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Lax C, Nicolás FE, Navarro E, Garre V. Molecular mechanisms that govern infection and antifungal resistance in Mucorales. Microbiol Mol Biol Rev 2024; 88:e0018822. [PMID: 38445820 PMCID: PMC10966947 DOI: 10.1128/mmbr.00188-22] [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] [Indexed: 03/07/2024] Open
Abstract
SUMMARYThe World Health Organization has established a fungal priority pathogens list that includes species critical or highly important to human health. Among them is the order Mucorales, a fungal group comprising at least 39 species responsible for the life-threatening infection known as mucormycosis. Despite the continuous rise in cases and the poor prognosis due to innate resistance to most antifungal drugs used in the clinic, Mucorales has received limited attention, partly because of the difficulties in performing genetic manipulations. The COVID-19 pandemic has further escalated cases, with some patients experiencing the COVID-19-associated mucormycosis, highlighting the urgent need to increase knowledge about these fungi. This review addresses significant challenges in treating the disease, including delayed and poor diagnosis, the lack of accurate global incidence estimation, and the limited treatment options. Furthermore, it focuses on the most recent discoveries regarding the mechanisms and genes involved in the development of the disease, antifungal resistance, and the host defense response. Substantial advancements have been made in identifying key fungal genes responsible for invasion and tissue damage, host receptors exploited by the fungus to invade tissues, and mechanisms of antifungal resistance. This knowledge is expected to pave the way for the development of new antifungals to combat mucormycosis. In addition, we anticipate significant progress in characterizing Mucorales biology, particularly the mechanisms involved in pathogenesis and antifungal resistance, with the possibilities offered by CRISPR-Cas9 technology for genetic manipulation of the previously intractable Mucorales species.
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Affiliation(s)
- Carlos Lax
- Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, Murcia, Spain
| | - Francisco E. Nicolás
- Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, Murcia, Spain
| | - Eusebio Navarro
- Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, Murcia, Spain
| | - Victoriano Garre
- Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, Murcia, Spain
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2
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Dogra S, Arora A, Aggarwal A, Passi G, Sharma A, Singh G, Barnwal RP. Mucormycosis Amid COVID-19 Crisis: Pathogenesis, Diagnosis, and Novel Treatment Strategies to Combat the Spread. Front Microbiol 2022; 12:794176. [PMID: 35058909 PMCID: PMC8763841 DOI: 10.3389/fmicb.2021.794176] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 11/30/2021] [Indexed: 01/01/2023] Open
Abstract
The havoc unleashed by COVID-19 pandemic has paved way for secondary ominous fungal infections like Mucormycosis. It is caused by a class of opportunistic pathogens from the order Mucorales. Fatality rates due to this contagious infection are extremely high. Numerous clinical manifestations result in damage to multiple organs subject to the patient's underlying condition. Lack of a proper detection method and reliable treatment has made the management of this infection troublesome. Several reports studying the behavior pattern of Mucorales inside the host by modulation of its defense mechanisms have helped in understanding the pathogenesis of this angio-invasive infection. Many recent advances in diagnosis and treatment of this fungal infection have not been much beneficial. Therefore, there is a need to foster more viable strategies. This article summarizes current and imminent approaches that could aid effective management of these secondary infections in these times of global pandemic. It is foreseen that the development of newer antifungal drugs, antimicrobial peptides, and nanotechnology-based approaches for drug delivery would help combat this infection and curb its spread.
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Affiliation(s)
- Shreya Dogra
- Department of Biophysics, Panjab University, Chandigarh, India
| | - Akanksha Arora
- Department of Biophysics, Panjab University, Chandigarh, India
| | - Aashni Aggarwal
- Department of Biophysics, Panjab University, Chandigarh, India
| | - Gautam Passi
- Department of Biophysics, Panjab University, Chandigarh, India
| | - Akanksha Sharma
- Department of Biophysics, Panjab University, Chandigarh, India
- University Institute of Pharmaceutical Sciences, Panjab University, Chandigarh, India
| | - Gurpal Singh
- University Institute of Pharmaceutical Sciences, Panjab University, Chandigarh, India
| | - Ravi P. Barnwal
- Department of Biophysics, Panjab University, Chandigarh, India
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COVID-19-associated-mucormycosis: possible role of free iron uptake and immunosuppression. Mol Biol Rep 2021; 49:747-754. [PMID: 34709573 PMCID: PMC8552432 DOI: 10.1007/s11033-021-06862-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 10/20/2021] [Indexed: 01/19/2023]
Abstract
COVID-19-associated-mucormycosis, commonly referred to as the "Black Fungus," is a rare secondary fungal infection in COVID-19 patients prompted by a group of mucor molds. Association of this rare fungal infection with SARS-CoV-2 infection has been declared as an endemic in India, with minor cases in several other countries around the globe. Although the fungal infection is not contagious like the viral infection, the causative fungal agent is omnipresent. Infection displays an overall mortality rate of around 50%, with many other secondary side effects posing a potential threat in exacerbating COVID-19 mortality rates. In this review, we have accessed the role of free iron availability in COVID-19 patients that might correlate to the pathogenesis of the causative fungal agent. Besides, we have analyzed the negative consequences of using immunosuppressive drugs in encouraging this opportunistic fungal infection.
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Chemistry and Biomedical Applications of Fungal Siderophores. Fungal Biol 2021. [DOI: 10.1007/978-3-030-53077-8_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Li B, Deng X, Kim SH, Buhrow L, Tomchick DR, Phillips MA, Michael AJ. Alternative pathways utilize or circumvent putrescine for biosynthesis of putrescine-containing rhizoferrin. J Biol Chem 2020; 296:100146. [PMID: 33277357 PMCID: PMC7857480 DOI: 10.1074/jbc.ra120.016738] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 12/02/2020] [Accepted: 12/04/2020] [Indexed: 11/23/2022] Open
Abstract
The siderophore rhizoferrin (N1,N4-dicitrylputrescine) is produced in fungi and bacteria to scavenge iron. Putrescine-producing bacterium Ralstonia pickettii synthesizes rhizoferrin and encodes a single nonribosomal peptide synthetase-independent siderophore (NIS) synthetase. From biosynthetic logic, we hypothesized that this single enzyme is sufficient for rhizoferrin biosynthesis. We confirmed this by expression of R. pickettii NIS synthetase in Escherichia coli, resulting in rhizoferrin production. This was further confirmed in vitro using the recombinant NIS synthetase, synthesizing rhizoferrin from putrescine and citrate. Heterologous expression of homologous lbtA from Legionella pneumophila, required for rhizoferrin biosynthesis in that species, produced siderophore activity in E. coli. Rhizoferrin is also synthesized by Francisella tularensis and Francisella novicida, but unlike R. pickettii or L. pneumophila, Francisella species lack putrescine biosynthetic pathways because of genomic decay. Francisella encodes a NIS synthetase FslA/FigA and an ornithine decarboxylase homolog FslC/FigC, required for rhizoferrin biosynthesis. Ornithine decarboxylase produces putrescine from ornithine, but we show here in vitro that FigA synthesizes N-citrylornithine, and FigC is an N-citrylornithine decarboxylase that together synthesize rhizoferrin without using putrescine. We co-expressed F. novicida figA and figC in E. coli and produced rhizoferrin. A 2.1 Å X-ray crystal structure of the FigC N-citrylornithine decarboxylase reveals how the larger substrate is accommodated and how active site residues have changed to recognize N-citrylornithine. FigC belongs to a new subfamily of alanine racemase-fold PLP-dependent decarboxylases that are not involved in polyamine biosynthesis. These data reveal a natural product biosynthetic workaround that evolved to bypass a missing precursor and re-establish it in the final structure.
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Affiliation(s)
- Bin Li
- Department of Biochemistry, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Xiaoyi Deng
- Department of Biochemistry, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Sok Ho Kim
- Department of Biochemistry, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Leann Buhrow
- Department of Biochemistry, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Diana R Tomchick
- Department of Biophysics, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Margaret A Phillips
- Department of Biochemistry, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Anthony J Michael
- Department of Biochemistry, UT Southwestern Medical Center, Dallas, Texas, USA.
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Lax C, Pérez-Arques C, Navarro-Mendoza MI, Cánovas-Márquez JT, Tahiri G, Pérez-Ruiz JA, Osorio-Concepción M, Murcia-Flores L, Navarro E, Garre V, Nicolás FE. Genes, Pathways, and Mechanisms Involved in the Virulence of Mucorales. Genes (Basel) 2020; 11:E317. [PMID: 32188171 PMCID: PMC7140881 DOI: 10.3390/genes11030317] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 03/06/2020] [Accepted: 03/09/2020] [Indexed: 12/19/2022] Open
Abstract
The order Mucorales is a group of ancient fungi with limited tools for gene manipulation. The main consequence of this manipulation unwillingness is the limited knowledge about its biology compared to other fungal groups. However, the emerging of mucormycosis, a fungal infection caused by Mucorales, is attracting the medical spotlight in recent years because the treatments available are not efficient in reducing the high mortality associated with this disease. The result of this renewed interest in Mucorales and mucormycosis is an extraordinarily productive effort to unveil their secrets during the last decade. In this review, we describe the most compelling advances related to the genetic study of virulence factors, pathways, and molecular mechanisms developed in these years. The use of a few genetic study models has allowed the characterization of virulence factors in Mucorales that were previously described in other pathogens, such as the uptake iron systems, the mechanisms of dimorphism, and azole resistances. More importantly, recent studies are identifying new genes and mechanisms controlling the pathogenic potential of Mucorales and their interactions with the host, offering new alternatives to develop specific strategies against mucormycosis.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Francisco Esteban Nicolás
- Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain; (C.L.); (C.P.-A.); (M.I.N.-M.); (J.T.C.-M.); (G.T.); (J.A.P.-R.); (M.O.-C.); (L.M.-F.); (V.G.)
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Lebreton A, Corre E, Jany JL, Brillet-Guéguen L, Pèrez-Arques C, Garre V, Monsoor M, Debuchy R, Le Meur C, Coton E, Barbier G, Meslet-Cladière L. Comparative genomics applied to Mucor species with different lifestyles. BMC Genomics 2020; 21:135. [PMID: 32039703 PMCID: PMC7011435 DOI: 10.1186/s12864-019-6256-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 10/31/2019] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Despite a growing number of investigations on early diverging fungi, the corresponding lineages have not been as extensively characterized as Ascomycota or Basidiomycota ones. The Mucor genus, pertaining to one of these lineages is not an exception. To this date, a restricted number of Mucor annotated genomes is publicly available and mainly correspond to the reference species, Mucor circinelloides, and to medically relevant species. However, the Mucor genus is composed of a large number of ubiquitous species as well as few species that have been reported to specifically occur in certain habitats. The present study aimed to expand the range of Mucor genomes available and identify potential genomic imprints of adaptation to different environments and lifestyles in the Mucor genus. RESULTS In this study, we report four newly sequenced genomes of Mucor isolates collected from non-clinical environments pertaining to species with contrasted lifestyles, namely Mucor fuscus and Mucor lanceolatus, two species used in cheese production (during ripening), Mucor racemosus, a recurrent cheese spoiler sometimes described as an opportunistic animal and human pathogen, and Mucor endophyticus, a plant endophyte. Comparison of these new genomes with those previously available for six Mucor and two Rhizopus (formerly identified as M. racemosus) isolates allowed global structural and functional description such as their TE content, core and species-specific genes and specialized genes. We proposed gene candidates involved in iron metabolism; some of these genes being known to be involved in pathogenicity; and described patterns such as a reduced number of CAZymes in the species used for cheese ripening as well as in the endophytic isolate that might be related to adaptation to different environments and lifestyles within the Mucor genus. CONCLUSIONS This study extended the descriptive data set for Mucor genomes, pointed out the complexity of obtaining a robust phylogeny even with multiple genes families and allowed identifying contrasting potentially lifestyle-associated gene repertoires. The obtained data will allow investigating further the link between genetic and its biological data, especially in terms of adaptation to a given habitat.
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Affiliation(s)
- Annie Lebreton
- Univ Brest, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, F-29280, Plouzané, France
| | - Erwan Corre
- Station Biologique de Roscoff, Plateforme ABiMS, CNRS: FR2424, Sorbonne Université (UPMC), Paris VI, Place Georges Teissier, 74 29682, Roscoff Cedex, BP, France
| | - Jean-Luc Jany
- Univ Brest, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, F-29280, Plouzané, France
| | - Loraine Brillet-Guéguen
- Station Biologique de Roscoff, Plateforme ABiMS, CNRS: FR2424, Sorbonne Université (UPMC), Paris VI, Place Georges Teissier, 74 29682, Roscoff Cedex, BP, France
- CNRS, Integrative Biology of Marine Models (LBI2M), Station Biologique de Roscoff (SBR), Sorbonne Université, 29680, Roscoff, France
| | - Carlos Pèrez-Arques
- Department of Genetics and Microbiology, Faculty of Biology, University of Murcia, 30100, Murcia, Spain
| | - Victoriano Garre
- Department of Genetics and Microbiology, Faculty of Biology, University of Murcia, 30100, Murcia, Spain
| | - Misharl Monsoor
- Station Biologique de Roscoff, Plateforme ABiMS, CNRS: FR2424, Sorbonne Université (UPMC), Paris VI, Place Georges Teissier, 74 29682, Roscoff Cedex, BP, France
| | - Robert Debuchy
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, University Paris-Sud, Université Paris-Saclay, CEDEX 91198, Gif-sur-Yvette, France
| | - Christophe Le Meur
- Univ Brest, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, F-29280, Plouzané, France
| | - Emmanuel Coton
- Univ Brest, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, F-29280, Plouzané, France
| | - Georges Barbier
- Univ Brest, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, F-29280, Plouzané, France
| | - Laurence Meslet-Cladière
- Univ Brest, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, F-29280, Plouzané, France.
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Ramakrishnan G, Pérez NM, Carroll C, Moore MM, Nakamoto RK, Fox TE. Citryl Ornithine Is an Intermediate in a Three-Step Biosynthetic Pathway for Rhizoferrin in Francisella. ACS Chem Biol 2019; 14:1760-1766. [PMID: 31260252 DOI: 10.1021/acschembio.9b00297] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The Gram-negative bacterium Francisella tularensis secretes the siderophore rhizoferrin to scavenge necessary iron from the environment. Rhizoferrin, also produced by a variety of fungi and bacteria, comprises two citrate molecules linked by amide bonds to a central putrescine (diaminobutane) moiety. Genetic analysis has determined that rhizoferrin production in F. tularensis requires two enzymes: FslA, a siderophore synthetase of the nonribosomal peptide synthetase-independent siderophore synthetase (NIS) family, and FslC, a pyridoxal-phosphate-dependent decarboxylase. To discern the steps in the biosynthetic pathway, we tested F. tularensis strain LVS and its ΔfslA and ΔfslC mutants for the ability to incorporate potential precursors into rhizoferrin. Unlike putrescine supplementation, supplementation with ornithine greatly enhanced siderophore production by LVS. Radioactivity from L-[U-14C] ornithine, but not from L-[1-14C] ornithine, was efficiently incorporated into rhizoferrin by LVS. Although neither the ΔfslA nor the ΔfslC mutant produced rhizoferrin, a putative siderophore intermediate labeled by both [U-14C] ornithine and [1-14C] ornithine was secreted by the ΔfslC mutant. Rhizoferrin was identified by liquid chromatography and mass spectrometry in LVS culture supernatants, while citryl-ornithine was detected as the siderophore intermediate in the culture supernatant of the ΔfslC mutant. Our findings support a three-step pathway for rhizoferrin production in Francisella; unlike the fungus Rhizopus delemar, where putrescine functions as a primary precursor for rhizoferrin, biosynthesis in Francisella preferentially starts with ornithine as the substrate for FslA-mediated condensation with citrate. Decarboxylation of this citryl ornithine intermediate by FslC is necessary for a second condensation reaction with citrate to produce rhizoferrin.
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Affiliation(s)
| | | | - Cassandra Carroll
- Department of Biological Sciences, Simon Fraser University, Burnaby V5A 1S6, Canada
| | - Margo M. Moore
- Department of Biological Sciences, Simon Fraser University, Burnaby V5A 1S6, Canada
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Distribution and Evolution of Nonribosomal Peptide Synthetase Gene Clusters in the Ceratocystidaceae. Genes (Basel) 2019; 10:genes10050328. [PMID: 31052158 PMCID: PMC6563098 DOI: 10.3390/genes10050328] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 03/29/2019] [Accepted: 04/01/2019] [Indexed: 01/07/2023] Open
Abstract
In filamentous fungi, genes in secondary metabolite biosynthetic pathways are generally clustered. In the case of those pathways involved in nonribosomal peptide production, a nonribosomal peptide synthetase (NRPS) gene is commonly found as a main element of the cluster. Large multifunctional enzymes are encoded by members of this gene family that produce a broad spectrum of bioactive compounds. In this research, we applied genome-based identification of nonribosomal peptide biosynthetic gene clusters in the family Ceratocystidaceae. For this purpose, we used the whole genome sequences of species from the genera Ceratocystis,Davidsoniella,Thielaviopsis, Endoconidiophora,Bretziella, Huntiella, and Ambrosiella. To identify and characterize the clusters, different bioinformatics and phylogenetic approaches, as well as PCR-based methods were used. In all genomes studied, two highly conserved NRPS genes (one monomodular and one multimodular) were identified and their potential products were predicted to be siderophores. Expression analysis of two Huntiella species (H. moniliformis and H. omanensis) confirmed the accuracy of the annotations and proved that the genes in both clusters are expressed. Furthermore, a phylogenetic analysis showed that both NRPS genes of the Ceratocystidaceae formed distinct and well supported clades in their respective phylograms, where they grouped with other known NRPSs involved in siderophore production. Overall, these findings improve our understanding of the diversity and evolution of NRPS biosynthetic pathways in the family Ceratocystidaceae.
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Halo BA, Al-Yahyai RA, Al-Sadi AM. Aspergillus terreus Inhibits Growth and Induces Morphological Abnormalities in Pythium aphanidermatum and Suppresses Pythium-Induced Damping-Off of Cucumber. Front Microbiol 2018; 9:95. [PMID: 29449831 PMCID: PMC5799290 DOI: 10.3389/fmicb.2018.00095] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 01/16/2018] [Indexed: 01/27/2023] Open
Abstract
The study investigated the efficacy of two isolates of Aspergillus terreus (65P and 9F) on the growth, morphology and pathogenicity of Pythium aphanidermatum on cucumber. In vitro tests showed that the two isolates inhibited the growth of P. aphanidermatum in culture. Investigating P. aphanidermatum hyphae close to the inhibition zone showed that the hyphae showed abnormal growth and loss of internal content. Treating P. aphanidermatum with the culture filtrate (CF) of A. terreus resulted in significant rise in cellular leakage of P. aphanidermatum mycelium. Testing glucanase enzyme activity by both A. terreus isolates showed a significant increase in glucanase activity. This suggests that the cell walls of Pythium, which consist of glucan, are affected by the glucanase enzyme produced by A. terreus. In addition, Aspergillus isolates produced siderephore, which is suggested to be involved in inhibition of Pythium growth. Also, the CFs of 65P and 9F isolates significantly reduced spore production by P. aphanidermatum compared to the control (P < 0.05). In bioassay tests, the two isolates of A. terreus increased the survival rate of cucumber seedlings from 10 to 20% in the control seedlings treated with P. aphanidermatum to 38-39% when the biocontrol agents were used. No disease symptoms were observed on cucumber seedlings only treated with the isolates 65P and 9F of A. terreus. In addition, the A. terreus isolates did not have any negative effects on the growth of cucumber seedlings. This study shows that isolates of A. terreus can help suppress Pythium-induced damping-off of cucumber, which is suggested to be through the effect of A. terreus and its glucanase enzyme on P. aphanidermatum mycelium.
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Affiliation(s)
| | | | - Abdullah M. Al-Sadi
- Department of Crop Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Muscat, Oman
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Gerwien F, Skrahina V, Kasper L, Hube B, Brunke S. Metals in fungal virulence. FEMS Microbiol Rev 2018; 42:4562650. [PMID: 29069482 PMCID: PMC5812535 DOI: 10.1093/femsre/fux050] [Citation(s) in RCA: 133] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 10/19/2017] [Indexed: 12/25/2022] Open
Abstract
Metals are essential for life, and they play a central role in the struggle between infecting microbes and their hosts. In fact, an important aspect of microbial pathogenesis is the 'nutritional immunity', in which metals are actively restricted (or, in an extended definition of the term, locally enriched) by the host to hinder microbial growth and virulence. Consequently, fungi have evolved often complex regulatory networks, uptake and detoxification systems for essential metals such as iron, zinc, copper, nickel and manganese. These systems often differ fundamentally from their bacterial counterparts, but even within the fungal pathogens we can find common and unique solutions to maintain metal homeostasis. Thus, we here compare the common and species-specific mechanisms used for different metals among different fungal species-focusing on important human pathogens such as Candida albicans, Aspergillus fumigatus or Cryptococcus neoformans, but also looking at model fungi such as Saccharomyces cerevisiae or A. nidulans as well-studied examples for the underlying principles. These direct comparisons of our current knowledge reveal that we have a good understanding how model fungal pathogens take up iron or zinc, but that much is still to learn about other metals and specific adaptations of individual species-not the least to exploit this knowledge for new antifungal strategies.
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Affiliation(s)
- Franziska Gerwien
- Department Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology– Hans Knoell Institute, 07745 Jena, Germany
| | - Volha Skrahina
- Department Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology– Hans Knoell Institute, 07745 Jena, Germany
| | - Lydia Kasper
- Department Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology– Hans Knoell Institute, 07745 Jena, Germany
| | - Bernhard Hube
- Department Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology– Hans Knoell Institute, 07745 Jena, Germany
| | - Sascha Brunke
- Department Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology– Hans Knoell Institute, 07745 Jena, Germany
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Affiliation(s)
- Clara Baldin
- The Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor, University of California Los Angeles (UCLA) Medical Center and the St. John’s Cardiovascular Research Center, Torrance, California, United States of America
| | - Ashraf S. Ibrahim
- The Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor, University of California Los Angeles (UCLA) Medical Center and the St. John’s Cardiovascular Research Center, Torrance, California, United States of America
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
- * E-mail:
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Martín LB, Rodríguez MÁM, Mercier N, Lafont MO, Fernández EO, de la Parte AR, Estefanía M. Rhizopus arrhizus Invasive Infection due to Self-Inflicted Scratch Injuries in a Diabetic Patient with Non-ketotic Acidosis. Mycopathologia 2017. [PMID: 28646276 DOI: 10.1007/s11046-017-0158-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Mucormycosis is a rare infection caused by members included in the subphylum Mucoromycotina. Characterized by the histopathological hallmark of angioinvasion, these infections affect most often patients with certain underlying conditions carrying immunosuppression (haematological neoplasias, diabetic ketoacidosis and other forms of acidosis, and iron overload) or immunocompetent patients with traumatic mucocutaneous barriers breakdown and direct inoculation of the mould. A case is presented in which a rare underlying condition (non-ketotic acidosis) and a rare cause of cutaneous injuries collide. Prognosis, treatment options and management decisions are described thoroughly.
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14
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Ramakrishnan G. Iron and Virulence in Francisella tularensis. Front Cell Infect Microbiol 2017; 7:107. [PMID: 28421167 PMCID: PMC5378763 DOI: 10.3389/fcimb.2017.00107] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 03/16/2017] [Indexed: 12/12/2022] Open
Abstract
Francisella tularensis, the causative agent of tularemia, is a Gram-negative bacterium that infects a variety of cell types including macrophages, and propagates with great efficiency in the cytoplasm. Iron, essential for key enzymatic and redox reactions, is among the nutrients required to support this pathogenic lifestyle and the bacterium relies on specialized mechanisms to acquire iron within the host environment. Two distinct pathways for iron acquisition are encoded by the F. tularensis genome- a siderophore-dependent ferric iron uptake system and a ferrous iron transport system. Genes of the Fur-regulated fslABCDEF operon direct the production and transport of the siderophore rhizoferrin. Siderophore biosynthesis involves enzymes FslA and FslC, while export across the inner membrane is mediated by FslB. Uptake of the rhizoferrin- ferric iron complex is effected by the siderophore receptor FslE in the outer membrane in a TonB-independent process, and FslD is responsible for uptake across the inner membrane. Ferrous iron uptake relies largely on high affinity transport by FupA in the outer membrane, while the Fur-regulated FeoB protein mediates transport across the inner membrane. FslE and FupA are paralogous proteins, sharing sequence similarity and possibly sharing structural features as well. This review summarizes current knowledge of iron acquisition in this organism and the critical role of these uptake systems in bacterial pathogenicity.
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Affiliation(s)
- Girija Ramakrishnan
- Department of Medicine/Division of Infectious Diseases, University of VirginiaCharlottesville, VA, USA
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15
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The Legionella pneumophila Siderophore Legiobactin Is a Polycarboxylate That Is Identical in Structure to Rhizoferrin. Infect Immun 2015. [PMID: 26195554 DOI: 10.1128/iai.00808-15] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Legionella pneumophila, the agent of Legionnaires' disease, secretes a siderophore (legiobactin) that promotes bacterial infection of the lung. In past work, we determined that cytoplasmic LbtA (from Legiobactin gene A) promotes synthesis of legiobactin, inner membrane LbtB aids in export of the siderophore, and outer membrane LbtU and inner membrane LbtC help mediate ferrilegiobactin uptake and assimilation. However, the past studies examined legiobactin contained within bacterial culture supernatants. By utilizing high-pressure liquid chromatography that incorporates hydrophilic interaction-based chemistry, we have now purified legiobactin from supernatants of virulent strain 130b that is suitable for detailed chemical analysis. High-resolution mass spectrometry (MS) revealed that the molecular mass of (protonated) legiobactin is 437.140 Da. On the basis of the results obtained from both MS analysis and various forms of nuclear magnetic resonance, we found that legiobactin is composed of two citric acid residues linked by a putrescine bridge and thus is identical in structure to rhizoferrin, a polycarboxylate-type siderophore made by many fungi and several unrelated bacteria. Both purified legiobactin and rhizoferrin obtained from the fungus Cunninghamella elegans were able to promote Fe(3+) uptake by wild-type L. pneumophila as well as enhance growth of iron-starved bacteria. These results did not occur with 130b mutants lacking lbtU or lbtC, indicating that both endogenously made legiobactin and exogenously derived rhizoferrin are assimilated by L. pneumophila in an LbtU- and LbtC-dependent manner.
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Liu M, Lin L, Gebremariam T, Luo G, Skory CD, French SW, Chou TF, Edwards JE, Ibrahim AS. Fob1 and Fob2 Proteins Are Virulence Determinants of Rhizopus oryzae via Facilitating Iron Uptake from Ferrioxamine. PLoS Pathog 2015; 11:e1004842. [PMID: 25974051 PMCID: PMC4431732 DOI: 10.1371/journal.ppat.1004842] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 03/31/2015] [Indexed: 12/20/2022] Open
Abstract
Dialysis patients with chronic renal failure receiving deferoxamine for treating iron overload are uniquely predisposed for mucormycosis, which is most often caused by Rhizopus oryzae. Although the deferoxamine siderophore is not secreted by Mucorales, previous studies established that Rhizopus species utilize iron from ferrioxamine (iron-rich form of deferoxamine). Here we determined that the CBS domain proteins of Fob1 and Fob2 act as receptors on the cell surface of R. oryzae during iron uptake from ferrioxamine. Fob1 and Fob2 cell surface expression was induced in the presence of ferrioxamine and bound radiolabeled ferrioxamine. A R. oryzae strain with targeted reduced Fob1/Fob2 expression was impaired for iron uptake, germinating, and growing on medium with ferrioxamine as the sole source of iron. This strain also exhibited reduced virulence in a deferoxamine-treated, but not the diabetic ketoacidotic (DKA), mouse model of mucormycosis. The mechanism by which R. oryzae obtains iron from ferrioxamine involves the reductase/permease uptake system since the growth on ferrioxamine supplemented medium is associated with elevated reductase activity and the use of the ferrous chelator bathophenanthroline disulfonate abrogates iron uptake and growth on medium supplemented with ferrioxamine as a sole source of iron. Finally, R. oryzae mutants with reduced copies of the high affinity iron permease (FTR1) or with decreased FTR1 expression had an impaired iron uptake from ferrioxamine in vitro and reduced virulence in the deferoxamine-treated mouse model of mucormycosis. These two receptors appear to be conserved in Mucorales, and can be the subject of future novel therapy to maintain the use of deferoxamine for treating iron-overload. Deferoxamine is an iron-chelating agent often used to treat patients with acute iron poisoning, such as seen in dialysis patients with chronic renal failure. These patients are uniquely predisposed to a deadly fungal infection, called mucormycosis, because deferoxamine supplies iron that supports growth of fungi causing this infection. Apart from the important basic knowledge in delineating iron uptake mechanisms in cells, understanding how organisms causing mucormycosis obtain iron from ferrioxamine (deferoxamine bound with iron) is likely to develop strategies to treat mucormycosis infections in patients treated with deferoxamine. In this study we identified two cell surface receptors that bind ferrioxamine and facilitate iron uptake in Rhizopus oryzae, the most causative fungus of mucormycosis. These receptors are required for full virulence of R. oryzae in mice treated with deferoxamine. From genetic and biochemical studies it appears that the fungus binds ferrioxamine via these two receptors then liberates iron through a chemical modification step prior to transporting into the fungal cell without the internalization of deferoxamine.
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Affiliation(s)
- Mingfu Liu
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-University of California, Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
| | - Lin Lin
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-University of California, Los Angeles (UCLA) Medical Center, Torrance, California, United States of America; David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, California, United States of America
| | - Teclegiorgis Gebremariam
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-University of California, Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
| | - Guanpingsheng Luo
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-University of California, Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
| | - Christopher D Skory
- National Center for Agricultural Utilization Research, United States Department of Agriculture (USDA), Peoria, Illinois, United States of America
| | - Samuel W French
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-University of California, Los Angeles (UCLA) Medical Center, Torrance, California, United States of America; Department of Pathology, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, California, United States of America
| | - Tsui-Fen Chou
- Division of Medical Genetics, Department of Pediatrics, Harbor-University of California, Los Angeles Medical Center and Los Angeles Biomedical Research Institute, Torrance, California, United States of America
| | - John E Edwards
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-University of California, Los Angeles (UCLA) Medical Center, Torrance, California, United States of America; David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, California, United States of America
| | - Ashraf S Ibrahim
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-University of California, Los Angeles (UCLA) Medical Center, Torrance, California, United States of America; David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, California, United States of America
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17
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Abstract
Siderophores are chelators synthesized by microbes to sequester iron. This article summarizes the knowledge on the fungal siderophore metabolism with a focus on Aspergillus fumigatus. In recent years, A. fumigatus became a role model for fungal biosynthesis, uptake and degradation of siderophores as well as regulation of siderophore-mediated iron handling and the elucidation of siderophore functions. Siderophore functions comprise uptake, intracellular transport and storage of iron. This proved to be crucial not only for adaptation to iron starvation conditions but also for germination, asexual and sexual propagation, antioxidative defense, mutual interaction, microbial competition as well as virulence in plant and animal hosts. Recent studies also indicate the high potential of siderophores and its biosynthetic pathway to improve diagnosis and therapy of fungal infections.
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Affiliation(s)
- Hubertus Haas
- Division of Molecular Biology/Biocenter, Innsbruck Medical University, Innrain 80-82, A-6020 Innsbruck, Austria.
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18
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Schwartze VU, Winter S, Shelest E, Marcet-Houben M, Horn F, Wehner S, Linde J, Valiante V, Sammeth M, Riege K, Nowrousian M, Kaerger K, Jacobsen ID, Marz M, Brakhage AA, Gabaldón T, Böcker S, Voigt K. Gene expansion shapes genome architecture in the human pathogen Lichtheimia corymbifera: an evolutionary genomics analysis in the ancient terrestrial mucorales (Mucoromycotina). PLoS Genet 2014; 10:e1004496. [PMID: 25121733 PMCID: PMC4133162 DOI: 10.1371/journal.pgen.1004496] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 05/24/2014] [Indexed: 01/12/2023] Open
Abstract
Lichtheimia species are the second most important cause of mucormycosis in Europe. To provide broader insights into the molecular basis of the pathogenicity-associated traits of the basal Mucorales, we report the full genome sequence of L. corymbifera and compared it to the genome of Rhizopus oryzae, the most common cause of mucormycosis worldwide. The genome assembly encompasses 33.6 MB and 12,379 protein-coding genes. This study reveals four major differences of the L. corymbifera genome to R. oryzae: (i) the presence of an highly elevated number of gene duplications which are unlike R. oryzae not due to whole genome duplication (WGD), (ii) despite the relatively high incidence of introns, alternative splicing (AS) is not frequently observed for the generation of paralogs and in response to stress, (iii) the content of repetitive elements is strikingly low (<5%), (iv) L. corymbifera is typically haploid. Novel virulence factors were identified which may be involved in the regulation of the adaptation to iron-limitation, e.g. LCor01340.1 encoding a putative siderophore transporter and LCor00410.1 involved in the siderophore metabolism. Genes encoding the transcription factors LCor08192.1 and LCor01236.1, which are similar to GATA type regulators and to calcineurin regulated CRZ1, respectively, indicating an involvement of the calcineurin pathway in the adaption to iron limitation. Genes encoding MADS-box transcription factors are elevated up to 11 copies compared to the 1-4 copies usually found in other fungi. More findings are: (i) lower content of tRNAs, but unique codons in L. corymbifera, (ii) Over 25% of the proteins are apparently specific for L. corymbifera. (iii) L. corymbifera contains only 2/3 of the proteases (known to be essential virulence factors) in comparison to R. oryzae. On the other hand, the number of secreted proteases, however, is roughly twice as high as in R. oryzae.
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Affiliation(s)
- Volker U. Schwartze
- University of Jena, Institute of Microbiology, Department of Microbiology and Molecular Biology, Jena, Germany
- Leibniz Institute for Natural Product Research and Infection Biology, Department of Molecular and Applied Microbiology, Hans Knöll Institute, Jena, Germany
| | - Sascha Winter
- University of Jena, Department of Bioinformatics, Jena, Germany
| | - Ekaterina Shelest
- Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, Systems Biology/Bioinformatics, Jena, Germany
| | - Marina Marcet-Houben
- Centre for Genomic Regulation (CRG), Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Fabian Horn
- Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, Systems Biology/Bioinformatics, Jena, Germany
| | - Stefanie Wehner
- University of Jena, Department of Bioinformatics, Jena, Germany
| | - Jörg Linde
- Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, Systems Biology/Bioinformatics, Jena, Germany
| | - Vito Valiante
- Leibniz Institute for Natural Product Research and Infection Biology, Department of Molecular and Applied Microbiology, Hans Knöll Institute, Jena, Germany
| | - Michael Sammeth
- Centre Nacional d'Anàlisi Genòmica (CNAG), Functional Bioinformatics, Barcelona, Spain
- Laboratório Nacional de Computação Científica (LNCC), Petrópolis, Rio de Janeiro, Brazil
| | | | - Minou Nowrousian
- Ruhr University Bochum, Department of General and Molecular Botany, Bochum, Germany
| | - Kerstin Kaerger
- University of Jena, Institute of Microbiology, Department of Microbiology and Molecular Biology, Jena, Germany
- Leibniz Institute for Natural Product Research and Infection Biology, Department of Molecular and Applied Microbiology, Hans Knöll Institute, Jena, Germany
| | - Ilse D. Jacobsen
- Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, Department of Microbial Immunology, Jena, Germany
| | - Manja Marz
- University of Jena, Department of Bioinformatics, Jena, Germany
| | - Axel A. Brakhage
- University of Jena, Institute of Microbiology, Department of Microbiology and Molecular Biology, Jena, Germany
- Leibniz Institute for Natural Product Research and Infection Biology, Department of Molecular and Applied Microbiology, Hans Knöll Institute, Jena, Germany
| | - Toni Gabaldón
- Centre for Genomic Regulation (CRG), Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | | | - Kerstin Voigt
- University of Jena, Institute of Microbiology, Department of Microbiology and Molecular Biology, Jena, Germany
- Leibniz Institute for Natural Product Research and Infection Biology, Department of Molecular and Applied Microbiology, Hans Knöll Institute, Jena, Germany
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19
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Larcher G, Dias M, Razafimandimby B, Bomal D, Bouchara JP. Siderophore production by pathogenic mucorales and uptake of deferoxamine B. Mycopathologia 2013; 176:319-28. [PMID: 23982284 DOI: 10.1007/s11046-013-9693-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 08/07/2013] [Indexed: 01/05/2023]
Abstract
Clinical reports have established that mucormycosis, mainly caused by Rhizopus spp., frequently occurs in patients treated with deferoxamine B (DFO, Desferal(®)) which is misappropriated by these fungi. Siderophore production by twenty mucoralean isolates was therefore investigated using a commercial iron-depleted culture medium. Siderophore production was detected for most of the isolates. Our experiments confirmed that feroxamine B (iron chelate of DFO) promoted in vitro growth of Rhizopus arrhizus. Electrophoretic analysis of somatic extracts revealed iron-regulated proteins of 60 and 32 kDa which were lacking in iron-depleted culture conditions. Using a fluorescent derivative of deferoxamine B, we showed by fluorescence microscopy the entry of the siderophore within the fungal cells, thus suggesting a shuttle mechanism encompassing the uptake of the entire siderophore-ion complex into the cell. This useful tool renders possible a better understanding of iron metabolism in Mucorales which could lead to the development of new diagnostic method or new antifungal therapy using siderophores as imaging contrast agents or active drug vectors.
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Affiliation(s)
- Gérald Larcher
- Groupe d'Etude des Interactions Hôte-Pathogène, UPRES-EA 3142, Institut de Biologie en Santé, IRIS, Centre Hospitalier Universitaire, L'UNAM Université, Université d'Angers, 4, Rue Larrey, 49933, Angers Cédex, France,
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20
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Ibrahim AS, Spellberg B, Walsh TJ, Kontoyiannis DP. Pathogenesis of mucormycosis. Clin Infect Dis 2012; 54 Suppl 1:S16-22. [PMID: 22247441 DOI: 10.1093/cid/cir865] [Citation(s) in RCA: 427] [Impact Index Per Article: 35.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Mucormycosis is a life-threatening infection that occurs in patients who are immunocompromised because of diabetic ketoacidosis, neutropenia, organ transplantation, and/or increased serum levels of available iron. Because of the increasing prevalence of diabetes mellitus, cancer, and organ transplantation, the number of patients at risk for this deadly infection is increasing. Despite aggressive therapy, which includes disfiguring surgical debridement and frequently adjunctive toxic antifungal therapy, the overall mortality rate is high. New strategies to prevent and treat mucormycosis are urgently needed. Understanding the pathogenesis of mucormycosis and the host response to invading hyphae ultimately will provide targets for novel therapeutic interventions. In this supplement, we review the current knowledge about the virulence traits used by the most common etiologic agent of mucormycosis, Rhizopus oryzae. Because patients with elevated serum levels of available iron are uniquely susceptible to mucormycosis and these infections are highly angioinvasive, emphasis is placed on the ability of the organism to acquire iron from the host and on its interactions with endothelial cells lining blood vessels. Several promising therapeutic strategies in preclinical stages are identified.
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Affiliation(s)
- Ashraf S Ibrahim
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, University of California-Los Angeles, 1124 W Carson St., Torrance, CA 90502, USA.
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21
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Purification and structural characterization of siderophore (corynebactin) from Corynebacterium diphtheriae. PLoS One 2012; 7:e34591. [PMID: 22514641 PMCID: PMC3326035 DOI: 10.1371/journal.pone.0034591] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Accepted: 03/02/2012] [Indexed: 12/31/2022] Open
Abstract
During infection, Corynebacterium diphtheriae must compete with host iron-sequestering mechanisms for iron. C. diphtheriae can acquire iron by a siderophore-dependent iron-uptake pathway, by uptake and degradation of heme, or both. Previous studies showed that production of siderophore (corynebactin) by C. diphtheriae is repressed under high-iron growth conditions by the iron-activated diphtheria toxin repressor (DtxR) and that partially purified corynebactin fails to react in chemical assays for catecholate or hydroxamate compounds. In this study, we purified corynebactin from supernatants of low-iron cultures of the siderophore-overproducing, DtxR-negative mutant strain C. diphtheriae C7(β) ΔdtxR by sequential anion-exchange chromatography on AG1-X2 and Source 15Q resins, followed by reverse-phase high-performance liquid chromatography (RP-HPLC) on Zorbax C8 resin. The Chrome Azurol S (CAS) chemical assay for siderophores was used to detect and measure corynebactin during purification, and the biological activity of purified corynebactin was shown by its ability to promote growth and iron uptake in siderophore-deficient mutant strains of C. diphtheriae under iron-limiting conditions. Mass spectrometry and NMR analysis demonstrated that corynebactin has a novel structure, consisting of a central lysine residue linked through its α- and ε- amino groups by amide bonds to the terminal carboxyl groups of two different citrate residues. Corynebactin from C. diphtheriae is structurally related to staphyloferrin A from Staphylococcus aureus and rhizoferrin from Rhizopus microsporus in which d-ornithine or 1,4-diaminobutane, respectively, replaces the central lysine residue that is present in corynebactin.
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22
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Ibrahim AS, Gebremariam T, Lin L, Luo G, Husseiny MI, Skory CD, Fu Y, French SW, Edwards JE, Spellberg B. The high affinity iron permease is a key virulence factor required for Rhizopus oryzae pathogenesis. Mol Microbiol 2010; 77:587-604. [PMID: 20545847 DOI: 10.1111/j.1365-2958.2010.07234.x] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Rhizopus oryzae is the most common cause of mucormycosis, an angioinvasive fungal infection that causes more then 50% mortality rate despite first-line therapy. Clinical and animal model data clearly demonstrate that the presence of elevated available serum iron predisposes the host to mucormycosis. The high affinity iron permease gene (FTR1) is required for R. oryzae iron transport in iron-depleted environments. Here we demonstrate that FTR1 is required for full virulence of R. oryzae in mice. We show that FTR1 is expressed during infection in diabetic ketoacidosis (DKA) mice. In addition, we disrupted FTR1 by double cross-over homologous recombination, but multinucleated R. oryzae could not be forced to segregate to a homokaryotic null allele. Nevertheless, a reduction of the relative copy number of FTR1 and inhibition of FTR1 expression by RNAi compromised the ability of R. oryzae to acquire iron in vitro and reduced its virulence in DKA mice. Importantly, passive immunization with anti-Ftr1p immune sera protected DKA mice from infection with R. oryzae. Thus, FTR1 is a virulence factor for R. oryzae, and anti-Ftr1p passive immunotherapy deserves further evaluation as a strategy to improve outcomes of deadly mucormycosis.
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Affiliation(s)
- Ashraf S Ibrahim
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-University of California Los Angeles (UCLA) Medical Center, Torrance, CA, USA.
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23
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Holinsworth B, Martin JD. Siderophore production by marine-derived fungi. Biometals 2009; 22:625-32. [PMID: 19350395 PMCID: PMC2706916 DOI: 10.1007/s10534-009-9239-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Accepted: 03/23/2009] [Indexed: 10/20/2022]
Abstract
Siderophore production by marine-derived fungi has not been extensively explored. Three studies have investigated the ability of marine-derived fungi to produce siderophores in response to iron limitation [(Vala et al. in Indian J Mar Sci 29:339-340, 2000; Can J Microbiol 52:603-607, 2006); Baakza et al. in J Exp Mar Biol Ecol 311:1-9, 2004]. In all, 24 of 28 marine fungal strains were found to secrete hydroxamate or carboxylate siderophores; no evidence was found for production of catecholate siderophores. These studies did not determine the structures of the iron-binding compounds. More recently, a study of the natural products secreted by a marine Penicillium bilaii revealed that this strain produced the rare catecholate siderophore pistillarin when grown under relatively high iron concentrations (Capon et al. J Nat Prod 70:1746-1752, 2007). Additionally, the production of rhizoferrin by a marine isolate of Cunninghamella elegans (ATCC36112) is reported in this manuscript. The current state of knowledge about marine fungal siderophores is reviewed in light of these promising results.
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Affiliation(s)
- Brian Holinsworth
- Department of Natural Sciences, Northeastern State University, 611 N. Grand Ave., Tahlequah, OK 74464
| | - Jessica D. Martin
- Department of Natural Sciences, Northeastern State University, 611 N. Grand Ave., Tahlequah, OK 74464
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24
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Ibrahim AS, Spellberg B, Edwards J. Iron acquisition: a novel perspective on mucormycosis pathogenesis and treatment. Curr Opin Infect Dis 2008; 21:620-5. [PMID: 18978530 DOI: 10.1097/qco.0b013e3283165fd1] [Citation(s) in RCA: 168] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
PURPOSE OF REVIEW Mucormycosis is an increasingly common fungal infection with an unacceptably high mortality despite first-line antifungal therapy. Iron acquisition is a critical step in the causative organisms' pathogenetic mechanism. Therefore, abrogation of fungal iron acquisition is a promising therapeutic strategy to impact clinical outcomes for this deadly disease. RECENT FINDINGS The increased risk of mucormycosis in patients with renal failure receiving deferoxamine iron chelation therapy is explained by the fact that deferoxamine actually acts as a siderophore for the agents of mucormycosis, supplying previously unavailable iron to the fungi. The iron liberated from deferoxamine is likely transported into the fungus by the high-affinity iron permease. In contrast, two other iron chelators, deferiprone and deferasirox, do not supply iron to the fungus and were shown to be cidal against Zygomycetes in vitro. Further, both iron chelators were shown to effectively treat mucormycosis in animal models, and one has been successfully used as salvage therapy for a patient with rhinocerebral mucormycosis. SUMMARY Further investigation and development of iron chelators as adjunctive therapy for mucormycosis is warranted.
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Affiliation(s)
- Ashraf S Ibrahim
- Division of Infectious Diseases, Harbor-UCLA Medical Center, 1124 West Carson St, RB2, Torrance, CA 90502, USA.
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25
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Oide S, Krasnoff SB, Gibson DM, Turgeon BG. Intracellular siderophores are essential for ascomycete sexual development in heterothallic Cochliobolus heterostrophus and homothallic Gibberella zeae. EUKARYOTIC CELL 2007; 6:1339-53. [PMID: 17601875 PMCID: PMC1951124 DOI: 10.1128/ec.00111-07] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Connections between fungal development and secondary metabolism have been reported previously, but as yet, no comprehensive analysis of a family of secondary metabolites and their possible role in fungal development has been reported. In the present study, mutant strains of the heterothallic ascomycete Cochliobolus heterostrophus, each lacking one of 12 genes (NPS1 to NPS12) encoding a nonribosomal peptide synthetase (NRPS), were examined for a role in sexual development. One type of strain (Delta nps2) was defective in ascus/ascospore development in homozygous Delta nps2 crosses. Homozygous crosses of the remaining 11 Delta nps strains showed wild-type (WT) fertility. Phylogenetic, expression, and biochemical analyses demonstrated that the NRPS encoded by NPS2 is responsible for the biosynthesis of ferricrocin, the intracellular siderophore of C. heterostrophus. Functional conservation of NPS2 in both heterothallic C. heterostrophus and the unrelated homothallic ascomycete Gibberella zeae was demonstrated. G. zeae Delta nps2 strains are concomitantly defective in intracellular siderophore (ferricrocin) biosynthesis and sexual development. Exogenous application of iron partially restored fertility to C. heterostrophus and G. zeae Delta nps2 strains, demonstrating that abnormal sexual development of Delta nps2 strains is at least partly due to their iron deficiency. Exogenous application of the natural siderophore ferricrocin to C. heterostrophus and G. zeae Delta nps2 strains restored WT fertility. NPS1, a G. zeae NPS gene that groups phylogenetically with NPS2, does not play a role in sexual development. Overall, these data demonstrate that iron and intracellular siderophores are essential for successful sexual development of the heterothallic ascomycete C. heterostrophus and the homothallic ascomycete G. zeae.
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Affiliation(s)
- Shinichi Oide
- Department of Plant Pathology and Plant-Microbe Biology, 334 Plant Science Bldg., Cornell University, Ithaca, NY 14853, USA
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26
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Sullivan JT, Jeffery EF, Shannon JD, Ramakrishnan G. Characterization of the siderophore of Francisella tularensis and role of fslA in siderophore production. J Bacteriol 2006; 188:3785-95. [PMID: 16707671 PMCID: PMC1482922 DOI: 10.1128/jb.00027-06] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We determined that LVS and Schu S4 strains of the human pathogen Francisella tularensis express a siderophore when grown under iron-limiting conditions. We purified this siderophore by conventional column chromatography and high-pressure liquid chromatography and used mass spectrometric analysis to demonstrate that it is structurally similar to the polycarboxylate siderophore rhizoferrin. The siderophore promoted the growth of LVS and Schu S4 strains in iron-limiting media. We identified a potential siderophore biosynthetic gene cluster encoded by fslABCD in the F. tularensis genome. The first gene in the cluster, fslA, encodes a member of the superfamily of nonribosomal peptide synthetase-independent siderophore synthetases (NIS synthetases) characterized by the aerobactin synthetases IucA and IucC. We determined that fslA is transcribed as part of an operon with downstream gene fslB and that the expression of the locus is induced by iron starvation. A targeted in-frame nonpolar deletion of fslA in LVS resulted in the loss of siderophore expression and in a reduced ability of F. tularensis to grow under conditions of iron limitation. Siderophore activity and the ability to grow under iron limitation could be regained by introducing the fslA(+) gene on a complementing plasmid. Our results suggest that the fslA-dependent siderophore is important for survival of F. tularensis in an iron-deficient environment.
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Affiliation(s)
- Jonathan Tabb Sullivan
- University of Virginia Health System, MR4 Bldg., Rm. 2126, P.O. Box 801367, Charlottesville, VA 22908-5621, USA
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Tanabe T, Funahashi T, Nakao H, Miyoshi SI, Shinoda S, Yamamoto S. Identification and characterization of genes required for biosynthesis and transport of the siderophore vibrioferrin in Vibrio parahaemolyticus. J Bacteriol 2004; 185:6938-49. [PMID: 14617658 PMCID: PMC262695 DOI: 10.1128/jb.185.23.6938-6949.2003] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In response to low iron availability, Vibrio parahaemolyticus synthesizes and secretes a polyhydroxycarboxylate-type siderophore vibrioferrin which is composed of 1 mol each of 2-ketoglutaric acid, L-alanine, ethanolamine, and citric acid. We have previously reported the cloning and characterization of the pvuA gene, which encodes the 78-kDa outer membrane receptor protein for ferric vibrioferrin. In this study, nine genes involved in the biosynthesis and transport of vibrioferrin have been identified in the genomic regions surrounding the pvuA gene. The genes were sequenced, and gene disruptants were constructed by insertion mutation for phenotype analysis. Five of the genes, named pvsABCDE, constitute an operon that is expressed under iron-limiting conditions. Homology searches of their predicted protein products suggested that the four genes pvsABDE are implicated in the biosynthesis of the siderophore. Another gene in the same operon, pvsC, encodes a putative exporter that is homologous to members of the major facilitator superfamily of multidrug efflux pumps. The remaining four genes, named pvuBCDE, encode proteins strongly homologous to Escherichia coli FecBCDE, respectively, which are components of the ATP-binding cassette transporter system for ferric dicitrate. Reverse transcriptase PCR analysis revealed that these transport genes are transcribed as a single mRNA with the upstream genes, psuA and pvuA. Phenotypic comparison between the wild-type strain and its targeted gene disruptants supported the biological functions for the respective operons that were expected on the basis of the homology search.
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Affiliation(s)
- Tomotaka Tanabe
- Faculty of Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
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Drechsel H, Thieken A, Reissbrodt R, Jung G, Winkelmann G. Alpha-keto acids are novel siderophores in the genera Proteus, Providencia, and Morganella and are produced by amino acid deaminases. J Bacteriol 1993; 175:2727-33. [PMID: 8478334 PMCID: PMC204576 DOI: 10.1128/jb.175.9.2727-2733.1993] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Growth promotion and iron transport studies revealed that certain alpha-keto acids generated by amino acid deaminases, by enterobacteria of the Proteus-Providencia-Morganella group (of the tribe Proteeae), show significant siderophore activity. Their iron-binding properties were confirmed by the chrome azurol S assay and UV spectra. These compounds form ligand-to-metal charge transfer bands in the range of 400 to 500 nm. Additional absorption bands of the enolized ligands at 500 to 700 nm are responsible for color formation. Siderophore activity was most pronounced with alpha-keto acids possessing an aromatic or heteroaromatic side chain, like phenylpyruvic acid and indolylpyruvic acid, resulting from deamination of phenylalanine and tryptophan, respectively. In addition, alpha-keto acids possessing longer nonpolar side chains, like alpha-ketoisocaproic acid or alpha-ketoisovaleric acid and even alpha-ketoadipic acid, also showed siderophore activity which was absent or negligible with smaller alpha-keto acids or those possessing polar functional groups, like pyruvic acid, alpha-ketobutyric acid, or alpha-ketoglutaric acid. The fact that deaminase-negative enterobacteria, like Escherichia coli and Salmonella spp., could not utilize alpha-keto acids supports the view that specific iron-carboxylate transport systems have evolved in members of the tribe Proteeae and are designed to recognize ferric complexes of both alpha-hydroxy acids and alpha-keto acids, of which the latter can easily be generated by L-amino acid deaminases in an amino acid-rich medium. Exogenous siderophores, like ferric hydroxamates (ferrichromes) and ferric polycarboxylates (rhizoferrin and citrate), were also utilized by members of the tribe Proteeae.
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Affiliation(s)
- H Drechsel
- Institut für Organische Chemie, Universität Tübingen, Germany
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Drechsel H, Freund S, Nicholson G, Haag H, Jung O, Zähner H, Jung G. Purification and chemical characterization of staphyloferrin B, a hydrophilic siderophore from staphylococci. Biometals 1993; 6:185-92. [PMID: 8400765 DOI: 10.1007/bf00205858] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
This paper describes the chemical characterization of staphyloferrin B, a new complexone type siderophore isolated from low iron cultures of Staphylococcus hyicus DSM 20459. Purification of the very hydrophilic metabolite was achieved by anion exchange high performance liquid chromatography HPLC. Mass spectrometry showed a molecular mass of 448 amu. Hydrolysis with 8 M HCl revealed the presence of L-2,3-diaminopropionic acid, citrate, ethylenediamine and succinic semialdehyde. The connections between the four building blocks were determined by two-dimensional nuclear magnetic resonance measurements. UV/Vis and circular dichroism spectra are consistent with the proposed structure, which could also be confirmed by precursor feeding. The siderophore activity of staphyloferrin B was demonstrated by iron transport measurements.
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Affiliation(s)
- H Drechsel
- Organische Chemie I, Universitat Tübingen, Germany
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