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Sepúlveda VE, Goldman WE, Matute DR. Genotypic diversity, virulence, and molecular genetic tools in Histoplasma. Microbiol Mol Biol Rev 2024; 88:e0007623. [PMID: 38819148 PMCID: PMC11332355 DOI: 10.1128/mmbr.00076-23] [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] [Indexed: 06/01/2024] Open
Abstract
SUMMARYHistoplasmosis is arguably the most common fungal respiratory infection worldwide, with hundreds of thousands of new infections occurring annually in the United States alone. The infection can progress in the lung or disseminate to visceral organs and can be difficult to treat with antifungal drugs. Histoplasma, the causative agent of the disease, is a pathogenic fungus that causes life-threatening lung infections and is globally distributed. The fungus has the ability to germinate from conidia into either hyphal (mold) or yeast form, depending on the environmental temperature. This transition also regulates virulence. Histoplasma and histoplasmosis have been classified as being of emergent importance, and in 2022, the World Health Organization included Histoplasma as 1 of the 19 most concerning human fungal pathogens. In this review, we synthesize the current understanding of the ecological niche, evolutionary history, and virulence strategies of Histoplasma. We also describe general patterns of the symptomatology and epidemiology of histoplasmosis. We underscore areas where research is sorely needed and highlight research avenues that have been productive.
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Affiliation(s)
- Victoria E. Sepúlveda
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - William E. Goldman
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Daniel R. Matute
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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Azimova D, Herrera N, Duvenage L, Voorhies M, Rodriguez RA, English BC, Hoving JC, Rosenberg O, Sil A. Cbp1, a fungal virulence factor under positive selection, forms an effector complex that drives macrophage lysis. PLoS Pathog 2022; 18:e1010417. [PMID: 35731824 PMCID: PMC9255746 DOI: 10.1371/journal.ppat.1010417] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 07/05/2022] [Accepted: 03/07/2022] [Indexed: 12/03/2022] Open
Abstract
Intracellular pathogens secrete effectors to manipulate their host cells. Histoplasma capsulatum (Hc) is a fungal intracellular pathogen of humans that grows in a yeast form in the host. Hc yeasts are phagocytosed by macrophages, where fungal intracellular replication precedes macrophage lysis. The most abundant virulence factor secreted by Hc yeast cells is Calcium Binding Protein 1 (Cbp1), which is absolutely required for macrophage lysis. Here we take an evolutionary, structural, and cell biological approach to understand Cbp1 function. We find that Cbp1 is present only in the genomes of closely related dimorphic fungal species of the Ajellomycetaceae family that lead primarily intracellular lifestyles in their mammalian hosts (Histoplasma, Paracoccidioides, and Emergomyces), but not conserved in the extracellular fungal pathogen Blastomyces dermatitidis. We observe a high rate of fixation of non-synonymous substitutions in the Cbp1 coding sequences, indicating that Cbp1 is under positive selection. We determine the de novo structures of Hc H88 Cbp1 and the Paracoccidioides americana (Pb03) Cbp1, revealing a novel "binocular" fold consisting of a helical dimer arrangement wherein two helices from each monomer contribute to a four-helix bundle. In contrast to Pb03 Cbp1, we show that Emergomyces Cbp1 orthologs are unable to stimulate macrophage lysis when expressed in the Hc cbp1 mutant. Consistent with this result, we find that wild-type Emergomyces africanus yeast are able to grow within primary macrophages but are incapable of lysing them. Finally, we use subcellular fractionation of infected macrophages and indirect immunofluorescence to show that Cbp1 localizes to the macrophage cytosol during Hc infection, making this the first instance of a phagosomal human fungal pathogen directing an effector into the cytosol of the host cell. We additionally show that Cbp1 forms a complex with Yps-3, another known Hc virulence factor that accesses the cytosol. Taken together, these data imply that Cbp1 is a fungal virulence factor under positive selection that localizes to the cytosol to trigger host cell lysis.
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Affiliation(s)
- Dinara Azimova
- University of California San Francisco, San Francisco, California, United States of America
| | - Nadia Herrera
- University of California San Francisco, San Francisco, California, United States of America
| | - Lucian Duvenage
- AFRICA Medical Mycology Research Unit, Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, Cape Town, South Africa
| | - Mark Voorhies
- University of California San Francisco, San Francisco, California, United States of America
| | - Rosa A. Rodriguez
- University of California San Francisco, San Francisco, California, United States of America
| | - Bevin C. English
- University of California Davis, Davis, California, United States of America
| | - Jennifer C. Hoving
- AFRICA Medical Mycology Research Unit, Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, Cape Town, South Africa
| | - Oren Rosenberg
- University of California San Francisco, San Francisco, California, United States of America
| | - Anita Sil
- University of California San Francisco, San Francisco, California, United States of America
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Bakuła Z, Siedlecki P, Gromadka R, Gawor J, Gromadka A, Pomorski JJ, Panagiotopoulou H, Jagielski T. A first insight into the genome of Prototheca wickerhamii, a major causative agent of human protothecosis. BMC Genomics 2021; 22:168. [PMID: 33750287 PMCID: PMC7941945 DOI: 10.1186/s12864-021-07491-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 02/26/2021] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Colourless microalgae of the Prototheca genus are the only known plants that have consistently been implicated in a range of clinically relevant opportunistic infections in both animals and humans. The Prototheca algae are emerging pathogens, whose incidence has increased importantly over the past two decades. Prototheca wickerhamii is a major human pathogen, responsible for at least 115 cases worldwide. Although the algae are receiving more attention nowadays, there is still a substantial knowledge gap regarding their biology, and pathogenicity in particular. Here we report, for the first time, the complete nuclear genome, organelle genomes, and transcriptome of the P. wickerhamii type strain ATCC 16529. RESULTS The assembled genome size was of 16.7 Mbp, making it the smallest and most compact genome sequenced so far among the protothecans. Key features of the genome included a high overall GC content (64.5%), a high number (6081) and proportion (45.9%) of protein-coding genes, and a low repetitive sequence content (2.2%). The vast majority (90.6%) of the predicted genes were confirmed with the corresponding transcripts upon RNA-sequencing analysis. Most (93.2%) of the genes had their putative function assigned when searched against the InterProScan database. A fourth (23.3%) of the genes were annotated with an enzymatic activity possibly associated with the adaptation to the human host environment. The P. wickerhamii genome encoded a wide array of possible virulence factors, including those already identified in two model opportunistic fungal pathogens, i.e. Candida albicans and Trichophyton rubrum, and thought to be involved in invasion of the host or elicitation of the adaptive stress response. Approximately 6% of the P. wickerhamii genes matched a Pathogen-Host Interaction Database entry and had a previously experimentally proven role in the disease development. Furthermore, genes coding for proteins (e.g. ATPase, malate dehydrogenase) hitherto considered as potential virulence factors of Prototheca spp. were demonstrated in the P. wickerhamii genome. CONCLUSIONS Overall, this study is the first to describe the genetic make-up of P. wickerhamii and discovers proteins possibly involved in the development of protothecosis.
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Affiliation(s)
- Zofia Bakuła
- Department of Medical Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, I. Miecznikowa 1, 02-096, Warsaw, Poland
| | - Paweł Siedlecki
- Department of Systems Biology, University of Warsaw, I. Miecznikowa 1, 02-096, Warsaw, Poland.,Department of Bioinformatics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, A. Pawińskiego 5a, 02-106, Warsaw, Poland
| | - Robert Gromadka
- DNA Sequencing and Synthesis Facility, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, A. Pawińskiego 5a, 02-106, Warsaw, Poland
| | - Jan Gawor
- DNA Sequencing and Synthesis Facility, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, A. Pawińskiego 5a, 02-106, Warsaw, Poland
| | - Agnieszka Gromadka
- Department of Bioinformatics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, A. Pawińskiego 5a, 02-106, Warsaw, Poland
| | - Jan J Pomorski
- Museum and Institute of Zoology, Polish Academy of Sciences, Wilcza 64, 00-679, Warsaw, Poland
| | - Hanna Panagiotopoulou
- Museum and Institute of Zoology, Polish Academy of Sciences, Wilcza 64, 00-679, Warsaw, Poland
| | - Tomasz Jagielski
- Department of Medical Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, I. Miecznikowa 1, 02-096, Warsaw, Poland.
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Min B, Yoon H, Park J, Oh YL, Kong WS, Kim JG, Choi IG. Unusual genome expansion and transcription suppression in ectomycorrhizal Tricholoma matsutake by insertions of transposable elements. PLoS One 2020; 15:e0227923. [PMID: 31978083 PMCID: PMC6980582 DOI: 10.1371/journal.pone.0227923] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 01/02/2020] [Indexed: 12/15/2022] Open
Abstract
Genome sequencing of Tricholoma matsutake revealed its unusually large size as 189.0 Mbp, which is a consequence of extraordinarily high transposable element (TE) content. We identified that 702 genes were surrounded by TEs, and 83.2% of these genes were not transcribed at any developmental stage. This observation indicated that the insertion of TEs alters the transcription of the genes neighboring these TEs. Repeat-induced point mutation, such as C to T hypermutation with a bias over "CpG" dinucleotides, was also recognized in this genome, representing a typical defense mechanism against TEs during evolution. Many transcription factor genes were activated in both the primordia and fruiting body stages, which indicates that many regulatory processes are shared during the developmental stages. Small secreted protein genes (<300 aa) were dominantly transcribed in the hyphae, where symbiotic interactions occur with the hosts. Comparative analysis with 37 Agaricomycetes genomes revealed that IstB-like domains (PF01695) were conserved across taxonomically diverse mycorrhizal genomes, where the T. matsutake genome contained four copies of this domain. Three of the IstB-like genes were overexpressed in the hyphae. Similar to other ectomycorrhizal genomes, the CAZyme gene set was reduced in T. matsutake, including losses in the glycoside hydrolase genes. The T. matsutake genome sequence provides insight into the causes and consequences of genome size inflation.
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Affiliation(s)
- Byoungnam Min
- Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, Korea
| | - Hyeokjun Yoon
- School of Life Sciences and Biotechnology, College of Natural Sciences, Kyungpook National University, Daegu, Korea
| | - Julius Park
- Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, Korea
| | - Youn-Lee Oh
- Mushroom Research Division, National Institute of Horticulture and Herbal Science (NIHHS), Rural Development Administration (RDA), Eumseong, Korea
| | - Won-Sik Kong
- Mushroom Research Division, National Institute of Horticulture and Herbal Science (NIHHS), Rural Development Administration (RDA), Eumseong, Korea
- * E-mail: (IC); (WK); (JK)
| | - Jong-Guk Kim
- School of Life Sciences and Biotechnology, College of Natural Sciences, Kyungpook National University, Daegu, Korea
- * E-mail: (IC); (WK); (JK)
| | - In-Geol Choi
- Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, Korea
- * E-mail: (IC); (WK); (JK)
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Fillinger RJ, Anderson MZ. Seasons of change: Mechanisms of genome evolution in human fungal pathogens. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2019; 70:165-174. [PMID: 30826447 DOI: 10.1016/j.meegid.2019.02.031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 02/23/2019] [Accepted: 02/26/2019] [Indexed: 06/09/2023]
Abstract
Fungi are a diverse kingdom of organisms capable of thriving in various niches across the world including those in close association with multicellular eukaryotes. Fungal pathogens that contribute to human disease reside both within the host as commensal organisms of the microbiota and the environment. Their niche of origin dictates how infection initiates but also places specific selective pressures on the fungal pathogen that contributes to its genome organization and genetic repertoire. Recent efforts to catalogue genomic variation among major human fungal pathogens have unveiled evolutionary themes that shape the fungal genome. Mechanisms ranging from large scale changes such as aneuploidy and ploidy cycling as well as more targeted mutations like base substitutions and gene copy number variations contribute to the evolution of these species, which are often under multiple competing selective pressures with their host, environment, and other microbes. Here, we provide an overview of the major selective pressures and mechanisms acting to evolve the genome of clinically important fungal pathogens of humans.
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Affiliation(s)
- Robert J Fillinger
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH 43210, USA
| | - Matthew Z Anderson
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH 43210, USA; Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA.
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English BC, Van Prooyen N, Örd T, Örd T, Sil A. The transcription factor CHOP, an effector of the integrated stress response, is required for host sensitivity to the fungal intracellular pathogen Histoplasma capsulatum. PLoS Pathog 2017; 13:e1006589. [PMID: 28953979 PMCID: PMC5633207 DOI: 10.1371/journal.ppat.1006589] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 10/09/2017] [Accepted: 08/17/2017] [Indexed: 02/06/2023] Open
Abstract
The ability of intracellular pathogens to manipulate host-cell viability is critical to successful infection. Some pathogens promote host-cell survival to protect their replicative niche, whereas others trigger host-cell death to facilitate release and dissemination of the pathogen after intracellular replication has occurred. We previously showed that the intracellular fungal pathogen Histoplasma capsulatum (Hc) uses the secreted protein Cbp1 to actively induce apoptosis in macrophages; interestingly, cbp1 mutant strains are unable to kill macrophages and display severely reduced virulence in the mouse model of Hc infection. To elucidate the mechanism of Cbp1-induced host-cell death, we performed a comprehensive alanine scanning mutagenesis and identified all amino acid residues that are required for Cbp1 to trigger macrophage lysis. Here we demonstrate that Hc strains expressing lytic CBP1 alleles activate the integrated stress response (ISR) in infected macrophages, as indicated by an increase in eIF2α phosphorylation as well as induction of the transcription factor CHOP and the pseudokinase Tribbles 3 (TRIB3). In contrast, strains bearing a non-lytic allele of CBP1 fail to activate the ISR, whereas a partially lytic CBP1 allele triggers intermediate levels of activation. We further show that macrophages deficient for CHOP or TRIB3 are partially resistant to lysis during Hc infection, indicating that the ISR is critical for susceptibility to Hc-mediated cell death. Moreover, we show that CHOP-dependent macrophage lysis is critical for efficient spread of Hc infection to other macrophages. Notably, CHOP knockout mice display reduced macrophage apoptosis and diminished fungal burden and are markedly resistant to Hc infection. Together, these data indicate that Cbp1 is required for Hc to induce the ISR and mediate a CHOP-dependent virulence pathway in the host. Histoplasma capsulatum is the causative agent of histoplasmosis, a fungal infection that can be fatal in a wide range of mammalian hosts, including otherwise healthy, immunocompetent individuals. Histoplasma cells replicate to very high levels within host macrophages, eventually causing macrophage death and the release of live fungal cells. Here, we show that Histoplasma yeast use the secreted protein Cbp1 to activate a specific signaling pathway in the host cell to cause macrophage death during infection. Importantly, this signaling cascade is essential for pathogenesis, and mice deficient for a central component of this pathway are resistant to Histoplasma infection. Our study is the first demonstration that Histoplasma employs a secreted effector to alter host signaling pathways to promote virulence, and thus provides key insight into the pathogenesis strategies of this important human fungal pathogen.
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Affiliation(s)
- Bevin C. English
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, California, United States of America
| | - Nancy Van Prooyen
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, California, United States of America
- FLX Bio, South San Francisco, California, United States of America
| | - Tiit Örd
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
- Estonian Biocentre, Tartu, Estonia
| | | | - Anita Sil
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, California, United States of America
- * E-mail:
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Hernández-Chávez MJ, Pérez-García LA, Niño-Vega GA, Mora-Montes HM. Fungal Strategies to Evade the Host Immune Recognition. J Fungi (Basel) 2017; 3:jof3040051. [PMID: 29371567 PMCID: PMC5753153 DOI: 10.3390/jof3040051] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 09/18/2017] [Accepted: 09/19/2017] [Indexed: 12/23/2022] Open
Abstract
The recognition of fungal cells by the host immune system is key during the establishment of a protective anti-fungal response. Even though the immune system has evolved a vast number of processes to control these organisms, they have developed strategies to fight back, avoiding the proper recognition by immune components and thus interfering with the host protective mechanisms. Therefore, the strategies to evade the immune system are as important as the virulence factors and attributes that damage the host tissues and cells. Here, we performed a thorough revision of the main fungal tactics to escape from the host immunosurveillance processes. These include the composition and organization of the cell wall, the fungal capsule, the formation of titan cells, biofilms, and asteroid bodies; the ability to undergo dimorphism; and the escape from nutritional immunity, extracellular traps, phagocytosis, and the action of humoral immune effectors.
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Affiliation(s)
- Marco J Hernández-Chávez
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta s/n, col. Noria Alta, C.P., Guanajuato Gto. 36050, México.
| | - Luis A Pérez-García
- Unidad Académica Multidisciplinaria Zona Huasteca, Universidad Autónoma de San Luis Potosí, Romualdo del Campo 501, Fracc. Rafael Curiel, C.P., Cd. Valle SLP. 79060, México.
| | - Gustavo A Niño-Vega
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta s/n, col. Noria Alta, C.P., Guanajuato Gto. 36050, México.
| | - Héctor M Mora-Montes
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta s/n, col. Noria Alta, C.P., Guanajuato Gto. 36050, México.
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Fungal Dimorphism and Virulence: Molecular Mechanisms for Temperature Adaptation, Immune Evasion, and In Vivo Survival. Mediators Inflamm 2017. [PMID: 28626345 PMCID: PMC5463121 DOI: 10.1155/2017/8491383] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The thermally dimorphic fungi are a unique group of fungi within the Ascomycota phylum that respond to shifts in temperature by converting between hyphae (22–25°C) and yeast (37°C). This morphologic switch, known as the phase transition, defines the biology and lifestyle of these fungi. The conversion to yeast within healthy and immunocompromised mammalian hosts is essential for virulence. In the yeast phase, the thermally dimorphic fungi upregulate genes involved with subverting host immune defenses. This review highlights the molecular mechanisms governing the phase transition and recent advances in how the phase transition promotes infection.
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Revisiting old friends: Developments in understanding Histoplasma capsulatum pathogenesis. J Microbiol 2016; 54:265-76. [DOI: 10.1007/s12275-016-6044-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 02/02/2016] [Indexed: 12/27/2022]
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Isaac DT, Berkes CA, English BC, Murray DH, Lee YN, Coady A, Sil A. Macrophage cell death and transcriptional response are actively triggered by the fungal virulence factor Cbp1 during H. capsulatum infection. Mol Microbiol 2015; 98:910-929. [PMID: 26288377 PMCID: PMC5002445 DOI: 10.1111/mmi.13168] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/12/2015] [Indexed: 01/10/2023]
Abstract
Microbial pathogens induce or inhibit death of host cells during infection, with significant consequences for virulence and disease progression. Death of an infected host cell can either facilitate release and dissemination of intracellular pathogens or promote pathogen clearance. Histoplasma capsulatum is an intracellular fungal pathogen that replicates robustly within macrophages and triggers macrophage lysis by unknown means. To identify H. capsulatum effectors of macrophage lysis, we performed a genetic screen and discovered three mutants that grew to wild-type levels within macrophages but failed to elicit host-cell death. Each mutant was defective in production of the previously identified secreted protein Cbp1 (calcium-binding protein 1), whose role in intracellular growth had not been fully investigated. We found that Cbp1 was dispensable for high levels of intracellular growth but required to elicit a unique transcriptional signature in macrophages, including genes whose induction was previously associated with endoplasmic reticulum stress and host-cell death. Additionally, Cbp1 was required for activation of cell-death caspases-3/7, and macrophage death during H. capsulatum infection was dependent on the pro-apoptotic proteins Bax and Bak. Taken together, these findings strongly suggest that the ability of Cbp1 to actively program host-cell death is an essential step in H. capsulatum pathogenesis.
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Affiliation(s)
- Dervla T. Isaac
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA 94143-0414
| | - Charlotte A. Berkes
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA 94143-0414
- Department of Biology, Merrimack College, North Andover, MA
| | - Bevin C. English
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA 94143-0414
| | - Davina Hocking Murray
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA 94143-0414
| | - Young Nam Lee
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA 94143-0414
| | - Alison Coady
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA 94143-0414
| | - Anita Sil
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA 94143-0414
- Howard Hughes Medical Institute, San Francisco, CA
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Wodak SJ, Malevanets A, MacKinnon SS. The Landscape of Intertwined Associations in Homooligomeric Proteins. Biophys J 2015; 109:1087-100. [PMID: 26340815 DOI: 10.1016/j.bpj.2015.08.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 06/06/2015] [Accepted: 08/03/2015] [Indexed: 01/22/2023] Open
Abstract
We present an overview of the full repertoire of intertwined associations in homooligomeric proteins. This overview summarizes recent findings on the different categories of intertwined associations in known protein structures, their assembly modes, the properties of their interfaces, and their structural plasticity. Furthermore, the current body of knowledge on the so-called three-dimensional domain-swapped systems is reexamined in the context of the wider landscape of intertwined homooligomers, with a particular focus on the mechanistic aspects that underpin intertwined self-association processes in proteins. Insights gained from this integrated overview into the physical and biological roles of intertwining are highlighted.
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Affiliation(s)
- Shoshana J Wodak
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada; Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada; VIB Structural Biology Research Center, Brussels, Belgium.
| | | | - Stephen S MacKinnon
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada; Cyclica, Inc., Toronto, Ontario, Canada
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Boyce KJ, Andrianopoulos A. Fungal dimorphism: the switch from hyphae to yeast is a specialized morphogenetic adaptation allowing colonization of a host. FEMS Microbiol Rev 2015; 39:797-811. [DOI: 10.1093/femsre/fuv035] [Citation(s) in RCA: 131] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/02/2015] [Indexed: 01/19/2023] Open
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Polvi EJ, Li X, O’Meara TR, Leach MD, Cowen LE. Opportunistic yeast pathogens: reservoirs, virulence mechanisms, and therapeutic strategies. Cell Mol Life Sci 2015; 72:2261-87. [PMID: 25700837 PMCID: PMC11113693 DOI: 10.1007/s00018-015-1860-z] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Revised: 02/06/2015] [Accepted: 02/11/2015] [Indexed: 12/21/2022]
Abstract
Life-threatening invasive fungal infections are becoming increasingly common, at least in part due to the prevalence of medical interventions resulting in immunosuppression. Opportunistic fungal pathogens of humans exploit hosts that are immunocompromised, whether by immunosuppression or genetic predisposition, with infections originating from either commensal or environmental sources. Fungal pathogens are armed with an arsenal of traits that promote pathogenesis, including the ability to survive host physiological conditions and to switch between different morphological states. Despite the profound impact of fungal pathogens on human health worldwide, diagnostic strategies remain crude and treatment options are limited, with resistance to antifungal drugs on the rise. This review will focus on the global burden of fungal infections, the reservoirs of these pathogens, the traits of opportunistic yeast that lead to pathogenesis, host genetic susceptibilities, and the challenges that must be overcome to combat antifungal drug resistance and improve clinical outcome.
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Affiliation(s)
- Elizabeth J. Polvi
- Department of Molecular Genetics, University of Toronto, 1 King’s College Circle, Medical Sciences Building, Room 4368, Toronto, ON M5S 1A8 Canada
| | - Xinliu Li
- Department of Molecular Genetics, University of Toronto, 1 King’s College Circle, Medical Sciences Building, Room 4368, Toronto, ON M5S 1A8 Canada
| | - Teresa R. O’Meara
- Department of Molecular Genetics, University of Toronto, 1 King’s College Circle, Medical Sciences Building, Room 4368, Toronto, ON M5S 1A8 Canada
| | - Michelle D. Leach
- Department of Molecular Genetics, University of Toronto, 1 King’s College Circle, Medical Sciences Building, Room 4368, Toronto, ON M5S 1A8 Canada
- Aberdeen Fungal Group, Institute of Medical Sciences, School of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, UK
| | - Leah E. Cowen
- Department of Molecular Genetics, University of Toronto, 1 King’s College Circle, Medical Sciences Building, Room 4368, Toronto, ON M5S 1A8 Canada
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Affiliation(s)
- Gregory M. Gauthier
- Department of Medicine, University of Wisconsin, Madison, Wisconsin, United States of America
- * E-mail:
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Vylkova S, Lorenz MC. Modulation of phagosomal pH by Candida albicans promotes hyphal morphogenesis and requires Stp2p, a regulator of amino acid transport. PLoS Pathog 2014; 10:e1003995. [PMID: 24626429 PMCID: PMC3953444 DOI: 10.1371/journal.ppat.1003995] [Citation(s) in RCA: 129] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Accepted: 01/30/2014] [Indexed: 12/23/2022] Open
Abstract
Candida albicans, the most important fungal pathogen of humans, has a unique interaction with macrophages in which phagocytosis induces a switch from the yeast to hyphal form, allowing it to escape by rupturing the immune cell. While a variety of factors induce this switch in vitro, including neutral pH, it is not clear what triggers morphogenesis within the macrophage where the acidic environment should inhibit this transition. In vitro, C. albicans grown in similar conditions in which amino acids are the primary carbon source generate large quantities of ammonia to raise the extracellular pH and induce the hyphal switch. We show here that C. albicans cells neutralize the macrophage phagosome and that neutral pH is a key inducer of germination in phagocytosed cells by using a mutant lacking STP2, a transcription factor that regulates the expression of multiple amino acid permeases, that is completely deficient in alkalinization in vitro. Phagocytosed stp2Δ mutant cells showed significant reduction in hypha formation and escaped from macrophages less readily compared to wild type cells; as a result stp2Δ mutant cells were killed at a higher rate and caused less damage to RAW264.7 macrophages. Stp2p-regulated import leads to alkalinization of the phagosome, since the majority of the wild type cells fail to co-localize with acidophilic dyes, whereas the stp2Δ mutant cells were located in acidic phagosomes. Furthermore, stp2Δ mutant cells were able to form hyphae and escape from neutral phagosomes, indicating that the survival defect in these cells was pH dependent. Finally, these defects are reflected in an attenuation of virulence in a mouse model of disseminated candidiasis. Altogether our results suggest that C. albicans utilizes amino acids to promote neutralization of the phagosomal pH, hyphal morphogenesis, and escape from macrophages. The innate immune system represents a key barrier that fungal pathogens such as Candida albicans must overcome in order to disseminate through the host. C. albicans cells phagocytosed by macrophages initiate a complex program that involves a large-scale reprogramming of metabolism and transcription and results in the switch to a hyphal form that can penetrate and kill the macrophage. Though a number of signals are known to induce this morphological transition in vitro, what does so following phagocytosis has been unclear. We previously showed that C. albicans rapidly neutralizes acidic, nutrient-poor media that resembles the phagolysosome and that this is deficient in mutants impaired in amino acid import due to a mutation in STP2. In this paper, we investigate whether this happens within the macrophage as well. We show here that, in contrast to wild-type cells, stp2Δ mutants occupy an acidic phagosome and are unable to initiate hyphal differentiation. Because of this, they are more sensitive to killing and do less damage to the macrophages than cells that can neutralize the phagolysosome. We conclude that alteration of phagosomal pH is an important virulence adaptation in this species.
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Affiliation(s)
- Slavena Vylkova
- Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center, Houston, Texas, United States of America
| | - Michael C. Lorenz
- Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center, Houston, Texas, United States of America
- * E-mail:
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16
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Brandhorst TT, Roy R, Wüthrich M, Nanjappa S, Filutowicz H, Galles K, Tonelli M, McCaslin DR, Satyshur K, Klein B. Structure and function of a fungal adhesin that binds heparin and mimics thrombospondin-1 by blocking T cell activation and effector function. PLoS Pathog 2013; 9:e1003464. [PMID: 23853587 PMCID: PMC3708853 DOI: 10.1371/journal.ppat.1003464] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Accepted: 05/13/2013] [Indexed: 01/22/2023] Open
Abstract
Blastomyces adhesin-1 (BAD-1) is a 120-kD surface protein on B. dermatitidis yeast. We show here that BAD-1 contains 41 tandem repeats and that deleting even half of them impairs fungal pathogenicity. According to NMR, the repeats form tightly folded 17-amino acid loops constrained by a disulfide bond linking conserved cysteines. Each loop contains a highly conserved WxxWxxW motif found in thrombospondin-1 (TSP-1) type 1 heparin-binding repeats. BAD-1 binds heparin specifically and saturably, and is competitively inhibited by soluble heparin, but not related glycosaminoglycans. According to SPR analysis, the affinity of BAD-1 for heparin is 33 nM±14 nM. Putative heparin-binding motifs are found both at the N-terminus and within each tandem repeat loop. Like TSP-1, BAD-1 blocks activation of T cells in a manner requiring the heparan sulfate-modified surface molecule CD47, and impairs effector functions. The tandem repeats of BAD-1 thus confer pathogenicity, harbor motifs that bind heparin, and suppress T-cell activation via a CD47-dependent mechanism, mimicking mammalian TSP-1.
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Affiliation(s)
- T. Tristan Brandhorst
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - René Roy
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
- The Medical Scientist Training Program, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
- The Cell and Molecular Biology Graduate Training Program, College of Agriculture and Life Science, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Marcel Wüthrich
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Som Nanjappa
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Hanna Filutowicz
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Kevin Galles
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Marco Tonelli
- The Department of Biochemistry, The Biophysics Instrumentation Facility, College of Agriculture and Life Science, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Darrell R. McCaslin
- The Department of Biochemistry, The Biophysics Instrumentation Facility, College of Agriculture and Life Science, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Kenneth Satyshur
- The Department of Bacteriology, The College of Agriculture and Life Science, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Bruce Klein
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
- Internal Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
- Medical Microbiology and Immunology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
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17
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Mahmood F, Hakimiyan A, Jayaraman V, Wood S, Sivaramakrishnan G, Rehman T, Reuhs BL, Chubinskaya S, Shafikhani SH. A novel human antimicrobial factor targets Pseudomonas aeruginosa through its type III secretion system. J Med Microbiol 2013; 62:531-539. [PMID: 23288430 DOI: 10.1099/jmm.0.051227-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Pseudomonas aeruginosa is an important opportunistic bacterial pathogen. Despite its metabolic and virulence versatility, it has not been shown to infect articular joints, which are areas that are rarely infected with bacteria in general. We hypothesized that articular joints possess antimicrobial activity that limits bacterial survival in these environments. We report that cartilages secrete a novel antimicrobial factor, henceforth referred to as the cartilage-associated antimicrobial factor (CA-AMF), with potent antimicrobial activity. Importantly, CA-AMF exhibited significantly more antimicrobial activity against P. aeruginosa strains with a functional type III secretion system (T3SS). We propose that CA-AMF represents a new class of human antimicrobial factors in innate immunity, one which has evolved to selectively target pathogenic bacteria among the beneficial and commensal microflora. The T3SS is the first example, to the best of our knowledge, of a pathogen-specific molecular target in this antimicrobial defence system.
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Affiliation(s)
- Fareeha Mahmood
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA
| | - Arnavaz Hakimiyan
- Department of Food Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Vijayakumar Jayaraman
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA
| | - Stephen Wood
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA
| | | | - Tooba Rehman
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA
| | - Bradley L Reuhs
- Department of Food Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Susanna Chubinskaya
- Department of Biochemistry, Rush University Medical Center, Chicago, IL 60612, USA
| | - Sasha H Shafikhani
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA
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18
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Weber SS, Parente AFA, Borges CL, Parente JA, Bailão AM, de Almeida Soares CM. Analysis of the secretomes of Paracoccidioides mycelia and yeast cells. PLoS One 2012; 7:e52470. [PMID: 23272246 PMCID: PMC3525554 DOI: 10.1371/journal.pone.0052470] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Accepted: 11/13/2012] [Indexed: 11/19/2022] Open
Abstract
Paracoccidioides, a complex of several phylogenetic species, is the causative agent of paracoccidioidomycosis. The ability of pathogenic fungi to develop a multifaceted response to the wide variety of stressors found in the host environment is important for virulence and pathogenesis. Extracellular proteins represent key mediators of the host-parasite interaction. To analyze the expression profile of the proteins secreted by Paracoccidioides, Pb01 mycelia and yeast cells, we used a proteomics approach combining two-dimensional electrophoresis with matrix-assisted laser desorption ionization quadrupole time-of-flight mass spectrometry (MALDI-Q-TOF MS/MS). From three biological replicates, 356 and 388 spots were detected, in mycelium and yeast cell secretomes, respectively. In this study, 160 non-redundant proteins/isoforms were indentified, including 30 and 24 proteins preferentially secreted in mycelia and yeast cells, respectively. In silico analyses revealed that 65% of the identified proteins/isoforms were secreted primarily via non-conventional pathways. We also investigated the influence of protein export inhibition in the phagocytosis of Paracoccidioides by macrophages. The addition of Brefeldin A to the culture medium significantly decreased the production of secreted proteins by both Paracoccidioides and internalized yeast cells by macrophages. In contrast, the addition of concentrated culture supernatant to the co-cultivation significantly increased the number of internalized yeast cells by macrophages. Importantly, the proteins detected in the fungal secretome were also identified within macrophages. These results indicate that Paracoccidioides extracellular proteins are important for the fungal interaction with the host.
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Affiliation(s)
- Simone Schneider Weber
- Laboratório de Biologia Molecular, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, Goiás, Brazil
| | - Ana Flávia Alves Parente
- Laboratório de Biologia Molecular, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, Goiás, Brazil
| | - Clayton Luiz Borges
- Laboratório de Biologia Molecular, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, Goiás, Brazil
| | - Juliana Alves Parente
- Laboratório de Biologia Molecular, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, Goiás, Brazil
| | - Alexandre Melo Bailão
- Laboratório de Biologia Molecular, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, Goiás, Brazil
| | - Célia Maria de Almeida Soares
- Laboratório de Biologia Molecular, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, Goiás, Brazil
- * E-mail:
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19
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Machado FS, Rodriguez NE, Adesse D, Garzoni LR, Esper L, Lisanti MP, Burk RD, Albanese C, Van Doorslaer K, Weiss LM, Nagajyothi F, Nosanchuk JD, Wilson ME, Tanowitz HB. Recent developments in the interactions between caveolin and pathogens. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 729:65-82. [PMID: 22411314 DOI: 10.1007/978-1-4614-1222-9_5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The role of caveolin and caveolae in the pathogenesis of infection has only recently been appreciated. In this chapter, we have highlighted some important new data on the role of caveolin in infections due to bacteria, viruses and fungi but with particular emphasis on the protozoan parasites Leishmania spp., Trypanosoma cruzi and Toxoplasma gondii. This is a continuing area of research and the final chapter has not been written on this topic.
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Affiliation(s)
- Fabiana S Machado
- Department of Biochemistry and Immunology, Federal University of Minas Gerais, Belo Horizonte, Brazil.
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20
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Edwards JA, Rappleye CA. Histoplasma mechanisms of pathogenesis--one portfolio doesn't fit all. FEMS Microbiol Lett 2011; 324:1-9. [PMID: 22092757 PMCID: PMC3228276 DOI: 10.1111/j.1574-6968.2011.02363.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Revised: 07/12/2011] [Accepted: 07/13/2011] [Indexed: 01/15/2023] Open
Abstract
Histoplasma capsulatum is the leading cause of endemic mycosis in the world. Analyses of clinical isolates from different endemic regions show important diversity within the species. Recent molecular studies of two isolates, the Chemotype I NAm2 strain G217B and the Chemotype II Panamanian strain G186A, reveal significant genetic, structural, and molecular differences between these representative Histoplasma strains. Some of these variations have functional consequences, representing distinct molecular mechanisms that facilitate Histoplasma pathogenesis. The realization of Histoplasma strain diversity highlights the importance of characterizing Histoplasma virulence factors in the context of specific clinical strain isolates.
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Affiliation(s)
- Jessica A. Edwards
- Departments of Microbiology and Internal Medicine, The Center for Microbial Interface Biology, Ohio State University, 484 W. 12Avenue, Columbus, OH 43210, USA
| | - Chad A. Rappleye
- Departments of Microbiology and Internal Medicine, The Center for Microbial Interface Biology, Ohio State University, 484 W. 12Avenue, Columbus, OH 43210, USA
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21
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Collette JR, Lorenz MC. Mechanisms of immune evasion in fungal pathogens. Curr Opin Microbiol 2011; 14:668-75. [PMID: 21955887 DOI: 10.1016/j.mib.2011.09.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 09/06/2011] [Accepted: 09/08/2011] [Indexed: 10/17/2022]
Abstract
The incidence of life-threatening fungal infections has continued to increase in recent years, predominantly in patients debilitated by iatrogenic interventions or immunological dysfunctions. While the picture of the immunology of fungal infections grows increasingly complex, it is clear that the phagocyte-pathogen interaction is a critical determinant of establishing an infection. About 10 years ago, genome-scale approaches began to elucidate the intricate and extensive fungal response to phagocytosis and in the last few years it has become clear that some of this response actively modulates immune cell function. Fungal pathogens avoid detection by masking pathogen-associated molecular patterns, such as cell wall carbohydrates, and by downregulating the complement cascade. Once detected, various species interfere with phagocytosis and intracellular trafficking, and can repress production of antimicrobials like nitric oxide (NO). For the most part, the molecular mechanisms behind these behaviors are not yet known. This review discusses recent discoveries and insights into how fungi manipulate the host-pathogen interaction.
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Affiliation(s)
- John R Collette
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center, 6431 Fannin St., Houston, TX 77030, United States
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22
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Seider K, Brunke S, Schild L, Jablonowski N, Wilson D, Majer O, Barz D, Haas A, Kuchler K, Schaller M, Hube B. The facultative intracellular pathogen Candida glabrata subverts macrophage cytokine production and phagolysosome maturation. THE JOURNAL OF IMMUNOLOGY 2011; 187:3072-86. [PMID: 21849684 DOI: 10.4049/jimmunol.1003730] [Citation(s) in RCA: 160] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Although Candida glabrata is an important human pathogenic yeast, its pathogenicity mechanisms are largely unknown. Immune evasion strategies seem to play key roles during infection, since very little inflammation is observed in mouse models. Furthermore, C. glabrata multiplies intracellularly after engulfment by macrophages. In this study, we sought to identify the strategies that enable C. glabrata to survive phagosome biogenesis and antimicrobial activities within human monocyte-derived macrophages. We show that, despite significant intracellular proliferation, macrophage damage or apoptosis was not apparent, and production of reactive oxygen species was inhibited. Additionally, with the exception of GM-CSF, levels of pro- and anti-inflammatory cytokines were only marginally increased. We demonstrate that adhesion to and internalization by macrophages occur within minutes, and recruitment of endosomal early endosomal Ag 1 and lysosomal-associated membrane protein 1 indicates phagosome maturation. However, phagosomes containing viable C. glabrata, but not heat-killed yeasts, failed to recruit cathepsin D and were only weakly acidified. This inhibition of acidification did not require fungal viability, but it had a heat-sensitive surface attribute. Therefore, C. glabrata modifies the phagosome into a nonacidified environment and multiplies until the host cells finally lyse and release the fungi. Our results suggest persistence of C. glabrata within macrophages as a possible immune evasion strategy.
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Affiliation(s)
- Katja Seider
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knoell Institute, 07745 Jena, Germany
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23
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Lorenz MC. Host–microbe interactions: fungi. Curr Opin Microbiol 2010; 13:389-91. [DOI: 10.1016/j.mib.2010.05.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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24
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Seider K, Heyken A, Lüttich A, Miramón P, Hube B. Interaction of pathogenic yeasts with phagocytes: survival, persistence and escape. Curr Opin Microbiol 2010; 13:392-400. [PMID: 20627672 DOI: 10.1016/j.mib.2010.05.001] [Citation(s) in RCA: 118] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Revised: 05/05/2010] [Accepted: 05/06/2010] [Indexed: 10/19/2022]
Abstract
Pathogenic yeasts, either from the environment or the normal flora, have to face phagocytic cells that constitute the first line of defence during infection. In order to evade or counteract attack by phagocytes, pathogenic yeasts have acquired a repertoire of strategies to survive, colonize and infect the host. In this review we focus on the interaction of yeasts, such as Candida, Histoplasma or Cryptococcus species, with macrophages or neutrophils. We discuss strategies used by these fungi to prevent phagocytosis or to counteract phagocytic activities. We go on to describe the strategies that permit intracellular survival within phagocytes and that may eventually lead to damage of and escape from the phagocyte.
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Affiliation(s)
- Katja Seider
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knoell Institute Jena (HKI), Jena, Germany
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25
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d’Enfert C. Hidden killers: persistence of opportunistic fungal pathogens in the human host. Curr Opin Microbiol 2009; 12:358-64. [DOI: 10.1016/j.mib.2009.05.008] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Revised: 05/18/2009] [Accepted: 05/19/2009] [Indexed: 12/22/2022]
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26
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Holbrook ED, Rappleye CA. Histoplasma capsulatum pathogenesis: making a lifestyle switch. Curr Opin Microbiol 2008; 11:318-24. [PMID: 18573684 DOI: 10.1016/j.mib.2008.05.010] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2008] [Accepted: 05/09/2008] [Indexed: 01/14/2023]
Abstract
The dimorphism of Histoplasma reflects a developmental switch in morphology and lifestyle that is necessary for virulence. The dimorphism regulating kinase DRK1 and the Histoplasma WOR1 homolog RYP1 mediate the thermally induced transition to the pathogenic yeast-phase program. The genes expressed as part of this regulon influence the host-pathogen interaction to favor Histoplasma virulence. While surface localized HSP60 supports yeast attachment to host macrophages, yeast alpha-glucan polysaccharides conceal immunostimulatory cell wall beta-glucans from detection by macrophage receptors. Intramacrophage growth of yeast cells is facilitated by CBP a secreted, protease-resistant calcium-binding protein tailored to function within the phagolysosomal environment. In some Histoplasma strains, YPS3 promotes dissemination of yeast from pulmonary infection sites. The Histoplasma yeast-phase program includes additional cell surface and extracellular molecules that potentially function in further aspects of Histoplasma virulence.
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Affiliation(s)
- Eric D Holbrook
- Department of Microbiology, Ohio State University, Columbus, OH 43210, United States
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