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Pederick VG, Eijkelkamp BA, Begg SL, Ween MP, McAllister LJ, Paton JC, McDevitt CA. ZnuA and zinc homeostasis in Pseudomonas aeruginosa. Sci Rep 2015; 5:13139. [PMID: 26290475 PMCID: PMC4542158 DOI: 10.1038/srep13139] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 07/21/2015] [Indexed: 11/09/2022] Open
Abstract
Pseudomonas aeruginosa is a ubiquitous environmental bacterium and a clinically significant opportunistic human pathogen. Central to the ability of P. aeruginosa to colonise both environmental and host niches is the acquisition of zinc. Here we show that P. aeruginosa PAO1 acquires zinc via an ATP-binding cassette (ABC) permease in which ZnuA is the high affinity, zinc-specific binding protein. Zinc uptake in Gram-negative organisms predominantly occurs via an ABC permease, and consistent with this expectation a P. aeruginosa ΔznuA mutant strain showed an ~60% reduction in cellular zinc accumulation, while other metal ions were essentially unaffected. Despite the major reduction in zinc accumulation, minimal phenotypic differences were observed between the wild-type and ΔznuA mutant strains. However, the effect of zinc limitation on the transcriptome of P. aeruginosa PAO1 revealed significant changes in gene expression that enable adaptation to low-zinc conditions. Genes significantly up-regulated included non-zinc-requiring paralogs of zinc-dependent proteins and a number of novel import pathways associated with zinc acquisition. Collectively, this study provides new insight into the acquisition of zinc by P. aeruginosa PAO1, revealing a hitherto unrecognized complexity in zinc homeostasis that enables the bacterium to survive under zinc limitation.
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Affiliation(s)
- Victoria G Pederick
- Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Bart A Eijkelkamp
- Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Stephanie L Begg
- Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Miranda P Ween
- Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Lauren J McAllister
- Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - James C Paton
- Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Christopher A McDevitt
- Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia
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Leyn SA, Rodionov DA. Comparative genomics of DtxR family regulons for metal homeostasis in Archaea. J Bacteriol 2015; 197:451-8. [PMID: 25404694 PMCID: PMC4285986 DOI: 10.1128/jb.02386-14] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 11/09/2014] [Indexed: 01/15/2023] Open
Abstract
The DtxR family consists of metal-dependent transcription factors (DtxR-TFs) that regulate the expression of genes involved in metal homeostasis in the cell. The majority of characterized DtxR-TFs belong to Bacteria. In the current work, we applied a comparative genomics approach to predict DNA-binding sites and reconstruct regulons for DtxR-TFs in Archaea. As a result, we inferred 575 candidate binding sites for 139 DtxR-TFs in 77 genomes from 15 taxonomic orders. Novel DNA motifs of archaeal DtxR-TFs that have a common palindromic structure were classified into 10 distinct groups. By combining functional regulon reconstructions with phylogenetic analysis, we selected 28 DtxR-TF clades and assigned them metal specificities and regulator names. The reconstructed FetR (ferrous iron), MntR (manganese), and ZntR (zinc) regulons largely contain known or putative metal uptake transporters from the FeoAB, NRAMP, ZIP, and TroA families. A novel family of putative iron transporters (named Irt), including multiple FetR-regulated paralogs, was identified in iron-oxidizing Archaea from the Sulfolobales order. The reconstructed DtxR-TF regulons were reconciled with available transcriptomics data in Archaeoglobus, Halobacterium, and Thermococcus spp.
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Affiliation(s)
- Semen A Leyn
- A. A. Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, Russia
| | - Dmitry A Rodionov
- A. A. Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, Russia Sanford-Burnham Medical Research Institute, La Jolla, California, USA
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Cerasi M, Liu JZ, Ammendola S, Poe AJ, Petrarca P, Pesciaroli M, Pasquali P, Raffatellu M, Battistoni A. The ZupT transporter plays an important role in zinc homeostasis and contributes to Salmonella enterica virulence. Metallomics 2014; 6:845-53. [PMID: 24430377 DOI: 10.1039/c3mt00352c] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Zinc is an essential metal for cellular homeostasis and function in both eukaryotes and prokaryotes. To acquire this essential nutrient, bacteria employ transporters characterized by different affinity for the metal. Several studies have investigated the role of the high affinity transporter ZnuABC in the bacterial response to zinc shortage, showing that this transporter has a key role in adapting bacteria to zinc starvation. In contrast, the role of the low affinity zinc importer ZupT has been the subject of limited investigations. Here we show that a Salmonella strain lacking ZupT is impaired in its ability to grow in metal devoid environments and that a znuABC zupT strain exhibits a severe growth defect in zinc devoid media, is hypersensitive to oxidative stress and contains reduced levels of intracellular free zinc. Moreover, we show that ZupT also plays a role in the ability of S. Typhimurium to colonize the host tissues. During systemic infections, the single zupT mutant strain was attenuated only in Nramp1(+/+) mice, but competition experiments between znuABC and znuABC zupT mutants revealed that ZupT contributes to metal uptake in vivo independently of the presence of a functional Nramp1 transporter. Altogether, the here reported results show that ZupT plays an important role in Salmonella zinc homeostasis, being involved in metal import both in vitro and in infected animals.
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Affiliation(s)
- Mauro Cerasi
- Dipartimento di Biologia, Università di Roma Tor Vergata, Via della Ricerca Scientifica, 00133 Rome, Italy.
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54
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Metal ion homeostasis in Listeria monocytogenes and importance in host-pathogen interactions. Adv Microb Physiol 2014; 65:83-123. [PMID: 25476765 DOI: 10.1016/bs.ampbs.2014.08.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Listeria monocytogenes is responsible for one of the most life-threatening food-borne infections and the leading cause of food-poisoning associated deaths in the UK. Infection may be of the unborn/newly born infant where disease may manifest as listeric abortion, stillbirth or late-onset neonatal listeriosis, while in adults, infection usually affects the central nervous system causing meningitis. Crucial to the survival of L. monocytogenes, both inside and outside the host, is its ability to acquire metals which act as cofactors for a broad range of its cellular proteins. However, L. monocytogenes must also protect itself against the innate toxicity of metals. The importance of metals in host-pathogen interactions is illustrated by the restriction of metals (including zinc and iron) in vertebrates in response to infection and the use of high levels of metals (copper and zinc) as part of the antimicrobial defences within host phagocytes. As such, L. monocytogenes is equipped with various mechanisms to tightly control its cellular metal pools and avoid metal poisoning. These include multiple DNA-binding metal-responsive transcription factors, metal-acquisition, metal-detoxification and metal-storage systems, some of which represent key L. monocytogenes virulence determinants. This review discusses current knowledge of the role of metals in L. monocytogenes infections, with a focus on the mechanisms that contribute to zinc and copper homeostasis in this organism. The requirement to precisely control cellular metal levels may impose a vulnerability to L. monocytogenes which can be exploited in antimicrobials and therapeutics.
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Ni Z, Jiang L, Feng L, Wang L, Liu B. Transcriptional adaptation of Shigella flexneri during adherence to epithelial cells. J Basic Microbiol 2014; 55:186-94. [PMID: 25291620 DOI: 10.1002/jobm.201400414] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 08/12/2014] [Indexed: 11/11/2022]
Abstract
Shigella adhesion to host cells is a transitional stage from an extracellular to an intracellular environment. However, the dynamic adaptations of Shigella during adhesion are poorly understood. To address this, we performed the first transcriptome analysis of Shigella flexneri 2457T during adhesion. A total of 1,757 genes were differentially regulated (>twofold). The majority of plasmid-borne ipa-mxi-spa locus genes were downregulated, indicating these virulence genes were strictly regulated after successful adhesion. Altered expression of genes involved in stress response indicates that adherent S. flexneri encountered envelope stress and oxidative stress. Shigella flexneri also experienced reduced energy production during adherence. Transcript profiling and cell culture assays using glpD and glpK mutants showed that enhancement of glycerol catabolism were related with adhesion ability of S. flexneri. In addition, regulation of expression of some ionic transport system may be required for S. flexneri adhesion. Expression levels of 26 genes were further examined using qRT-PCR, which were congruent with transcriptome data. A comparison with expression profile during intracellular growth revealed major differences in genes involved in translation, surface modification, and utilization of carbon and iron. These results contribute to the knowledge of the adaptation mechanisms of S. flexneri during adhesion.
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Affiliation(s)
- Zhiwei Ni
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China; The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Tianjin, China
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56
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Bhubhanil S, Sittipo P, Chaoprasid P, Nookabkaew S, Sukchawalit R, Mongkolsuk S. Control of zinc homeostasis in Agrobacterium tumefaciens via zur and the zinc uptake genes znuABC and zinT. MICROBIOLOGY-SGM 2014; 160:2452-2463. [PMID: 25227896 DOI: 10.1099/mic.0.082446-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The Agrobacterium tumefaciens zinc uptake regulator (Zur) was shown to negatively regulate the zinc uptake genes znuABC, encoding a zinc transport system belonging to the ATP-binding cassette (ABC) transporter family, and zinT, which encodes a periplasmic zinc-binding protein. The expression of znuABC and zinT was inducible when cells were grown in medium containing a metal chelator (EDTA), and this induction was shown to be specific for zinc depletion. The expression of znuABC was reduced in response to increased zinc in a dose-dependent manner, and zinT had a less pronounced but similar pattern of zinc-regulated expression. The inactivation of zur led to constitutively high expression of znuABC and zinT. In addition, a zur mutant had an increased total zinc content compared to the WT NTL4 strain, whereas the inactivation of zinT caused a reduction in the total zinc content. The zinT gene is shown to play a dominant role and to be more important than znuA and znuB for A. tumefaciens survival under zinc deprivation. ZinT can function even when ZnuABC is inactivated. However, mutations in zur, znuA, znuB or zinT did not affect the virulence of A. tumefaciens.
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Affiliation(s)
- Sakkarin Bhubhanil
- Center of Excellence on Environmental Health and Toxicology (EHT), Ministry of Education, Bangkok, Thailand.,Applied Biological Sciences, Chulabhorn Graduate Institute, Lak Si, Bangkok 10210, Thailand
| | - Panida Sittipo
- Laboratory of Pharmacology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand.,Environmental Toxicology, Chulabhorn Graduate Institute, Lak Si, Bangkok 10210, Thailand.,Center of Excellence on Environmental Health and Toxicology (EHT), Ministry of Education, Bangkok, Thailand
| | - Paweena Chaoprasid
- Laboratory of Pharmacology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand.,Environmental Toxicology, Chulabhorn Graduate Institute, Lak Si, Bangkok 10210, Thailand.,Center of Excellence on Environmental Health and Toxicology (EHT), Ministry of Education, Bangkok, Thailand
| | - Sumontha Nookabkaew
- Laboratory of Pharmacology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand
| | - Rojana Sukchawalit
- Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand.,Center of Excellence on Environmental Health and Toxicology (EHT), Ministry of Education, Bangkok, Thailand.,Applied Biological Sciences, Chulabhorn Graduate Institute, Lak Si, Bangkok 10210, Thailand
| | - Skorn Mongkolsuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.,Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand.,Center of Excellence on Environmental Health and Toxicology (EHT), Ministry of Education, Bangkok, Thailand
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57
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Bobrov AG, Kirillina O, Fetherston JD, Miller MC, Burlison JA, Perry RD. The Yersinia pestis siderophore, yersiniabactin, and the ZnuABC system both contribute to zinc acquisition and the development of lethal septicaemic plague in mice. Mol Microbiol 2014; 93:759-75. [PMID: 24979062 DOI: 10.1111/mmi.12693] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/23/2014] [Indexed: 01/06/2023]
Abstract
Bacterial pathogens must overcome host sequestration of zinc (Zn(2+) ), an essential micronutrient, during the infectious disease process. While the mechanisms to acquire chelated Zn(2+) by bacteria are largely undefined, many pathogens rely upon the ZnuABC family of ABC transporters. Here we show that in Yersinia pestis, irp2, a gene encoding the synthetase (HMWP2) for the siderophore yersiniabactin (Ybt) is required for growth under Zn(2+) -deficient conditions in a strain lacking ZnuABC. Moreover, growth stimulation with exogenous, purified apo-Ybt provides evidence that Ybt may serve as a zincophore for Zn(2+) acquisition. Studies with the Zn(2+) -dependent transcriptional reporter znuA::lacZ indicate that the ability to synthesize Ybt affects the levels of intracellular Zn(2+) . However, the outer membrane receptor Psn and TonB as well as the inner membrane (IM) ABC transporter YbtPQ, which are required for Fe(3+) acquisition by Ybt, are not needed for Ybt-dependent Zn(2+) uptake. In contrast, the predicted IM protein YbtX, a member of the Major Facilitator Superfamily, was essential for Ybt-dependent Zn(2+) uptake. Finally, we show that the ZnuABC system and the Ybt synthetase HMWP2, presumably by Ybt synthesis, both contribute to the development of a lethal infection in a septicaemic plague mouse model.
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Affiliation(s)
- Alexander G Bobrov
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky, Lexington, KY, USA
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58
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Choi S, Bird AJ. Zinc'ing sensibly: controlling zinc homeostasis at the transcriptional level. Metallomics 2014; 6:1198-215. [PMID: 24722954 DOI: 10.1039/c4mt00064a] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
Zinc-responsive transcription factors are found in all kingdoms of life and include the transcriptional activators ZntR, SczA, Zap1, bZip19, bZip23, and MTF-1, and transcriptional repressors Zur, AdcR, Loz1, and SmtB. These factors have two defining features; their activity is regulated by zinc and they all play a central role in zinc homeostasis by controlling the expression of genes that directly affect zinc levels or its availability. This review summarizes what is known about the mechanisms by which each of these factors sense changes in intracellular zinc levels and how they control zinc homeostasis through target gene regulation. Other factors that influence zinc ion sensing are also discussed.
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Affiliation(s)
- Sangyong Choi
- Department of Human Sciences, The Ohio State University, Columbus, OH 43210, USA
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59
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Crane JK, Broome JE, Reddinger RM, Werth BB. Zinc protects against Shiga-toxigenic Escherichia coli by acting on host tissues as well as on bacteria. BMC Microbiol 2014; 14:145. [PMID: 24903402 PMCID: PMC4072484 DOI: 10.1186/1471-2180-14-145] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 05/21/2014] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Zinc supplements can treat or prevent enteric infections and diarrheal disease. Many articles on zinc in bacteria, however, highlight the essential nature of this metal for bacterial growth and virulence, suggesting that zinc should make infections worse, not better. To address this paradox, we tested whether zinc might have protective effects on intestinal epithelium as well as on the pathogen. RESULTS Using polarized monolayers of T84 cells we found that zinc protected against damage induced by hydrogen peroxide, as measured by trans-epithelial electrical resistance. Zinc also reduced peroxide-induced translocation of Shiga toxin (Stx) across T84 monolayers from the apical to basolateral side. Zinc was superior to other divalent metals to (iron, manganese, and nickel) in protecting against peroxide-induced epithelial damage, while copper also showed a protective effect.The SOS bacterial stress response pathway is a powerful regulator of Stx production in STEC. We examined whether zinc's known inhibitory effects on Stx might be mediated by blocking the SOS response. Zinc reduced expression of recA, a reliable marker of the SOS. Zinc was more potent and more efficacious than other metals tested in inhibiting recA expression induced by hydrogen peroxide, xanthine oxidase, or the antibiotic ciprofloxacin. The close correlation between zinc's effects on recA/SOS and on Stx suggested that inhibition of the SOS response is one mechanism by which zinc protects against STEC infection. CONCLUSIONS Zinc's ability to protect against enteric bacterial pathogens may be the result of its combined effects on host tissues as well as inhibition of virulence in some pathogens. Research focused solely on the effects of zinc on pathogenic microbes may give an incomplete picture by failing to account for protective effects of zinc on host epithelia.
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Affiliation(s)
- John K Crane
- Department of Medicine, Division of Infectious Diseases, University at Buffalo, Room 317 Biomedical Research Bldg, 3435 Main St, Buffalo, NY 14214, USA.
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Plumptre CD, Eijkelkamp BA, Morey JR, Behr F, Couñago RM, Ogunniyi AD, Kobe B, O'Mara ML, Paton JC, McDevitt CA. AdcA and AdcAII employ distinct zinc acquisition mechanisms and contribute additively to zinc homeostasis inStreptococcus pneumoniae. Mol Microbiol 2014; 91:834-51. [DOI: 10.1111/mmi.12504] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/21/2013] [Indexed: 12/21/2022]
Affiliation(s)
- Charles D. Plumptre
- Research Centre for Infectious Diseases; School of Molecular and Biomedical Science; University of Adelaide; Adelaide South Australia Australia
| | - Bart A. Eijkelkamp
- Research Centre for Infectious Diseases; School of Molecular and Biomedical Science; University of Adelaide; Adelaide South Australia Australia
| | - Jacqueline R. Morey
- Research Centre for Infectious Diseases; School of Molecular and Biomedical Science; University of Adelaide; Adelaide South Australia Australia
| | - Felix Behr
- Research Centre for Infectious Diseases; School of Molecular and Biomedical Science; University of Adelaide; Adelaide South Australia Australia
| | - Rafael M. Couñago
- School of Chemistry and Molecular Biosciences; University of Queensland; Brisbane Queensland Australia
- Australian Infectious Diseases Research Centre; University of Queensland; Brisbane Queensland Australia
- Institute for Molecular Bioscience; University of Queensland; Brisbane Queensland Australia
| | - Abiodun D. Ogunniyi
- Research Centre for Infectious Diseases; School of Molecular and Biomedical Science; University of Adelaide; Adelaide South Australia Australia
| | - Bostjan Kobe
- School of Chemistry and Molecular Biosciences; University of Queensland; Brisbane Queensland Australia
- Australian Infectious Diseases Research Centre; University of Queensland; Brisbane Queensland Australia
- Institute for Molecular Bioscience; University of Queensland; Brisbane Queensland Australia
| | - Megan L. O'Mara
- School of Chemistry and Molecular Biosciences; University of Queensland; Brisbane Queensland Australia
- School of Mathematics and Physics; University of Queensland; Brisbane Queensland Australia
| | - James C. Paton
- Research Centre for Infectious Diseases; School of Molecular and Biomedical Science; University of Adelaide; Adelaide South Australia Australia
| | - Christopher A. McDevitt
- Research Centre for Infectious Diseases; School of Molecular and Biomedical Science; University of Adelaide; Adelaide South Australia Australia
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Cerasi M, Ammendola S, Battistoni A. Competition for zinc binding in the host-pathogen interaction. Front Cell Infect Microbiol 2013; 3:108. [PMID: 24400228 PMCID: PMC3872050 DOI: 10.3389/fcimb.2013.00108] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 12/11/2013] [Indexed: 11/13/2022] Open
Abstract
Due to its favorable chemical properties, zinc is used as a structural or catalytic cofactor in a very large number of proteins. Despite the apparent abundance of this metal in all cell types, the intracellular pool of loosely bound zinc ions available for biological exchanges is in the picomolar range and nearly all zinc is tightly bound to proteins. In addition, to limit bacterial growth, some zinc-sequestering proteins are produced by eukaryotic hosts in response to infections. Therefore, to grow and multiply in the infected host, bacterial pathogens must produce high affinity zinc importers, such as the ZnuABC transporter which is present in most Gram-negative bacteria. Studies carried in different bacterial species have established that disruption of ZnuABC is usually associated with a remarkable loss of pathogenicity. The critical involvement of zinc in a plethora of metabolic and virulence pathways and the presence of very low number of zinc importers in most bacterial species mark zinc homeostasis as a very promising target for the development of novel antimicrobial strategies.
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Affiliation(s)
- Mauro Cerasi
- Dipartimento di Biologia, Università di Roma Tor Vergata Rome, Italy
| | - Serena Ammendola
- Dipartimento di Biologia, Università di Roma Tor Vergata Rome, Italy
| | - Andrea Battistoni
- Dipartimento di Biologia, Università di Roma Tor Vergata Rome, Italy ; Istituto Nazionale Biostrutture e Biosistemi, Consorzio Interuniversitario Rome, Italy
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Porcheron G, Garénaux A, Proulx J, Sabri M, Dozois CM. Iron, copper, zinc, and manganese transport and regulation in pathogenic Enterobacteria: correlations between strains, site of infection and the relative importance of the different metal transport systems for virulence. Front Cell Infect Microbiol 2013; 3:90. [PMID: 24367764 PMCID: PMC3852070 DOI: 10.3389/fcimb.2013.00090] [Citation(s) in RCA: 237] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Accepted: 11/18/2013] [Indexed: 02/05/2023] Open
Abstract
For all microorganisms, acquisition of metal ions is essential for survival in the environment or in their infected host. Metal ions are required in many biological processes as components of metalloproteins and serve as cofactors or structural elements for enzymes. However, it is critical for bacteria to ensure that metal uptake and availability is in accordance with physiological needs, as an imbalance in bacterial metal homeostasis is deleterious. Indeed, host defense strategies against infection either consist of metal starvation by sequestration or toxicity by the highly concentrated release of metals. To overcome these host strategies, bacteria employ a variety of metal uptake and export systems and finely regulate metal homeostasis by numerous transcriptional regulators, allowing them to adapt to changing environmental conditions. As a consequence, iron, zinc, manganese, and copper uptake systems significantly contribute to the virulence of many pathogenic bacteria. However, during the course of our experiments on the role of iron and manganese transporters in extraintestinal Escherichia coli (ExPEC) virulence, we observed that depending on the strain tested, the importance of tested systems in virulence may be different. This could be due to the different set of systems present in these strains, but literature also suggests that as each pathogen must adapt to the particular microenvironment of its site of infection, the role of each acquisition system in virulence can differ from a particular strain to another. In this review, we present the systems involved in metal transport by Enterobacteria and the main regulators responsible for their controlled expression. We also discuss the relative role of these systems depending on the pathogen and the tissues they infect.
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Affiliation(s)
- Gaëlle Porcheron
- INRS-Institut Armand Frappier Laval, QC, Canada ; Centre de Recherche en Infectiologie Porcine et Aviaire, Faculté de Médecine Vétérinaire, Université de Montréal Saint-Hyacinthe, QC, Canada
| | - Amélie Garénaux
- INRS-Institut Armand Frappier Laval, QC, Canada ; Centre de Recherche en Infectiologie Porcine et Aviaire, Faculté de Médecine Vétérinaire, Université de Montréal Saint-Hyacinthe, QC, Canada
| | - Julie Proulx
- INRS-Institut Armand Frappier Laval, QC, Canada ; Centre de Recherche en Infectiologie Porcine et Aviaire, Faculté de Médecine Vétérinaire, Université de Montréal Saint-Hyacinthe, QC, Canada
| | - Mourad Sabri
- INRS-Institut Armand Frappier Laval, QC, Canada ; Centre de Recherche en Infectiologie Porcine et Aviaire, Faculté de Médecine Vétérinaire, Université de Montréal Saint-Hyacinthe, QC, Canada
| | - Charles M Dozois
- INRS-Institut Armand Frappier Laval, QC, Canada ; Centre de Recherche en Infectiologie Porcine et Aviaire, Faculté de Médecine Vétérinaire, Université de Montréal Saint-Hyacinthe, QC, Canada ; Groupe de Recherche sur les Maladies Infectieuses du Porc, Faculté de Médecine Vétérinaire, Université de Montréal Saint-Hyacinthe, QC, Canada
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Bersch B, Bougault C, Roux L, Favier A, Vernet T, Durmort C. New insights into histidine triad proteins: solution structure of a Streptococcus pneumoniae PhtD domain and zinc transfer to AdcAII. PLoS One 2013; 8:e81168. [PMID: 24312273 PMCID: PMC3842936 DOI: 10.1371/journal.pone.0081168] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 10/09/2013] [Indexed: 12/18/2022] Open
Abstract
Zinc (Zn2+) homeostasis is critical for pathogen host colonization and invasion. Polyhistidine triad (Pht) proteins, located at the surface of various streptococci, have been proposed to be involved in Zn2+ homeostasis. The phtD gene, coding for a Zn2+-binding protein, is organized in an operon with adcAII coding for the extracellular part of a Zn2+ transporter. In the present work, we investigate the relationship between PhtD and AdcAII using biochemical and structural biology approaches. Immuno-precipitation experiments on purified membranes of Streptococcus pneumoniae (S. pneumoniae) demonstrate that native PhtD and AdcAII interact in vivo confirming our previous in vitro observations. NMR was used to demonstrate Zn2+ transfer from the Zn2+-bound form of a 137 amino acid N-terminal domain of PhtD (t-PhtD) to AdcAII. The high resolution NMR structure of t-PhtD shows that Zn2+ is bound in a tetrahedral site by histidines 83, 86, and 88 as well as by glutamate 63. Comparison of the NMR parameters measured for apo- and Zn2+-t-PhtD shows that the loss of Zn2+ leads to a diminished helical propensity at the C-terminus and increases the local dynamics and overall molecular volume. Structural comparison with the crystal structure of a 55-long fragment of PhtA suggests that Pht proteins are built from short repetitive units formed by three β-strands containing the conserved HxxHxH motif. Taken together, these results support a role for S. pneumoniae PhtD as a Zn2+ scavenger for later release to the surface transporter AdcAII, leading to Zn2+ uptake.
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Affiliation(s)
- Beate Bersch
- Institut de Biologie Structurale, Université Grenoble Alpes, Grenoble, France ; Institut de Biologie Structurale, Direction des Sciences du Vivant, Commissariat à l'Energie Atomique et aux Energies Alternatives, Grenoble, France ; Institut de Biologie Structurale, Centre National de la Recherche Scientifique, Grenoble, France
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The Salmonella enterica ZinT structure, zinc affinity and interaction with the high-affinity uptake protein ZnuA provide insight into the management of periplasmic zinc. Biochim Biophys Acta Gen Subj 2013; 1840:535-44. [PMID: 24128931 DOI: 10.1016/j.bbagen.2013.10.010] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 09/17/2013] [Accepted: 10/07/2013] [Indexed: 11/22/2022]
Abstract
BACKGROUND In Gram-negative bacteria the ZnuABC transporter ensures adequate zinc import in Zn(II)-poor environments, like those encountered by pathogens within the infected host. Recently, the metal-binding protein ZinT was suggested to operate as an accessory component of ZnuABC in periplasmic zinc recruitment. Since ZinT is known to form a ZinT-ZnuA complex in the presence of Zn(II) it was proposed to transfer Zn(II) to ZnuA. The present work was undertaken to test this claim. METHODS ZinT and its structural relationship with ZnuA have been characterized by multiple biophysical techniques (X-ray crystallography, SAXS, analytical ultracentrifugation, fluorescence spectroscopy). RESULTS The metal-free and metal-bound crystal structures of Salmonella enterica ZinT show one Zn(II) binding site and limited structural changes upon metal removal. Spectroscopic titrations with Zn(II) yield a KD value of 22±2nM for ZinT, while those with ZnuA point to one high affinity (KD<20nM) and one low affinity Zn(II) binding site (KD in the micromolar range). Sedimentation velocity experiments established that Zn(II)-bound ZinT interacts with ZnuA, whereas apo-ZinT does not. The model of the ZinT-ZnuA complex derived from small angle X-ray scattering experiments points to a disposition that favors metal transfer as the metal binding cavities of the two proteins face each other. CONCLUSIONS ZinT acts as a Zn(II)-buffering protein that delivers Zn(II) to ZnuA. GENERAL SIGNIFICANCE Knowledge of the ZinT-ZnuA relationship is crucial for understanding bacterial Zn(II) uptake.
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Role of the zinc uptake ABC transporter of Moraxella catarrhalis in persistence in the respiratory tract. Infect Immun 2013; 81:3406-13. [PMID: 23817618 DOI: 10.1128/iai.00589-13] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Moraxella catarrhalis is a human respiratory tract pathogen that causes otitis media in children and lower respiratory tract infections in adults with chronic obstructive pulmonary disease. We have identified and characterized a zinc uptake ABC transporter that is present in all strains of M. catarrhalis tested. A mutant in which the znu gene cluster is knocked out shows markedly impaired growth compared to the wild type in medium that contains trace zinc; growth is restored to wild-type levels by supplementing medium with zinc but not with other divalent cations. Thermal-shift assays showed that the purified recombinant substrate binding protein ZnuA binds zinc but does not bind other divalent cations. Invasion assays with human respiratory epithelial cells demonstrated that the zinc ABC transporter of M. catarrhalis is critical for invasion of respiratory epithelial cells, an observation that is especially relevant because an intracellular reservoir of M. catarrhalis is present in the human respiratory tract and this reservoir is important for persistence. The znu knockout mutant showed marked impairment in its capacity to persist in the respiratory tract compared to the wild type in a mouse pulmonary clearance model. We conclude that the zinc uptake ABC transporter mediates uptake of zinc in environments with very low zinc concentrations and is critical for full virulence of M. catarrhalis in the respiratory tract in facilitating intracellular invasion of epithelial cells and persistence in the respiratory tract.
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66
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Lin H, Gudmestad NC. Aspects of pathogen genomics, diversity, epidemiology, vector dynamics, and disease management for a newly emerged disease of potato: zebra chip. PHYTOPATHOLOGY 2013; 103:524-537. [PMID: 23268582 DOI: 10.1094/phyto-09-12-0238-rvw] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
An overview is provided for the aspects of history, biology, genomics, genetics, and epidemiology of zebra chip (ZC), a destructive disease of potato (Solanum tuberosum) that represents a major threat to the potato industries in the United States as well as other potato-production regions in the world. The disease is associated with a gram-negative, phloem-limited, insect-vectored, unculturable prokaryote, 'Candidatus Liberibacter solanacearum', that belongs to the Rhizobiaceae family of α-Proteobacteria. The closest cultivated relatives of 'Ca. L. solanacearum' are members of the group of bacteria known as the α-2 subgroup. In spite of the fact that Koch's postulates sensu stricto have not been fulfilled, a great deal of progress has been made in understanding the ZC disease complex since discovery of the disease. Nevertheless, more research is needed to better understand vector biology, disease mechanisms, host response, and epidemiology in the context of vector-pathogen-plant interactions. Current ZC management strategies focus primarily on psyllid control. The ultimate control of ZC likely relies on host resistance. Unfortunately, all commercial potato cultivars are susceptible to ZC. Elucidation of the 'Ca. L. solanacearum' genome sequence has provided insights into the genetic basis of virulence and physiological and metabolic capability of this organism. Finally, the most effective, sustainable management of ZC is likely to be based on integrated strategies, including removal or reduction of vectors or inocula, improvement of host resistance to the presumptive pathogen and psyllid vectors, and novel gene-based therapeutic treatment.
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Affiliation(s)
- Hong Lin
- United States Department of Agriculture-Agricultural Research Service Crop Diseases, Pests and Genetics Research Unit 9611, S. Riverbend Avenue, Parlier, CA 93648, USA.
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67
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Maynaud G, Brunel B, Mornico D, Durot M, Severac D, Dubois E, Navarro E, Cleyet-Marel JC, Le Quéré A. Genome-wide transcriptional responses of two metal-tolerant symbiotic Mesorhizobium isolates to zinc and cadmium exposure. BMC Genomics 2013; 14:292. [PMID: 23631387 PMCID: PMC3668242 DOI: 10.1186/1471-2164-14-292] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Accepted: 04/18/2013] [Indexed: 11/10/2022] Open
Abstract
Background Mesorhizobium metallidurans STM 2683T and Mesorhizobium sp. strain STM 4661 were isolated from nodules of the metallicolous legume Anthyllis vulneraria from distant mining spoils. They tolerate unusually high Zinc and Cadmium concentrations as compared to other mesorhizobia. This work aims to study the gene expression profiles associated with Zinc or Cadmium exposure and to identify genes involved in metal tolerance in these two metallicolous Mesorhizobium strains of interest for mine phytostabilization purposes. Results The draft genomes of the two Mezorhizobium strains were sequenced and used to map RNAseq data obtained after Zinc or Cadmium stresses. Comparative genomics and transcriptomics allowed the rapid discovery of metal-specific or/and strain-specific genes. Respectively 1.05% (72/6,844) and 0.97% (68/6,994) predicted Coding DNA Sequences (CDS) for STM 2683 and STM 4661 were significantly differentially expressed upon metal exposure. Among these, a significant number of CDS involved in transport (13/72 and 13/68 for STM 2683 and STM 4661, respectively) and sequestration (15/72 and 16/68 for STM 2683 and STM 4661, respectively) were identified. Thirteen CDS presented homologs in both strains and were differentially regulated by Zinc and/or Cadmium. For instance, several PIB-type ATPases and genes likely to participate in metal sequestration were identified. Among the conserved CDS that showed differential regulation in the two isolates, we also found znuABC homologs encoding for a high affinity ABC-type Zinc import system probably involved in Zinc homeostasis. Additionally, global analyses suggested that both metals also repressed significantly the translational machinery. Conclusions The comparative RNAseq-based approach revealed a relatively low number of genes significantly regulated in the two Mesorhizobium strains. Very few of them were involved in the non-specific metal response, indicating that the approach was well suited for identifying genes that specifically respond to Zinc and Cadmium. Among significantly up-regulated genes, several encode metal efflux and sequestration systems which can be considered as the most widely represented mechanisms of rhizobial metal tolerance. Downstream functional studies will increase successful phytostabilization strategies by selecting appropriate metallicolous rhizobial partners.
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68
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Jalalvand F, Su YC, Mörgelin M, Brant M, Hallgren O, Westergren-Thorsson G, Singh B, Riesbeck K. Haemophilus influenzae protein F mediates binding to laminin and human pulmonary epithelial cells. J Infect Dis 2012; 207:803-13. [PMID: 23230060 DOI: 10.1093/infdis/jis754] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The mucosal pathogen nontypeable Haemophilus influenzae (NTHi) adheres to the respiratory epithelium or, in the case of epithelial damage, to the underlying basement membrane and extracellular matrix that, among other proteins, consists of laminin. We have recently identified protein F, an ABC transporter involved in NTHi immune evasion. Homology modeling of the protein F tertiary structure revealed a strong resemblance to the streptococcal laminin-binding proteins Lbp and Lmb. Here, we show that protein F promotes binding of NTHi to laminin and primary bronchial epithelial cells. Analyses with recombinant proteins and synthetic peptides revealed that the N-terminal part of protein F contains the host-interacting region. Moreover, protein F exists in all clinical isolates, and isogenic NTHi Δhpf mutants display significantly reduced binding to laminin and epithelial cells. We thus suggest protein F to be an important and ubiquitous NTHi adhesin.
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Affiliation(s)
- Farshid Jalalvand
- Medical Microbiology, Department of Laboratory Medicine Malmö, Skåne University Hospital, Malmö, Sweden
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The zinc-responsive regulon of Neisseria meningitidis comprises 17 genes under control of a Zur element. J Bacteriol 2012; 194:6594-603. [PMID: 23043002 DOI: 10.1128/jb.01091-12] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Zinc is a bivalent cation essential for bacterial growth and metabolism. The human pathogen Neisseria meningitidis expresses a homologue of the Zinc uptake regulator Zur, which has been postulated to repress the putative zinc uptake protein ZnuD. In this study, we elucidated the transcriptome of meningococci in response to zinc by microarrays and quantitative real-time PCR (qRT-PCR). We identified 15 genes that were repressed and two genes that were activated upon zinc addition. All transcription units (genes and operons) harbored a putative Zur binding motif in their promoter regions. A meningococcal Zur binding consensus motif (Zur box) was deduced in silico, which harbors a conserved central palindrome consisting of hexameric inverted repeats separated by three nucleotides (TGTTATDNHATAACA). In vitro binding of recombinant meningococcal Zur to this Zur box was shown for the first time using electrophoretic mobility shift assays. Zur binding to DNA depended specifically on the presence of zinc and was sensitive to mutations in the palindromic sequence. The Zur regulon among genes of unknown function comprised genes involved in zinc uptake, tRNA modification, and ribosomal assembly. In summary, this is the first study of the transcriptional response to zinc in meningococci.
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Lewis VG, Ween MP, McDevitt CA. The role of ATP-binding cassette transporters in bacterial pathogenicity. PROTOPLASMA 2012; 249:919-942. [PMID: 22246051 DOI: 10.1007/s00709-011-0360-8] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 11/29/2011] [Indexed: 05/31/2023]
Abstract
The ATP-binding cassette transporter superfamily is present in all three domains of life. This ubiquitous class of integral membrane proteins have diverse biological functions, but their fundamental role involves the unidirectional translocation of compounds across cellular membranes in an ATP coupled process. The importance of this class of proteins in eukaryotic systems is well established as typified by their association with genetic diseases and roles in the multi-drug resistance of cancer. In stark contrast, the ABC transporters of prokaryotes have not been exhaustively investigated due to the sheer number of different roles and organisms in which they function. In this review, we examine the breadth of functions associated with microbial ABC transporters in the context of their contribution to bacterial pathogenicity and virulence.
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Affiliation(s)
- Victoria G Lewis
- Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia, 5005, Australia
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PA2800 plays an important role in both antibiotic susceptibility and virulence in Pseudomonas aeruginosa. Curr Microbiol 2012; 65:601-9. [PMID: 22878555 DOI: 10.1007/s00284-012-0196-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 07/04/2012] [Indexed: 10/28/2022]
Abstract
Pseudomonas aeruginosa is an important human pathogen which causes a variety of infections. P. aeruginosa infections are often difficult to treat due to the pathogen's resistance to many antibiotics. Previously, it has been reported that a transposon insertion mutant in gene PA2800 of P. aeruginosa PAO1 was more sensitive to tetracycline and ciprofloxacin. Further characterization of this gene, a vacJ homolog, in this study indicated that this gene plays an important role in both antibiotic susceptibility and virulence in P. aeruginosa. The role of PA2800 in antibiotic susceptibility probably signifies its involvement in maintaining outer membrane stability, similar to the role of vacJ in E. coli and Shigella flexneri. However, in contrast to vacJ in other bacteria, PA2800 also affects antibiotic susceptibility by affecting the expression of oprH in P. aeruginosa. As shown by in vivo studies using a Drosophila melanogaster infection model, significantly increased virulence was observed in the PA2800 mutant when compared to the wild type, and such a difference is likely a result of disrupted outer membrane stability and altered expression of znuA in the mutant. The role of PA2800 or vacJ in antibiotic susceptibility and pathogenicity seems to be unique in P. aeruginosa in which it affects both outer membrane stability as well as gene expression.
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Chimalapati S, Cohen JM, Camberlein E, MacDonald N, Durmort C, Vernet T, Hermans PWM, Mitchell T, Brown JS. Effects of deletion of the Streptococcus pneumoniae lipoprotein diacylglyceryl transferase gene lgt on ABC transporter function and on growth in vivo. PLoS One 2012; 7:e41393. [PMID: 22911788 PMCID: PMC3404074 DOI: 10.1371/journal.pone.0041393] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 06/21/2012] [Indexed: 12/14/2022] Open
Abstract
Lipoproteins are an important class of surface associated proteins that have diverse roles and frequently are involved in the virulence of bacterial pathogens. As prolipoproteins are attached to the cell membrane by a single enzyme, prolipoprotein diacylglyceryl transferase (Lgt), deletion of the corresponding gene potentially allows the characterisation of the overall importance of lipoproteins for specific bacterial functions. We have used a Δlgt mutant strain of Streptococcus pneumoniae to investigate the effects of loss of lipoprotein attachment on cation acquisition, growth in media containing specific carbon sources, and virulence in different infection models. Immunoblots of triton X-114 extracts, flow cytometry and immuno-fluorescence microscopy confirmed the Δlgt mutant had markedly reduced lipoprotein expression on the cell surface. The Δlgt mutant had reduced growth in cation depleted medium, increased sensitivity to oxidative stress, reduced zinc uptake, and reduced intracellular levels of several cations. Doubling time of the Δlgt mutant was also increased slightly when grown in medium with glucose, raffinose and maltotriose as sole carbon sources. These multiple defects in cation and sugar ABC transporter function for the Δlgt mutant were associated with only slightly delayed growth in complete medium. However the Δlgt mutant had significantly reduced growth in blood or bronchoalveolar lavage fluid and a marked impairment in virulence in mouse models of nasopharyngeal colonisation, sepsis and pneumonia. These data suggest that for S. pneumoniae loss of surface localisation of lipoproteins has widespread effects on ABC transporter functions that collectively prevent the Δlgt mutant from establishing invasive infection.
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Affiliation(s)
- Suneeta Chimalapati
- Centre for Respiratory Research, Department of Medicine, Royal Free and University College Medical School, Rayne Institute, London, United Kingdom
| | - Jonathan M. Cohen
- Centre for Respiratory Research, Department of Medicine, Royal Free and University College Medical School, Rayne Institute, London, United Kingdom
- Infectious Diseases & Microbiology Unit, UCL Institute of Child Health, London, United Kingdom
| | - Emilie Camberlein
- Centre for Respiratory Research, Department of Medicine, Royal Free and University College Medical School, Rayne Institute, London, United Kingdom
| | - Nathanael MacDonald
- Centre for Respiratory Research, Department of Medicine, Royal Free and University College Medical School, Rayne Institute, London, United Kingdom
| | - Claire Durmort
- CEA, Institut de Biologie Structurale Jean-Pierre Ebel, Grenoble, France
- CNRS, Institut de Biologie Structurale Jean-Pierre Ebel, Grenoble, France
- Université Joseph Fourier – Grenoble 1, Institut de Biologie Structurale Jean-Pierre Ebel, Grenoble, France
| | - Thierry Vernet
- CEA, Institut de Biologie Structurale Jean-Pierre Ebel, Grenoble, France
- CNRS, Institut de Biologie Structurale Jean-Pierre Ebel, Grenoble, France
- Université Joseph Fourier – Grenoble 1, Institut de Biologie Structurale Jean-Pierre Ebel, Grenoble, France
| | - Peter W. M. Hermans
- Laboratory of Pediatric Infectious Diseases, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Timothy Mitchell
- Division of Infection and Immunity, IBLS, University of Glasgow, Glasgow, United Kingdom
| | - Jeremy S. Brown
- Centre for Respiratory Research, Department of Medicine, Royal Free and University College Medical School, Rayne Institute, London, United Kingdom
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Bayle L, Chimalapati S, Schoehn G, Brown J, Vernet T, Durmort C. Zinc uptake by Streptococcus pneumoniae depends on both AdcA and AdcAII and is essential for normal bacterial morphology and virulence. Mol Microbiol 2011; 82:904-16. [PMID: 22023106 DOI: 10.1111/j.1365-2958.2011.07862.x] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Zinc is an essential trace metal for living cells. The ABC transporter AdcABC was previously shown to be required for zinc uptake by Streptococcus pneumoniae. As we have recently described AdcAII as another zinc-binding lipoprotein, we have investigated the role of both AdcA and AdcAII in S. pneumoniae zinc metabolism. Deletion of either adcA or adcAII but not phtD reduced S. pneumoniae zinc uptake, with dual mutation of both adcA and adcAII further decreasing zinc import. For the Δ(adcA/adcAII) mutant, growth and intracellular concentrations of zinc were both greatly reduced in low zinc concentration. When grown in zinc-deficient medium, the Δ(adcA/adcAII) mutant displayed morphological defects related to aberrant septation. Growth and morphology of the Δ(adcA/adcAII) mutant recovered after supplementation with zinc. Dual deletion of adcA and adcAII strongly impaired growth of the pneumococcus in bronchoalveolar lavage fluid and human serum, and prevented S. pneumoniae establishing infection in mouse models of nasopharyngeal colonization, pneumonia and sepsis without altering the capsule. Taken together, our results show that AdcA and AdcAII play an essential and redundant role in specifically importing zinc into the pneumococcus, and that both zinc transporters are required for proper cell division and for S. pneumoniae survival during infection.
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Affiliation(s)
- Lucie Bayle
- CEA, Institut de Biologie Structurale Jean-Pierre Ebel, Grenoble, 41 Rue Jules Horowitz, 38027 Grenoble cedex 1, France
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Two zinc uptake systems contribute to the full virulence of Listeria monocytogenes during growth in vitro and in vivo. Infect Immun 2011; 80:14-21. [PMID: 22025520 DOI: 10.1128/iai.05904-11] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report here the identification and characterization of two zinc uptake systems, ZurAM and ZinABC, in the intracellular pathogen Listeria monocytogenes. Transcription of both operons was zinc responsive and regulated by the zinc-sensing repressor Zur. Deletion of either zurAM or zinA had no detectable effect on growth in defined media, but a double zurAM zinA mutant was unable to grow in the absence of zinc supplementation. Deletion of zinA had no detectable effect on intracellular growth in HeLa epithelial cells. In contrast, growth of the zurAM mutant was significantly impaired in these cells, indicating the importance of the ZurAM system during intracellular growth. Notably, the deletion of both zinA and zurAM severely attenuated intracellular growth, with the double mutant being defective in actin-based motility and unable to spread from cell to cell. Deletion of either zurAM or zinA had a significant effect on virulence in an oral mouse model, indicating that both zinc uptake systems are important in vivo and establishing the importance of zinc acquisition during infection by L. monocytogenes. The presence of two zinc uptake systems may offer a mechanism by which L. monocytogenes can respond to zinc deficiency within a variety of environments and during different stages of infection, with each system making distinct contributions under different stress conditions.
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Graham AI, Sanguinetti G, Bramall N, McLeod CW, Poole RK. Dynamics of a starvation-to-surfeit shift: a transcriptomic and modelling analysis of the bacterial response to zinc reveals transient behaviour of the Fur and SoxS regulators. MICROBIOLOGY-SGM 2011; 158:284-292. [PMID: 22016571 DOI: 10.1099/mic.0.053843-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We describe a hybrid transcriptomic and modelling analysis of the dynamics of a bacterial response to stress, namely the addition of 200 µM Zn to Escherichia coli growing in severely Zn-depleted medium and of cells growing at different Zn concentrations at steady state. Genes that changed significantly in response to the transition were those reported previously to be associated with zinc deficiency (zinT, znuA, ykgM) or excess (basR, cpxP, cusF). Cellular Zn levels were confirmed by ICP-AES to be 14- to 28-fold greater after Zn addition but there was also 6- to 8-fold more cellular Fe 30 min after Zn addition. Statistical modelling of the transcriptomic data generated from the Zn shift focused on the role of ten key regulators; ArsR, BaeR, CpxR, CusR, Fur, OxyR, SoxS, ZntR, ZraR and Zur. The data and modelling reveal a transient change in the activity of the iron regulator Fur and of the oxidative stress regulator SoxS, neither of which is evident from the steady-state transcriptomic analyses. We hypothesize a competitive binding mechanism that combines these observations and existing data on the physiology of Zn and Fe uptake. Formalizing the mechanism in a differential equation model shows that it can reproduce qualitatively the behaviour seen in the data. This gives new insights into the interplay of these two fundamental metal ions in gene regulation and bacterial physiology, as well as highlighting the importance of dynamic studies to reverse-engineer systems behaviour.
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Affiliation(s)
- Alison I Graham
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Guido Sanguinetti
- School of Informatics, University of Edinburgh, Informatics Forum, 10 Crichton Street, Edinburgh EH8 9AB, UK
| | - Neil Bramall
- Centre for Analytical Sciences, The University of Sheffield, Western Bank, Sheffield S3 7HF, UK
| | - Cameron W McLeod
- Centre for Analytical Sciences, The University of Sheffield, Western Bank, Sheffield S3 7HF, UK
| | - Robert K Poole
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Western Bank, Sheffield S10 2TN, UK
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Lim J, Lee KM, Kim SH, Kim Y, Kim SH, Park W, Park S. YkgM and ZinT proteins are required for maintaining intracellular zinc concentration and producing curli in enterohemorrhagic Escherichia coli (EHEC) O157:H7 under zinc deficient conditions. Int J Food Microbiol 2011; 149:159-70. [DOI: 10.1016/j.ijfoodmicro.2011.06.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Revised: 04/18/2011] [Accepted: 06/21/2011] [Indexed: 11/29/2022]
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