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Hansen P, Haubenthal T, Reiter C, Kniewel J, Bosse-Plois K, Niemann HH, von Bargen K, Haas A. Differential Effects of Rhodococcus equi Virulence-Associated Proteins on Macrophages and Artificial Lipid Membranes. Microbiol Spectr 2023; 11:e0341722. [PMID: 36786596 PMCID: PMC10100859 DOI: 10.1128/spectrum.03417-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 01/06/2023] [Indexed: 02/15/2023] Open
Abstract
Virulence-associated protein A (VapA) of Rhodococcus equi is a pathogenicity factor required for the multiplication of virulent R. equi strains within spacious macrophage vacuoles. The production of VapA is characteristic for R. equi isolates from pneumonic foals. VapB and VapN proteins in R. equi isolates from infected pig (VapB) and cattle (VapN) have amino acid sequences very similar to VapA and consequently have been assumed to be its functional correlates. Using model membrane experiments, phagosome pH acidification analysis, lysosome size measurements, protein partitioning, and degradation assays, we provide support for the view that VapA and VapN promote intracellular multiplication of R. equi by neutralizing the pH of the R. equi-containing vacuole. VapB does not neutralize vacuole pH, is not as membrane active as VapA, and does not support intracellular multiplication. This study also shows that the size of the sometimes enormous R. equi-containing vacuoles or the partitioning of purified Vaps into organic phases are not features that have predictive value for virulence of R. equi, whereas the ability of Vaps to increase phagosome pH is coupled to virulence. IMPORTANCE Rhodococcus equi is a major cause of life-threatening pneumonia in foals and occasionally in immunocompromised persons. Virulence-associated protein A (VapA) promotes R. equi multiplication in lung macrophages, which are the major host cells during foal infection. In this study, we compare cellular, biochemical, and biophysical phenotypes associated with VapA to those of VapB (typically produced by isolates from pigs) or VapN (isolates from cattle). Our data support the hypothesis that only some Vaps support multiplication in macrophages by pH neutralization of the phagosomes that R. equi inhabit.
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Affiliation(s)
- Philipp Hansen
- Institute for Cell Biology, University of Bonn, Bonn, Germany
| | | | - Caroline Reiter
- Institute for Cell Biology, University of Bonn, Bonn, Germany
| | - Jana Kniewel
- Institute for Cell Biology, University of Bonn, Bonn, Germany
| | | | | | | | - Albert Haas
- Institute for Cell Biology, University of Bonn, Bonn, Germany
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2
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Rivera-Velez A, Huber L, Sinha S, Cohen ND. Fitness cost conferred by the novel erm(51) and rpoB mutation on environmental multidrug resistant-Rhodococcus equi. Vet Microbiol 2022; 273:109531. [PMID: 35944389 DOI: 10.1016/j.vetmic.2022.109531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 08/02/2022] [Accepted: 08/03/2022] [Indexed: 11/25/2022]
Abstract
Rhodococcus equi is a common cause of severe pneumonia in foals. Emergence of macrolide-resistant R. equi isolated from foals and their environment has been reported in the United States. A novel erm(51) gene was recently identified in R. equi in soil from horse farms in Kentucky. Our objective was to determine the effect of the erm(51) gene and associated rpoB mutation on the fitness of multidrug resistant-R. equi (MDR-R. equierm(51)+, rpoB+) under different nutrient conditions. Bacterial growth curves were generated for 3 MDR-R. equierm(51)+, rpoB+ isolates and 3 wild-type (WTN) R. equi isolates recovered from environmental samples of farms in central Kentucky. Growth was measured over 30.5 h in brain-heart infusion broth (BHI), minimal medium (MM), and minimal medium without iron (MM-I). All isolates had significantly (P < 0.05) higher growth in BHI compared to either MM or MM-I. MDR-R. equierm(51)+, rpoB+ exhibited significantly lower growth compared to WTN isolates in BHI (nutrient-rich condition), but not in either MM or MM-I (nutrient-restricted conditions). This study indicates that under nutrient-rich conditions fitness of MDR-R. equierm(51)+, rpoB+ is reduced relative to susceptible isolates; however, under nutrient-restricted conditions MDR-R. equierm(51)+, rpoB+ isolates grow similarly to susceptible isolates. These findings indicate that MDR-R. equierm(51)+, rpoB+ might be outcompeted by susceptible isolates in nature when practices to reduce antimicrobial pressure, such as reducing antimicrobial use in foals, are implemented. But it also raises the concern that these resistant genotypes might persist in the environment of horse-breeding farms in the face of selective pressures such as antimicrobials or nutrient restriction.
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Affiliation(s)
- Andres Rivera-Velez
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA.
| | - Laura Huber
- Pathobiology Department, College of Veterinary Medicine, Auburn University, 1130 wire Rd, Auburn, AL 36832, USA.
| | - Samiran Sinha
- Department of Statistics, Texas A&M University, College Station, TX 77843, USA.
| | - Noah D Cohen
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA.
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Undabarrena A, Valencia R, Cumsille A, Zamora-Leiva L, Castro-Nallar E, Barona-Gomez F, Cámara B. Rhodococcus comparative genomics reveals a phylogenomic-dependent non-ribosomal peptide synthetase distribution: insights into biosynthetic gene cluster connection to an orphan metabolite. Microb Genom 2021; 7:000621. [PMID: 34241590 PMCID: PMC8477407 DOI: 10.1099/mgen.0.000621] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 06/04/2021] [Indexed: 01/14/2023] Open
Abstract
Natural products (NPs) are synthesized by biosynthetic gene clusters (BGCs), whose genes are involved in producing one or a family of chemically related metabolites. Advances in comparative genomics have been favourable for exploiting huge amounts of data and discovering previously unknown BGCs. Nonetheless, studying distribution patterns of novel BGCs and elucidating the biosynthesis of orphan metabolites remains a challenge. To fill this knowledge gap, our study developed a pipeline for high-quality comparative genomics for the actinomycete genus Rhodococcus , which is metabolically versatile, yet understudied in terms of NPs, leading to a total of 110 genomes, 1891 BGCs and 717 non-ribosomal peptide synthetases (NRPSs). Phylogenomic inferences showed four major clades retrieved from strains of several ecological habitats. BiG-SCAPE sequence similarity BGC networking revealed 44 unidentified gene cluster families (GCFs) for NRPS, which presented a phylogenomic-dependent evolution pattern, supporting the hypothesis of vertical gene transfer. As a proof of concept, we analysed in-depth one of our marine strains, Rhodococcus sp. H-CA8f, which revealed a unique BGC distribution within its phylogenomic clade, involved in producing a chloramphenicol-related compound. While this BGC is part of the most abundant and widely distributed NRPS GCF, corason analysis unveiled major differences regarding its genetic context, co-occurrence patterns and modularity. This BGC is composed of three sections, two well-conserved right/left arms flanking a very variable middle section, composed of nrps genes. The presence of two non-canonical domains in H-CA8f’s BGC may contribute to adding chemical diversity to this family of NPs. Liquid chromatography-high resolution MS and dereplication efforts retrieved a set of related orphan metabolites, the corynecins, which to our knowledge are reported here for the first time in Rhodococcus . Overall, our data provide insights to connect BGC uniqueness with orphan metabolites, by revealing key comparative genomic features supported by models of BGC distribution along phylogeny.
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Affiliation(s)
- Agustina Undabarrena
- Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química y Centro de Biotecnología Daniel Alkalay Lowitt, Universidad Técnica Federico Santa María, Valparaíso 2340000, Chile
| | - Ricardo Valencia
- Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química y Centro de Biotecnología Daniel Alkalay Lowitt, Universidad Técnica Federico Santa María, Valparaíso 2340000, Chile
- Present address: Institute of Quantitative Biology, Biochemistry and Biotechnology, School of Biological Sciences, University of Edinburgh, King’s Buildings, Edinburgh, UK
| | - Andrés Cumsille
- Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química y Centro de Biotecnología Daniel Alkalay Lowitt, Universidad Técnica Federico Santa María, Valparaíso 2340000, Chile
| | - Leonardo Zamora-Leiva
- Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química y Centro de Biotecnología Daniel Alkalay Lowitt, Universidad Técnica Federico Santa María, Valparaíso 2340000, Chile
| | - Eduardo Castro-Nallar
- Center for Bioinformatics and Integrative Biology, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Francisco Barona-Gomez
- Evolution of Metabolic Diversity Laboratory, Unidad de Genómica Avanzada (Langebio), Cinvestav, Irapuato, Guanajuato, Mexico
| | - Beatriz Cámara
- Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química y Centro de Biotecnología Daniel Alkalay Lowitt, Universidad Técnica Federico Santa María, Valparaíso 2340000, Chile
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Sangkanjanavanich N, Kakuda T, Suzuki Y, Sasaki Y, Takai S. Identification of genes required for the fitness of Rhodococcus equi during the infection of mice via signature-tagged transposon mutagenesis. J Vet Med Sci 2021; 83:1182-1190. [PMID: 34108307 PMCID: PMC8437726 DOI: 10.1292/jvms.21-0256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Rhodococcus equi is a Gram-positive facultative intracellular bacterium that causes pyogranulomatous pneumonia in foals and immunocompromised people. In the present study, signature-tagged transposon mutagenesis was applied for the negative selection of R. equi mutants that cannot survive in vivo. Twenty-five distinguishable plasmid-transposon (plasposon) vectors by polymerase chain reaction (PCR), each containing a unique oligonucleotide tag, were constructed and used to select the transposon mutants that have in vivo fitness defects using a mouse systemic infection model. Of the 4,560 transposon mutants, 102 mutants were isolated via a real-time PCR-based screening as the mutants were unable to survive in the mouse model. Finally, 50 single transposon insertion sites were determined via the self-cloning strategy. The insertion of the transposon was seen on the virulence plasmid in 15 of the 50 mutants, whereas the remaining 35 mutants had the insertion of transposon on the chromosome. The chromosomal mutants contained transposon insertions in genes involved in cellular metabolism, DNA repair and recombination, gene regulation, non-ribosomal peptide synthesis, and unknown functions. Additionally, seven of the chromosomal mutants showed a reduced ability to multiply in the macrophages in vitro. In this study, we have identified several biosynthetic pathways as fitness factors associated with the growth within macrophages and survival in mice.
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Affiliation(s)
- Nuttapone Sangkanjanavanich
- Laboratory of Animal Hygiene, School of Veterinary Medicine, Kitasato University, Higashi 23-35-1, Towada, Aomori 034-8628, Japan
| | - Tsutomu Kakuda
- Laboratory of Animal Hygiene, School of Veterinary Medicine, Kitasato University, Higashi 23-35-1, Towada, Aomori 034-8628, Japan
| | - Yasunori Suzuki
- Laboratory of Animal Hygiene, School of Veterinary Medicine, Kitasato University, Higashi 23-35-1, Towada, Aomori 034-8628, Japan
| | - Yukako Sasaki
- Laboratory of Animal Hygiene, School of Veterinary Medicine, Kitasato University, Higashi 23-35-1, Towada, Aomori 034-8628, Japan
| | - Shinji Takai
- Laboratory of Animal Hygiene, School of Veterinary Medicine, Kitasato University, Higashi 23-35-1, Towada, Aomori 034-8628, Japan
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Hofmann M, Heine T, Malik L, Hofmann S, Joffroy K, Senges CHR, Bandow JE, Tischler D. Screening for Microbial Metal-Chelating Siderophores for the Removal of Metal Ions from Solutions. Microorganisms 2021; 9:microorganisms9010111. [PMID: 33466508 PMCID: PMC7824959 DOI: 10.3390/microorganisms9010111] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 12/30/2020] [Indexed: 11/17/2022] Open
Abstract
To guarantee the supply of critical elements in the future, the development of new technologies is essential. Siderophores have high potential in the recovery and recycling of valuable metals due to their metal-chelating properties. Using the Chrome azurol S assay, 75 bacterial strains were screened to obtain a high-yield siderophore with the ability to complex valuable critical metal ions. The siderophore production of the four selected strains Nocardioides simplex 3E, Pseudomonas chlororaphis DSM 50083, Variovorax paradoxus EPS, and Rhodococcus erythropolis B7g was optimized, resulting in significantly increased siderophore production of N. simplex and R. erythropolis. Produced siderophore amounts and velocities were highly dependent on the carbon source. The genomes of N. simplex and P. chlororaphis were sequenced. Bioinformatical analyses revealed the occurrence of an achromobactin and a pyoverdine gene cluster in P. chlororaphis, a heterobactin and a requichelin gene cluster in R. erythropolis, and a desferrioxamine gene cluster in N. simplex. Finally, the results of the previous metal-binding screening were validated by a proof-of-concept development for the recovery of metal ions from aqueous solutions utilizing C18 columns functionalized with siderophores. We demonstrated the recovery of the critical metal ions V(III), Ga(III), and In(III) from mixed metal solutions with immobilized siderophores of N. simplex and R. erythropolis.
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Affiliation(s)
- Marika Hofmann
- Institute of Biosciences, TU Bergakademie Freiberg, 09599 Freiberg, Germany; (T.H.); (L.M.); (S.H.); (K.J.)
- Correspondence: (M.H.); (D.T.)
| | - Thomas Heine
- Institute of Biosciences, TU Bergakademie Freiberg, 09599 Freiberg, Germany; (T.H.); (L.M.); (S.H.); (K.J.)
| | - Luise Malik
- Institute of Biosciences, TU Bergakademie Freiberg, 09599 Freiberg, Germany; (T.H.); (L.M.); (S.H.); (K.J.)
| | - Sarah Hofmann
- Institute of Biosciences, TU Bergakademie Freiberg, 09599 Freiberg, Germany; (T.H.); (L.M.); (S.H.); (K.J.)
| | - Kristin Joffroy
- Institute of Biosciences, TU Bergakademie Freiberg, 09599 Freiberg, Germany; (T.H.); (L.M.); (S.H.); (K.J.)
| | - Christoph Helmut Rudi Senges
- Applied Microbiology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, 44780 Bochum, Germany; (C.H.R.S.); (J.E.B.)
| | - Julia Elisabeth Bandow
- Applied Microbiology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, 44780 Bochum, Germany; (C.H.R.S.); (J.E.B.)
| | - Dirk Tischler
- Microbial Biotechnology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, 44780 Bochum, Germany
- Correspondence: (M.H.); (D.T.)
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GAPDH, rhbC, and vapA gene expression in Rhodococcus equi cultured under different iron concentrations. Microb Pathog 2019; 139:103885. [PMID: 31790793 DOI: 10.1016/j.micpath.2019.103885] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 11/07/2019] [Accepted: 11/21/2019] [Indexed: 11/22/2022]
Abstract
The ability of Rhodococcus equi to survive in macrophages and cause pneumonia in foals depends on vapA and rhbC genes, which produce the virulence-associated protein A (VapA) and the rhequichelin siderophore, respectively. Virulent R. equi acquires Fe from transferrin by unknown mechanisms. Our objectives were to determine the role of GAPDH in Fe homeostasis, to further characterize GAPDH, rhbC, and vapA expression under iron homeostasis, and to document the occurrence of rhbC gene in R. equi isolates. Therefore, vapA + R. equi was cultured under excessive, physiologic, and restricted iron concentrations, and quantitative culture and gene expression were performed. The relative expression of GAPDH, rhbC, and vapA after 48 h of culture were analyzed by qPCR. To determine the rhbC occurrence, total DNA was extracted from R. equi isolated from foals with clinical rhodococcosis (n = 22), healthy horses (feces, n = 16; nasal swab, n = 9), soil (n = 6), and 2 ATCC reference strains. Conventional PCR was performed to identify genus/species, vapA, and rhbC genes. Iron restriction proportionally decreased R. equi growth rates, and induced high expression of both GAPDH and vapA. The putative role of GAPDH in R. equi iron homeostasis should be further investigated. rhbC was significantly up-regulated under both Fe excess and critical starvation. The rhbC gene was identified in all clinical isolates and soil, but it was absent in 2 isolates from healthy horses, suggesting that rhequichelin is not required for R. equi nasal and intestinal colonization.
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7
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Mourenza Á, Bravo-Santano N, Pradal I, Gil JA, Mateos LM, Letek M. Mycoredoxins Are Required for Redox Homeostasis and Intracellular Survival in the Actinobacterial Pathogen Rhodococcus equi. Antioxidants (Basel) 2019; 8:antiox8110558. [PMID: 31731720 PMCID: PMC6912445 DOI: 10.3390/antiox8110558] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 11/11/2019] [Accepted: 11/13/2019] [Indexed: 12/11/2022] Open
Abstract
Rhodococcus equi is a facultative intracellular pathogen that can survive within macrophages of a wide variety of hosts, including immunosuppressed humans. Current antibiotherapy is often ineffective, and novel therapeutic strategies are urgently needed to tackle infections caused by this pathogen. In this study, we identified three mycoredoxin-encoding genes (mrx) in the genome of R. equi, and we investigated their role in virulence. Importantly, the intracellular survival of a triple mrx-null mutant (Δmrx1Δmrx2Δmrx3) in murine macrophages was fully impaired. However, each mycoredoxin alone could restore the intracellular proliferation rate of R. equi Δmrx1Δmrx2Δmrx3 to wild type levels, suggesting that these proteins could have overlapping functions during host cell infection. Experiments with the reduction-oxidation sensitive green fluorescent protein 2 (roGFP2) biosensor confirmed that R. equi was exposed to redox stress during phagocytosis, and mycoredoxins were involved in preserving the redox homeostasis of the pathogen. Thus, we studied the importance of each mycoredoxin for the resistance of R. equi to different oxidative stressors. Interestingly, all mrx genes did have overlapping roles in the resistance to sodium hypochlorite. In contrast, only mrx1 was essential for the survival against high concentrations of nitric oxide, while mrx3 was not required for the resistance to hydrogen peroxide. Our results suggest that all mycoredoxins have important roles in redox homeostasis, contributing to the pathogenesis of R. equi and, therefore, these proteins may be considered interesting targets for the development of new anti-infectives.
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Affiliation(s)
- Álvaro Mourenza
- Department of Molecular Biology, Area of Microbiology, University of León, 24071 León, Spain; (Á.M.); (I.P.); (J.A.G.)
| | | | - Inés Pradal
- Department of Molecular Biology, Area of Microbiology, University of León, 24071 León, Spain; (Á.M.); (I.P.); (J.A.G.)
| | - Jose A. Gil
- Department of Molecular Biology, Area of Microbiology, University of León, 24071 León, Spain; (Á.M.); (I.P.); (J.A.G.)
| | - Luis M. Mateos
- Department of Molecular Biology, Area of Microbiology, University of León, 24071 León, Spain; (Á.M.); (I.P.); (J.A.G.)
- Correspondence: (L.M.M.); (M.L.)
| | - Michal Letek
- Health Sciences Research Centre, University of Roehampton, London SW15 4JD, UK;
- Correspondence: (L.M.M.); (M.L.)
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Effect of Macrolide and Rifampin Resistance on Fitness of Rhodococcus equi during Intramacrophage Replication and In Vivo. Infect Immun 2019; 87:IAI.00281-19. [PMID: 31331959 DOI: 10.1128/iai.00281-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Accepted: 07/17/2019] [Indexed: 01/20/2023] Open
Abstract
The soil-dwelling, saprophytic actinomycete Rhodococcus equi is a facultative intracellular pathogen of macrophages and causes severe bronchopneumonia when inhaled by susceptible foals. Standard treatment for R. equi disease is dual-antimicrobial therapy with a macrolide and rifampin. Thoracic ultrasonography and early treatment with antimicrobials prior to the development of clinical signs are used as means of controlling endemic R. equi infection on many farms. Concurrently with the increased use of macrolides and rifampin for chemoprophylaxis and the treatment of subclinically affected foals, a significant increase in the incidence of macrolide- and rifampin-resistant R. equi isolates has been documented. Previously, our laboratory demonstrated decreased fitness of R. equi strains that were resistant to macrolides, rifampin, or both, resulting in impaired in vitro growth in iron-restricted media and in soil. The objective of this study was to examine the effect of macrolide and/or rifampin resistance on intracellular replication of R. equi in equine pulmonary macrophages and in an in vivo mouse infection model in the presence and absence of antibiotics. In equine macrophages, the macrolide-resistant strain did not increase in bacterial numbers over time and the dual macrolide- and rifampin-resistant strain exhibited decreased proliferation compared to the susceptible isolate. In the mouse model, in the absence of antibiotics, the susceptible R. equi isolate outcompeted the macrolide- or rifampin-resistant strains.
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Ronan JL, Kadi N, McMahon SA, Naismith JH, Alkhalaf LM, Challis GL. Desferrioxamine biosynthesis: diverse hydroxamate assembly by substrate-tolerant acyl transferase DesC. Philos Trans R Soc Lond B Biol Sci 2019; 373:rstb.2017.0068. [PMID: 29685972 DOI: 10.1098/rstb.2017.0068] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/10/2017] [Indexed: 12/16/2022] Open
Abstract
Hydroxamate groups play key roles in the biological function of diverse natural products. Important examples include trichostatin A, which inhibits histone deacetylases via coordination of the active site zinc(II) ion with a hydroxamate group, and the desferrioxamines, which use three hydroxamate groups to chelate ferric iron. Desferrioxamine biosynthesis in Streptomyces species involves the DesD-catalysed condensation of various N-acylated derivatives of N-hydroxycadaverine with two molecules of N-succinyl-N-hydroxycadaverine to form a range of linear and macrocyclic tris-hydroxamates. However, the mechanism for assembly of the various N-acyl-N-hydroxycadaverine substrates of DesD from N-hydroxycadaverine has until now been unclear. Here we show that the desC gene of Streptomyces coelicolor encodes the acyl transferase responsible for this process. DesC catalyses the N-acylation of N-hydroxycadaverine with acetyl, succinyl and myristoyl-CoA, accounting for the diverse array of desferrioxamines produced by S. coelicolor The X-ray crystal structure of DesE, the ferrioxamine lipoprotein receptor, in complex with ferrioxamine B (which is derived from two units of N-succinyl-N-hydroxycadaverine and one of N-acetyl-N-hydroxycadaverine) was also determined. This showed that the acetyl group of ferrioxamine B is solvent exposed, suggesting that the corresponding acyl group in longer chain congeners can protrude from the binding pocket, providing insights into their likely function. This article is part of a discussion meeting issue 'Frontiers in epigenetic chemical biology'.This article is part of a discussion meeting issue 'Frontiers in epigenetic chemical biology'.
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Affiliation(s)
- Jade L Ronan
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
| | - Nadia Kadi
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
| | - Stephen A McMahon
- Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews KY16 9ST, UK
| | - James H Naismith
- Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews KY16 9ST, UK
| | - Lona M Alkhalaf
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
| | - Gregory L Challis
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
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Effect of Macrolide and Rifampin Resistance on the Fitness of Rhodococcus equi. Appl Environ Microbiol 2019; 85:AEM.02665-18. [PMID: 30683740 DOI: 10.1128/aem.02665-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Accepted: 01/16/2019] [Indexed: 12/18/2022] Open
Abstract
Rhodococcus equi is a leading cause of severe pneumonia in foals. Standard treatment is dual antimicrobial therapy with a macrolide and rifampin, but the emergence of macrolide- and rifampin-resistant R. equi isolates is an increasing problem. The objective of this study was to determine the effect of macrolide and/or rifampin resistance on fitness of R. equi Three unique isogenic sets were created, each consisting of four R. equi strains, as follows: a susceptible parent isolate, strains resistant to macrolides or rifampin, and a dual macrolide- and rifampin-resistant strain. Each isogenic set's bacterial growth curve was generated in enriched medium, minimal medium (MM), and minimal medium without iron (MM-I). Bacterial survival in soil was analyzed over 12 months at -20°C, 4°C, 25°C, and 37°C, and the ability of these strains to retain antimicrobial resistance during sequential subculturing was determined. Insertion of the mobile element conferring macrolide resistance had minimal effect on in vitro growth. However, two of three rpoB mutations conferring rifampin resistance resulted in a decreased growth rate in MM. In soil, macrolide- or rifampin-resistant R. equi strains exhibited limited growth compared to that of the susceptible R. equi isolate at all temperatures except -20°C. During subculturing, macrolide resistance was lost over time, and two of three rpoB mutations reverted to the wild-type form. The growth of rifampin-resistant R. equi colonies is delayed under nutrient restriction. In soil, possession of rifampin or macrolide resistance results in decreased fitness. Both macrolide and rifampin resistance can be lost after repeated subculturing.IMPORTANCE This work advances our understanding of the opportunistic environmental pathogen Rhodococcus equi, a disease agent affecting horses and immunocompromised people. R. equi is one of the most common causes of severe pneumonia in young horses. For decades, the standard treatment for R. equi pneumonia in horses has been dual antimicrobial therapy with a macrolide and rifampin; effective alternatives to this combination are lacking. The World Health Organization classifies these antimicrobial agents as critically important for human medicine. Widespread macrolide and rifampin resistance in R. equi isolates is a major emerging problem for the horse-breeding industry and might also adversely impact human health if resistant strains infect people or transfer resistance mechanisms to other pathogens. This study details the impact of antimicrobial resistance on R. equi fitness, a vital step for understanding the ecology and epidemiology of resistant R. equi isolates, and will support development of novel strategies to combat antimicrobial resistance.
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Conjugational delivery of chromosomal integrative constructs for gene expression in the carbendazim-degrading Rhodococcus erythropolis D-1. ANN MICROBIOL 2018. [DOI: 10.1007/s13213-018-1382-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
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12
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Trautman EP, Crawford JM. A New Nucleoside Antibiotic Chokes Bacterial RNA Polymerase. Biochemistry 2017; 56:4923-4924. [PMID: 28885002 DOI: 10.1021/acs.biochem.7b00680] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Eric P Trautman
- Department of Chemistry, Yale University , New Haven, Connecticut 06520, United States.,Chemical Biology Institute, Yale University , West Haven, Connecticut 06516, United States
| | - Jason M Crawford
- Department of Chemistry, Yale University , New Haven, Connecticut 06520, United States.,Chemical Biology Institute, Yale University , West Haven, Connecticut 06516, United States.,Department of Microbial Pathogenesis, Yale School of Medicine , New Haven, Connecticut 06536, United States
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Ceniceros A, Dijkhuizen L, Petrusma M, Medema MH. Genome-based exploration of the specialized metabolic capacities of the genus Rhodococcus. BMC Genomics 2017; 18:593. [PMID: 28793878 PMCID: PMC5550956 DOI: 10.1186/s12864-017-3966-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 07/27/2017] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Bacteria of the genus Rhodococcus are well known for their ability to degrade a large range of organic compounds. Some rhodococci are free-living, saprophytic bacteria; others are animal and plant pathogens. Recently, several studies have shown that their genomes encode putative pathways for the synthesis of a large number of specialized metabolites that are likely to be involved in microbe-microbe and host-microbe interactions. To systematically explore the specialized metabolic potential of this genus, we here performed a comprehensive analysis of the biosynthetic coding capacity across publicly available rhododoccal genomes, and compared these with those of several Mycobacterium strains as well as that of their mutual close relative Amycolicicoccus subflavus. RESULTS Comparative genomic analysis shows that most predicted biosynthetic gene cluster families in these strains are clade-specific and lack any homology with gene clusters encoding the production of known natural products. Interestingly, many of these clusters appear to encode the biosynthesis of lipopeptides, which may play key roles in the diverse environments were rhodococci thrive, by acting as biosurfactants, pathogenicity factors or antimicrobials. We also identified several gene cluster families that are universally shared among all three genera, which therefore may have a more 'primary' role in their physiology. Inactivation of these clusters by mutagenesis might help to generate weaker strains that can be used as live vaccines. CONCLUSIONS The genus Rhodococcus thus provides an interesting target for natural product discovery, in view of its large and mostly uncharacterized biosynthetic repertoire, its relatively fast growth and the availability of effective genetic tools for its genomic modification.
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Affiliation(s)
- Ana Ceniceros
- Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 7, 9747, AG, Groningen, The Netherlands
| | - Lubbert Dijkhuizen
- Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 7, 9747, AG, Groningen, The Netherlands.
| | - Mirjan Petrusma
- Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 7, 9747, AG, Groningen, The Netherlands
| | - Marnix H Medema
- Bioinformatics Group, Wageningen University, Droevendaalsesteeg 1, 6708, PB, Wageningen, The Netherlands.
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Identification and characterization of a FAD-dependent putrescine N-hydroxylase (GorA) from Gordonia rubripertincta CWB2. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/j.molcatb.2016.08.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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15
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Influence of Plasmid Type on the Replication of Rhodococcus equi in Host Macrophages. mSphere 2016; 1:mSphere00186-16. [PMID: 27747295 PMCID: PMC5061997 DOI: 10.1128/msphere.00186-16] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 08/31/2016] [Indexed: 11/20/2022] Open
Abstract
The soil-dwelling, saprophytic actinomycete Rhodococcus equi is a multihost, facultative intracellular pathogen of macrophages. When inhaled by susceptible foals, it causes severe bronchopneumonia. It is also a pathogen of pigs, which may develop submaxillary lymphadenitis upon exposure. R. equi isolates obtained from foals and pigs possess conjugative plasmids housing a pathogenicity island (PAI) containing a novel family of genes of unknown function called the virulence-associated protein or vap family. The PAI regions of the equine and swine plasmids differ in vap gene composition, with equine isolates possessing six vap genes, including the major virulence determinant vapA, while the PAIs of swine isolates house vapB and five other unique vap genes. Possession of the pVAPA-type virulence plasmid by equine isolates bestows the capacity for intramacrophage replication essential for disease development in vivo. Swine isolates of R. equi are largely unstudied. Here, we show that R. equi isolates from pigs, carrying pVAPB-type plasmids, are able to replicate in a plasmid-dependent manner in macrophages obtained from a variety of species (murine, swine, and equine) and anatomical locations. Similarly, equine isolates carrying pVAPA-type plasmids are capable of replication in swine macrophages. Plasmid swapping between equine and swine strains through conjugation did not alter the intracellular replication capacity of the parental strain, indicating that coevolution of the plasmid and chromosome is not crucial for this attribute. These results demonstrate that while distinct plasmid types exist among R. equi isolates obtained from equine and swine sources, this tropism is not determined by host species-specific intramacrophage replication capabilities. IMPORTANCE This work greatly advances our understanding of the opportunistic pathogen Rhodococcus equi, a disease agent of animals and immunocompromised people. Clinical isolates from diseased foals carry a conjugative virulence plasmid, pVAPA1037, that expresses Vap proteins, including VapA, essential for intramacrophage replication and virulence in vivo. The understudied R. equi isolates from pigs carry a related but different plasmid, pVAPB, expressing distinct Vap proteins, including VapB. In this work, we document for the first time that R. equi isolates carrying pVAPB-type plasmids are capable of intramacrophage replication. Moreover, we show that R. equi isolates carrying either plasmid type can replicate in both equine and swine macrophages, indicating that host species tropism is not due to species-specific intramacrophage replication capabilities defined by plasmid type. Furthermore, plasmid swapping between equine and swine strains did not alter intracellular replication capacity, indicating that coevolution of the plasmid and chromosome is not essential for intracellular growth.
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16
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Chloroquine inhibits Rhodococcus equi replication in murine and foal alveolar macrophages by iron-starvation. Vet Microbiol 2016; 188:16-24. [PMID: 27139025 DOI: 10.1016/j.vetmic.2016.03.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 03/11/2016] [Accepted: 03/25/2016] [Indexed: 11/24/2022]
Abstract
Rhodococcus equi preferentially infects macrophages causing pyogranulomatous pneumonia in young foals. Both the vapA and rhbC genes are up-regulated in an iron (Fe)-deprived environment, such as that found within macrophages. Chloroquine (CQ) is a drug widely used against malaria that suppresses the intracellular availability of Fe in eukaryotic cells. The main objective of this study was to evaluate the ability of CQ to inhibit replication of virulent R. equi within murine (J774A.1) and foal alveolar macrophages (AMs) and to verify whether the mechanism of inhibition could be Fe-deprivation-dependent. CQ effect on R. equi extracellular survival and toxicity to J774A.1 were evaluated. R. equi survival within J774A.1 and foal AMs was evaluated under CQ (10 and 20μM), bovine saturated transferrin (bHTF), and bovine unsaturated transferrin (bATF) exposure. To explore the action mechanism of CQ, the superoxide anion production, the lysozyme activity, as well as the relative mRNA expression of vapA and rhbC were examined. CQ at≤20μM had no effect on R. equi extracellular multiplication and J774A.1 viability. Exposure to CQ significantly and markedly reduced survival of R. equi within J774A.1 and foal AMs. Treatment with bHTF did not reverse CQ effect on R. equi. Exposure to CQ did not affected superoxide anion production or lysozyme activity, however vapA and rhbC expression was significantly increased. Our results reinforce the hypothesis that intracellular availability of Fe is required for R. equi survival, and our initial hypothesis that CQ can limit replication of R. equi in J774A.1 and foal AMs, most likely by Fe starvation.
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17
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Stefańska I, Witkowski L, Rzewuska M, Dzieciątkowski T. Development and evaluation of the internal-controlled real-time PCR assay for Rhodococcus equi detection in various clinical specimens. J Vet Med Sci 2015; 78:543-9. [PMID: 26655770 PMCID: PMC4873842 DOI: 10.1292/jvms.15-0516] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Rhodococcus equi is the causative agent of rhodococcosis in horses,
resulting in significant morbidity and mortality in foals. This bacterium has also been
isolated from a variety of animals and is being increasingly reported as a cause of
infection in humans, mainly in immunosuppressed individuals. Laboratory diagnostics of
R. equi infections based only on conventional microbiological methods
shows low accuracy and can lead to misidentification. The objective of the study was to
develop and evaluate a real-time PCR assay for direct detection of R.
equi in various clinical specimens, including tissue samples. The
species-specific region of the gene encoding R. equi cholesterol oxidase,
choE, was used as a qPCR-target. The diagnostic applicability of the
assay was confirmed by testing various tissue specimens obtained from horses with clinical
signs of rhodoccocal infection and swine submaxillary lymph nodes. The rate of R.
equi detection in clinical specimens by the developed assay was higher in
comparison to the culture method (90% vs. 60.0% of positive samples) and conventional PCR
(90.0% vs. 20.0% of positive samples). In case of 13 samples that were negative in the
culture-based method, R. equi was detected by the developed assay. Only
in one case, it gave negative result for culture-positive sample. The assay may provide a
simple and rapid tool to complement the classical methods of R. equi
detection based on culture and phenotypic identification of isolates, as the performed
evaluation indicated a high specificity and accuracy of the results.
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Affiliation(s)
- Ilona Stefańska
- Department of Preclinical Sciences, Faculty of Veterinary Medicine, Warsaw University of Life Sciences, 8 Ciszewskiego St., 02-786 Warsaw, Poland
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18
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Transcriptome reprogramming by plasmid-encoded transcriptional regulators is required for host niche adaption of a macrophage pathogen. Infect Immun 2015; 83:3137-45. [PMID: 26015480 DOI: 10.1128/iai.00230-15] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 05/18/2015] [Indexed: 11/20/2022] Open
Abstract
Rhodococcus equi is a facultative intracellular pathogen of macrophages, relying on the presence of a conjugative virulence plasmid harboring a 21-kb pathogenicity island (PAI) for growth in host macrophages. The PAI encodes a family of 6 virulence-associated proteins (Vaps) in addition to 20 other proteins. The contribution of these to virulence has remained unclear. We show that the presence of only 3 virulence plasmid genes (of 73 in total) is required and sufficient for intracellular growth. These include a single vap family member, vapA, and two PAI-located transcriptional regulators, virR and virS. Both transcriptional regulators are essential for wild-type-level expression of vapA, yet vapA expression alone is not sufficient to allow intracellular growth. A whole-genome microarray analysis revealed that VirR and VirS substantially integrate themselves into the chromosomal regulatory network, significantly altering the transcription of 18% of all chromosomal genes. This pathoadaptation involved significant enrichment of select gene ontologies, in particular, enrichment of genes involved in transport processes, energy production, and cellular metabolism, suggesting a major change in cell physiology allowing the bacterium to grow in the hostile environment of the host cell. The results suggest that following the acquisition of the virulence plasmid by an avirulent ancestor of R. equi, coevolution between the plasmid and the chromosome took place, allowing VirR and VirS to regulate the transcription of chromosomal genes in a process that ultimately promoted intracellular growth. Our findings suggest a mechanism for cooption of existing chromosomal traits during the evolution of a pathogenic bacterium from an avirulent saprophyte.
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19
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Bonchi C, Imperi F, Minandri F, Visca P, Frangipani E. Repurposing of gallium-based drugs for antibacterial therapy. Biofactors 2014; 40:303-12. [PMID: 24532037 DOI: 10.1002/biof.1159] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 01/16/2014] [Accepted: 01/19/2014] [Indexed: 12/21/2022]
Abstract
While the occurrence and spread of antibiotic resistance in bacterial pathogens is vanishing current anti-infective therapies, the antibiotic discovery pipeline is drying up. In the last years, the repurposing of existing drugs for new clinical applications has become a major research area in drug discovery, also in the field of anti-infectives. This review discusses the potential of repurposing previously approved gallium formulations in antibacterial chemotherapy. Gallium has no proven function in biological systems, but it can act as an iron-mimetic in both prokaryotic and eukaryotic cells. The activity of gallium mostly relies on its ability to replace iron in redox enzymes, thus impairing their function and ultimately hampering cell growth. Cancer cells and bacteria are preferential gallium targets due to their active metabolism and fast growth. The wealth of knowledge on the pharmacological properties of gallium has opened the door to the repurposing of gallium-based drugs for the treatment of infections sustained by antibiotic-resistant bacterial pathogens, such as Acinetobacter baumannii or Pseudomonas aeruginosa, and for suppression of Mycobacterium tuberculosis growth. The promising antibacterial activity of gallium both in vitro and in different animal models of infection raises the hope that gallium will confirm its efficacy in clinical trials, and will become a valuable therapeutic option to cure otherwise untreatable bacterial infections.
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Affiliation(s)
- Carlo Bonchi
- Department of Sciences, University "Roma Tre,", Rome, Italy
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20
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González-Iglesias P, Scortti M, MacArthur I, Hapeshi A, Rodriguez H, Prescott JF, Vazquez-Boland JA. Mouse lung infection model to assess Rhodococcus equi virulence and vaccine protection. Vet Microbiol 2014; 172:256-64. [PMID: 24852140 DOI: 10.1016/j.vetmic.2014.03.026] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 03/19/2014] [Accepted: 03/22/2014] [Indexed: 11/30/2022]
Abstract
The pathogenic actinomycete Rhodococcus equi causes severe purulent lung infections in foals and immunocompromised people. Although relatively unsusceptible to R. equi, mice are widely used for in vivo studies with this pathogen. The most commonly employed mouse model is based on systemic (intravenous) infection and determination of R. equi burdens in spleen and liver. Here, we investigated the murine lung for experimental infection studies with R. equi. Using a 10(7)CFU intranasal challenge in BALB/c mice, virulent R. equi consistently survived in quantifiable numbers up to 10 days in the lungs whereas virulence-deficient R. equi bacteria were rapidly cleared. An internally controlled virulence assay was developed in which the test R. equi strains are co-inoculated and monitored in the same mouse. Isogenic R. equi bacteria lacking either the plasmid vapA gene or the entire virulence plasmid were compared using this competitive assay. Both strains showed no significant differences in in vivo fitness in the lung, indicating that the single loss of the virulence factor VapA was sufficient to account for the full attenuation seen in the absence of the virulence plasmid. To test the adequacy of the lung infection model for monitoring R. equi vaccine efficacy, BALB/c mice were immunized with live R. equi and challenged intranasally. Vaccination conferred protection against acute pulmonary challenge with virulent R. equi. Our data indicate that the murine lung infection model provides a useful tool for both R. equi virulence and vaccine studies.
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Affiliation(s)
- Patricia González-Iglesias
- Microbial Pathogenesis Unit, School of Biomedical Sciences and The Roslin Institute, University of Edinburgh, Edinburgh, UK
| | - Mariela Scortti
- Microbial Pathogenesis Unit, School of Biomedical Sciences and The Roslin Institute, University of Edinburgh, Edinburgh, UK; Departamento de Bioquímica y Biología Molecular IV, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid, Spain.
| | - Iain MacArthur
- Microbial Pathogenesis Unit, School of Biomedical Sciences and The Roslin Institute, University of Edinburgh, Edinburgh, UK
| | - Alexia Hapeshi
- Microbial Pathogenesis Unit, School of Biomedical Sciences and The Roslin Institute, University of Edinburgh, Edinburgh, UK
| | - Héctor Rodriguez
- Microbial Pathogenesis Unit, School of Biomedical Sciences and The Roslin Institute, University of Edinburgh, Edinburgh, UK; Irish Equine Centre, Johnstown, Naas, Ireland
| | - John F Prescott
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Canada
| | - José A Vazquez-Boland
- Microbial Pathogenesis Unit, School of Biomedical Sciences and The Roslin Institute, University of Edinburgh, Edinburgh, UK
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Cauchard S, Giguère S, Venner M, Muscatello G, Cauchard J, Cohen ND, Haas A, Hines SA, Hondalus MK, Horohov DW, Meijer WG, Prescott JF, Vázquez-Boland J. Rhodococcus equi research 2008-2012: report of the Fifth International Havemeyer Workshop. Equine Vet J 2014; 45:523-6. [PMID: 23909447 DOI: 10.1111/evj.12103] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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22
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Minandri F, Bonchi C, Frangipani E, Imperi F, Visca P. Promises and failures of gallium as an antibacterial agent. Future Microbiol 2014; 9:379-97. [DOI: 10.2217/fmb.14.3] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
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23
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IcgA is a virulence factor of Rhodococcus equi that modulates intracellular growth. Infect Immun 2014; 82:1793-800. [PMID: 24549327 DOI: 10.1128/iai.01670-13] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Virulence of the intracellular pathogen Rhodococcus equi depends on a 21.3-kb pathogenicity island located on a conjugative plasmid. To date, the only nonregulatory pathogenicity island-encoded virulence factor identified is the cell envelope-associated VapA protein. Although the pathogenicity islands from porcine and equine R. equi isolates have undergone major rearrangements, the virR operon (virR-icgA-vapH-orf7-virS) is highly conserved in both, suggesting these genes play an important role in pathogenicity. VirR and VirS are transcriptional regulators controlling expression of pathogenicity island genes, including vapA. Here, we show that while vapH and orf7 are dispensable for intracellular growth of R. equi, deletion of icgA, formerly known as orf5, encoding a major facilitator superfamily transport protein, elicited an enhanced growth phenotype in macrophages and a significant reduction in macrophage viability, while extracellular growth in broth remained unaffected. Transcription of virS, located downstream of icgA, and vapA was not affected by the icgA deletion during growth in broth or in macrophages, showing that the enhanced growth phenotype caused by deletion of icgA was not mediated through abnormal transcription of these genes. Transcription of icgA increased 6-fold within 2 h following infection of macrophages and remained significantly higher 48 h postinfection compared to levels at the start of the infection. The major facilitator superfamily transport protein IcgA is the first factor identified in R. equi that negatively affects intracellular replication. Aside from VapA, it is only the second pathogenicity island-encoded structural protein shown to play a direct role in intracellular growth of this pathogenic actinomycete.
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Bosello M, Zeyadi M, Kraas FI, Linne U, Xie X, Marahiel MA. Structural characterization of the heterobactin siderophores from Rhodococcus erythropolis PR4 and elucidation of their biosynthetic machinery. JOURNAL OF NATURAL PRODUCTS 2013; 76:2282-2290. [PMID: 24274668 DOI: 10.1021/np4006579] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
In this study, the isolation, the structural characterization, and the elucidation of the biosynthetic origin of heterobactins, catecholate-hydroxamate mixed-type siderophores from Rhodococcus erythropolis PR4, are reported. The structure elucidation of heterobactin A was accomplished via MS(n) analysis and NMR spectroscopy and revealed the noteworthy presence of a peptide bond between the guanidine group of an arginine residue and a 2,3-dihydroxybenzoate moiety. The two heterobactin S1 and S2 variants are derivatives of heterobactin A that have sulfonation modifications on the aromatic rings. The bioinformatic analysis of the R. erythropolis PR4 genome and the subsequent genetic and biochemical characterization of the putative biosynthetic machinery identified the gene cluster responsible for the biosynthesis of the heterobactins. Interestingly, the HtbG NRPS presents an unprecedented C-PCP-A domain organization within the second module of the synthetase that may help the correct elongation of the peptide intermediate. Finally, the present work revises the structure of heterobactin A that was described by Carrano et al. in 2001.
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Affiliation(s)
- Mattia Bosello
- Biochemistry, Department of Chemistry, Philipps-University Marburg , Hans-Meerwein-Strasse D-35043 Marburg, Germany
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Vázquez-Boland JA, Giguère S, Hapeshi A, MacArthur I, Anastasi E, Valero-Rello A. Rhodococcus equi: the many facets of a pathogenic actinomycete. Vet Microbiol 2013; 167:9-33. [PMID: 23993705 DOI: 10.1016/j.vetmic.2013.06.016] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 06/27/2013] [Indexed: 12/20/2022]
Abstract
Rhodococcus equi is a soil-dwelling pathogenic actinomycete that causes pulmonary and extrapulmonary pyogranulomatous infections in a variety of animal species and people. Young foals are particularly susceptible and develop a life-threatening pneumonic disease that is endemic at many horse-breeding farms worldwide. R. equi is a facultative intracellular parasite of macrophages that replicates within a modified phagocytic vacuole. Its pathogenicity depends on a virulence plasmid that promotes intracellular survival by preventing phagosome-lysosome fusion. Species-specific tropism of R. equi for horses, pigs and cattle appears to be determined by host-adapted virulence plasmid types. Molecular epidemiological studies of these plasmids suggest that human R. equi infection is zoonotic. Analysis of the recently determined R. equi genome sequence has identified additional virulence determinants on the bacterial chromosome. This review summarizes our current understanding of the clinical aspects, biology, pathogenesis and immunity of this fascinating microbe with plasmid-governed infectivity.
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Affiliation(s)
- José A Vázquez-Boland
- Microbial Pathogenesis Unit, School of Biomedical Sciences and Edinburgh Infectious Diseases, University of Edinburgh, Edinburgh EH9 3JT, UK; Grupo de Patogenómica Bacteriana, Facultad de Veterinaria, Universidad de León, 24071 León, Spain.
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26
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Miranda-CasoLuengo AA, Miranda-CasoLuengo R, Lieggi NT, Luo H, Simpson JC, Meijer WG. A real-time impedance based method to assess Rhodococcus equi virulence. PLoS One 2013; 8:e60612. [PMID: 23555995 PMCID: PMC3610927 DOI: 10.1371/journal.pone.0060612] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 02/28/2013] [Indexed: 11/19/2022] Open
Abstract
Rhodococcus equi is a facultative intracellular pathogen of macrophages and the causative agent of foal pneumonia. R. equi virulence is usually assessed by analyzing intracellular growth in macrophages by enumeration of bacteria following cell lysis, which is time consuming and does not allow for a high throughput analysis. This paper describes the use of an impedance based real-time method to characterize proliferation of R. equi in macrophages, using virulent and attenuated strains lacking the vapA gene or virulence plasmid. Image analysis suggested that the time-dependent cell response profile (TCRP) is governed by cell size and roundness as well as cytoxicity of infecting R. equi strains. The amplitude and inflection point of the resulting TCRP were dependent on the multiplicity of infection as well as virulence of the infecting strain, thus distinguishing between virulent and attenuated strains.
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Affiliation(s)
| | - Raúl Miranda-CasoLuengo
- UCD School of Biomolecular and Biomedical Science and Conway Institute, University College Dublin, Dublin, Ireland
| | - Nora T. Lieggi
- UCD School of Biology and Environmental Science and Conway Institute, University College Dublin, Dublin, Ireland
| | - Haixia Luo
- UCD School of Biomolecular and Biomedical Science and Conway Institute, University College Dublin, Dublin, Ireland
| | - Jeremy C. Simpson
- UCD School of Biology and Environmental Science and Conway Institute, University College Dublin, Dublin, Ireland
| | - Wim G. Meijer
- UCD School of Biomolecular and Biomedical Science and Conway Institute, University College Dublin, Dublin, Ireland
- * E-mail:
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