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Krasulova K, Neuzilova B, Dvorakova Bendova K, Novy Z, Popper M, Hajduch M, Petrik M. Preclinical characterisation of gallium-68 labeled ferrichrome siderophore stereoisomers for PET imaging applications. EJNMMI Radiopharm Chem 2024; 9:20. [PMID: 38436776 PMCID: PMC10912063 DOI: 10.1186/s41181-024-00249-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 02/23/2024] [Indexed: 03/05/2024] Open
Abstract
BACKGROUND Siderophores are small iron-binding molecules produced by microorganisms to facilitate iron acquisition from the environment. Radiolabelled siderophores offer a promising solution for infection imaging, as they can specifically target the pathophysiological mechanisms of pathogens. Gallium-68 can replace the iron in siderophores, enabling molecular imaging with positron emission tomography (PET). Stereospecific interactions play a crucial role in the recognition of receptors, transporters, and iron utilisation. Furthermore, these interactions have an impact on the host environment, affecting pharmacokinetics and biodistribution. This study examines the influence of siderophore stereoisomerism on imaging properties, with a focus on ferrirubin (FR) and ferrirhodin (FRH), two cis-trans isomeric siderophores of the ferrichrome type. RESULTS Tested siderophores were labelled with gallium-68 with high radiochemical purity. The resulting complexes differed in their in vitro characteristics. [68Ga]Ga-FRH showed less hydrophilic properties and higher protein binding values than [68Ga]Ga-FR. The stability studies confirmed the high radiochemical stability of both [68Ga]Ga-siderophores in all examined media. Both siderophores were found to be taken up by S. aureus, K. pneumoniae and P. aeruginosa with similar efficacy. The biodistribution tested in normal mice showed rapid renal clearance with low blood pool retention and fast clearance from examined organs for [68Ga]Ga-FR, whereas [68Ga]Ga-FRH showed moderate retention in blood, resulting in slower pharmacokinetics. PET/CT imaging of mice injected with [68Ga]Ga-FR and [68Ga]Ga-FRH confirmed findings from ex vivo biodistribution studies. In a mouse model of S. aureus myositis, both radiolabeled siderophores showed radiotracer accumulation at the site of infection. CONCLUSIONS The 68Ga-complexes of stereoisomers ferrirubin and ferrirhodin revealed different pharmacokinetic profiles. In vitro uptake was not affected by isomerism. Both compounds had uptake with the same bacterial culture with similar efficacy. PET/CT imaging showed that the [68Ga]Ga-complexes accumulate at the site of S. aureus infection, highlighting the potential of [68Ga]Ga-FR as a promising tool for infection imaging. In contrast, retention of the radioactivity in the blood was observed for [68Ga]Ga-FRH. In conclusion, the stereoisomerism of potential radiotracers should be considered, as even minor structural differences can influence their pharmacokinetics and, consequently, the results of PET imaging.
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Affiliation(s)
- Kristyna Krasulova
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 5, 779 00, Olomouc, Czech Republic.
| | - Barbora Neuzilova
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 5, 779 00, Olomouc, Czech Republic
| | - Katerina Dvorakova Bendova
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 5, 779 00, Olomouc, Czech Republic
| | - Zbynek Novy
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 5, 779 00, Olomouc, Czech Republic
- Czech Advanced Technology and Research Institute, Palacky University, Krizkovskeho 511/8, 779 00, Olomouc, Czech Republic
| | - Miroslav Popper
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 5, 779 00, Olomouc, Czech Republic
| | - Marian Hajduch
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 5, 779 00, Olomouc, Czech Republic
- Czech Advanced Technology and Research Institute, Palacky University, Krizkovskeho 511/8, 779 00, Olomouc, Czech Republic
- University Hospital Olomouc, I.P. Pavlova 6, 779 00, Olomouc, Czech Republic
| | - Milos Petrik
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 5, 779 00, Olomouc, Czech Republic.
- Czech Advanced Technology and Research Institute, Palacky University, Krizkovskeho 511/8, 779 00, Olomouc, Czech Republic.
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Zhang H, Yang J, Cheng J, Zeng J, Ma X, Lin J. PQS and pyochelin in Pseudomonas aeruginosa share inner membrane transporters to mediate iron uptake. Microbiol Spectr 2024; 12:e0325623. [PMID: 38171001 PMCID: PMC10846271 DOI: 10.1128/spectrum.03256-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 11/29/2023] [Indexed: 01/05/2024] Open
Abstract
Bacteria absorb different forms of iron through various channels to meet their needs. Our previous studies have shown that TseF, a type VI secretion system effector for Fe uptake, facilitates the delivery of outer membrane vesicle-associated Pseudomonas quinolone signal (PQS)-Fe3+ to bacterial cells by a process involving the Fe(III) pyochelin receptor FptA and the porin OprF. However, the form in which the PQS-Fe3+ complex enters the periplasm and how it is moved into the cytoplasm remain unclear. Here, we first demonstrate that the PQS-Fe3+ complex enters the cell directly through FptA or OprF. Next, we show that inner membrane transporters such as FptX, PchHI, and FepBCDG are not only necessary for Pseudomonas aeruginosa to absorb PQS-Fe3+ and pyochelin (PCH)-Fe3+ but are also necessary for the virulence of P. aeruginosa toward Galleria mellonella larvae. Furthermore, we suggest that the function of PQS-Fe3+ (but not PQS)-mediated quorum-sensing regulation is dependent on FptX, PchHI, and FepBCDG. Additionally, the findings indicate that unlike FptX, neither FepBCDG nor PchHI play roles in the autoregulatory loop involving PchR, but further deletion of fepBCDG and pchHI can reverse the inactive PchR phenotype caused by fptX deletion and reactivate the expression of the PCH pathway genes under iron-limited conditions. Finally, this work identifies the interaction between FptX, PchHI, and FepBCDG, indicating that a larger complex could be formed to mediate the uptake of PQS-Fe3+ and PCH-Fe3+. These results pave the way for a better understanding of the PQS and PCH iron absorption pathways and provide future directions for research on tackling P. aeruginosa infections.IMPORTANCEPseudomonas aeruginosa has evolved a number of strategies to acquire the iron it needs from its host, with the most common being the synthesis, secretion, and uptake of siderophores such as pyoverdine, pyochelin, and the quorum-sensing signaling molecule Pseudomonas quinolone signal (PQS). However, despite intensive studies of the siderophore uptake pathways of P. aeruginosa, our understanding of how siderophores transport iron across the inner membrane into the cytoplasm is still incomplete. Herein, we reveal that PQS and pyochelin in P. aeruginosa share inner membrane transporters such as FptX, PchHI, and FepBCDG to mediate iron uptake. Meanwhile, PQS and pyochelin-mediated signaling operate to a large extent via these inner membrane transporters. Our study revealed the existence of shared uptake pathways between PQS and pyochelin, which could lead us to reexamine the role of these two molecules in the iron uptake and virulence of P. aeruginosa.
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Affiliation(s)
- Heng Zhang
- Shaanxi Key Laboratory of Chinese Jujube, College of Life Sciences, Yan’an University, Yan’an, China
| | - Jianshe Yang
- Shaanxi Key Laboratory of Chinese Jujube, College of Life Sciences, Yan’an University, Yan’an, China
| | - Juanli Cheng
- Shaanxi Key Laboratory of Chinese Jujube, College of Life Sciences, Yan’an University, Yan’an, China
| | - Jing Zeng
- Shaanxi Key Laboratory of Chinese Jujube, College of Life Sciences, Yan’an University, Yan’an, China
| | - Xin Ma
- Shaanxi Key Laboratory of Chinese Jujube, College of Life Sciences, Yan’an University, Yan’an, China
| | - Jinshui Lin
- Shaanxi Key Laboratory of Chinese Jujube, College of Life Sciences, Yan’an University, Yan’an, China
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3
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Hussein SM, Sofoluwe A, Paleja A, Duhme-Klair A, Thomas MS. Identification of a system for hydroxamate xenosiderophore-mediated iron transport in Burkholderia cenocepacia. MICROBIOLOGY (READING, ENGLAND) 2024; 170:001425. [PMID: 38189440 PMCID: PMC10866019 DOI: 10.1099/mic.0.001425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 12/19/2023] [Indexed: 01/09/2024]
Abstract
One of the mechanisms employed by the opportunistic pathogen Burkholderia cenocepacia to acquire the essential element iron is the production and release of two ferric iron chelating compounds (siderophores), ornibactin and pyochelin. Here we show that B. cenocepacia is also able to take advantage of a range of siderophores produced by other bacteria and fungi ('xenosiderophores') that chelate iron exclusively by means of hydroxamate groups. These include the tris-hydroxamate siderophores ferrioxamine B, ferrichrome, ferricrocin and triacetylfusarinine C, the bis-hydroxamates alcaligin and rhodotorulic acid, and the monohydroxamate siderophore cepabactin. We also show that of the 24 TonB-dependent transporters encoded by the B. cenocepacia genome, two (FhuA and FeuA) are involved in the uptake of hydroxamate xenosiderophores, with FhuA serving as the exclusive transporter of iron-loaded ferrioxamine B, triacetylfusarinine C, alcaligin and rhodotorulic acid, while both FhuA and FeuA are able to translocate ferrichrome-type siderophores across the outer membrane. Finally, we identified FhuB, a putative cytoplasmic membrane-anchored ferric-siderophore reductase, as being obligatory for utilization of all of the tested bis- and tris-hydroxamate xenosiderophores apart from alcaligin.
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Affiliation(s)
- Syakira Mohammed Hussein
- Division of Clinical Medicine, School of Medicine and Population Health, University of Sheffield, Medical School, Beech Hill Road, Sheffield S10 2RX, UK
| | - Aderonke Sofoluwe
- Division of Clinical Medicine, School of Medicine and Population Health, University of Sheffield, Medical School, Beech Hill Road, Sheffield S10 2RX, UK
- Department of Immunobiology, School of Immunology & Microbial Sciences, King’s College London, London WC2R 2LS, UK
| | - Ameya Paleja
- Division of Clinical Medicine, School of Medicine and Population Health, University of Sheffield, Medical School, Beech Hill Road, Sheffield S10 2RX, UK
| | - Anne Duhme-Klair
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK
| | - Mark S. Thomas
- Division of Clinical Medicine, School of Medicine and Population Health, University of Sheffield, Medical School, Beech Hill Road, Sheffield S10 2RX, UK
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4
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Naka H, Haygood MG. The dual role of TonB genes in turnerbactin uptake and carbohydrate utilization in the shipworm symbiont Teredinibacter turnerae. Appl Environ Microbiol 2023; 89:e0074423. [PMID: 38009998 PMCID: PMC10734418 DOI: 10.1128/aem.00744-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 10/01/2023] [Indexed: 11/29/2023] Open
Abstract
IMPORTANCE This study highlights diversity in iron acquisition and regulation in bacteria. The mechanisms of iron acquisition and its regulation in Teredinibacter turnerae, as well as its connection to cellulose utilization, a hallmark phenotype of T. turnerae, expand the paradigm of bacterial iron acquisition. Two of the four TonB genes identified in T. turnerae exhibit functional redundancy and play a crucial role in siderophore-mediated iron transport. Unlike typical TonB genes in bacteria, none of the TonB genes in T. turnerae are clearly iron regulated. This unusual regulation could be explained by another important finding in this study, namely, that the two TonB genes involved in iron transport are also essential for cellulose utilization as a carbon source, leading to the expression of TonB genes even under iron-rich conditions.
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Affiliation(s)
- Hiroaki Naka
- Department of Medicinal Chemistry, The University of Utah, Salt Lake City, Utah, USA
- Division of Genetics, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, Oregon, USA
| | - Margo G. Haygood
- Department of Medicinal Chemistry, The University of Utah, Salt Lake City, Utah, USA
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5
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Will V, Gasser V, Kuhn L, Fritsch S, Heinrichs DE, Schalk IJ. Siderophore specificities of the Pseudomonas aeruginosa TonB-dependent transporters ChtA and ActA. FEBS Lett 2023; 597:2963-2974. [PMID: 37758521 DOI: 10.1002/1873-3468.14740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 09/12/2023] [Accepted: 09/13/2023] [Indexed: 09/29/2023]
Abstract
Iron is an essential nutrient for the survival and virulence of Pseudomonas aeruginosa. The pathogen expresses at least 15 different iron-uptake pathways, the majority involving small iron chelators called siderophores. P. aeruginosa produces two siderophores, but can also use many produced by other microorganisms. This implies that the bacterium expresses appropriate TonB-dependent transporters (TBDTs) at the outer membrane to import the ferric form of each of the siderophores used. Here, we show that the two α-carboxylate-type siderophores rhizoferrin-Fe and staphyloferrin A-Fe are transported into P. aeruginosa cells by the TBDT ActA. Among the mixed α-carboxylate/hydroxamate-type siderophores, we found aerobactin-Fe to be transported by ChtA and schizokinen-Fe and arthrobactin-Fe by ChtA and another unidentified TBDT. Our findings enhance the understanding of the adaptability of P. aeruginosa and hold significant implications for developing novel strategies to combat antibiotic resistance.
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Affiliation(s)
- Virginie Will
- CNRS, University of Strasbourg, UMR7242, ESBS, Strasbourg, France
- University of Strasbourg, UMR7242, ESBS, Strasbourg, France
| | - Véronique Gasser
- CNRS, University of Strasbourg, UMR7242, ESBS, Strasbourg, France
- University of Strasbourg, UMR7242, ESBS, Strasbourg, France
| | - Lauriane Kuhn
- Plateforme Proteomique Strasbourg - Esplanade, Institut de Biologie Moléculaire et Cellulaire, CNRS FR1589, Strasbourg Cedex, France
| | - Sarah Fritsch
- CNRS, University of Strasbourg, UMR7242, ESBS, Strasbourg, France
- University of Strasbourg, UMR7242, ESBS, Strasbourg, France
| | - David E Heinrichs
- Department of Microbiology and Immunology, University of Western Ontario, London, Canada
| | - Isabelle J Schalk
- CNRS, University of Strasbourg, UMR7242, ESBS, Strasbourg, France
- University of Strasbourg, UMR7242, ESBS, Strasbourg, France
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6
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Liu J, Zhao SY, Hu JY, Chen QX, Jiao SM, Xiao HC, Zhang Q, Xu J, Zhao JF, Zhou HB, Zheng JX, Sun PH. Novel Coumarin Derivatives Inhibit the Quorum Sensing System and Iron Homeostasis as Antibacterial Synergists against Pseudomonas aeruginosa. J Med Chem 2023; 66:14735-14754. [PMID: 37874867 DOI: 10.1021/acs.jmedchem.3c01268] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2023]
Abstract
Pseudomonas aeruginosa (P. aeruginosa) is well-known to cause biofilm-associated drug resistance and infections that often lead to treatment failure. Herein, we reported a dual-acting antibiofilm strategy by inhibiting both the bacterial quorum sensing system and the iron uptake system. A series of coumarin derivatives were synthesized and evaluated, and compound 4t was identified as the most effective biofilm inhibitor (IC50 = 3.6 μM). Further mechanistic studies have confirmed that 4t not only inhibits the QS systems but also competes strongly with pyoverdine as an iron chelator, causing an iron deficiency in P. aeruginosa. Additionally, 4t significantly improved the synergistic antibacterial effects of ciprofloxacin and tobramycin by more than 200-1000-fold compared to the single-dose antibiotic treatments. Therefore, our study has shown that 4t is a potentially novel antibacterial synergist candidate to treat bacterial infections.
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Affiliation(s)
- Jun Liu
- Department of Oncology, The First Affiliated Hospital of Jinan University, Guangzhou, Guangdong 510632, P. R. China
- College of Pharmacy, Jinan University, Guangzhou, Guangdong 510632, P. R. China
| | - Si-Yu Zhao
- College of Pharmacy, Jinan University, Guangzhou, Guangdong 510632, P. R. China
| | - Jia-Yi Hu
- College of Pharmacy, Jinan University, Guangzhou, Guangdong 510632, P. R. China
| | - Qiu-Xian Chen
- College of Pharmacy, Jinan University, Guangzhou, Guangdong 510632, P. R. China
| | - Shu-Meng Jiao
- College of Pharmacy, Jinan University, Guangzhou, Guangdong 510632, P. R. China
| | - Hai-Chuan Xiao
- College of Pharmacy, Jinan University, Guangzhou, Guangdong 510632, P. R. China
| | - Qiang Zhang
- College of Pharmacy, Jinan University, Guangzhou, Guangdong 510632, P. R. China
| | - Jun Xu
- College of Pharmacy, Jinan University, Guangzhou, Guangdong 510632, P. R. China
| | - Jian-Fu Zhao
- Department of Oncology, The First Affiliated Hospital of Jinan University, Guangzhou, Guangdong 510632, P. R. China
| | - Hai-Bo Zhou
- College of Pharmacy, Jinan University, Guangzhou, Guangdong 510632, P. R. China
| | - Jun-Xia Zheng
- School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou, Guangdong 510006, P. R. China
| | - Ping-Hua Sun
- Department of Oncology, The First Affiliated Hospital of Jinan University, Guangzhou, Guangdong 510632, P. R. China
- College of Pharmacy, Shihezi University, Shihezi, Xinjiang 832099, P. R. China
- College of Pharmacy, Jinan University, Guangzhou, Guangdong 510632, P. R. China
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7
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Ullah I, Lang M. Key players in the regulation of iron homeostasis at the host-pathogen interface. Front Immunol 2023; 14:1279826. [PMID: 37942316 PMCID: PMC10627961 DOI: 10.3389/fimmu.2023.1279826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 10/03/2023] [Indexed: 11/10/2023] Open
Abstract
Iron plays a crucial role in the biochemistry and development of nearly all living organisms. Iron starvation of pathogens during infection is a striking feature utilized by a host to quell infection. In mammals and some other animals, iron is essentially obtained from diet and recycled from erythrocytes. Free iron is cytotoxic and is readily available to invading pathogens. During infection, most pathogens utilize host iron for their survival. Therefore, to ensure limited free iron, the host's natural system denies this metal in a process termed nutritional immunity. In this fierce battle for iron, hosts win over some pathogens, but others have evolved mechanisms to overdrive the host barriers. Production of siderophores, heme iron thievery, and direct binding of transferrin and lactoferrin to bacterial receptors are some of the pathogens' successful strategies which are highlighted in this review. The intricate interplay between hosts and pathogens in iron alteration systems is crucial for understanding host defense mechanisms and pathogen virulence. This review aims to elucidate the current understanding of host and pathogen iron alteration systems and propose future research directions to enhance our knowledge in this field.
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Affiliation(s)
- Inam Ullah
- CAS Center for Excellence in Biotic Interactions, College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Minglin Lang
- CAS Center for Excellence in Biotic Interactions, College of Life Science, University of Chinese Academy of Sciences, Beijing, China
- College of Life Science, Agricultural University of Hebei, Baoding, China
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Puja H, Mislin GLA, Rigouin C. Engineering Siderophore Biosynthesis and Regulation Pathways to Increase Diversity and Availability. Biomolecules 2023; 13:959. [PMID: 37371539 PMCID: PMC10296737 DOI: 10.3390/biom13060959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 05/23/2023] [Accepted: 06/01/2023] [Indexed: 06/29/2023] Open
Abstract
Siderophores are small metal chelators synthesized by numerous organisms to access iron. These secondary metabolites are ubiquitously present on Earth, and because their production represents the main strategy to assimilate iron, they play an important role in both positive and negative interactions between organisms. In addition, siderophores are used in biotechnology for diverse applications in medicine, agriculture and the environment. The generation of non-natural siderophore analogs provides a new opportunity to create new-to-nature chelating biomolecules that can offer new properties to expand applications. This review summarizes the main strategies of combinatorial biosynthesis that have been used to generate siderophore analogs. We first provide a brief overview of siderophore biosynthesis, followed by a description of the strategies, namely, precursor-directed biosynthesis, the design of synthetic or heterologous pathways and enzyme engineering, used in siderophore biosynthetic pathways to create diversity. In addition, this review highlights the engineering strategies that have been used to improve the production of siderophores by cells to facilitate their downstream utilization.
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Affiliation(s)
- Hélène Puja
- CNRS-UMR7242, Biotechnologie et Signalisation Cellulaire, 300 Bld Sébastien Brant, 67412 Illkirch, France (G.L.A.M.)
- Institut de Recherche de l’Ecole de Biotechnologie de Strasbourg (IREBS), Université de Strasbourg, 300 Bld Sébastien Brant, 67412 Illkirch, France
| | - Gaëtan L. A. Mislin
- CNRS-UMR7242, Biotechnologie et Signalisation Cellulaire, 300 Bld Sébastien Brant, 67412 Illkirch, France (G.L.A.M.)
- Institut de Recherche de l’Ecole de Biotechnologie de Strasbourg (IREBS), Université de Strasbourg, 300 Bld Sébastien Brant, 67412 Illkirch, France
| | - Coraline Rigouin
- CNRS-UMR7242, Biotechnologie et Signalisation Cellulaire, 300 Bld Sébastien Brant, 67412 Illkirch, France (G.L.A.M.)
- Institut de Recherche de l’Ecole de Biotechnologie de Strasbourg (IREBS), Université de Strasbourg, 300 Bld Sébastien Brant, 67412 Illkirch, France
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9
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Naka H, Haygood MG. The dual role of TonB genes in turnerbactin uptake and carbohydrate utilization in the shipworm symbiont Teredinibacter turnerae. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.23.529781. [PMID: 36865190 PMCID: PMC9980095 DOI: 10.1101/2023.02.23.529781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Teredinibacter turnerae is an intracellular bacterial symbiont that resides in the gills of shipworms, wood-eating bivalve mollusks. This bacterium produces a catechol siderophore, turnerbactin, required for the survival of this bacterium under iron limiting conditions. The turnerbactin biosynthetic genes are contained in one of the secondary metabolite clusters conserved among T. turnerae strains. However, Fe(III)-turnerbactin uptake mechanisms are largely unknown. Here, we show that the first gene of the cluster, fttA a homologue of Fe(III)-siderophore TonB-dependent outer membrane receptor (TBDR) genes is indispensable for iron uptake via the endogenous siderophore, turnerbactin, as well as by an exogenous siderophore, amphi-enterobactin, ubiquitously produced by marine vibrios. Furthermore, three TonB clusters containing four tonB genes were identified, and two of these genes, tonB1b and tonB2, functioned not only for iron transport but also for carbohydrate utilization when cellulose was a sole carbon source. Gene expression analysis revealed that none of the tonB genes and other genes in those clusters were clearly regulated by iron concentration while turnerbactin biosynthesis and uptake genes were up-regulated under iron limiting conditions, highlighting the importance of tonB genes even in iron rich conditions, possibly for utilization of carbohydrates derived from cellulose.
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Affiliation(s)
- Hiroaki Naka
- Department of Medicinal Chemistry, the University of Utah
- Division of Genetics, Oregon National Primate Research Center, Oregon Health & Science University
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10
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Rejuvenating the Activity of Usual Antibiotics on Resistant Gram-Negative Bacteria: Recent Issues and Perspectives. Int J Mol Sci 2023; 24:ijms24021515. [PMID: 36675027 PMCID: PMC9864949 DOI: 10.3390/ijms24021515] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 01/05/2023] [Accepted: 01/09/2023] [Indexed: 01/13/2023] Open
Abstract
Antibiotic resistance continues to evolve and spread beyond all boundaries, resulting in an increase in morbidity and mortality for non-curable infectious diseases. Due to the failure of conventional antimicrobial therapy and the lack of introduction of a novel class of antibiotics, novel strategies have recently emerged to combat these multidrug-resistant infectious microorganisms. In this review, we highlight the development of effective antibiotic combinations and of antibiotics with non-antibiotic activity-enhancing compounds to address the widespread emergence of antibiotic-resistant strains.
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11
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Schalk IJ, Perraud Q. Pseudomonas aeruginosa and its multiple strategies to access iron. Environ Microbiol 2022; 25:811-831. [PMID: 36571575 DOI: 10.1111/1462-2920.16328] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 12/21/2022] [Indexed: 12/27/2022]
Abstract
Pseudomonas aeruginosa is a ubiquitous bacterium found in many natural and man-made environments. It is also a pathogen for plants, animals, and humans. As for almost all living organisms, iron is an essential nutrient for the growth of P. aeruginosa. The bacterium has evolved complex systems to access iron and maintain its homeostasis to survive in diverse natural and dynamic host environments. To access ferric iron, P. aeruginosa is able to produce two siderophores (pyoverdine and pyochelin), as well as use a variety of siderophores produced by other bacteria (mycobactins, enterobactin, ferrioxamine, ferrichrome, vibriobactin, aerobactin, rhizobactin and schizokinen). Furthermore, it can also use citrate, in addition to catecholamine neuromediators and plant-derived mono catechols, as siderophores. The P. aeruginosa genome also encodes three heme-uptake pathways (heme being an iron source) and one ferrous iron acquisition pathway. This review aims to summarize current knowledge concerning the molecular mechanisms involved in all the iron and heme acquisition strategies used by P. aeruginosa.
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Affiliation(s)
- Isabelle J Schalk
- CNRS, UMR7242, ESBS, Strasbourg, France.,University of Strasbourg, UMR7242, ESBS, Strasbourg, France
| | - Quentin Perraud
- CNRS, UMR7242, ESBS, Strasbourg, France.,University of Strasbourg, UMR7242, ESBS, Strasbourg, France
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12
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Iron acquisition strategies in pseudomonads: mechanisms, ecology, and evolution. Biometals 2022:10.1007/s10534-022-00480-8. [PMID: 36508064 PMCID: PMC10393863 DOI: 10.1007/s10534-022-00480-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 12/05/2022] [Indexed: 12/14/2022]
Abstract
AbstractIron is important for bacterial growth and survival, as it is a common co-factor in essential enzymes. Although iron is very abundant in the earth crust, its bioavailability is low in most habitats because ferric iron is largely insoluble under aerobic conditions and at neutral pH. Consequently, bacteria have evolved a plethora of mechanisms to solubilize and acquire iron from environmental and host stocks. In this review, I focus on Pseudomonas spp. and first present the main iron uptake mechanisms of this taxa, which involve the direct uptake of ferrous iron via importers, the production of iron-chelating siderophores, the exploitation of siderophores produced by other microbial species, and the use of iron-chelating compounds produced by plants and animals. In the second part of this review, I elaborate on how these mechanisms affect interactions between bacteria in microbial communities, and between bacteria and their hosts. This is important because Pseudomonas spp. live in diverse communities and certain iron-uptake strategies might have evolved not only to acquire this essential nutrient, but also to gain relative advantages over competitors in the race for iron. Thus, an integrative understanding of the mechanisms of iron acquisition and the eco-evolutionary dynamics they drive at the community level might prove most useful to understand why Pseudomonas spp., in particular, and many other bacterial species, in general, have evolved such diverse iron uptake repertoires.
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Plant-Derived Catechols Are Substrates of TonB-Dependent Transporters and Sensitize Pseudomonas aeruginosa to Siderophore-Drug Conjugates. mBio 2022; 13:e0149822. [PMID: 35770947 PMCID: PMC9426570 DOI: 10.1128/mbio.01498-22] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen responsible for acute and chronic infections in immunocompromised hosts. This organism is known to compete efficiently against coinfecting microorganisms, due in part to the secretion of antimicrobial molecules and the synthesis of siderophore molecules with high affinity for iron. P. aeruginosa possess a large repertoire of TonB-dependent transporters for the uptake of its own, as well as xenosiderophores released from other bacteria or fungi. Here, we show that P. aeruginosa is also capable of utilizing plant-derived polyphenols as an iron source. We found that exclusively plant-derived phenols containing a catechol group (i.e., chlorogenic acid, caffeic acid, quercetin, luteolin) induce the expression of the TonB-dependent transporters PiuA or PirA. This induction requires the two-component system PirR-PirS. Chlorogenic acid in its Fe(III)-loaded form was actively transported by PiuA and PirA and supported growth under iron-limiting conditions. Coincidentally, PiuA and PirA are also the main TonB transporters for the recently approved siderophore-drug conjugate cefiderocol. Surprisingly, quercetin supplementation increased the susceptibility of P. aeruginosa to siderophore-drug conjugates, due to induction of piuA and pirA expression mediated by the PirR-PirS two-component system. These findings suggest a potential novel therapeutic application for these biologically active dietary polyphenols.
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Fritsch S, Gasser V, Peukert C, Pinkert L, Kuhn L, Perraud Q, Normant V, Brönstrup M, Schalk IJ. Uptake Mechanisms and Regulatory Responses to MECAM- and DOTAM-Based Artificial Siderophores and Their Antibiotic Conjugates in Pseudomonas aeruginosa. ACS Infect Dis 2022; 8:1134-1146. [PMID: 35500104 DOI: 10.1021/acsinfecdis.2c00049] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The development of new antibiotics against Gram-negative bacteria has to deal with the low permeability of the outer membrane. This obstacle can be overcome by utilizing siderophore-dependent iron uptake pathways as entrance routes for antibiotic uptake. Iron-chelating siderophores are actively imported by bacteria, and their conjugation to antibiotics allows smuggling the latter into bacterial cells. Synthetic siderophore mimetics based on MECAM (1,3,5-N,N',N″-tris-(2,3-dihydroxybenzoyl)-triaminomethylbenzene) and DOTAM (1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane) cores, both chelating iron via catechol groups, have been recently applied as versatile carriers of functional cargo. In the present study, we show that MECAM and the MECAM-ampicillin conjugate 3 transport iron into Pseudomonas aeruginosa cells via the catechol-type outer membrane transporters PfeA and PirA and DOTAM solely via PirA. Differential proteomics and quantitative real-time polymerase chain reaction (qRT-PCR) showed that MECAM import induced the expression of pfeA, whereas 3 led to an increase in the expression of pfeA and ampc, a gene conferring ampicillin resistance. The presence of DOTAM did not induce the expression of pirA but upregulated the expression of two zinc transporters (cntO and PA0781), pointing out that bacteria become zinc starved in the presence of this compound. Iron uptake experiments with radioactive 55Fe demonstrated that import of this nutrient by MECAM and DOTAM was as efficient as with the natural siderophore enterobactin. The study provides a functional validation for DOTAM- and MECAM-based artificial siderophore mimetics as vehicles for the delivery of cargo into Gram-negative bacteria.
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Affiliation(s)
- Sarah Fritsch
- CNRS, University of Strasbourg, UMR7242, ESBS, Bld Sébastien Brant, F-67412 Illkirch, Strasbourg 67070, France
| | - Véronique Gasser
- CNRS, University of Strasbourg, UMR7242, ESBS, Bld Sébastien Brant, F-67412 Illkirch, Strasbourg 67070, France
| | - Carsten Peukert
- Department of Chemical Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, Braunschweig 38124, Germany
| | - Lukas Pinkert
- Department of Chemical Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, Braunschweig 38124, Germany
| | - Lauriane Kuhn
- Plateforme Proteomique Strasbourg-Esplanade, Institut de Biologie Moléculaire et Cellulaire, CNRS, FR1589, 15 rue Descartes, Strasbourg Cedex F-67084, France
| | - Quentin Perraud
- CNRS, University of Strasbourg, UMR7242, ESBS, Bld Sébastien Brant, F-67412 Illkirch, Strasbourg 67070, France
| | - Vincent Normant
- CNRS, University of Strasbourg, UMR7242, ESBS, Bld Sébastien Brant, F-67412 Illkirch, Strasbourg 67070, France
| | - Mark Brönstrup
- Department of Chemical Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, Braunschweig 38124, Germany
- German Center for Infection Research (DZIF), Site Hannover-Braunschweig, Braunschweig 38124, Germany
- Center of Biomolecular Drug Research (BMWZ), Leibniz Universität, Hannover 30159, Germany
| | - Isabelle J. Schalk
- CNRS, University of Strasbourg, UMR7242, ESBS, Bld Sébastien Brant, F-67412 Illkirch, Strasbourg 67070, France
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Liu L, Wang W, Wu S, Gao H. Recent Advances in the Siderophore Biology of Shewanella. Front Microbiol 2022; 13:823758. [PMID: 35250939 PMCID: PMC8891985 DOI: 10.3389/fmicb.2022.823758] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 01/12/2022] [Indexed: 11/17/2022] Open
Abstract
Despite the abundance of iron in nature, iron acquisition is a challenge for life in general because the element mostly exists in the extremely insoluble ferric (Fe3+) form in oxic environments. To overcome this, microbes have evolved multiple iron uptake strategies, a common one of which is through the secretion of siderophores, which are iron-chelating metabolites generated endogenously. Siderophore-mediated iron transport, a standby when default iron transport routes are abolished under iron rich conditions, is essential under iron starvation conditions. While there has been a wealth of knowledge about the molecular basis of siderophore synthesis, uptake and regulation in model bacteria, we still know surprisingly little about siderophore biology in diverse environmental microbes. Shewanella represent a group of γ-proteobacteria capable of respiring a variety of organic and inorganic substrates, including iron ores. This respiratory process relies on a large number of iron proteins, c-type cytochromes in particular. Thus, iron plays an essential and special role in physiology of Shewanella. In addition, these bacteria use a single siderophore biosynthetic system to produce an array of macrocyclic dihydroxamate siderophores, some of which show particular biological activities. In this review, we first outline current understanding of siderophore synthesis, uptake and regulation in model bacteria, and subsequently discuss the siderophore biology in Shewanella.
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Affiliation(s)
- Lulu Liu
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Wei Wang
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Shihua Wu
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Haichun Gao
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, China
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Normant V, Kuhn L, Munier M, Hammann P, Mislin GLA, Schalk IJ. How the Presence of Hemin Affects the Expression of the Different Iron Uptake Pathways in Pseudomonas aeruginosa Cells. ACS Infect Dis 2022; 8:183-196. [PMID: 34878758 DOI: 10.1021/acsinfecdis.1c00525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Iron is an essential nutriment for almost all organisms, but this metal is poorly bioavailable. During infection, bacteria access iron from the host by importing either iron or heme. Pseudomonas aeruginosa, a gram-negative pathogen, secretes two siderophores, pyoverdine (PVD) and pyochelin (PCH), to access iron and is also able to use many siderophores produced by other microorganisms (called xenosiderophores). To access heme, P. aeruginosa uses three distinct uptake pathways, named Has, Phu, and Hxu. We previously showed that P. aeruginosa expresses the Has and Phu heme uptake systems and the PVD- and PCH-dependent iron uptake pathways in iron-restricted growth conditions, using proteomic and RT-qPCR approaches. Here, using the same approaches, we show that physiological concentrations of hemin in the bacterial growth medium result in the repression of the expression of the proteins of the PVD- and PCH-dependent iron uptake pathways, leading to less production of these two siderophores. This indicates that the pathogen adapts its phenotype to use hemin as an iron source rather than produce PVD and PCH to access iron. Moreover, the presence of both hemin and a xenosiderophore resulted in (i) the strong induction of the expression of the proteins of the added xenosiderophore uptake pathway, (ii) repression of the PVD- and PCH-dependent iron uptake pathways, and (iii) no effect on the expression levels of the Has, Phu, or Hxu systems, indicating that bacteria use both xenosiderophores and heme to access iron.
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Affiliation(s)
- Vincent Normant
- CNRS/Université de Strasbourg, UMR7242, ESBS, Bld Sébastien Brant, Illkirch, F-67412 Strasbourg, France
| | - Lauriane Kuhn
- Plateforme Proteomique Strasbourg - Esplanade, Institut de Biologie Moléculaire et Cellulaire, CNRS, FR1589, 15 rue Descartes, F-67084 Strasbourg Cedex, France
| | - Mathilde Munier
- CNRS/Université de Strasbourg, UMR7242, ESBS, Bld Sébastien Brant, Illkirch, F-67412 Strasbourg, France
| | - Philippe Hammann
- Plateforme Proteomique Strasbourg - Esplanade, Institut de Biologie Moléculaire et Cellulaire, CNRS, FR1589, 15 rue Descartes, F-67084 Strasbourg Cedex, France
| | - Gaëtan L. A. Mislin
- CNRS/Université de Strasbourg, UMR7242, ESBS, Bld Sébastien Brant, Illkirch, F-67412 Strasbourg, France
| | - Isabelle J. Schalk
- CNRS/Université de Strasbourg, UMR7242, ESBS, Bld Sébastien Brant, Illkirch, F-67412 Strasbourg, France
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Iron Homeostasis in Pseudomonas aeruginosa: Targeting Iron Acquisition and Storage as an Antimicrobial Strategy. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1386:29-68. [DOI: 10.1007/978-3-031-08491-1_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Liu J, Hou JS, Chang YQ, Peng LJ, Zhang XY, Miao ZY, Sun PH, Lin J, Chen WM. New Pqs Quorum Sensing System Inhibitor as an Antibacterial Synergist against Multidrug-Resistant Pseudomonas aeruginosa. J Med Chem 2021; 65:688-709. [PMID: 34951310 DOI: 10.1021/acs.jmedchem.1c01781] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Development of new bacterial biofilm inhibitors as antibacterial synergists is an effective strategy to solve the resistance of Pseudomonas aeruginosa. In this paper, a series of 3-hydroxy-pyridin-4(1H)-ones were synthesized and evaluated, and the hit compound (20p) was identified with the effects of inhibiting the production of pyocyanin (IC50 = 8.6 μM) and biofilm formation (IC50 = 4.5 μM). Mechanistic studies confirmed that 20p inhibits the formation of bacterial biofilm by inhibiting the expression of pqsA, blocking pqs quorum sensing system quinolone biosynthesis. Moreover, we systematically investigated the bactericidal effects of combining currently approved antibiotics for CF including tobramycin, ciprofloxacin, and colistin E with 20p, which showed obvious antibacterial synergy to overcome antibiotics resistance in multidrug-resistant P. aeruginosa biofilms. The result indicates that compound 20p may be used in the future as a potentially novel antibacterial synergist candidate for the treatment of P. aeruginosa infections.
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Affiliation(s)
- Jun Liu
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Jin-Song Hou
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Yi-Qun Chang
- Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia
| | - Li-Jun Peng
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Xiao-Yi Zhang
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Zhi-Ying Miao
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Ping-Hua Sun
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Jing Lin
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Wei-Min Chen
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
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Tirry N, Kouchou A, El Omari B, Ferioun M, El Ghachtouli N. Improved chromium tolerance of Medicago sativa by plant growth-promoting rhizobacteria (PGPR). J Genet Eng Biotechnol 2021; 19:149. [PMID: 34613510 PMCID: PMC8494867 DOI: 10.1186/s43141-021-00254-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 09/25/2021] [Indexed: 12/15/2022]
Abstract
Background Soil pollution by heavy metals increases the bioavailability of metals like hexavalent chromium (Cr (VI)), subsequently limiting plant growth and reducing the efficiency of phytoremediation. Plant growth-promoting rhizobacteria (PGPR) have substantial potential to enhance plant growth as well as plant tolerance to metal stress. The aim of this research was to investigate Cr (VI) phytoremediation enhancement by PGPR. Results The results showed that the 27 rhizobacterial isolates studied were confirmed as Cr (VI)-resistant PGPR, by using classical biochemical tests (phosphate solubilization, nitrogen fixation, indole acetic acid, exopolysaccharides, hydrogen cyanide, siderophores, ammonia, cellulase, pectinase, and chitinase production) and showed variable levels of Cr (VI) resistance (300–600 mg/L). The best four selected Cr (VI)-resistant PGPR (NT15, NT19, NT20, and NT27) retained most of the PGP traits in the presence of 100–200 mg/L concentrations of Cr (VI). The inoculation of Medicago sativa with any of these four isolates improved the shoot and root dry weight. The NT27 isolate identified using 16S rDNA gene sequence analyses as a strain of Pseudomonas sp. was most effective in terms of plant growth promotion and stress level decrease. It increased shoot and root dry weights of M. sativa by 97.6 and 95.4%, respectively, in the presence of Cr (VI) when compared to non-inoculated control plants. It also greatly increased chlorophyll content and decreased the levels of stress markers, malondialdehyde, hydrogen peroxide, and proline. The results of the effect of Pseudomonas sp. on Cr content and bioaccumulation factor (BAF) of the shoots and roots of M. sativa plants showed the increase of plant biomass concomitantly with the increase of Cr root concentration in inoculated plants. This would lead to a higher potential of Cr (VI) phytostabilization. Conclusions This study demonstrates that the association M. sativa-Pseudomonas sp. may be an efficient biological system for the bioremediation of Cr (VI)-contaminated soils.
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Affiliation(s)
- Nabil Tirry
- Microbial Biotechnology and Bioactive Molecules Laboratory, Sciences and Technology Faculty, Sidi Mohamed Ben Abdellah University, Fes, Morocco
| | - Aziza Kouchou
- Microbial Biotechnology and Bioactive Molecules Laboratory, Sciences and Technology Faculty, Sidi Mohamed Ben Abdellah University, Fes, Morocco
| | - Bouchra El Omari
- Microbial Biotechnology and Bioactive Molecules Laboratory, Sciences and Technology Faculty, Sidi Mohamed Ben Abdellah University, Fes, Morocco
| | - Mohamed Ferioun
- Microbial Biotechnology and Bioactive Molecules Laboratory, Sciences and Technology Faculty, Sidi Mohamed Ben Abdellah University, Fes, Morocco
| | - Naïma El Ghachtouli
- Microbial Biotechnology and Bioactive Molecules Laboratory, Sciences and Technology Faculty, Sidi Mohamed Ben Abdellah University, Fes, Morocco.
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The Biology of Colicin M and Its Orthologs. Antibiotics (Basel) 2021; 10:antibiotics10091109. [PMID: 34572691 PMCID: PMC8469651 DOI: 10.3390/antibiotics10091109] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 09/06/2021] [Accepted: 09/09/2021] [Indexed: 12/24/2022] Open
Abstract
The misuse of antibiotics during the last decades led to the emergence of multidrug resistant pathogenic bacteria. This phenomenon constitutes a major public health issue. Consequently, the discovery of new antibacterials in the short term is crucial. Colicins, due to their antibacterial properties, thus constitute good candidates. These toxin proteins, produced by E. coli to kill enteric relative competitors, exhibit cytotoxicity through ionophoric activity or essential macromolecule degradation. Among the 25 colicin types known to date, colicin M (ColM) is the only one colicin interfering with peptidoglycan biosynthesis. Accordingly, ColM develops its lethal activity in E. coli periplasm by hydrolyzing the last peptidoglycan precursor, lipid II, into two dead-end products, thereby leading to cell lysis. Since the discovery of its unusual mode of action, several ColM orthologs have also been identified based on sequence alignments; all of the characterized ColM-like proteins display the same enzymatic activity of lipid II degradation and narrow antibacterial spectra. This publication aims at being an exhaustive review of the current knowledge on this new family of antibacterial enzymes as well as on their potential use as food preservatives or therapeutic agents.
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21
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Structural insights into a novel family of integral membrane siderophore reductases. Proc Natl Acad Sci U S A 2021; 118:2101952118. [PMID: 34417315 DOI: 10.1073/pnas.2101952118] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Gram-negative bacteria take up the essential ion Fe3+ as ferric-siderophore complexes through their outer membrane using TonB-dependent transporters. However, the subsequent route through the inner membrane differs across many bacterial species and siderophore chemistries and is not understood in detail. Here, we report the crystal structure of the inner membrane protein FoxB (from Pseudomonas aeruginosa) that is involved in Fe-siderophore uptake. The structure revealed a fold with two tightly bound heme molecules. In combination with in vitro reduction assays and in vivo iron uptake studies, these results establish FoxB as an inner membrane reductase involved in the release of iron from ferrioxamine during Fe-siderophore uptake.
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Duncan TR, Werner-Washburne M, Northup DE. DIVERSITY OF SIDEROPHORE-PRODUCING BACTERIAL CULTURES FROM CARLSBAD CAVERNS NATIONAL PARK (CCNP) CAVES, CARLSBAD, NEW MEXICO. JOURNAL OF CAVE AND KARST STUDIES : THE NATIONAL SPELEOLOGICAL SOCIETY BULLETIN 2021; 83:29-43. [PMID: 34556971 PMCID: PMC8455092 DOI: 10.4311/2019es0118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Siderophores are microbially-produced ferric iron chelators. They are essential for microbial survival, but their presence and function for cave microorganisms have not been extensively studied. Cave environments are nutrient-limited and previous evidence suggests siderophore usage in carbonate caves. We hypothesize that siderophores are likely used as a mechanism in caves to obtain critical nutrients such as iron. Cave bacteria were collected from Long-term parent cultures (LT PC) or Short-term parent cultures (ST PC) inoculated with ferromanganese deposits (FMD) and carbonate secondary minerals from Lechuguilla and Spider caves in Carlsbad Caverns National Park (CCNP), NM. LT PC were incubated for 10-11 years to identify potential chemolithoheterotrophic cultures able to survive in nutrient-limited conditions. ST PC were incubated for 1-3 days to identify a broader diversity of cave isolates. A total of 170 LT and ST cultures,18 pure and 152 mixed, were collected and used to classify siderophore production and type and to identify siderophore producers. Siderophore production was slow to develop (>10 days) in LT cultures with a greater number of weak siderophore producers in comparison to the ST cultures that produced siderophores in <10 days, with a majority of strong siderophore producers. Overall, 64% of the total cultures were siderophore producers, which the majority preferred hydroxamate siderophores. Siderophore producers were classified into Proteobacteria (Alpha-, Beta-, or Gamma-), Actinobacteria, Bacteroidetes, and Firmicutes phyla using 16S rRNA gene sequencing. Our study supports our hypothesis that cave bacteria have the capability to produce siderophores in the subsurface to obtain critical ferric iron.
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Roche B, Mislin GLA, Schalk IJ. Identification of the fatty acid coenzyme-A ligase FadD1 as an interacting partner of FptX in the Pseudomonas aeruginosa pyochelin pathway. FEBS Lett 2020; 595:370-378. [PMID: 33289089 DOI: 10.1002/1873-3468.14012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 11/23/2020] [Accepted: 11/25/2020] [Indexed: 01/06/2023]
Abstract
Pseudomonas aeruginosa is one of the most important nosocomial bacteria emerging as a highly multidrug-resistant pathogen. P. aeruginosa produces two siderophores including pyochelin (PCH) to fulfil its need for iron during infections. We know that both outer and inner membrane proteins FptA and FptX are involved in the ferri-PCH uptake, but this process requires increasing molecular and biochemical knowledge. Here, using bacterial two-hybrid and copurification assays we identified the fatty acid coenzyme-A ligase FadD1 as a novel interacting partner of the inner membrane transporter FptX and found that FadD1 may play a role in PCH production. We managed to purify the FadD1-FptX inner membrane complex and obtained low-resolution 3D models, opening the way for future high-resolution structures.
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Affiliation(s)
- Béatrice Roche
- UMR7242, ESBS, CNRS, Illkirch, France.,UMR7242, ESBS, Université de Strasbourg, Illkirch, France
| | - Gaëtan L A Mislin
- UMR7242, ESBS, CNRS, Illkirch, France.,UMR7242, ESBS, Université de Strasbourg, Illkirch, France
| | - Isabelle J Schalk
- UMR7242, ESBS, CNRS, Illkirch, France.,UMR7242, ESBS, Université de Strasbourg, Illkirch, France
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Southwell JW, Black CM, Duhme-Klair AK. Experimental Methods for Evaluating the Bacterial Uptake of Trojan Horse Antibacterials. ChemMedChem 2020; 16:1063-1076. [PMID: 33238066 DOI: 10.1002/cmdc.202000806] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Indexed: 01/10/2023]
Abstract
The field of antibacterial siderophore conjugates, referred to as Trojan Horse antibacterials, has received increasing attention in recent years, driven by the rise of antimicrobial resistance. Trojan Horse antibacterials offer an opportunity to exploit the specific pathways present in bacteria for active iron uptake, potentially allowing the drugs to bypass membrane-associated resistance mechanisms. Hence, the Trojan Horse approach might enable the redesigning of old antibiotics and the development of antibacterials that target specific pathogens. Critical parts of evaluating such Trojan Horse antibacterials and improving their design are the quantification of their bacterial uptake and the identification of the pathways by which this occurs. In this minireview, we highlight a selection of the biological and chemical methods used to study the uptake of Trojan Horse antibacterials, exemplified with case studies, some of which have led to drug candidates in clinical development or approved antibiotics.
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Affiliation(s)
- James W Southwell
- Department of Chemistry, University of York, Heslington, North Yorkshire, YO10 5DD, UK
| | - Conor M Black
- Department of Chemistry, University of York, Heslington, North Yorkshire, YO10 5DD, UK
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Hydroxamate siderophores: Natural occurrence, chemical synthesis, iron binding affinity and use as Trojan horses against pathogens. Eur J Med Chem 2020; 208:112791. [DOI: 10.1016/j.ejmech.2020.112791] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Revised: 08/23/2020] [Accepted: 08/24/2020] [Indexed: 12/11/2022]
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Phenotypic Adaptation of Pseudomonas aeruginosa in the Presence of Siderophore-Antibiotic Conjugates during Epithelial Cell Infection. Microorganisms 2020; 8:microorganisms8111820. [PMID: 33218210 PMCID: PMC7699141 DOI: 10.3390/microorganisms8111820] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 11/12/2020] [Accepted: 11/15/2020] [Indexed: 12/14/2022] Open
Abstract
Iron acquisition pathways have often been considered to be gateways for the uptake of antibiotics into bacteria. Bacteria excrete chelators, called siderophores, to access iron. Antibiotic molecules can be covalently attached to siderophores for their transport into pathogens during the iron-uptake process. P. aeruginosa produces two siderophores and is also able to use many siderophores produced by other bacteria. We investigated the phenotypic plasticity of iron-uptake pathway expression in an epithelial cell infection assay in the presence of two different siderophore-antibiotic conjugates, one with a hydroxamate siderophore and the second with a tris-catechol. Proteomic and RT-qPCR approaches showed that P. aeruginosa was able to sense the presence of both compounds in its environment and adapt the expression of its iron uptake pathways to access iron via them. Moreover, the catechol-type siderophore-antibiotic was clearly more efficient in inducing the expression of its corresponding transporter than the hydroxamate compound when both were simultaneously present. In parallel, the expression of the proteins of the two iron uptake pathways using siderophores produced by P. aeruginosa was significantly repressed in the presence of both conjugates. Altogether, the data indicate that catechol-type siderophores are more promising vectors for antibiotic vectorization using a Trojan-horse strategy.
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Normant V, Josts I, Kuhn L, Perraud Q, Fritsch S, Hammann P, Mislin GLA, Tidow H, Schalk IJ. Nocardamine-Dependent Iron Uptake in Pseudomonas aeruginosa: Exclusive Involvement of the FoxA Outer Membrane Transporter. ACS Chem Biol 2020; 15:2741-2751. [PMID: 32902248 DOI: 10.1021/acschembio.0c00535] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Iron is a key nutrient for almost all living organisms. Paradoxically, it is poorly soluble and consequently poorly bioavailable. Bacteria have thus developed multiple strategies to access this metal. One of the most common consists of the use of siderophores, small compounds that chelate ferric iron with very high affinity. Many bacteria are able to produce their own siderophores or use those produced by other microorganisms (exosiderophores) in a piracy strategy. Pseudomonas aeruginosa produces two siderophores, pyoverdine and pyochelin, and is also able to use a large panel of exosiderophores. We investigated the ability of P. aeruginosa to use nocardamine (NOCA) and ferrioxamine B (DFOB) as exosiderophores under iron-limited planktonic growth conditions. Proteomic and RT-qPCR approaches showed induction of the transcription and expression of the outer membrane transporter FoxA in the presence of NOCA or DFOB in the bacterial environment. Expression of the proteins of the heme- or pyoverdine- and pyochelin-dependent iron uptake pathways was not affected by the presence of these two tris-hydroxamate siderophores. 55Fe uptake assays using foxA mutants showed ferri-NOCA to be exclusively transported by FoxA, whereas ferri-DFOB was transported by FoxA and at least one other unidentified transporter. The crystal structure of FoxA complexed with NOCA-Fe revealed very similar siderophore binding sites between NOCA-Fe and DFOB-Fe. We discuss iron uptake by hydroxamate exosiderophores in P. aeruginosa cells in light of these results.
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Affiliation(s)
- Vincent Normant
- CNRS, UMR7242, ESBS, Université de Strasbourg, Bld Sébastien Brant, F-67412 Illkirch, France
| | - Inokentijs Josts
- The Hamburg Centre for Ultrafast Imaging, University of Hamburg, Hamburg, Germany
- Department of Chemistry, Institute for Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany
| | - Lauriane Kuhn
- Plateforme Proteomique Strasbourg - Esplanade, Institut de Biologie Moléculaire et Cellulaire, CNRS, FR1589, 15 rue Descartes, F-67084 Strasbourg Cedex, France
| | - Quentin Perraud
- CNRS, UMR7242, ESBS, Université de Strasbourg, Bld Sébastien Brant, F-67412 Illkirch, France
| | - Sarah Fritsch
- CNRS, UMR7242, ESBS, Université de Strasbourg, Bld Sébastien Brant, F-67412 Illkirch, France
| | - Philippe Hammann
- Plateforme Proteomique Strasbourg - Esplanade, Institut de Biologie Moléculaire et Cellulaire, CNRS, FR1589, 15 rue Descartes, F-67084 Strasbourg Cedex, France
| | - Gaëtan L. A. Mislin
- CNRS, UMR7242, ESBS, Université de Strasbourg, Bld Sébastien Brant, F-67412 Illkirch, France
| | - Henning Tidow
- The Hamburg Centre for Ultrafast Imaging, University of Hamburg, Hamburg, Germany
- Department of Chemistry, Institute for Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany
| | - Isabelle J. Schalk
- CNRS, UMR7242, ESBS, Université de Strasbourg, Bld Sébastien Brant, F-67412 Illkirch, France
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28
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Liu J, Hou JS, Li YB, Miao ZY, Sun PH, Lin J, Chen WM. Novel 2-Substituted 3-Hydroxy-1,6-dimethylpyridin-4(1H)-ones as Dual-Acting Biofilm Inhibitors of Pseudomonas aeruginosa. J Med Chem 2020; 63:10921-10945. [DOI: 10.1021/acs.jmedchem.0c00763] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Jun Liu
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Jin-Song Hou
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Yi-Bin Li
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Zhi-Ying Miao
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Ping-Hua Sun
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Jing Lin
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Wei-Min Chen
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
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Transcriptomic Study of Substrate-Specific Transport Mechanisms for Iron and Carbon in the Marine Copiotroph Alteromonas macleodii. mSystems 2020; 5:5/2/e00070-20. [PMID: 32345736 PMCID: PMC7190382 DOI: 10.1128/msystems.00070-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
As the major facilitators of the turnover of organic matter in the marine environment, the ability of heterotrophic bacteria to acquire specific compounds within the diverse range of dissolved organic matter will affect the regeneration of essential nutrients such as iron and carbon. TonB-dependent transporters are a prevalent cellular tool in Gram-negative bacteria that allow a relatively high-molecular-weight fraction of organic matter to be directly accessed. However, these transporters are not well characterized in marine bacteria, limiting our understanding of the flow of specific substrates through the marine microbial loop. Here, we characterize the TonB-dependent transporters responsible for iron and carbon acquisition in a representative marine copiotroph and examine their distribution across the genus Alteromonas. We provide evidence that substrate-specific bioavailability is niche specific, particularly for iron complexes, indicating that transport capacity may serve as a significant control on microbial community dynamics and the resultant cycling of organic matter. Iron is an essential micronutrient for all microbial growth in the marine environment, and in heterotrophic bacteria, iron is tightly linked to carbon metabolism due to its central role as a cofactor in enzymes of the respiratory chain. Here, we present the iron- and carbon-regulated transcriptomes of a representative marine copiotroph, Alteromonas macleodii ATCC 27126, and characterize its cellular transport mechanisms. ATCC 27126 has distinct metabolic responses to iron and carbon limitation and, accordingly, uses distinct sets of TonB-dependent transporters for the acquisition of iron and carbon. These distinct sets of TonB-dependent transporters were of a similar number, indicating that the diversity of carbon and iron substrates available to ATCC 27126 is of a similar scale. For the first time in a marine bacterium, we have also identified six characteristic inner membrane permeases for the transport of siderophores via an ATPase-independent mechanism. An examination of the distribution of specific TonB-dependent transporters in 31 genomes across the genus Alteromonas points to niche specialization in transport capacity, particularly for iron. We conclude that the substrate-specific bioavailability of both iron and carbon in the marine environment will likely be a key control on the processing of organic matter through the microbial loop. IMPORTANCE As the major facilitators of the turnover of organic matter in the marine environment, the ability of heterotrophic bacteria to acquire specific compounds within the diverse range of dissolved organic matter will affect the regeneration of essential nutrients such as iron and carbon. TonB-dependent transporters are a prevalent cellular tool in Gram-negative bacteria that allow a relatively high-molecular-weight fraction of organic matter to be directly accessed. However, these transporters are not well characterized in marine bacteria, limiting our understanding of the flow of specific substrates through the marine microbial loop. Here, we characterize the TonB-dependent transporters responsible for iron and carbon acquisition in a representative marine copiotroph and examine their distribution across the genus Alteromonas. We provide evidence that substrate-specific bioavailability is niche specific, particularly for iron complexes, indicating that transport capacity may serve as a significant control on microbial community dynamics and the resultant cycling of organic matter.
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30
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Perraud Q, Cantero P, Roche B, Gasser V, Normant VP, Kuhn L, Hammann P, Mislin GLA, Ehret-Sabatier L, Schalk IJ. Phenotypic Adaption of Pseudomonas aeruginosa by Hacking Siderophores Produced by Other Microorganisms. Mol Cell Proteomics 2020; 19:589-607. [PMID: 32024770 PMCID: PMC7124469 DOI: 10.1074/mcp.ra119.001829] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 12/23/2019] [Indexed: 12/31/2022] Open
Abstract
Bacteria secrete siderophores to access iron, a key nutrient poorly bioavailable and the source of strong competition between microorganisms in most biotopes. Many bacteria also use siderophores produced by other microorganisms (exosiderophores) in a piracy strategy. Pseudomonas aeruginosa, an opportunistic pathogen, produces two siderophores, pyoverdine and pyochelin, and is also able to use a panel of exosiderophores. We first investigated expression of the various iron-uptake pathways of P. aeruginosa in three different growth media using proteomic and RT-qPCR approaches and observed three different phenotypic patterns, indicating complex phenotypic plasticity in the expression of the various iron-uptake pathways. We then investigated the phenotypic plasticity of iron-uptake pathway expression in the presence of various exosiderophores (present individually or as a mixture) under planktonic growth conditions, as well as in an epithelial cell infection assay. In all growth conditions tested, catechol-type exosiderophores were clearly more efficient in inducing the expression of their corresponding transporters than the others, showing that bacteria opt for the use of catechol siderophores to access iron when they are present in the environment. In parallel, expression of the proteins of the pyochelin pathway was significantly repressed under most conditions tested, as well as that of proteins of the pyoverdine pathway, but to a lesser extent. There was no effect on the expression of the heme and ferrous uptake pathways. Overall, these data provide precise insights on how P. aeruginosa adjusts the expression of its various iron-uptake pathways (phenotypic plasticity and switching) to match varying levels of iron and competition.
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Affiliation(s)
- Quentin Perraud
- Université de Strasbourg, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France; CNRS, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France
| | - Paola Cantero
- Laboratoire de Spectrométrie de Masse BioOrganique, Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France
| | - Béatrice Roche
- Université de Strasbourg, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France; CNRS, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France
| | - Véronique Gasser
- Université de Strasbourg, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France; CNRS, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France
| | - Vincent P Normant
- Université de Strasbourg, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France; CNRS, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France
| | - Lauriane Kuhn
- Plateforme Proteomique Strasbourg - Esplanade, Institut de Biologie Moléculaire et Cellulaire, CNRS, FR1589, 15 rue Descartes, F-67084 Strasbourg Cedex, France
| | - Philippe Hammann
- Plateforme Proteomique Strasbourg - Esplanade, Institut de Biologie Moléculaire et Cellulaire, CNRS, FR1589, 15 rue Descartes, F-67084 Strasbourg Cedex, France
| | - Gaëtan L A Mislin
- Université de Strasbourg, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France; CNRS, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France
| | - Laurence Ehret-Sabatier
- Laboratoire de Spectrométrie de Masse BioOrganique, Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France
| | - Isabelle J Schalk
- Université de Strasbourg, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France; CNRS, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France.
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31
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Kuo TH, Yang CT, Chang HY, Hsueh YP, Hsu CC. Nematode-Trapping Fungi Produce Diverse Metabolites during Predator-Prey Interaction. Metabolites 2020; 10:metabo10030117. [PMID: 32245081 PMCID: PMC7143726 DOI: 10.3390/metabo10030117] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 03/12/2020] [Accepted: 03/16/2020] [Indexed: 12/21/2022] Open
Abstract
Nematode-trapping fungi are natural antagonists of nematodes. These predatory fungi are capable of switching their lifestyle from a saprophytic to predatory stage in the presence of nematodes by developing specialized trapping devices to capture and consume nematodes. The biochemical mechanisms of such predator–prey interaction have become increasingly studied given the potential application of nematode-trapping fungi as biocontrol agents, but the involved fungal metabolites remain underexplored. Here, we report a comprehensive liquid–chromatography mass spectrometry (LC–MS) metabolomics study on one hundred wild isolates of nematode-trapping fungi in three different species, Arthrobotrysoligospora, Arthrobotrys thaumasia, and Arthrobotrys musiformis. Molecular networking analysis revealed that the fungi were capable of producing thousands of metabolites, and such chemical diversity of metabolites was notably increased as the fungi switched lifestyle to the predatory stage. Structural annotations by tandem mass spectrometry revealed that those fungal metabolites belonged to various structural families, such as peptide, siderophore, fatty alcohol, and fatty acid amide, and their production exhibited species specificity. Several small peptides (<1.5 kDa) produced by A.musiformis in the predatory stage were found, with their partial amino acid sequences resolved by the tandem mass spectra. Four fungal metabolites (desferriferrichrome, linoleyl alcohol, nonadecanamide, and citicoline) that were significantly enriched in the predatory stage were identified and validated by chemical standards, and their bioactivities against nematode prey were assessed. The availability of the metabolomics datasets will facilitate comparative studies on the metabolites of nematode-trapping fungi in the future.
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Affiliation(s)
- Ting-Hao Kuo
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Ching-Ting Yang
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Hsin-Yuan Chang
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Yen-Ping Hsueh
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
- Correspondence: (Y.-P.H.); (C.-C.H.)
| | - Cheng-Chih Hsu
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
- Correspondence: (Y.-P.H.); (C.-C.H.)
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32
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Thissera B, Alhadrami HA, Hassan MHA, Hassan HM, Behery FA, Bawazeer M, Yaseen M, Belbahri L, Rateb ME. Induction of Cryptic Antifungal Pulicatin Derivatives from Pantoea agglomerans by Microbial Co-Culture. Biomolecules 2020; 10:E268. [PMID: 32050703 PMCID: PMC7072716 DOI: 10.3390/biom10020268] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Revised: 02/03/2020] [Accepted: 02/06/2020] [Indexed: 02/06/2023] Open
Abstract
Microbial co-culture or mixed fermentation proved to be an efficient strategy to expand chemical diversity by the induction of cryptic biosynthetic pathways, and in many cases led to the production of new antimicrobial agents. In the current study, we report a rare example of the induction of silent/cryptic bacterial biosynthetic pathway by the co-culture of Durum wheat plant roots-associated bacterium Pantoea aggolomerans and date palm leaves-derived fungus Penicillium citrinum. The initial co-culture indicated a clear fungal growth inhibition which was confirmed by the promising antifungal activity of the co-culture total extract against Pc. LC-HRMS chemical profiling demonstrated a huge suppression in the production of secondary metabolites (SMs) of axenic cultures of both species with the emergence of new metabolites which were dereplicated as a series of siderophores. Large-scale co-culture fermentation led to the isolation of two new pulicatin derivatives together with six known metabolites which were characterised using HRESIMS and NMR analyses. During the in vitro antimicrobial evaluation of the isolated compounds, pulicatin H (2) exhibited the strongest antifungal activity against Pc, followed by aeruginaldehyde (1) and pulicatin F (4), hence explaining the initial growth suppression of Pc in the co-culture environment.
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Affiliation(s)
- Bathini Thissera
- School of Computing, Engineering & Physical Sciences, University of the West of Scotland, Paisley PA1 2BE, UK; (B.T.); (M.B.); (M.Y.)
| | - Hani A. Alhadrami
- Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia
- King Fahd Medical Research Centre, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Marwa H. A. Hassan
- Department of Pharmacognosy, Faculty of Pharmacy, Beni-Suef University, Beni-Suef 62514, Egypt; (M.H.A.H.); (H.M.H.)
| | - Hossam M. Hassan
- Department of Pharmacognosy, Faculty of Pharmacy, Beni-Suef University, Beni-Suef 62514, Egypt; (M.H.A.H.); (H.M.H.)
| | - Fathy A. Behery
- Department of Pharmacognosy, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt;
- Department of Pharmacy, College of Pharmacy, Riyadh Elm University, Riyadh 11681, Saudi Arabia
| | - Majed Bawazeer
- School of Computing, Engineering & Physical Sciences, University of the West of Scotland, Paisley PA1 2BE, UK; (B.T.); (M.B.); (M.Y.)
| | - Mohammed Yaseen
- School of Computing, Engineering & Physical Sciences, University of the West of Scotland, Paisley PA1 2BE, UK; (B.T.); (M.B.); (M.Y.)
| | - Lassaad Belbahri
- Laboratory of Soil Biology, University of Neuchatel, 2000 Neuchatel, Switzerland;
| | - Mostafa E. Rateb
- School of Computing, Engineering & Physical Sciences, University of the West of Scotland, Paisley PA1 2BE, UK; (B.T.); (M.B.); (M.Y.)
- Department of Pharmacognosy, Faculty of Pharmacy, Beni-Suef University, Beni-Suef 62514, Egypt; (M.H.A.H.); (H.M.H.)
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33
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Pandey A, Savino C, Ahn SH, Yang Z, Van Lanen SG, Boros E. Theranostic Gallium Siderophore Ciprofloxacin Conjugate with Broad Spectrum Antibiotic Potency. J Med Chem 2019; 62:9947-9960. [PMID: 31580658 DOI: 10.1021/acs.jmedchem.9b01388] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Pathogenic bacteria scavenge ferric iron from the host for survival and proliferation using small-molecular chelators, siderophores. Here, we introduce and assess the gallium(III) complex of ciprofloxacin-functionalized desferrichrome (D2) as a potential therapeutic for bacterial infection using an in vitro assay and radiochemical, tracer-based approach. Ga-D2 exhibits a minimum inhibitory concentration of 0.23 μM in Escherichia coli, in line with the parent fluoroquinolone antibiotic. Competitive and mutant strain assays show that Ga-D2 relies on FhuA-mediated transport for internalization. Ga-D2 is potent against Pseudomonas aeruginosa (3.8 μM), Staphylococcus aureus (0.94 μM), and Klebsiella pneumoniae (12.5 μM), while Fe-D2 is inactive in these strains. Radiochemical experiments with E. coli reveal that 67Ga-D2 is taken up more efficiently than 67Ga-citrate. In naive mice, 67Ga-D2 clears renally and is excreted 13% intact in the urine. These pharmacokinetic and bacterial growth inhibitory properties qualify Ga-D2 for future investigations as a diagnosis and treatment tool for infection.
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Affiliation(s)
- Apurva Pandey
- Department of Chemistry , Stony Brook University , 100 Nicolls Road , Stony Brook 11790 , New York , United States
| | - Chloé Savino
- Department of Chemistry , Stony Brook University , 100 Nicolls Road , Stony Brook 11790 , New York , United States
| | - Shin Hye Ahn
- Department of Chemistry , Stony Brook University , 100 Nicolls Road , Stony Brook 11790 , New York , United States
| | - Zhaoyong Yang
- Institute of Medicinal Biotechnology , Chinese Academy of Medical Sciences and Peking Union Medical College , Beijing 100050 , People's Republic of China
| | - Steven G Van Lanen
- Department of Pharmaceutical Sciences, College of Pharmacy , University of Kentucky , Lexington 40536 , Kentucky , United States
| | - Eszter Boros
- Department of Chemistry , Stony Brook University , 100 Nicolls Road , Stony Brook 11790 , New York , United States
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34
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Lewis RW, Islam A, Opdahl L, Davenport JR, Sullivan TS. Comparative Genomics, Siderophore Production, and Iron Scavenging Potential of Root Zone Soil Bacteria Isolated from 'Concord' Grape Vineyards. MICROBIAL ECOLOGY 2019; 78:699-713. [PMID: 30770943 DOI: 10.1007/s00248-019-01324-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 01/10/2019] [Indexed: 06/09/2023]
Abstract
Iron (Fe) deficiency in crop production is a worldwide problem which often results in chlorosis in grapevines, particularly in calcareous soils. Siderophores secreted by microorganisms and Strategy II plants can chelate Fe and other metals in soil solution, and siderophore-Fe complexes can then be utilized by plants and microbes. Plants may also shift rhizosphere conditions to favor siderophore-producing microbes, which can increase plant available Fe. Between-row cover crops (barley, rye, wheat, wheat/vetch) were planted as living mulch to address grapevine chlorosis by enhancing soil health in two vineyards in central Washington. The objectives of the current study were to (1) enrich for siderophore-producing organisms from within the indigenous rooting zone community of 'Concord' grapevines, and (2) perform comparative genomics on putative siderophore producing organisms to assess potentially important Fe acquisition-related functional domains and protein families. A high-throughput, chrome azurol S (CAS)-based enrichment assay was used to select siderophore-producing microbes from 'Concord' grapevine root zone soil. Next-generation whole genome sequencing allowed the assembly and annotation of ten full genomes. Phylogenetic analysis revealed two distinct clades among the genomes using the 40 nearest neighbors available in the public database, all of which were of the Pseudomonas genus. Significant differences in functional domain abundances were observed between the clades including iron acquisition and metabolism of amino acids, carbon, nitrogen, phosphate, and sulfur. Diverse mechanisms of Fe uptake and siderophore production/uptake were identified in the protein families of the genomes. The sequenced organisms are likely pseudomonads which are well-suited for iron scavenging, suggesting a potential role in Fe turnover in vineyard systems.
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Affiliation(s)
- Ricky W Lewis
- Department of Crop and Soil Sciences, Washington State University, PO Box 646420, Pullman, WA, USA
| | - Anjuman Islam
- Department of Crop and Soil Sciences, Washington State University, PO Box 646420, Pullman, WA, USA
| | - Lee Opdahl
- Department of Crop and Soil Sciences, Washington State University, PO Box 646420, Pullman, WA, USA
| | - Joan R Davenport
- Irrigated Agriculture Research and Extension Center, Washington State University, 24106 N. Bunn Road, Prosser, WA, USA
| | - Tarah S Sullivan
- Department of Crop and Soil Sciences, Washington State University, PO Box 646420, Pullman, WA, USA.
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35
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Taouai M, Chakroun K, Sommer R, Michaud G, Giacalone D, Ben Maaouia MA, Vallin-Butruille A, Mathiron D, Abidi R, Darbre T, Cragg PJ, Mullié C, Reymond JL, O'Toole GA, Benazza M. Glycocluster Tetrahydroxamic Acids Exhibiting Unprecedented Inhibition of Pseudomonas aeruginosa Biofilms. J Med Chem 2019; 62:7722-7738. [PMID: 31449405 DOI: 10.1021/acs.jmedchem.9b00481] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Opportunistic Gram-negative Pseudomonas aeruginosa uses adhesins (e.g., LecA and LecB lectins, type VI pili and flagella) and iron to invade host cells with the formation of a biofilm, a thick barrier that protects bacteria from drugs and host immune system. Hindering iron uptake and disrupting adhesins' function could be a relevant antipseudomonal strategy. To test this hypothesis, we designed an iron-chelating glycocluster incorporating a tetrahydroxamic acid and α-l-fucose bearing linker to interfere with both iron uptake and the glycan recognition process involving the LecB lectin. Iron depletion led to increased production of the siderophore pyoverdine by P. aeruginosa to counteract the loss of iron uptake, and strong biofilm inhibition was observed not only with the α-l-fucocluster (72%), but also with its α-d-manno (84%), and α-d-gluco (92%) counterparts used as negative controls. This unprecedented finding suggests that both LecB and biofilm inhibition are closely related to the presence of hydroxamic acid groups.
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Affiliation(s)
- Marwa Taouai
- Laboratoire de Glycochimie des Antimicrobiens et des Agroressources (LG2A-UMR7378-CNRS) , CNRS-Université de Picardie Jules Verne , 10 Rue Baudelocque , 80039 Amiens Cédex , France.,Laboratoire LACReSNE, Unité "Interactions Moléculaires Spécifiques", Faculté des Sciences de Bizerte , Université de Carthage Zarzouna-Bizerte TN 7021 , Tunisie
| | - Khouloud Chakroun
- Laboratoire de Glycochimie des Antimicrobiens et des Agroressources (LG2A-UMR7378-CNRS) , CNRS-Université de Picardie Jules Verne , 10 Rue Baudelocque , 80039 Amiens Cédex , France.,Department of Microbiology and Immunology , Geisel School of Medicine at Dartmouth , Room 202, Remsen Building 66, College Street , Hanover , New Hampshire 03755 , United States
| | - Roman Sommer
- Chemical Biology of Carbohydrates , Helmholtz Institute for Pharmaceutical Research Saarland , 66123 Saarbrücken , Germany
| | - Gaelle Michaud
- Chemistry and Biochemistry , University of Berne , Freistrasse 3 , 3012 Berne , Switzerland
| | - David Giacalone
- Department of Microbiology and Immunology , Geisel School of Medicine at Dartmouth , Room 202, Remsen Building 66, College Street , Hanover , New Hampshire 03755 , United States
| | - Mohamed Amine Ben Maaouia
- Laboratoire de Glycochimie des Antimicrobiens et des Agroressources (LG2A-UMR7378-CNRS) , CNRS-Université de Picardie Jules Verne , 10 Rue Baudelocque , 80039 Amiens Cédex , France.,Laboratoire LACReSNE, Unité "Interactions Moléculaires Spécifiques", Faculté des Sciences de Bizerte , Université de Carthage Zarzouna-Bizerte TN 7021 , Tunisie
| | - Aurélie Vallin-Butruille
- Laboratoire de Glycochimie des Antimicrobiens et des Agroressources (LG2A-UMR7378-CNRS) , CNRS-Université de Picardie Jules Verne , 10 Rue Baudelocque , 80039 Amiens Cédex , France
| | - David Mathiron
- Laboratoire de Glycochimie des Antimicrobiens et des Agroressources (LG2A-UMR7378-CNRS) , CNRS-Université de Picardie Jules Verne , 10 Rue Baudelocque , 80039 Amiens Cédex , France
| | - Rym Abidi
- Laboratoire LACReSNE, Unité "Interactions Moléculaires Spécifiques", Faculté des Sciences de Bizerte , Université de Carthage Zarzouna-Bizerte TN 7021 , Tunisie
| | - Tamis Darbre
- Chemistry and Biochemistry , University of Berne , Freistrasse 3 , 3012 Berne , Switzerland
| | - Peter J Cragg
- School of Pharmacy and Biomolecular Science University of Brighton , Brighton BN2 4GJ , U.K
| | - Catherine Mullié
- Laboratoire de Glycochimie des Antimicrobiens et des Agroressources (LG2A-UMR7378-CNRS) , CNRS-Université de Picardie Jules Verne , 10 Rue Baudelocque , 80039 Amiens Cédex , France
| | - Jean-Louis Reymond
- Chemistry and Biochemistry , University of Berne , Freistrasse 3 , 3012 Berne , Switzerland
| | - George A O'Toole
- Department of Microbiology and Immunology , Geisel School of Medicine at Dartmouth , Room 202, Remsen Building 66, College Street , Hanover , New Hampshire 03755 , United States
| | - Mohammed Benazza
- Laboratoire de Glycochimie des Antimicrobiens et des Agroressources (LG2A-UMR7378-CNRS) , CNRS-Université de Picardie Jules Verne , 10 Rue Baudelocque , 80039 Amiens Cédex , France
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36
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Kong H, Cheng W, Wei H, Yuan Y, Yang Z, Zhang X. An overview of recent progress in siderophore-antibiotic conjugates. Eur J Med Chem 2019; 182:111615. [PMID: 31434038 DOI: 10.1016/j.ejmech.2019.111615] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 08/01/2019] [Accepted: 08/09/2019] [Indexed: 01/09/2023]
Abstract
Multi-drug resistant infections caused by Gram-negative bacteria have become one of the most important reasons for the failure of clinical anti-infective treatment. Siderophore-antibiotic conjugates, which were designed based on a "Trojan horse" strategy wherein features enabled active uptake to bypass the Gram-negative cell wall, have been expected to be a weapon for anti-infective treatment in the clinic. Herein, we review antibiotic drug design strategies based on mimics of nature siderophores reported in recent years, we also focus our attention on the relationship between the type of linker and the corresponding antibacterial activity.
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Affiliation(s)
- Huimin Kong
- Department of Pediatrics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| | - Weiyan Cheng
- Department of Pharmacy, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China; Henan Key Laboratory of Precision Clinical Pharmacy, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| | - Han Wei
- Department of Pharmacy, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China; Henan Key Laboratory of Precision Clinical Pharmacy, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| | - Yongliang Yuan
- Department of Pharmacy, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China; Henan Key Laboratory of Precision Clinical Pharmacy, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| | - Zhiheng Yang
- Department of Pharmacy, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China; Henan Key Laboratory of Precision Clinical Pharmacy, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China.
| | - Xiaojian Zhang
- Department of Pharmacy, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China; Henan Key Laboratory of Precision Clinical Pharmacy, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
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37
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Becerra G, Igeño MI, Merchán F, Sánchez-Clemente R, Blasco R. New evolving strategies revealed by transcriptomic analysis of a fur - mutant of the cyanotrophic bacterium Pseudomonas pseudoalcaligenes CECT 5344. Microb Biotechnol 2019; 13:148-161. [PMID: 31006999 PMCID: PMC6922518 DOI: 10.1111/1751-7915.13408] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 03/26/2019] [Accepted: 03/27/2019] [Indexed: 12/14/2022] Open
Abstract
The transcriptomic analysis (RNA-seq) of a fur mutant of P. pseudoalcaligenes CECT 5344 has revealed that Fur regulates the expression of more than 100 genes in this bacterial strain, most of them negatively. The highest upregulated genes in response to fur deletion, with respect to the wild type, both cultivated in LB medium, corresponded to genes implicated in iron uptake. They include both TonB-dependent siderophore transporters for the active transport across the outer membrane, and ABC-type and MSF-type transporters for the active transport across the cytoplasmic membrane. Therefore, the main response of this bacterium to iron limitation is expressing genes necessary for metabolism of Fe siderophores produced by other microorganisms (xenosiderophores). The number of genes whose expression decreased in the fur- mutant, as well as its normalized expression (fold change), was lower. Among them, it is remarkable the presence of one of the two cas operons of the two CRISP/Cas clusters was detected in the genome of this bacterium. The transcriptome was validated by qPCR, including the decrease in the expression of cas genes (cse1). The expression of cse1 was also decreased by limiting the amount of iron, carbon or nitrogen in the medium, or by adding menadione, a compound that causes oxidative stress. The higher decrease in cse1 expression was triggered by the addition of cyanide in minimal medium. These results suggest that this bacterium responds to stress conditions, and especially to cyanide, taking a reasonable risk with respect to both the uptake of (TonB-dependent receptors gates) and the tolerance to (reduced immunity) foreign nucleic acids. In conjunction, this can be considered a yet unknown molecular mechanism forcing bacterial evolution.
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Affiliation(s)
- Gracia Becerra
- Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Veterinaria, Universidad de Extremadura, Caceres, Spain
| | - María Isabel Igeño
- Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Veterinaria, Universidad de Extremadura, Caceres, Spain.,Meat and Meat Products Research Institute (IProCar), BioMic Research Group, Universidad de Extremadura, Caceres, Spain
| | - Faustino Merchán
- Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Veterinaria, Universidad de Extremadura, Caceres, Spain.,Meat and Meat Products Research Institute (IProCar), BioMic Research Group, Universidad de Extremadura, Caceres, Spain
| | - Rubén Sánchez-Clemente
- Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Veterinaria, Universidad de Extremadura, Caceres, Spain.,Meat and Meat Products Research Institute (IProCar), BioMic Research Group, Universidad de Extremadura, Caceres, Spain
| | - Rafael Blasco
- Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Veterinaria, Universidad de Extremadura, Caceres, Spain.,Meat and Meat Products Research Institute (IProCar), BioMic Research Group, Universidad de Extremadura, Caceres, Spain
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38
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Conroy BS, Grigg JC, Kolesnikov M, Morales LD, Murphy MEP. Staphylococcus aureus heme and siderophore-iron acquisition pathways. Biometals 2019; 32:409-424. [PMID: 30911924 DOI: 10.1007/s10534-019-00188-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 03/18/2019] [Indexed: 11/24/2022]
Abstract
Staphylococcus aureus is a versatile opportunistic human pathogen. Infection by this bacterium requires uptake of iron from the human host, but iron is highly restricted in this environment. Staphylococcus aureus iron sufficiency is achieved primarily through uptake of heme and high-affinity iron chelators, known as siderophores. Two siderophores (staphyloferrins) are produced and secreted by S. aureus into the extracellular environment to capture iron. Staphylococcus aureus expresses specific uptake systems for staphyloferrins and more general uptake systems for siderophores produced by other microorganisms. The S. aureus heme uptake system uses highly-specific cell surface receptors to extract heme from hemoglobin and hemoglobin-haptoglobin complexes for transport into the cytoplasm where it is degraded to liberate iron. Initially thought to be independent systems, recent findings indicate that these iron uptake pathways intersect. IruO is a reductase that releases iron from heme and some ferric-siderophores. Moreover, multifunctional SbnI produces a precursor for staphyloferrin B biosynthesis, and also binds heme to regulate expression of the staphyloferrin B biosynthesis pathway. Intersection of the S. aureus iron uptake pathways is hypothesized to be important for rapid adaptation to available iron sources. Components of the heme and siderophore uptake systems are currently being targeted in the development of therapeutics against S. aureus.
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Affiliation(s)
- Brigid S Conroy
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, V6T 1Z3, Canada
| | - Jason C Grigg
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, V6T 1Z3, Canada
| | - Maxim Kolesnikov
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, V6T 1Z3, Canada
| | - L Daniela Morales
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, V6T 1Z3, Canada
| | - Michael E P Murphy
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, V6T 1Z3, Canada.
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39
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Czerwonka G, Gmiter D, Guzy A, Rogala P, Jabłońska-Wawrzycka A, Borkowski A, Cłapa T, Narożna D, Kowalczyk P, Syczewski M, Drabik M, Dańczuk M, Kaca W. A benzimidazole-based ruthenium(IV) complex inhibits Pseudomonas aeruginosa biofilm formation by interacting with siderophores and the cell envelope, and inducing oxidative stress. BIOFOULING 2019; 35:59-74. [PMID: 30727772 DOI: 10.1080/08927014.2018.1564818] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 12/11/2018] [Accepted: 12/24/2018] [Indexed: 06/09/2023]
Abstract
Pseudomonas aeruginosa biofilm-associated infections are a serious medical problem, and new compounds and therapies acting through novel mechanisms are much needed. Herein, the authors report a ruthenium(IV) complex that reduces P. aeruginosa PAO1 biofilm formation by 84%, and alters biofilm morphology and the living-to-dead cell ratio at 1 mM concentration. Including the compound in the culture medium altered the pigments secreted by PAO1, and fluorescence spectra revealed a decrease in pyoverdine. Scanning electron microscopy showed that the ruthenium complex did not penetrate the bacterial cell wall, but accumulated on external cell structures. Fluorescence quenching experiments indicated strong binding of the ruthenium complex to both plasmid DNA and bovine serum albumin. Formamidopyrimidine DNA N-glycosylase (Fpg) protein digestion of plasmid DNA isolated after ruthenium(IV) complex treatment revealed the generation of oxidative stress, which was further proved by the observed upregulation of catalase and superoxide dismutase gene expression.
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Affiliation(s)
- Grzegorz Czerwonka
- a Department of Microbiology, Institute of Biology , Jan Kochanowski University in Kielce , Poland
| | - Dawid Gmiter
- a Department of Microbiology, Institute of Biology , Jan Kochanowski University in Kielce , Poland
| | - Anna Guzy
- a Department of Microbiology, Institute of Biology , Jan Kochanowski University in Kielce , Poland
| | - Patrycja Rogala
- b Institute of Chemistry , Jan Kochanowski University in Kielce , Poland
| | | | - Andrzej Borkowski
- c Faculty of Geology, Geomicrobiology Laboratory , University of Warsaw , Warsaw , Poland
| | - Tomasz Cłapa
- d Department of Biochemistry and Biotechnology , Poznan University of Life Sciences , Poznań , Poland
| | - Dorota Narożna
- d Department of Biochemistry and Biotechnology , Poznan University of Life Sciences , Poznań , Poland
| | - Paweł Kowalczyk
- e Department of Animal Nutrition , The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences , Jabłonna , Poland
| | | | - Marcin Drabik
- g Department of Astrophysics, Institute of Physics , Jan Kochanowski University in Kielce , Poland
| | - Magdalena Dańczuk
- h Faculty of Environmental, Geomatic and Energy Engineering , Kielce University of Technology , Kielce , Poland
| | - Wiesław Kaca
- a Department of Microbiology, Institute of Biology , Jan Kochanowski University in Kielce , Poland
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40
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Abstract
Copper-binding metallophores, or chalkophores, play a role in microbial copper homeostasis that is analogous to that of siderophores in iron homeostasis. The best-studied chalkophores are members of the methanobactin (Mbn) family-ribosomally produced, posttranslationally modified natural products first identified as copper chelators responsible for copper uptake in methane-oxidizing bacteria. To date, Mbns have been characterized exclusively in those species, but there is genomic evidence for their production in a much wider range of bacteria. This review addresses the current state of knowledge regarding the function, biosynthesis, transport, and regulation of Mbns. While the roles of several proteins in these processes are supported by substantial genetic and biochemical evidence, key aspects of Mbn manufacture, handling, and regulation remain unclear. In addition, other natural products that have been proposed to mediate copper uptake as well as metallophores that have biologically relevant roles involving copper binding, but not copper uptake, are discussed.
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Affiliation(s)
- Grace E Kenney
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, USA; ,
| | - Amy C Rosenzweig
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, USA; ,
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
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41
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Kenney GE, Rosenzweig AC. Methanobactins: Maintaining copper homeostasis in methanotrophs and beyond. J Biol Chem 2018; 293:4606-4615. [PMID: 29348173 PMCID: PMC5880147 DOI: 10.1074/jbc.tm117.000185] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Methanobactins (Mbns) are ribosomally produced, post-translationally modified natural products that bind copper with high affinity and specificity. Originally identified in methanotrophic bacteria, which have a high need for copper, operons encoding these compounds have also been found in many non-methanotrophic bacteria. The proteins responsible for Mbn biosynthesis include several novel enzymes. Mbn transport involves export through a multidrug efflux pump and re-internalization via a TonB-dependent transporter. Release of copper from Mbn and the molecular basis for copper regulation of Mbn production remain to be elucidated. Future work is likely to result in the identification of new enzymatic chemistry, opportunities for bioengineering and drug targeting of copper metabolism, and an expanded understanding of microbial metal homeostasis.
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Affiliation(s)
- Grace E Kenney
- Departments of Molecular Biosciences, Evanston, Illinois 60208
| | - Amy C Rosenzweig
- Departments of Molecular Biosciences, Evanston, Illinois 60208; Chemistry, Northwestern University, Evanston, Illinois 60208.
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42
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Becker F, Wienand K, Lechner M, Frey E, Jung H. Interactions mediated by a public good transiently increase cooperativity in growing Pseudomonas putida metapopulations. Sci Rep 2018; 8:4093. [PMID: 29511247 PMCID: PMC5840296 DOI: 10.1038/s41598-018-22306-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 02/21/2018] [Indexed: 01/13/2023] Open
Abstract
Bacterial communities have rich social lives. A well-established interaction involves the exchange of a public good in Pseudomonas populations, where the iron-scavenging compound pyoverdine, synthesized by some cells, is shared with the rest. Pyoverdine thus mediates interactions between producers and non-producers and can constitute a public good. This interaction is often used to test game theoretical predictions on the "social dilemma" of producers. Such an approach, however, underestimates the impact of specific properties of the public good, for example consequences of its accumulation in the environment. Here, we experimentally quantify costs and benefits of pyoverdine production in a specific environment, and build a model of population dynamics that explicitly accounts for the changing significance of accumulating pyoverdine as chemical mediator of social interactions. The model predicts that, in an ensemble of growing populations (metapopulation) with different initial producer fractions (and consequently pyoverdine contents), the global producer fraction initially increases. Because the benefit of pyoverdine declines at saturating concentrations, the increase need only be transient. Confirmed by experiments on metapopulations, our results show how a changing benefit of a public good can shape social interactions in a bacterial population.
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Affiliation(s)
- Felix Becker
- Microbiology, Department Biology 1, Ludwig-Maximilians-Universität Munich, Grosshaderner Strasse 2-4, D-82152 Martinsried, Germany
| | - Karl Wienand
- Arnold-Sommerfeld-Center for Theoretical Physics and Center for Nanoscience, Ludwig-Maximilians-Universität, Theresienstrasse 37, D-80333, Munich, Germany
| | - Matthias Lechner
- Arnold-Sommerfeld-Center for Theoretical Physics and Center for Nanoscience, Ludwig-Maximilians-Universität, Theresienstrasse 37, D-80333, Munich, Germany
| | - Erwin Frey
- Arnold-Sommerfeld-Center for Theoretical Physics and Center for Nanoscience, Ludwig-Maximilians-Universität, Theresienstrasse 37, D-80333, Munich, Germany.
| | - Heinrich Jung
- Microbiology, Department Biology 1, Ludwig-Maximilians-Universität Munich, Grosshaderner Strasse 2-4, D-82152 Martinsried, Germany.
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43
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Abstract
Methanobactins (Mbns) are ribosomally produced, post-translationally modified peptide (RiPP) natural products that bind copper with high affinity using nitrogen-containing heterocycles and thioamide groups. In some methanotrophic bacteria, Mbns are secreted under conditions of copper starvation and then re-internalized as a copper source for the enzyme particulate methane monooxygenase (pMMO). Genome mining studies have led to the identification and classification of operons encoding the Mbn precursor peptide (MbnA) as well as a number of putative transport, regulatory, and biosynthetic proteins. These Mbn operons are present in non-methanotrophic bacteria as well, suggesting a broader role in and perhaps beyond copper acquisition. Genetic and biochemical studies indicate that specific operon-encoded proteins are involved in Mbn transport and provide insight into copper-responsive gene regulation in methanotrophs. Mbn biosynthesis is not yet understood, but combined analysis of Mbn structures, MbnA sequences, and operon content represents a powerful approach to elucidating the roles of specific biosynthetic enzymes. Future work will likely lead to the discovery of unique pathways for natural product biosynthesis and new mechanisms of microbial metal homeostasis.
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Affiliation(s)
- Laura M K Dassama
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA.
| | - Grace E Kenney
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA.
| | - Amy C Rosenzweig
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA. and Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
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44
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Butt AT, Thomas MS. Iron Acquisition Mechanisms and Their Role in the Virulence of Burkholderia Species. Front Cell Infect Microbiol 2017; 7:460. [PMID: 29164069 PMCID: PMC5681537 DOI: 10.3389/fcimb.2017.00460] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 10/18/2017] [Indexed: 11/19/2022] Open
Abstract
Burkholderia is a genus within the β-Proteobacteriaceae that contains at least 90 validly named species which can be found in a diverse range of environments. A number of pathogenic species occur within the genus. These include Burkholderia cenocepacia and Burkholderia multivorans, opportunistic pathogens that can infect the lungs of patients with cystic fibrosis, and are members of the Burkholderia cepacia complex (Bcc). Burkholderia pseudomallei is also an opportunistic pathogen, but in contrast to Bcc species it causes the tropical human disease melioidosis, while its close relative Burkholderia mallei is the causative agent of glanders in horses. For these pathogens to survive within a host and cause disease they must be able to acquire iron. This chemical element is essential for nearly all living organisms due to its important role in many enzymes and metabolic processes. In the mammalian host, the amount of accessible free iron is negligible due to the low solubility of the metal ion in its higher oxidation state and the tight binding of this element by host proteins such as ferritin and lactoferrin. As with other pathogenic bacteria, Burkholderia species have evolved an array of iron acquisition mechanisms with which to capture iron from the host environment. These mechanisms include the production and utilization of siderophores and the possession of a haem uptake system. Here, we summarize the known mechanisms of iron acquisition in pathogenic Burkholderia species and discuss the evidence for their importance in the context of virulence and the establishment of infection in the host. We have also carried out an extensive bioinformatic analysis to identify which siderophores are produced by each Burkholderia species that is pathogenic to humans.
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Affiliation(s)
- Aaron T Butt
- Department of Infection, Immunity and Cardiovascular Disease, Faculty of Medicine, Dentistry and Health, University of Sheffield, Sheffield, United Kingdom
| | - Mark S Thomas
- Department of Infection, Immunity and Cardiovascular Disease, Faculty of Medicine, Dentistry and Health, University of Sheffield, Sheffield, United Kingdom
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45
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Gao L, Guo Z, Wang Y, Wang Y, Wang K, Li B, Shen L. The Two-Operon-Coded ABC Transporter Complex FpvWXYZCDEF is Required for Pseudomonas aeruginosa Growth and Virulence Under Iron-Limiting Conditions. J Membr Biol 2017; 251:91-104. [PMID: 28975384 DOI: 10.1007/s00232-017-9979-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Accepted: 08/09/2017] [Indexed: 12/12/2022]
Abstract
Iron is essential for all organisms. Bacteria have devolved sophisticated systems to maintain intracellular iron homeostasis. FpvCDEF(PA2407-2410) has been reported as an ABC transporter involved in pyoverdine-Fe uptake which does not affect growth under iron-limiting condition, when it is deleted in PAO1. In this study, we proved that fpvCDEF and fpvWXYZ(PA2403-2406) constituted an ABC transporter complex containing two operons: fpvWXYZCDE and fpvF. The operon fpvWXYZCDE was regulated by iron negatively and the single gene operon fpvF was constitutively expressed. Inactivation of any one of the components, fpvW, fpvC, fpvD, fpvE, and fpvF, led to increased expression of fpvWXYZCDE suggesting that each component of fpvWXYZCDEF could be involved in iron uptake. The ABC transporter complex encoded by fpvWXYZCDEF plays important roles in growth, oxidative stress resistance, and virulence, since the deletion of fpvWXYZCDEF resulted in defective growth, increased sensitivity to H2O2, and decreased virulence compared with PAO1(ΔfpvCDEF) and the wild type PAO1 under iron-limiting condition.
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Affiliation(s)
- Lang Gao
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, Faculty of Life Sciences, Northwest University, Xi'an, 710069, China
| | - Zisheng Guo
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, Faculty of Life Sciences, Northwest University, Xi'an, 710069, China
| | - Yue Wang
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, Faculty of Life Sciences, Northwest University, Xi'an, 710069, China
| | - Yulu Wang
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, Faculty of Life Sciences, Northwest University, Xi'an, 710069, China
| | - Kerong Wang
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, Faculty of Life Sciences, Northwest University, Xi'an, 710069, China
| | - Bo Li
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, Faculty of Life Sciences, Northwest University, Xi'an, 710069, China.
| | - Lixin Shen
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, Faculty of Life Sciences, Northwest University, Xi'an, 710069, China.
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46
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Besserglick J, Olshvang E, Szebesczyk A, Englander J, Levinson D, Hadar Y, Gumienna-Kontecka E, Shanzer A. Ferrichrome Has Found Its Match: Biomimetic Analogues with Diversified Activity Map Discrete Microbial Targets. Chemistry 2017; 23:13181-13191. [DOI: 10.1002/chem.201702647] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Indexed: 12/17/2022]
Affiliation(s)
- Jenny Besserglick
- Department of Organic Chemistry; The Weizmann Institute of Science; Rehovot 7610001 Israel
| | - Evgenia Olshvang
- Department of Organic Chemistry; The Weizmann Institute of Science; Rehovot 7610001 Israel
| | - Agnieszka Szebesczyk
- Faculty of Chemistry; University of Wrocław; F. Joliot-Curie 14 50-383 Wrocław Poland
| | - Joseph Englander
- Department of Organic Chemistry; The Weizmann Institute of Science; Rehovot 7610001 Israel
| | - Dana Levinson
- Department of Plant Pathology and Microbiology; The R.H. Smith Faculty of Agriculture Food and Environment; The Hebrew University of Jerusalem; Rehovot 7610001 Israel
| | - Yitzhak Hadar
- Department of Plant Pathology and Microbiology; The R.H. Smith Faculty of Agriculture Food and Environment; The Hebrew University of Jerusalem; Rehovot 7610001 Israel
| | | | - Abraham Shanzer
- Department of Organic Chemistry; The Weizmann Institute of Science; Rehovot 7610001 Israel
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47
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Koh EI, Robinson AE, Bandara N, Rogers BE, Henderson JP. Copper import in Escherichia coli by the yersiniabactin metallophore system. Nat Chem Biol 2017; 13:1016-1021. [PMID: 28759019 PMCID: PMC5562518 DOI: 10.1038/nchembio.2441] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 06/20/2017] [Indexed: 12/13/2022]
Abstract
Copper plays a dual role as nutrient and toxin during bacterial infections. While uropathogenic Escherichia coli (UPEC) strains can use the copper-binding metallophore yersiniabactin (Ybt) to resist copper toxicity, Ybt also converts bioavailable copper to Cu(II)-Ybt in low copper conditions. Although E. coli have long been considered to lack a copper import pathway, we observed Ybt-mediated copper import in UPEC using canonical Fe(III)-Ybt transport proteins. UPEC removed copper from Cu(II)-Ybt with subsequent re-export of metal-free Ybt to the extracellular space. Copper released through this process became available to an E. coli cuproenzyme (the amine oxidase TynA), linking this import pathway to a nutrient acquisition function. Ybt-expressing E. coli thus engage in nutritional passivation, a strategy of minimizing a metal ion's toxicity while preserving its nutritional availability. Copper acquisition through this process may contribute to the marked virulence defect of Ybt transport-deficient UPEC.
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Affiliation(s)
- Eun-Ik Koh
- Center for Women's Infectious Diseases Research, Washington University School of Medicine, St. Louis, Missouri, USA.,Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, USA.,Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Anne E Robinson
- Center for Women's Infectious Diseases Research, Washington University School of Medicine, St. Louis, Missouri, USA.,Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, USA.,Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Nilantha Bandara
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Buck E Rogers
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Jeffrey P Henderson
- Center for Women's Infectious Diseases Research, Washington University School of Medicine, St. Louis, Missouri, USA.,Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, USA.,Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
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48
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Klahn P, Brönstrup M. Bifunctional antimicrobial conjugates and hybrid antimicrobials. Nat Prod Rep 2017; 34:832-885. [PMID: 28530279 DOI: 10.1039/c7np00006e] [Citation(s) in RCA: 119] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Covering: up to the end of 2016Novel antimicrobial drugs are continuously needed to counteract bacterial resistance development. An innovative molecular design strategy for novel antibiotic drugs is based on the hybridization of an antibiotic with a second functional entity. Such conjugates can be grouped into two major categories. In the first category (antimicrobial hybrids), both functional elements of the hybrid exert antimicrobial activity. Due to the dual targeting, resistance development can be significantly impaired, the pharmacokinetic properties can be superior compared to combination therapies with the single antibiotics, and the antibacterial potency is often enhanced in a synergistic manner. In the second category (antimicrobial conjugates), one functional moiety controls the accumulation of the other part of the conjugate, e.g. by mediating an active transport into the bacterial cell or blocking the efflux. This approach is mostly applied to translocate compounds across the cell envelope of Gram-negative bacteria through membrane-embedded transporters (e.g. siderophore transporters) that provide nutrition and signalling compounds to the cell. Such 'Trojan Horse' approaches can expand the antibacterial activity of compounds against Gram-negative pathogens, or offer new options for natural products that could not be developed as standalone antibiotics, e.g. due to their toxicity.
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Affiliation(s)
- P Klahn
- Department for Chemical Biology, Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany. and Institute for Organic Chemistry, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany.
| | - M Brönstrup
- Department for Chemical Biology, Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany.
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A Natural Chimeric Pseudomonas Bacteriocin with Novel Pore-Forming Activity Parasitizes the Ferrichrome Transporter. mBio 2017; 8:mBio.01961-16. [PMID: 28223456 PMCID: PMC5358913 DOI: 10.1128/mbio.01961-16] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Modular bacteriocins represent a major group of secreted protein toxins with a narrow spectrum of activity, involved in interference competition between Gram-negative bacteria. These antibacterial proteins include a domain for binding to the target cell and a toxin module at the carboxy terminus. Self-inhibition of producers is provided by coexpression of linked immunity genes that transiently inhibit the toxin's activity through formation of bacteriocin-immunity complexes or by insertion in the inner membrane, depending on the type of toxin module. We demonstrate strain-specific inhibitory activity for PmnH, a Pseudomonas bacteriocin with an unprecedented dual-toxin architecture, hosting both a colicin M domain, potentially interfering with peptidoglycan synthesis, and a novel colicin N-type domain, a pore-forming module distinct from the colicin Ia-type domain in Pseudomonas aeruginosa pyocin S5. A downstream-linked gene product confers PmnH immunity upon susceptible strains. This protein, ImnH, has a transmembrane topology similar to that of Pseudomonas colicin M-like and pore-forming immunity proteins, although homology with either of these is essentially absent. The enhanced killing activity of PmnH under iron-limited growth conditions reflects parasitism of the ferrichrome-type transporter for entry into target cells, a strategy shown here to be used as well by monodomain colicin M-like bacteriocins from pseudomonads. The integration of a second type of toxin module in a bacteriocin gene could offer a competitive advantage against bacteria displaying immunity against only one of both toxic activities.IMPORTANCE In their continuous struggle for ecological space, bacteria face a huge load of contenders, including phylogenetically related strains that compete for the same niche. One important group of secreted antibacterial proteins assisting in eliminating these rivals are modular bacteriocins of Gram-negative bacteria, comprising a domain for docking onto the cell envelope of a target cell, a translocation domain enabling subsequent cellular entry, and a toxin module that kills target cells via enzymatic or pore-forming activity. We here demonstrate the antagonistic function of a Pseudomonas bacteriocin with unique architecture that combines a putative enzymatic colicin M-like domain and a novel pore-forming toxin module. For target cell recognition and entry, this bacteriocin hybrid takes advantage of the ferrichrome transporter, also parasitized by enzymatic Pseudomonas bacteriocins devoid of the pore-forming module. Bacteriocins with an expanded toxin potential may represent an inventive bacterial strategy to alleviate immunity in target cells.
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