurale (CBS), Université de Montpellier, CNRS UMR 5048, INSERM U1054, France
| | - Pauline Nogaret
- Laboratory of Pathogen Host Interactions (LPHI), Université de Montpellier, CNRS UMR 5235, France
| | - Valérie Huteau
- Unité de Chimie Biologique Epigénétique, Institut Pasteur, Université Paris Cité, CNRS UMR3523, France
| | - Muriel Gelin
- Centre de Biologie Structurale (CBS), Université de Montpellier, CNRS UMR 5048, INSERM U1054, France
| | - David A Clément
- Unité de Chimie Biologique Epigénétique, Institut Pasteur, Université Paris Cité, CNRS UMR3523, France
| | - Gilles Labesse
- Centre de Biologie Structurale (CBS), Université de Montpellier, CNRS UMR 5048, INSERM U1054, France
| | - Sylvie Pochet
- Unité de Chimie Biologique Epigénétique, Institut Pasteur, Université Paris Cité, CNRS UMR3523, France
| | | | - Corinne Lionne
- Centre de Biologie Structurale (CBS), Université de Montpellier, CNRS UMR 5048, INSERM U1054, France
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3
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Sacher-Pirklbauer A, Klein-Jöbstl D, Sofka D, Blanc-Potard AB, Hilbert F. Phylogenetic Groups and Antimicrobial Resistance Genes in Escherichia coli from Different Meat Species. Antibiotics (Basel) 2021; 10:antibiotics10121543. [PMID: 34943755 PMCID: PMC8698590 DOI: 10.3390/antibiotics10121543] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [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: 10/31/2021] [Revised: 12/03/2021] [Accepted: 12/14/2021] [Indexed: 12/02/2022] Open
Abstract
Escherichia coli isolated from meat of different animal species may harbour antimicrobial resistance genes and may thus be a threat to human health. The objectives of this study were to define antimicrobial resistance genes in E. coli isolates from pork, beef, chicken- and turkey meat and analyse whether their resistance genotypes associated with phylogenetic groups or meat species. A total number of 313 E. coli samples were isolated using standard cultural techniques. In 98% of resistant isolates, a dedicated resistance gene could be identified by PCR. Resistance genes detected were tet(A) and tet(B) for tetracycline resistance, strA and aadA1 for streptomycin resistance, sulI and sulII for resistance against sulphonamides, dfr and aphA for kanamycin resistance and blaTEM for ampicillin resistance. One stx1 harbouring E. coli isolated from pork harboured the tet(A) gene and belonged to phylogenetic group B2, whilst another stx1 positive isolate from beef was multi-resistant and tested positive for blaTEM,aphA, strA–B, sulII, and tet(A) and belonged to phylogenetic group A. In conclusion, the distribution of resistance elements was almost identical and statistically indifferent in isolates of different meat species. Phylogenetic groups did not associate with the distribution of resistance genes and a rather low number of diverse resistance genes were detected. Most E. coli populations with different resistance genes against one drug often revealed statistically significant different MIC values.
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Affiliation(s)
- Angelika Sacher-Pirklbauer
- Institute of Food Safety, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine, 1210 Vienna, Austria; (A.S.-P.); (D.S.)
| | - Daniela Klein-Jöbstl
- Section of Herd Management, Clinic for Ruminats, University of Veterinary Medicine, 1210 Vienna, Austria;
| | - Dmitrij Sofka
- Institute of Food Safety, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine, 1210 Vienna, Austria; (A.S.-P.); (D.S.)
| | - Anne-Béatrice Blanc-Potard
- Laboratory of Pathogen-Host Interactions (LPHI), Université Montpellier, 34095 Montpellier, France;
- CNRS, UMR 5235, 34095 Montpellier, France
| | - Friederike Hilbert
- Institute of Food Safety, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine, 1210 Vienna, Austria; (A.S.-P.); (D.S.)
- Correspondence: ; Tel.: +43-125-0773-316
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Pont S, Blanc-Potard AB. Zebrafish Embryo Infection Model to Investigate Pseudomonas aeruginosa Interaction With Innate Immunity and Validate New Therapeutics. Front Cell Infect Microbiol 2021; 11:745851. [PMID: 34660345 PMCID: PMC8515127 DOI: 10.3389/fcimb.2021.745851] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [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] [Accepted: 09/08/2021] [Indexed: 12/26/2022] Open
Abstract
The opportunistic human pathogen Pseudomonas aeruginosa is responsible for a variety of acute infections and is a major cause of mortality in chronically infected patients with cystic fibrosis (CF). Considering the intrinsic and acquired resistance of P. aeruginosa to currently used antibiotics, new therapeutic strategies against this pathogen are urgently needed. Whereas virulence factors of P. aeruginosa are well characterized, the interplay between P. aeruginosa and the innate immune response during infection remains unclear. Zebrafish embryo is now firmly established as a potent vertebrate model for the study of infectious human diseases, due to strong similarities of its innate immune system with that of humans and the unprecedented possibilities of non-invasive real-time imaging. This model has been successfully developed to investigate the contribution of bacterial and host factors involved in P. aeruginosa pathogenesis, as well as rapidly assess the efficacy of anti-Pseudomonas molecules. Importantly, zebrafish embryo appears as the state-of-the-art model to address in vivo the contribution of innate immunity in the outcome of P. aeruginosa infection. Of interest, is the finding that the zebrafish encodes a CFTR channel closely related to human CFTR, which allowed to develop a model to address P. aeruginosa pathogenesis, innate immune response, and treatment evaluation in a CF context.
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Affiliation(s)
- Stéphane Pont
- Laboratory of Pathogen-Host Interactions (LPHI), Université Montpellier, Montpellier, France.,CNRS, UMR5235, Montpellier, France
| | - Anne-Béatrice Blanc-Potard
- Laboratory of Pathogen-Host Interactions (LPHI), Université Montpellier, Montpellier, France.,CNRS, UMR5235, Montpellier, France
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5
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Moussouni M, Berry L, Sipka T, Nguyen-Chi M, Blanc-Potard AB. Pseudomonas aeruginosa OprF plays a role in resistance to macrophage clearance during acute infection. Sci Rep 2021; 11:359. [PMID: 33432030 PMCID: PMC7801371 DOI: 10.1038/s41598-020-79678-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [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: 09/16/2020] [Accepted: 12/11/2020] [Indexed: 12/14/2022] Open
Abstract
While considered an extracellular pathogen, Pseudomonas aeruginosa has been reported to be engulfed by macrophages in cellular and animal models. However, the role of macrophages in P. aeruginosa clearance in vivo remains poorly studied. The major outer membrane porin OprF has been recently shown to be involved in P. aeruginosa fate within cultured macrophages and analysis of an oprF mutant may thus provide insights to better understand the relevance of this intramacrophage stage during infection. In the present study, we investigated for the first time the virulence of a P. aeruginosa oprF mutant in a vertebrate model that harbors functional macrophages, the zebrafish (Danio rerio) embryo, which offers powerful tools to address macrophage–pathogen interactions. We established that P. aeruginosa oprF mutant is attenuated in zebrafish embryos in a macrophage-dependent manner. Visualization and quantification of P. aeruginosa bacteria phagocytosed by macrophages after injection into closed cavities suggested that the attenuated phenotype of oprF mutant is not linked to higher macrophage recruitment nor better phagocytosis than wild-type strain. Using cultured macrophages, we showed an intramacrophage survival defect of P. aeruginosa oprF mutant, which is correlated with elevated association of bacteria with acidic compartments. Notably, treatment of embryos with bafilomycin, an inhibitor of acidification, increased the sensibility of embryos towards both wild-type and oprF mutant, and partially suppressed the attenuation of oprF mutant. Taken together, this work supports zebrafish embryo as state-of-the-art model to address in vivo the relevance of P. aeruginosa intramacrophage stage. Our results highlight the contribution of macrophages in the clearance of P. aeruginosa during acute infection and suggest that OprF protects P. aeruginosa against macrophage clearance by avoiding bacterial elimination in acidified phagosomes.
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Affiliation(s)
- Malika Moussouni
- Laboratory of Pathogen-Host Interactions (LPHI), CNRS-UMR5235, Université de Montpellier, Montpellier, France
| | - Laurence Berry
- Laboratory of Pathogen-Host Interactions (LPHI), CNRS-UMR5235, Université de Montpellier, Montpellier, France
| | - Tamara Sipka
- Laboratory of Pathogen-Host Interactions (LPHI), CNRS-UMR5235, Université de Montpellier, Montpellier, France
| | - Mai Nguyen-Chi
- Laboratory of Pathogen-Host Interactions (LPHI), CNRS-UMR5235, Université de Montpellier, Montpellier, France
| | - Anne-Béatrice Blanc-Potard
- Laboratory of Pathogen-Host Interactions (LPHI), CNRS-UMR5235, Université de Montpellier, Montpellier, France.
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6
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Blanc-Potard AB, Groisman EA. How Pathogens Feel and Overcome Magnesium Limitation When in Host Tissues. Trends Microbiol 2020; 29:98-106. [PMID: 32807623 DOI: 10.1016/j.tim.2020.07.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 07/16/2020] [Accepted: 07/22/2020] [Indexed: 12/29/2022]
Abstract
Host organisms utilize nutritional immunity to limit the availability of nutrients essential to an invading pathogen. Nutrients may include amino acids, nucleotide bases, and transition metals, the essentiality of which varies among pathogens. The mammalian macrophage protein Slc11a1 (previously Nramp1) mediates resistance to several intracellular pathogens. Slc11a1 is proposed to restrict growth of Salmonella enterica serovar Typhimurium in host tissues by causing magnesium deprivation. This is intriguing because magnesium is the most abundant divalent cation in all living cells. A pathogen's response to factors such as Slc11a1 that promote nutritional immunity may therefore reflect what the pathogen 'feels' in its cytoplasm, rather than the nutrient concentration in host cell compartments.
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Affiliation(s)
- Anne-Béatrice Blanc-Potard
- Laboratory of Pathogen Host Interactions, Université Montpellier, case 107, Place Eugène Bataillon, 34095, Montpellier cedex 5, France; CNRS, UMR5235, 34095, Montpellier Cedex 05, France.
| | - Eduardo A Groisman
- Department of Microbial Pathogenesis, Yale School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA; Yale Microbial Sciences Institute, P.O. Box 27389, West Haven, CT 06516, USA.
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Garai P, Berry L, Moussouni M, Bleves S, Blanc-Potard AB. Killing from the inside: Intracellular role of T3SS in the fate of Pseudomonas aeruginosa within macrophages revealed by mgtC and oprF mutants. PLoS Pathog 2019; 15:e1007812. [PMID: 31220187 PMCID: PMC6586356 DOI: 10.1371/journal.ppat.1007812] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [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: 01/18/2019] [Accepted: 05/02/2019] [Indexed: 12/19/2022] Open
Abstract
While considered solely an extracellular pathogen, increasing evidence indicates that Pseudomonas aeruginosa encounters intracellular environment in diverse mammalian cell types, including macrophages. In the present study, we have deciphered the intramacrophage fate of wild-type P. aeruginosa PAO1 strain by live and electron microscopy. P. aeruginosa first resided in phagosomal vacuoles and subsequently could be detected in the cytoplasm, indicating phagosomal escape of the pathogen, a finding also supported by vacuolar rupture assay. The intracellular bacteria could eventually induce cell lysis, both in a macrophage cell line and primary human macrophages. Two bacterial factors, MgtC and OprF, recently identified to be important for survival of P. aeruginosa in macrophages, were found to be involved in bacterial escape from the phagosome as well as in cell lysis caused by intracellular bacteria. Strikingly, type III secretion system (T3SS) genes of P. aeruginosa were down-regulated within macrophages in both mgtC and oprF mutants. Concordantly, cyclic di-GMP (c-di-GMP) level was increased in both mutants, providing a clue for negative regulation of T3SS inside macrophages. Consistent with the phenotypes and gene expression pattern of mgtC and oprF mutants, a T3SS mutant (ΔpscN) exhibited defect in phagosomal escape and macrophage lysis driven by internalized bacteria. Importantly, these effects appeared to be largely dependent on the ExoS effector, in contrast with the known T3SS-dependent, but ExoS independent, cytotoxicity caused by extracellular P. aeruginosa towards macrophages. Moreover, this macrophage damage caused by intracellular P. aeruginosa was found to be dependent on GTPase Activating Protein (GAP) domain of ExoS. Hence, our work highlights T3SS and ExoS, whose expression is modulated by MgtC and OprF, as key players in the intramacrophage life of P. aeruginosa which allow internalized bacteria to lyse macrophages. The ability of professional phagocytes to ingest and kill microorganisms is central to host defense and Pseudomonas aeruginosa has developed mechanisms to avoid being killed by phagocytes. While considered an extracellular pathogen, P. aeruginosa has been reported to be engulfed by macrophages in animal models. Here, we visualized the fate of P. aeruginosa within cultured macrophages, revealing macrophage lysis driven by intracellular P. aeruginosa. Two bacterial factors, MgtC and OprF, recently discovered to be involved in the intramacrophage survival of P. aeruginosa, appeared to play a role in this cytotoxicity caused by intracellular bacteria. We provided evidence that type III secretion system (T3SS) gene expression is lowered intracellularly in mgtC and oprF mutants. We further showed that intramacrophage P. aeruginosa uses its T3SS, specifically the ExoS effector, to promote phagosomal escape and cell lysis. We thus describe a transient intramacrophage stage of P. aeruginosa that could contribute to bacterial dissemination.
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Affiliation(s)
- Preeti Garai
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, CNRS-UMR5235, Montpellier, France
| | - Laurence Berry
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, CNRS-UMR5235, Montpellier, France
| | - Malika Moussouni
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, CNRS-UMR5235, Montpellier, France
| | - Sophie Bleves
- LISM, Institut de Microbiologie de la Méditerranée, CNRS & Aix-Marseille Univ, Marseille, France
| | - Anne-Béatrice Blanc-Potard
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, CNRS-UMR5235, Montpellier, France
- * E-mail:
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Moussouni M, Nogaret P, Garai P, Ize B, Vivès E, Blanc-Potard AB. Activity of a Synthetic Peptide Targeting MgtC on Pseudomonas aeruginosa Intramacrophage Survival and Biofilm Formation. Front Cell Infect Microbiol 2019; 9:84. [PMID: 31001488 PMCID: PMC6454036 DOI: 10.3389/fcimb.2019.00084] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [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: 12/20/2018] [Accepted: 03/11/2019] [Indexed: 01/29/2023] Open
Abstract
Antivirulence strategies aim to target pathogenicity factors while bypassing the pressure on the bacterium to develop resistance. The MgtC membrane protein has been proposed as an attractive target that is involved in the ability of several major bacterial pathogens, including Pseudomonas aeruginosa, to survive inside macrophages. In liquid culture, P. aeruginosa MgtC acts negatively on biofilm formation. However, a putative link between these two functions of MgtC in P. aeruginosa has not been experimentally addressed. In the present study, we first investigated the contribution of exopolysaccharides (EPS) in the intramacrophage survival defect and biofilm increase of mgtC mutant. Within infected macrophages, expression of EPS genes psl and alg was increased in a P. aeruginosa mgtC mutant strain comparatively to wild-type strain. However, the intramacrophage survival defect of mgtC mutant was not rescued upon introduction of psl or alg mutation, suggesting that MgtC intramacrophage role is unrelated to EPS production, whereas the increased biofilm formation of mgtC mutant was partially suppressed by introduction of psl mutation. We aimed to develop an antivirulence strategy targeting MgtC, by taking advantage of a natural antagonistic peptide, MgtR. Heterologous expression of mgtR in P. aeruginosa PAO1 was shown to reduce its ability to survive within macrophages. We investigated for the first time the biological effect of a synthetic MgtR peptide on P. aeruginosa. Exogenously added synthetic MgtR peptide lowered the intramacrophage survival of wild-type P. aeruginosa PAO1, thus mimicking the phenotype of an mgtC mutant as well as the effect of endogenously produced MgtR peptide. In correlation with this finding, addition of MgtR peptide to bacterial culture strongly reduced MgtC protein level, without reducing bacterial growth or viability, thus differing from classical antimicrobial peptides. On the other hand, the addition of exogenous MgtR peptide did not affect significantly biofilm formation, indicating an action toward EPS-independent phenotype rather than EPS-related phenotype. Cumulatively, our results show an antivirulence action of synthetic MgtR peptide, which may be more potent against acute infection, and provide a proof of concept for further exploitation of anti-Pseudomonas strategies.
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Affiliation(s)
- Malika Moussouni
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université Montpellier, Montpellier, France.,CNRS, UMR5235, Montpellier, France
| | - Pauline Nogaret
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université Montpellier, Montpellier, France.,CNRS, UMR5235, Montpellier, France
| | - Preeti Garai
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université Montpellier, Montpellier, France.,CNRS, UMR5235, Montpellier, France
| | - Bérengère Ize
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, CNRS & Aix-Marseille University of Marseille, Marseille, France
| | - Eric Vivès
- Centre de Recherche en Biologie cellulaire de Montpellier, CNRS UMR 5237, Montpellier, France
| | - Anne-Béatrice Blanc-Potard
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université Montpellier, Montpellier, France.,CNRS, UMR5235, Montpellier, France
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9
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Gannoun-Zaki L, Pätzold L, Huc-Brandt S, Baronian G, Elhawy MI, Gaupp R, Martin M, Blanc-Potard AB, Letourneur F, Bischoff M, Molle V. PtpA, a secreted tyrosine phosphatase from Staphylococcus aureus, contributes to virulence and interacts with coronin-1A during infection. J Biol Chem 2018; 293:15569-15580. [PMID: 30131335 DOI: 10.1074/jbc.ra118.003555] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [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: 04/20/2018] [Revised: 08/16/2018] [Indexed: 11/06/2022] Open
Abstract
Secretion of bacterial signaling proteins and adaptation to the host, especially during infection, are processes that are often linked in pathogenic bacteria. The human pathogen Staphylococcus aureus is equipped with a large arsenal of immune-modulating factors, allowing it to either subvert the host immune response or to create permissive niches for its survival. Recently, we showed that one of the low-molecular-weight protein tyrosine phosphatases produced by S. aureus, PtpA, is secreted during growth. Here, we report that deletion of ptpA in S. aureus affects intramacrophage survival and infectivity. We also observed that PtpA is secreted during macrophage infection. Immunoprecipitation assays identified several host proteins as putative intracellular binding partners for PtpA, including coronin-1A, a cytoskeleton-associated protein that is implicated in a variety of cellular processes. Of note, we demonstrated that coronin-1A is phosphorylated on tyrosine residues upon S. aureus infection and that its phosphorylation profile is linked to PtpA expression. Our results confirm that PtpA has a critical role during infection as a bacterial effector protein that counteracts host defenses.
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Affiliation(s)
- Laila Gannoun-Zaki
- From the Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, CNRS, UMR 5235, Montpellier 34000, France and
| | - Linda Pätzold
- the Institute of Medical Microbiology and Hygiene, University of Saarland, 66421 Homburg/Saar, Germany
| | - Sylvaine Huc-Brandt
- From the Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, CNRS, UMR 5235, Montpellier 34000, France and
| | - Grégory Baronian
- From the Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, CNRS, UMR 5235, Montpellier 34000, France and
| | - Mohamed Ibrahem Elhawy
- the Institute of Medical Microbiology and Hygiene, University of Saarland, 66421 Homburg/Saar, Germany
| | - Rosmarie Gaupp
- the Institute of Medical Microbiology and Hygiene, University of Saarland, 66421 Homburg/Saar, Germany
| | - Marianne Martin
- From the Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, CNRS, UMR 5235, Montpellier 34000, France and
| | - Anne-Béatrice Blanc-Potard
- From the Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, CNRS, UMR 5235, Montpellier 34000, France and
| | - François Letourneur
- From the Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, CNRS, UMR 5235, Montpellier 34000, France and
| | - Markus Bischoff
- the Institute of Medical Microbiology and Hygiene, University of Saarland, 66421 Homburg/Saar, Germany
| | - Virginie Molle
- From the Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, CNRS, UMR 5235, Montpellier 34000, France and
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10
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Rosas Olvera M, Vivès E, Molle V, Blanc-Potard AB, Gannoun-Zaki L. Endogenous and Exogenous KdpF Peptide Increases Susceptibility of Mycobacterium bovis BCG to Nitrosative Stress and Reduces Intramacrophage Replication. Front Cell Infect Microbiol 2017; 7:115. [PMID: 28428950 PMCID: PMC5382158 DOI: 10.3389/fcimb.2017.00115] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [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: 01/17/2017] [Accepted: 03/22/2017] [Indexed: 11/15/2022] Open
Abstract
Emerging antibiotic resistance in pathogenic bacteria like Mycobacterium sp., poses a threat to human health and therefore calls for the development of novel antibacterial strategies. We have recently discovered that bacterial membrane peptides, such as KdpF, possess anti-virulence properties when overproduced in pathogenic bacterial species. Overproduction of the KdpF peptide in Mycobacterium bovis BCG decreased bacterial replication within macrophages, without presenting antibacterial activity. We propose that KdpF functions as a regulatory molecule and interferes with bacterial virulence, potentially through interaction with the PDIM transporter MmpL7. We demonstrate here that KdpF overproduction in M. bovis BCG, increased bacterial susceptibility to nitrosative stress and thereby was responsible for lower replication rate within macrophages. Moreover, in a bacterial two-hybrid system, KdpF was able to interact not only with MmpL7 but also with two membrane proteins involved in nitrosative stress detoxification (NarI and NarK2), and a membrane protein of unknown function that is highly induced upon nitrosative stress (Rv2617c). Interestingly, we showed that the exogenous addition of KdpF synthetic peptide could affect the stability of proteins that interact with this peptide. Finally, the exogenous KdpF peptide presented similar biological effects as the endogenously expressed peptide including nitrosative stress susceptibility and reduced intramacrophage replication rate for M. bovis BCG. Taken together, our results establish a link between high levels of KdpF and nitrosative stress susceptibility to further highlight KdpF as a potent molecule with anti-virulence properties.
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Affiliation(s)
- Mariana Rosas Olvera
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université MontpellierMontpellier, France.,Centre National de la Recherche Scientifique, UMR5235Montpellier, France
| | - Eric Vivès
- CRBM, Centre National de la Recherche Scientifique UMR 5237Montpellier, France
| | - Virginie Molle
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université MontpellierMontpellier, France.,Centre National de la Recherche Scientifique, UMR5235Montpellier, France
| | - Anne-Béatrice Blanc-Potard
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université MontpellierMontpellier, France.,Centre National de la Recherche Scientifique, UMR5235Montpellier, France
| | - Laila Gannoun-Zaki
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université MontpellierMontpellier, France.,Centre National de la Recherche Scientifique, UMR5235Montpellier, France
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Belon C, Blanc-Potard AB. Intramacrophage Survival for Extracellular Bacterial Pathogens: MgtC As a Key Adaptive Factor. Front Cell Infect Microbiol 2016; 6:52. [PMID: 27242970 PMCID: PMC4869558 DOI: 10.3389/fcimb.2016.00052] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 04/26/2016] [Indexed: 01/06/2023] Open
Affiliation(s)
- Claudine Belon
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier (DIMNP Centre National de la Recherche Scientifique-UMR5235) Montpellier, France
| | - Anne-Béatrice Blanc-Potard
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier (DIMNP Centre National de la Recherche Scientifique-UMR5235) Montpellier, France
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Belon C, Rosas Olvera M, Vives E, Kremer L, Gannoun-Zaki L, Blanc-Potard AB. Use of the Salmonella MgtR peptide as an antagonist of the Mycobacterium MgtC virulence factor. Future Microbiol 2016; 11:215-25. [DOI: 10.2217/fmb.15.134] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Background: The MgtC virulence factor has been proposed as an attractive target for antivirulence strategies because it is shared by several important bacterial pathogens, including Salmonella enterica and Mycobacterium tuberculosis (Mtb). Aim: A natural antagonistic peptide, MgtR, which interacts with MgtC and modulates its stability, has been identified in Salmonella, and we investigated its efficiency to target MgtC in another pathogen. Materials & methods: We evaluated the interaction between Salmonella MgtR peptide and the Mtb MgtC protein using an in vivo bacterial two-hybrid system and we addressed the effect of exogenously added synthetic MgtR and endogenously expressed peptide. Results: MgtR peptide strongly interacted with Mtb MgtC protein and exogenously added synthetic MgtR peptide-reduced Mtb MgtC level and interfered with the dimerization of Mtb MgtC. Importantly, heterologous expression of MgtR in Mycobacterium bovis BCG resulted in increased phagocytosis and reduced intramacrophage survival. Conclusion: MgtR peptide can target Mtb MgtC protein and reduce mycobacterial macrophage resistance, thus providing a promising new scaffold for the development of antivirulence compounds.
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Affiliation(s)
- Claudine Belon
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 05, France
- CNRS, UMR5235, 34095 Montpellier Cedex 05, France
| | - Mariana Rosas Olvera
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 05, France
- CNRS, UMR5235, 34095 Montpellier Cedex 05, France
| | - Eric Vives
- Université de Montpellier, Montpellier, F-34090, France
| | - Laurent Kremer
- INSERM, DIMNP, CNRS-UMR5235, Montpellier, France
- Centre d’études d'agents Pathogènes et Biotechnologies pour la Santé (CPBS - FRE 3689), 1919 route de Mende, 34293 Montpellier, France
| | - Laila Gannoun-Zaki
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 05, France
- CNRS, UMR5235, 34095 Montpellier Cedex 05, France
| | - Anne-Béatrice Blanc-Potard
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 05, France
- CNRS, UMR5235, 34095 Montpellier Cedex 05, France
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Abstract
Pseudomonas aeruginosa is an extracellular pathogen known to impair host phagocytic functions. However, our recent results identify MgtC as a novel actor in P. aeruginosa virulence, which plays a role in an intramacrophage phase of this pathogen. In agreement with its intracellular function, P. aeruginosamgtC gene expression is strongly induced when the bacteria reside within macrophages. MgtC was previously known as a horizontally-acquired virulence factor important for multiplication inside macrophages in several intracellular bacterial pathogens. MgtC thus provides a singular example of a virulence determinant that subverts macrophages both in intracellular and extracellular pathogens. Moreover, we demonstrate that P. aeruginosa MgtC is required for optimal growth in Mg2+ deprived medium, a property shared by MgtC factors from intracellular pathogens and, under Mg2+ limitation, P. aeruginosa MgtC prevents biofilm formation. We propose that MgtC has a similar function in intracellular and extracellular pathogens, which contributes to macrophage resistance and fine-tune adaptation to the host in relation to the different bacterial lifestyles. MgtC thus appears as an attractive target for antivirulence strategies and our work provides a natural peptide as MgtC antagonist, which paves the way for the development of MgtC inhibitors.
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Affiliation(s)
- Audrey Bernut
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier (DIMNP CNRS-UMR5235), Place Eugène Bataillon, 34095 Montpellier Cedex 05, France
| | - Claudine Belon
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier (DIMNP CNRS-UMR5235), Place Eugène Bataillon, 34095 Montpellier Cedex 05, France
| | - Chantal Soscia
- CNRS & Aix-Marseille University, Laboratoire d'Ingénierie des Systèmes Macromoléculaires (UMR7255), IMM, 31 Chemin Joseph Aiguier, 13402 Marseille cedex 20, France
| | - Sophie Bleves
- CNRS & Aix-Marseille University, Laboratoire d'Ingénierie des Systèmes Macromoléculaires (UMR7255), IMM, 31 Chemin Joseph Aiguier, 13402 Marseille cedex 20, France
| | - Anne-Béatrice Blanc-Potard
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier (DIMNP CNRS-UMR5235), Place Eugène Bataillon, 34095 Montpellier Cedex 05, France
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Belon C, Soscia C, Bernut A, Laubier A, Bleves S, Blanc-Potard AB. A Macrophage Subversion Factor Is Shared by Intracellular and Extracellular Pathogens. PLoS Pathog 2015; 11:e1004969. [PMID: 26080006 PMCID: PMC4469704 DOI: 10.1371/journal.ppat.1004969] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [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: 12/18/2014] [Accepted: 05/21/2015] [Indexed: 01/03/2023] Open
Abstract
Pathogenic bacteria have developed strategies to adapt to host environment and resist host immune response. Several intracellular bacterial pathogens, including Salmonella enterica and Mycobacterium tuberculosis, share the horizontally-acquired MgtC virulence factor that is important for multiplication inside macrophages. MgtC is also found in pathogenic Pseudomonas species. Here we investigate for the first time the role of MgtC in the virulence of an extracellular pathogen, Pseudomonas aeruginosa. A P. aeruginosa mgtC mutant is attenuated in the systemic infection model of zebrafish embryos, and strikingly, the attenuated phenotype is dependent on the presence of macrophages. In ex vivo experiments, the P. aeruginosa mgtC mutant is more sensitive to macrophage killing than the wild-type strain. However, wild-type and mutant strains behave similarly toward macrophage killing when macrophages are treated with an inhibitor of the vacuolar proton ATPase. Importantly, P. aeruginosa mgtC gene expression is strongly induced within macrophages and phagosome acidification contributes to an optimal expression of the gene. Thus, our results support the implication of a macrophage intracellular stage during P. aeruginosa acute infection and suggest that Pseudomonas MgtC requires phagosome acidification to play its intracellular role. Moreover, we demonstrate that P. aeruginosa MgtC is required for optimal growth in Mg2+ deprived medium, a property shared by MgtC factors from intracellular pathogens and, under Mg2+ limitation, P. aeruginosa MgtC prevents biofilm formation. We propose that MgtC shares a similar function in intracellular and extracellular pathogens, which contributes to macrophage resistance and fine-tune adaptation to host immune response in relation to the different bacterial lifestyles. In addition, the phenotypes observed with the mgtC mutant in infection models can be mimicked in wild-type P. aeruginosa strain by producing a MgtC antagonistic peptide, thus highlighting MgtC as a promising new target for anti-virulence strategies. Pathogenic bacteria have to resist host immune response and MgtC is used by several intracellular pathogens to promote bacterial multiplication inside macrophages. Here we investigated MgtC’s role in the virulence of an extracellular pathogen, Pseudomonas aeruginosa. A P. aeruginosa mgtC mutant is attenuated in zebrafish embryos, but only in the presence of macrophages. Moreover, this mutant is more rapidly killed by macrophages than the wild-type strain. Both phenotypes can be mimicked upon production of a MgtC antagonistic peptide in wild-type Pseudomonas strain. MgtC thus provides a singular example of a virulence determinant that promotes strategies to subvert the antimicrobial behavior of macrophages, in both intracellular and extracellular pathogens and our results support an intramacrophage stage during in P. aeruginosa acute infection, as well as an interplay between MgtC role and phagosome acidification. In addition, P. aeruginosa MgtC is required for growth in Mg2+ deprived medium, a property shared by MgtC factors from intracellular pathogens, and limits biofilm formation. MgtC may share a similar function in intracellular and extracellular pathogens, with an outcome adapted to the different bacterial lifestyles
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Affiliation(s)
- Claudine Belon
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, CNRS-UMR5235, Montpellier, France
| | - Chantal Soscia
- CNRS & Aix-Marseille Université, Laboratoire d’Ingénierie des Systèmes Macromoléculaires (UMR7255), Marseille, France
| | - Audrey Bernut
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, CNRS-UMR5235, Montpellier, France
| | - Aurélie Laubier
- CNRS & Aix-Marseille Université, Laboratoire d’Ingénierie des Systèmes Macromoléculaires (UMR7255), Marseille, France
| | - Sophie Bleves
- CNRS & Aix-Marseille Université, Laboratoire d’Ingénierie des Systèmes Macromoléculaires (UMR7255), Marseille, France
- * E-mail: (SB); (ABBP)
| | - Anne-Béatrice Blanc-Potard
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, CNRS-UMR5235, Montpellier, France
- * E-mail: (SB); (ABBP)
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Belon C, Gannoun-Zaki L, Lutfalla G, Kremer L, Blanc-Potard AB. Mycobacterium marinum MgtC plays a role in phagocytosis but is dispensable for intracellular multiplication. PLoS One 2014; 9:e116052. [PMID: 25545682 PMCID: PMC4278808 DOI: 10.1371/journal.pone.0116052] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [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: 09/18/2014] [Accepted: 12/04/2014] [Indexed: 01/04/2023] Open
Abstract
MgtC is a virulence factor involved in intramacrophage growth that has been reported in several intracellular pathogens, including Mycobacterium tuberculosis and Salmonella enterica serovar Typhimurium. MgtC participates also in adaptation to Mg2+ deprivation. Herein, we have constructed a mgtC mutant in Mycobacterium marinum to further investigate the role of MgtC in mycobacteria. We show that the M. marinum mgtC gene (Mma mgtC) is strongly induced upon Mg2+ deprivation and is required for optimal growth in Mg2+-deprived medium. The behaviour of the Mma mgtC mutant has been investigated in the Danio rerio infection model using a transgenic reporter zebrafish line that specifically labels neutrophils. Although the mgtC mutant is not attenuated in the zebrafish embryo model based on survival curves, our results indicate that phagocytosis by neutrophils is enhanced with the mgtC mutant compared to the wild-type strain following subcutaneous injection. Increased phagocytosis of the mutant strain is also observed ex vivo with the murine J774 macrophage cell line. On the other hand, no difference was found between the mgtC mutant and the wild-type strain in bacterial adhesion to macrophages and in the internalization into epithelial cells. Unlike the role reported for MgtC in other intracellular pathogens, Mma MgtC does not contribute significantly to intramacrophage replication. Taken together, these results indicate an unanticipated function of Mma MgtC at early step of infection within phagocytic cells. Hence, our results indicate that although the MgtC function is conserved among pathogens regarding adaptation to Mg2+ deprivation, its role towards phagocytic cells can differ, possibly in relation with the specific pathogen's lifestyles.
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Affiliation(s)
- Claudine Belon
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Universités Montpellier 2 et 1, Place Eugène Bataillon, 34095, Montpellier, Cedex 05, France
- Centre National de la Recherche Scientifique, UMR5235, Montpellier, France
| | - Laïla Gannoun-Zaki
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Universités Montpellier 2 et 1, Place Eugène Bataillon, 34095, Montpellier, Cedex 05, France
- Centre National de la Recherche Scientifique, UMR5235, Montpellier, France
| | - Georges Lutfalla
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Universités Montpellier 2 et 1, Place Eugène Bataillon, 34095, Montpellier, Cedex 05, France
- Centre National de la Recherche Scientifique, UMR5235, Montpellier, France
| | - Laurent Kremer
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Universités Montpellier 2 et 1, Place Eugène Bataillon, 34095, Montpellier, Cedex 05, France
- Centre National de la Recherche Scientifique, UMR5235, Montpellier, France
- Institut national de la santé et de la recherche médicale, Montpellier, France
| | - Anne-Béatrice Blanc-Potard
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Universités Montpellier 2 et 1, Place Eugène Bataillon, 34095, Montpellier, Cedex 05, France
- Centre National de la Recherche Scientifique, UMR5235, Montpellier, France
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Gannoun-Zaki L, Belon C, Dupont C, Hilbert F, Kremer L, Blanc-Potard AB. Overexpression of theSalmonellaKdpF membrane peptide modulates expression ofkdpgenes and intramacrophage growth. FEMS Microbiol Lett 2014; 359:34-41. [DOI: 10.1111/1574-6968.12559] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 07/09/2014] [Accepted: 07/25/2014] [Indexed: 11/30/2022] Open
Affiliation(s)
- Laila Gannoun-Zaki
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques; Universités de Montpellier 2 et 1; CNRS-UMR5235; Montpellier; France
| | - Claudine Belon
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques; Universités de Montpellier 2 et 1; CNRS-UMR5235; Montpellier; France
| | - Christian Dupont
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques; Universités de Montpellier 2 et 1; CNRS-UMR5235; Montpellier; France
| | - Friederike Hilbert
- Institute of Meat Hygiene; Meat Technology and Food Science; University of Veterinary Medicine Vienna; Vienna Austria
| | - Laurent Kremer
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques; Universités de Montpellier 2 et 1; CNRS-UMR5235; Montpellier; France
- INSERM; DIMNP; CNRS-UMR5235; Montpellier France
| | - Anne-Béatrice Blanc-Potard
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques; Universités de Montpellier 2 et 1; CNRS-UMR5235; Montpellier; France
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Gannoun-Zaki L, Alibaud L, Carrère-Kremer S, Kremer L, Blanc-Potard AB. Overexpression of the KdpF membrane peptide in Mycobacterium bovis BCG results in reduced intramacrophage growth and altered cording morphology. PLoS One 2013; 8:e60379. [PMID: 23577107 PMCID: PMC3618439 DOI: 10.1371/journal.pone.0060379] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [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: 01/04/2013] [Accepted: 02/26/2013] [Indexed: 12/19/2022] Open
Abstract
Membrane peptides appear as an emerging class of regulatory molecules in bacteria, which can interact with membrane proteins, such as sensor kinases. To date, regulatory membrane peptides have been completely overlooked in mycobacteria. The 30 amino-acid-long KdpF peptide, which is co-transcribed with kdpABC genes and regulated by the KdpDE two-component system, is supposed to stabilize the KdpABC potassium transporter complex but may also exhibit unsuspected regulatory function(s) towards the KdpD sensor kinase. Herein, we showed by quantitative RT-PCR that the Mycobacterium bovis BCG kdpAB and kdpDE genes clusters are differentially induced in potassium-deprived broth medium or within infected macrophages. We have overexpressed the kdpF gene in M. bovis BCG to investigate its possible regulatory role and effect on mycobacterial virulence. Our results indicate that KdpF does not play a critical regulatory role on kdp genes expression despite the fact that KdpF interacts with the KdpD sensor kinase in a bacterial two-hybrid assay. However, overexpression of kdpF results in a significant reduction of M. bovis BCG growth in both murine and human primary macrophages, and is associated with a strong alteration of colonial morphology and impaired cording formation. To identify novel KdpF interactants, a mycobacterial library was screened using KdpF as bait in the bacterial two-hybrid system. This allowed us to identify members of the MmpL family of membrane proteins, known to participate in the biosynthesis/transport of various cell wall lipids, thus highlighting a possible link between KdpF and cell wall lipid metabolism. Taken together, these data suggest that KdpF overexpression reduces intramacrophage growth which may result from alteration of the mycobacterial cell wall.
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Affiliation(s)
- Laila Gannoun-Zaki
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Universités de Montpellier 2 et 1, CNRS-UMR5235, Montpellier, France
| | - Laeticia Alibaud
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Universités de Montpellier 2 et 1, CNRS-UMR5235, Montpellier, France
| | - Séverine Carrère-Kremer
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Universités de Montpellier 2 et 1, CNRS-UMR5235, Montpellier, France
| | - Laurent Kremer
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Universités de Montpellier 2 et 1, CNRS-UMR5235, Montpellier, France
- INSERM, DIMNP, CNRS-UMR5235, Montpellier, France
| | - Anne-Béatrice Blanc-Potard
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Universités de Montpellier 2 et 1, CNRS-UMR5235, Montpellier, France
- * E-mail:
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Howell AB, Botto H, Combescure C, Blanc-Potard AB, Gausa L, Matsumoto T, Tenke P, Sotto A, Lavigne JP. Dosage effect on uropathogenic Escherichia coli anti-adhesion activity in urine following consumption of cranberry powder standardized for proanthocyanidin content: a multicentric randomized double blind study. BMC Infect Dis 2010; 10:94. [PMID: 20398248 PMCID: PMC2873556 DOI: 10.1186/1471-2334-10-94] [Citation(s) in RCA: 158] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2009] [Accepted: 04/14/2010] [Indexed: 11/28/2022] Open
Abstract
Background Ingestion of cranberry (Vaccinium macrocarpon Ait.) has traditionally been utilized for prevention of urinary tract infections. The proanthocyanidins (PACs) in cranberry, in particular the A-type linkages have been implicated as important inhibitors of primarily P-fimbriated E. coli adhesion to uroepithelial cells. Additional experiments were required to investigate the persistence in urine samples over a broader time period, to determine the most effective dose per day and to determine if the urinary anti-adhesion effect following cranberry is detected within volunteers of different origins. Methods Two separate bioassays (a mannose-resistant hemagglutination assay and an original new human T24 epithelial cell-line assay) have assessed the ex-vivo urinary bacterial anti-adhesion activity on urines samples collected from 32 volunteers from Japan, Hungary, Spain and France in a randomized, double-blind versus placebo study. An in vivo Caenorhabditis elegans model was used to evaluate the influence of cranberry regimen on the virulence of E. coli strain. Results The results indicated a significant bacterial anti-adhesion activity in urine samples collected from volunteers that consumed cranberry powder compared to placebo (p < 0.001). This inhibition was clearly dose-dependent, prolonged (until 24 h with 72 mg of PAC) and increasing with the amount of PAC equivalents consumed in each cranberry powder regimen. An in vivo Caenorhabditis elegans model showed that cranberry acted against bacterial virulence: E. coli strain presented a reduced ability to kill worms after a growth in urines samples of patients who took cranberry capsules. This effect is particularly important with the regimen of 72 mg of PAC. Conclusions Administration of PAC-standardized cranberry powder at dosages containing 72 mg of PAC per day may offer some protection against bacterial adhesion and virulence in the urinary tract. This effect may offer a nyctohemeral protection.
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Affiliation(s)
- Amy B Howell
- Institut National de la Santé et de la Recherche Médicale, Espri26, Université Montpellier 1, Nîmes, France
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Abstract
Identification of short coding sequences is challenging, both experimentally and in silico, and functional natural peptides (< 50 amino acids) have to a large extent been overlooked in Gram-negative bacteria. Recent results have converged to highlight the role of hydrophobic peptides that form a novel class of active molecules in Escherichia coli and Salmonella enterica serovar Typhimurium. These peptides can play a regulatory role by interacting with protein partners at the inner membrane and by modulating protein partner activity or stability. Genome-wide analyses in both bacterial species have identified several conserved short open reading frames encoding a single transmembrane segment. We discuss the known and predicted membrane-associated peptides and the tools for their identification. Besides the identification of novel regulatory networks, characterization of peptides with a single transmembrane helix segment and proteins that interact with them provides a powerful opportunity to study interactions between alpha helices within biological membranes. In addition, some bioactive membrane peptides could provide a basis for engineering membrane protein antagonists.
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Affiliation(s)
- Eric Alix
- Inserm, ESPRI 26, Avenue J. F. Kennedy, 30908 Nîmes cedex 02, France
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Alix E, Miki T, Felix C, Rang C, Figueroa-Bossi N, Demettre E, Blanc-Potard AB. Interplay between MgtC and PagC in Salmonella enterica serovar Typhimurium. Microb Pathog 2008; 45:236-40. [PMID: 18620040 DOI: 10.1016/j.micpath.2008.06.001] [Citation(s) in RCA: 10] [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: 03/08/2008] [Revised: 06/03/2008] [Accepted: 06/13/2008] [Indexed: 10/21/2022]
Abstract
In Salmonella enterica serovar Typhimurium, MgtC and PagC are positively regulated by the PhoP-PhoQ two-component system, which is activated under magnesium deprivation. Both MgtC and PagC are of unknown function but have been involved in intramacrophage survival. We have found that the amount of PagC is lowered in a DeltamgtC mutant strain grown in magnesium depleted medium. However, the effect of MgtC on PagC does not account for the growth defect of a DeltamgtC mutant in macrophages since, in contrast to previous reports, our results indicate that PagC does not contribute to intramacrophage survival. In addition, a pagC null mutant is only poorly attenuated in Nramp1-negative or Nramp1-positive mice. On the other hand, a mgtC null mutant is significantly more attenuated with Nramp1-positive than Nramp1-negative mice, suggesting that a functional Nramp1 (Slc11a1) further limits the multiplication of this mutant within the host.
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Affiliation(s)
- Eric Alix
- Inserm, ESPRI 26, Avenue J.F. Kennedy, 30908 Nîmes Cedex 02, France
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Alix E, Blanc-Potard AB. Peptide-assisted degradation of the Salmonella MgtC virulence factor. EMBO J 2008; 27:546-57. [PMID: 18200043 DOI: 10.1038/sj.emboj.7601983] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2007] [Accepted: 12/20/2007] [Indexed: 01/04/2023] Open
Abstract
MgtC is a virulence factor common to several intracellular pathogens that is required for intramacrophage survival and growth in magnesium-depleted medium. In Salmonella enterica, MgtC is coexpressed with the MgtB magnesium transporter and transcription of the mgtCB operon is induced by magnesium deprivation. Despite the high level of mgtCB transcriptional induction in magnesium-depleted medium, the MgtC protein is hardly detected in a wild-type Salmonella strain. Here, we show that downregulation of MgtC expression is dependent on a hydrophobic peptide, MgtR, which is encoded by the mgtCB operon. Our results suggest that MgtR promotes MgtC degradation by the FtsH protease, providing a negative regulatory feedback. Bacterial two-hybrid assays demonstrate that MgtR interacts with the inner-membrane MgtC protein. We identified mutant derivatives of MgtR and MgtC that prevent both regulation and interaction between the two partners. In macrophages, overexpression of the MgtR peptide led to a decrease of the replication rate of Salmonella. This study highlights the role of peptides in bacterial regulatory mechanisms and provides a natural antagonist of the MgtC virulence factor.
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Lavigne JP, Blanc-Potard AB. Molecular evolution of Salmonella enterica serovar Typhimurium and pathogenic Escherichia coli: from pathogenesis to therapeutics. Infect Genet Evol 2007; 8:217-26. [PMID: 18226587 DOI: 10.1016/j.meegid.2007.11.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2007] [Revised: 11/20/2007] [Accepted: 11/22/2007] [Indexed: 12/31/2022]
Abstract
Salmonella enterica serovar Typhimurium (S. Typhimurium) and certain Escherichia coli are human pathogens that have evolved through the acquisition of multiple virulence determinants by horizontal gene transfer. Similar genetic elements, as pathogenicity islands and virulence plasmids, have driven molecular evolution of virulence in both species. In addition, the contribution of prophages has been recently highlighted as a reservoir for pathogenic diversity. Characterization of horizontally acquired virulence genes has several clinical implications. First, identification of virulence determinants that have a sporadic distribution and are specifically associated with a pathotype and/or a pathology can be useful markers for risk assessment and diagnosis. Secondly, virulence factors widely distributed in pathogenic strains, but absent from non-pathogenic bacteria, are interesting targets for the development of novel antimicrobial chemotherapies and vaccines. Here, we summarize the horizontally acquired virulence factors of S. Typhimurium, enterohemorrhagic E. coli O157:H7 and uropathogenic E. coli, and we describe their use in novel therapeutic approaches.
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Affiliation(s)
- Jean-Philippe Lavigne
- Institut National de la Santé et de la Recherche Médicale, Espri 26, Avenue J.F. Kennedy, 30908 Nîmes Cedex 02, France
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Abstract
Several bacterial pathogens have evolved strategies to survive in macrophages and create a replicative niche within phagosomes. The bacterial factor MgtC is a key player in intramacrophage survival, being important for virulence in diverse intracellular pathogens. MgtC is also required for growth under magnesium limitation. Recent studies provide new clues on the role of MgtC in macrophages, which seems to be unlinked to adaptation to a low Mg(2+) microenvironment. In addition, we discuss the unexpected finding that MgtC modulates host P-type ATPase activity.
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Affiliation(s)
- Eric Alix
- Inserm, Espri 26, Avenue J.F. Kennedy, 30908 Nîmes cedex 02, France
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Abstract
MgtC is required for intramacrophage replication of intracellular pathogens and growth in low Mg(2+) medium. A link between these two phenotypes has been proposed due to putative Mg(2+) deprivation inside phagosome. MgtC is part of a family of proteins that share a conserved N-terminal transmembrane domain and a variable C-terminal domain. A combination of predictive and experimental approaches indicates that the Salmonella MgtC C-terminal domain is cytoplasmic, adopts a fold also found in metal transporters and RNA interacting domain, and does not bind Mg(2+). MgtC homologues from diverse gamma-proteobacteria, including the extracellular pathogens Yersinia pestis, Photorhabdus luminescens and Pseudomonas aeruginosa, have been expressed in a SalmonellaDeltamgtC strain. The Y. pestis MgtC fully replaced the Salmonella MgtC whereas P. luminescens or P. aeruginosa MgtC complemented only in low Mg(2+) medium, thus dissociating for the first time the two MgtC-related phenotypes. In addition, we identified single amino acids changes that prevent or promote MgtC role in macrophages without affecting MgtC role in low Mg(2+) culture. A SalmonellaDeltamgtC strain showed elongated and autoaggregated bacteria in low Mg(2+) medium but not in macrophages. Taken together our results suggest that MgtC has a dual role when bacteria localize in macrophages or low Mg(2+) environment.
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Affiliation(s)
- Cécile Rang
- INSERM U431, Avenir Team, Faculté de Médecine, Avenue J. F. Kennedy, 30908 Nîmes Cedex 02, France
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Alix E, Godreuil S, Blanc-Potard AB. Identification of a Haarlem genotype-specific single nucleotide polymorphism in the mgtC virulence gene of Mycobacterium tuberculosis. J Clin Microbiol 2006; 44:2093-8. [PMID: 16757603 PMCID: PMC1489410 DOI: 10.1128/jcm.00278-06] [Citation(s) in RCA: 19] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
MgtC is a virulence factor common to several intracellular pathogens, including Mycobacterium tuberculosis, that might have been acquired through horizontal gene transfer. In the present study, we investigated the polymorphism of mgtC in clinical isolates representative of the main epidemic groups of M. tuberculosis. MgtC appears to have a low polymorphism rate in M. tuberculosis that consists exclusively of nonsynonymous mutations. We identified a single nucleotide polymorphism (SNP) at mgtC codon 182 (mgtC182) specifically associated with the Haarlem genotype. A simple PCR assay, called the "on/off switch assay," using phosphorothioate-modified primers and Pfu polymerase allowed us to distinguish Haarlem from non-Haarlem strains based on the mgtC182 SNP. The amino acid change (H182R) associated with the mgtC182 SNP in Haarlem strains does not appear to procure a selective advantage. Our results offer a simple and rapid tool to distinguish between Haarlem and non-Haarlem strains. In addition, the on/off switch assay, which allows the detection of SNPs on chromosomal DNA and M. tuberculosis cultures, provides a novel approach for the screening of known SNPs in M. tuberculosis.
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Affiliation(s)
- Eric Alix
- INSERM U431, Avenir Team, UFR de Médecine, CS 83021, Avenue Kennedy, 30908 Nimes Cedex 02, France
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Blanc-Potard AB, Labesse G, Figueroa-Bossi N, Bossi L. Mutation at the "exit gate" of the salmonella gyrase a subunit suppresses a defect in the gyrase B subunit. J Bacteriol 2005; 187:6841-4. [PMID: 16166547 PMCID: PMC1251596 DOI: 10.1128/jb.187.19.6841-6844.2005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Salmonella enterica serovar Typhimurium, an S431P substitution in the B subunit of gyrase (allele gyrB651) confers resistance to nalidixic acid and causes reduced DNA superhelicity and hypersensitivity to novobiocin. Selection for novobiocin resistance allowed isolation of a mutation in the gyrA gene (allele gyrA659), a T467S substitution, which partially suppresses the supercoiling defect of gyrB651. Modeling analysis suggests that this mutation acts by destabilizing the GyrA bottom dimer interface. This is the first example of a gyrA mutation that compensates for a gyrB defect.
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Affiliation(s)
- Anne-Béatrice Blanc-Potard
- Avenir team Institut National de la Santé et de la Recherche Médicale, Unité 431, Faculté de Médecine, CS 83021, Avenue J. F. Kennedy, 30908 Nîmes Cedex 02, France.
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27
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Lavigne JP, O'callaghan D, Blanc-Potard AB. Requirement of MgtC for Brucella suis intramacrophage growth: a potential mechanism shared by Salmonella enterica and Mycobacterium tuberculosis for adaptation to a low-Mg2+ environment. Infect Immun 2005; 73:3160-3. [PMID: 15845525 PMCID: PMC1087350 DOI: 10.1128/iai.73.5.3160-3163.2005] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A Brucella suis mgtC mutant is defective for growth within macrophages and in low-Mg(2+) medium. These phenotypes are strikingly similar to those observed with mgtC mutants from Salmonella enterica and Mycobacterium tuberculosis, two other pathogens that proliferate within phagosomes. MgtC appears as a remarkable virulence factor that would have been acquired by distantly related intracellular pathogens to contribute to the adaptation to a low-Mg(2+) environment in the phagosome.
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Affiliation(s)
- Jean-Philippe Lavigne
- Institut National de la Santé et de la Recherche Médicale, Unité 431, UFR de Médecine, CS 83021, Avenue J.F. Kennedy, 30908 NIMES Cedex 02, France
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Blanc-Potard AB, Lafay B. MgtC as a horizontally-acquired virulence factor of intracellular bacterial pathogens: evidence from molecular phylogeny and comparative genomics. J Mol Evol 2004; 57:479-86. [PMID: 14708580 DOI: 10.1007/s00239-003-2496-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
MgtC is a virulence factor required for intramacrophage survival and growth in low Mg2+ medium in two pathogens that are not phylogenetically related, Salmonella typhimurium and Mycobacterium tuberculosis. In S. typhimurium, mgtC is carried by the SPI-3 pathogenicity island and hybridization studies have suggested that the distribution of mgtC among enterobacteria is limited. In the present study, we searched for the presence of mgtC-like sequences in eubacterial genomes. Analyses of MgtC-like proteins phylogeny and mgtC-like chromosomal context support the hypothesis that mgtC has been acquired by horizontal gene transfer repeatedly throughout bacterial evolution. In addition, the phylogenetic analysis revealed the existence of a subgroup of proteins, that includes the S. typhimurium and M. tuberculosis MgtC proteins, as well as MgtC-related proteins from other pathogens that are able to survive in macrophages, B. melitensis and Y. pestis. We propose that MgtC has a similar function in all these distantly related pathogens, most likely providing the ability to grow in a low Mg2+ environment.
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Escobar-Páramo P, Clermont O, Blanc-Potard AB, Bui H, Le Bouguénec C, Denamur E. A specific genetic background is required for acquisition and expression of virulence factors in Escherichia coli. Mol Biol Evol 2004; 21:1085-94. [PMID: 15014151 DOI: 10.1093/molbev/msh118] [Citation(s) in RCA: 231] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In bacteria, the evolution of pathogenicity seems to be the result of the constant arrival of virulence factors (VFs) into the bacterial genome. However, the integration, retention, and/or expression of these factors may be the result of the interaction between the new arriving genes and the bacterial genomic background. To test this hypothesis, a phylogenetic analysis was done on a collection of 98 Escherichia coli/Shigella strains representing the pathogenic and commensal diversity of the species. The distribution of 17 VFs associated to the different E. coli pathovars was superimposed on the phylogenetic tree. Three major types of VFs can be recognized: (1) VFs that arrive and are expressed in different genetic backgrounds (such as VFs associated with the pathovars of mild chronic diarrhea: enteroaggregative, enteropathogenic, and diffusely-adhering E. coli), (2) VFs that arrive in different genetic backgrounds but are preferentially found, associated with a specific pathology, in only one particular background (such as VFs associated with extraintestinal diseases), and (3) VFs that require a particular genetic background for the arrival and expression of their virulence potential (such as VFs associated with pathovars typical of severe acute diarrhea: enterohemorragic, enterotoxigenic, and enteroinvasive E. coli strains). The possibility of a single arrival of VFs by chance, followed by a vertical transmission, was ruled out by comparing the evolutionary histories of some of these VFs to the strain phylogeny. These evidences suggest that important changes in the genome of E. coli have occurred during the diversification of the species, allowing the virulence factors associated with severe acute diarrhea to arrive in the population. Thus, the E. coli genome seems to be formed by an "ancestral" and a "derived" background, each one responsible for the acquisition and expression of different virulence factors.
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Guignot J, Breard J, Bernet-Camard MF, Peiffer I, Nowicki BJ, Servin AL, Blanc-Potard AB. Pyelonephritogenic diffusely adhering Escherichia coli EC7372 harboring Dr-II adhesin carries classical uropathogenic virulence genes and promotes cell lysis and apoptosis in polarized epithelial caco-2/TC7 cells. Infect Immun 2000; 68:7018-27. [PMID: 11083827 PMCID: PMC97812 DOI: 10.1128/iai.68.12.7018-7027.2000] [Citation(s) in RCA: 27] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Diffusely adhering Escherichia coli (DAEC) strains expressing adhesins of the Afa/Dr family bind to epithelial cells in a diffuse adherence pattern by recognizing a common receptor, the decay-accelerating factor (CD55). Recently, a novel CD55-binding adhesin, named Dr-II, was identified from the pyelonephritogenic strain EC7372. In this report, we show that despite the low level of sequence identity between Dr-II and other members of the Afa/Dr family, EC7372 induces pathophysiological effects similar to those induced by other Afa/Dr DAEC strains on the polarized epithelial cell line Caco-2/TC7. Specifically, the Dr-II adhesin was sufficient to promote CD55 and CD66e clustering around adhering bacteria and apical cytoskeleton rearrangements. Unlike other Afa/Dr DAEC strains, EC7372 expresses a functional hemolysin that promotes a rapid cellular lysis. In addition, cell death by apoptosis or necrosis was observed in EC7372-infected Caco-2/TC7 cells, depending on infection time. Our results indicate that EC7372 harbors a pathogenicity island (PAI) similar to the one described for the pyelonephritogenic strain CFT073, which carries both hly and pap operons. Cumulatively, our findings indicate that strain EC7372 can be considered a prototype of a subclass of Afa/Dr DAEC isolates that have acquired a PAI harboring several classical uropathogenic virulence genes.
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Affiliation(s)
- J Guignot
- Unité 510, Faculté de Pharmacie Paris XI, Institut National de la Santé et de la Recherche Médicale, F-92296 Châtenay-Malabry, France
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Peiffer I, Blanc-Potard AB, Bernet-Camard MF, Guignot J, Barbat A, Servin AL. Afa/Dr diffusely adhering Escherichia coli C1845 infection promotes selective injuries in the junctional domain of polarized human intestinal Caco-2/TC7 cells. Infect Immun 2000; 68:3431-42. [PMID: 10816495 PMCID: PMC97619 DOI: 10.1128/iai.68.6.3431-3442.2000] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The Afa/Dr diffusely adhering Escherichia coli (DAEC) C1845 strain harboring the F1845 fimbrial adhesin interacts with the brush border-associated CD55 molecule and promotes elongation of brush border microvilli resulting from rearrangement of the F-actin network. This phenomenon involves the activation of a cascade of signaling coupled to the glycosylphosphatidylinositol-anchored receptor of the F1845 adhesin. We provide evidence that infection of the polarized human intestinal cell line Caco-2/TC7 by strain C1845 is followed by an increase in the paracellular permeability for [(3)H]mannitol without a decrease of the transepithelial resistance of the monolayers. Alterations in the distribution of tight-junction (TJ)-associated occludin and ZO-1 protein are observed, whereas the distribution of the zonula adherens-associated E-cadherin is not affected. Using the recombinant E. coli strains HB101(pSSS1) and -(pSSS1C) expressing the F1845 fimbrial adhesin, we demonstrate that the adhesin-CD55 interaction is not sufficient for the induction of structural and functional TJ lesions. Moreover, using the actin filament-stabilizing agent Jasplakinolide, we demonstrate that the C1845-induced functional alterations in TJs are independent of the C1845-induced apical cytoskeleton rearrangements. The results indicated that pathogenic factor(s) other than F1845 adhesin may be operant in Afa/Dr DAEC C1845.
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Affiliation(s)
- I Peiffer
- Unité 510, Institut National de la Santé et de la Recherche Médicale, Faculté de Pharmacie Paris XI, F-92296 Châtenay-Malabry, France
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Blanc-Potard AB, Figueroa-Bossi N, Bossi L. Histidine operon deattenuation in dnaA mutants of Salmonella typhimurium correlates with a decrease in the gene dosage ratio between tRNA(His) and histidine biosynthetic loci. J Bacteriol 1999; 181:2938-41. [PMID: 10217789 PMCID: PMC93740 DOI: 10.1128/jb.181.9.2938-2941.1999] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Expression of the histidine operon of Salmonella typhimurium is increased in dnaA(Ts) mutants at 37 degrees C. This effect requires an intact his attenuator and can be suppressed by increasing the gene copy number of the hisR locus, which encodes the tRNA(His). We present data which suggest that the his deattenuation defect in dnaA(Ts) mutants results from the loss of a gene dosage gradient between the hisR locus, close to oriC, and the his operon, far from oriC. Some of the conclusions drawn here may apply to other operons as well.
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Affiliation(s)
- A B Blanc-Potard
- Centre de Génétique Moléculaire, Centre National de la Recherche Scientifique, 91198 Gif-sur-Yvette Cedex, France
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Abstract
Pathogenicity islands are chromosomal clusters of pathogen-specific virulence genes often found at tRNA loci. We have determined the molecular genetic structure of SPI-3, a 17-kb pathogenicity island located at the selC tRNA locus of Salmonella enterica serovar Typhimurium. The G+C content of SPI-3 (47.5%) differs from that of the Salmonella genome (52%), consistent with the notion that these sequences have been horizontally acquired. SPI-3 harbors 10 open reading frames organized in six transcriptional units, which include the previously described mgtCB operon encoding the macrophage survival protein MgtC and the Mg2+ transporter MgtB. Among the newly identified open reading frames, one exhibits sequence similarity to the ToxR regulatory protein of Vibrio cholerae and one is similar to the AIDA-I adhesin of enteropathogenic Escherichia coli. The distribution of SPI-3 sequences varies among the salmonellae: the right end of the island, which harbors the virulence gene mgtC, is present in all eight subspecies of Salmonella; however, a four-gene cluster at the center of SPI-3 is found in only some of the subspecies and is bracketed by remnants of insertion sequences, suggesting a multistep process in the evolution of SPI-3 sequences.
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Affiliation(s)
- A B Blanc-Potard
- Department of Molecular Microbiology, Howard Hughes Medical Institute, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Abstract
Pathogenicity islands are chromosomal clusters of horizontally acquired virulence genes that are often found at tRNA loci. The selC tRNA locus of Escherichia coli has served as the site of integration of two distinct pathogenicity islands which are responsible for converting benign strains into uro- and enteropathogens. Because virulence genes are targeted to the selC locus of E.coli, we investigated the homologous region of the Salmonella typhimurium chromosome for the presence of horizontally acquired sequences. At this site, we identified a 17 kb DNA segment that is both unique to Salmonella and necessary for virulence. This segment harbors a gene, mgtC, that is required for intramacrophage survival and growth in low Mg2+ media. The mgtC locus is regulated by the PhoP/PhoQ two-component system, a major regulator of virulence functions present in both pathogenic and non-pathogenic bacterial species. Cumulatively, our experiments indicate that the ability to replicate in low Mg2+ environments is necessary for Salmonella virulence, and suggest that a similar mechanism is responsible for the dissemination and acquisition of pathogenicity islands in enteric bacteria.
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Affiliation(s)
- A B Blanc-Potard
- Department of Molecular Microbiology, Washington University School of Medicine, 660 S.Euclid Ave, Campus Box 8230, St Louis, MO 63110, USA
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Garí E, Figueroa-Bossi N, Blanc-Potard AB, Spirito F, Schmid MB, Bossi L. A class of gyrase mutants of Salmonella typhimurium show quinolone-like lethality and require rec functions for viability. Mol Microbiol 1996; 21:111-22. [PMID: 8843438 DOI: 10.1046/j.1365-2958.1996.6221338.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We have identified a new class of DNA gyrase mutants of Salmonella typhimurium that show chronic derepression of the SOS regulon. Thus, these mutants mimic the response of wild-type cells to gyrase inhibitors of the quinolone family. SOS induction by conditional lethal mutations gyrA208 or gyrB652, like that mediated by quinolones, is completely dependent on the function of the recB gene product. Introduction of recA or recB null mutations into these strains exacerbates their temperature-sensitive phenotype and prevents growth at the otherwise permissive temperature of 37 degrees C. Selection of suppressors that concomitantly restore growth at 37 degrees C and SOS induction in a recB- background yielded mutations that relleve the RecB requirement for homologous recombination; namely, sbcB mutations as well as mutations at a new locus that was named sbcE. Such mutations also restore SOS induction in quinolone-treated gyr+ recB- strains. These findings indicate that Rec functions are needed for growth of the gyrase mutants at 37 degrees C and suggest that recombinational repair intermediates constitute the SOS-inducing signal in the mutants as well as in quinolone-treated wild-type bacteria. Unlike quinolones, however, the gyr mutations described in this study do not cause detectable accumulation of "cleavable' gyrase-DNA complexes in plasmid or chromosomal DNA. Yet gyrA208 (the only allele tested) was found to trigger RecB-mediated reckless degradation of chromosomal DNA in recA-cells at restrictive temperatures. Indirect evidence suggests that double-stranded DNA ends, entry sites for the RecBCD enzyme, are generated in the gyr mutants by the breakage of DNA-replication forks. We discuss how this could occur and how recombinational rescue of collapsed replication forks could account for cell survival (and SOS induction) in the gyr mutants as well as in quinolone-treated bacteria.
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Affiliation(s)
- E Garí
- Centre de Génétique Moléculaire du CNRS, Gif-sur-Yvette, France
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Blanc-Potard AB, Gari E, Spirito F, Figueroa-Bossi N, Bossi L. RNA polymerase (rpoB) mutants selected for increased resistance to gyrase inhibitors in Salmonella typhimurium. Mol Gen Genet 1995; 247:680-92. [PMID: 7616959 DOI: 10.1007/bf00290399] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Some rifampicin-resistance (RifR) mutations make bacteria slightly resistant to the gyrase inhibitors novobiocin (Nov) and nalidixic acid (Nal). This suggested that it might be possible to isolate rpoB mutants using either drug for positive selection. In an initial test, we confirmed the presence of Rif-resistant isolates among clones selected for Nov resistance. These mutants are also more resistant to Nal. In a subsequent experiment, we found that mutants selected for low-level resistance to Nal include isolates harboring mutations genetically linked to the rpoB locus; of two such mutants studied, one is temperature-sensitive for growth. These two mutants, which are only marginally affected in their response to Nov, are normally sensitive to Rif and thus might be representative of a new class of rpoB alleles. The Rif-resistant and Rif-sensitive rpoB alleles that increase resistance to gyrase inhibitors have one property in common: they all suppress, to varying degrees, the defect in his operon regulation (transcriptional deattenuation) caused by a gyrase defect or inhibition by novobiocin. To further analyse the transcription-supercoiling relationships in these mutants, we examined the ability of RNA polymerase to recruit gyrase activity during transcription. This was done by two independent approaches: (i) observing transcription-induced accumulation of hyper-negatively supercoiled plasmid DNA in a topA mutant background and (ii) measuring transcription-induced plasmid DNA cleavage in the presence of oxolinic acid. Results indicate that the rpoB alleles described in this study diminish the recruitment of gyrase activity by the transcription process. This property correlates with a decrease in the rate of transcription initiation.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- A B Blanc-Potard
- Centre de Génétique Moléculaire du Centre National de la Recherche Scientifique Associé à l'Université P. et M. Curie, Gif-sur-Yvette, France
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Blanc-Potard AB, Bossi L. Phenotypic suppression of DNA gyrase deficiencies by a deletion lowering the gene dosage of a major tRNA in Salmonella typhimurium. J Bacteriol 1994; 176:2216-26. [PMID: 7512550 PMCID: PMC205342 DOI: 10.1128/jb.176.8.2216-2226.1994] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
One of the pleiotropic phenotypes of mutations affecting DNA gyrase activity in Salmonella typhimurium is the constitutive deattenuation of the histidine operon. In the present work, we isolated and characterized a suppressor mutation which restores his attenuation in the presence of a defective gyrase. Such a suppressor, initially named sgdA1 (for suppressor gyrase deficiency), was found to correct additional phenotypes associated with defective gyrase function. These include the aberrant nucleoid partitioning of a gyrB mutant and the conditional lethality of a gyrA mutation. Furthermore, the sgdA1 mutation was found to confer low-level resistance to nalidixic acid. The last phenotype permitted isolation of a number of additional sgdA mutants. Genetic analysis established the recessive character of these alleles as well as the position of the sgdA locus at 57 U on the Salmonella genetic map. All of the sgdA mutants result from the same molecular event: a deletion removing three of the four tandemly repeated copies of argV, the gene which specifies tRNA(2Arg), the major arginine isoacceptor tRNA. These findings, combined with the observation of some Sgd-like phenotypes in a tRNA modification mutant (hisT mutant), lead us to propose that protein synthesis contributes, directly or indirectly, to the pathology of gyrase alterations in growing bacteria. We discuss plausible mechanisms which may be responsible for these effects.
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MESH Headings
- Base Sequence
- DNA Topoisomerases, Type II/genetics
- Gene Deletion
- Genes, Bacterial/genetics
- Genes, Bacterial/physiology
- Genes, Suppressor/genetics
- Genes, Suppressor/physiology
- Histidine/genetics
- Histidine/metabolism
- Molecular Sequence Data
- Mutation/drug effects
- Mutation/genetics
- Mutation/physiology
- Nalidixic Acid/pharmacology
- Phenotype
- RNA, Bacterial/genetics
- RNA, Bacterial/physiology
- RNA, Transfer, Arg/genetics
- RNA, Transfer, Arg/physiology
- Salmonella typhimurium/drug effects
- Salmonella typhimurium/enzymology
- Salmonella typhimurium/genetics
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Affiliation(s)
- A B Blanc-Potard
- Centre de Génétique Moléculaire, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
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