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Calvo AM, Dabholkar A, Wyman EM, Lohmar JM, Cary JW. Beyond morphogenesis and secondary metabolism: function of Velvet proteins and LaeA in fungal pathogenesis. Appl Environ Microbiol 2024:e0081924. [PMID: 39230285 DOI: 10.1128/aem.00819-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/05/2024] Open
Abstract
Velvet proteins, as well as the epigenetic regulator LaeA, are conserved in numerous fungal species, where, in response to environmental cues, they control several crucial cellular processes, including sexual and asexual morphogenesis, secondary metabolism, response to oxidative stress, and virulence. During the last two decades, knowledge of their mechanism of action as well as understanding their functional roles, has greatly increased, particularly in Aspergillus species. Research efforts from multiple groups followed, leading to the characterization of other Velvet and LaeA homologs in species of other fungal genera, including important opportunistic plant and animal pathogens. This review focuses mainly on the current knowledge of the role of Velvet and LaeA function in fungal pathogenesis. Velvet proteins and LaeA are unique to fungi, and for this reason, additional knowledge of these critical regulatory proteins will be important in the development of targeted control strategies to decrease the detrimental impact of fungal pathogens capable of causing disease in plants and animals.
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Affiliation(s)
- Ana M Calvo
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, USA
| | - Apoorva Dabholkar
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, USA
| | - Elizabeth M Wyman
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, USA
| | - Jessica M Lohmar
- Food and Feed Safety Research Unit, USDA/ARS, Southern Regional Research Center, New Orleans, Louisiana, USA
| | - Jeffrey W Cary
- Food and Feed Safety Research Unit, USDA/ARS, Southern Regional Research Center, New Orleans, Louisiana, USA
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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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3
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Chen W, Son YE, Cho HJ, Choi D, Park HS, Yu JH. Phylogenomics analysis of velvet regulators in the fungal kingdom. Microbiol Spectr 2024; 12:e0371723. [PMID: 38179919 PMCID: PMC10845976 DOI: 10.1128/spectrum.03717-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 12/03/2023] [Indexed: 01/06/2024] Open
Abstract
All life forms have evolved to respond appropriately to various environmental and internal cues. In the animal kingdom, the prototypical regulator class of such cellular responses is the Rel homology domain proteins including nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). Fungi, the close relatives of animals, have also evolved with their own NF-κB-like regulators called velvet family proteins to govern cellular and chemical development. Here, we conducted a detailed investigation of the taxonomic broad presence of velvet proteins. We observed that velvet proteins are widely distributed in the fungal kingdom. Moreover, we have identified and characterized 21 major velvet clades in fungi. We have further revealed that the highly conserved velvet domain is composed of three distinct motifs and acts as an evolutionarily independent domain, which can be shuffled with various functional domains. Such rearrangements of the velvet domain have resulted in the functional and type diversity of the present velvet regulators. Importantly, our in-deep analyses of the primary and 3D structures of the various velvet domains showed that the fungal velvet domains can be divided into two major clans: the VelB and the VosA clans. The 3D structure comparisons revealed a close similarity of the velvet domain with many other eukaryotic DNA-binding proteins, including those of the Rel, Runt, and signal transducer and activator of transcription families, sharing a common β-sandwich fold. Altogether, this study improves our understanding of velvet regulators in the fungal kingdom.IMPORTANCEFungi are the relatives of animals in Opisthokonta and closely associated with human life by interactive ways such as pathogenicity, food, and secondary metabolites including beneficial ones like penicillin and harmful ones like the carcinogenic aflatoxins. Similar to animals, fungi have also evolved with NF-κB-like velvet family regulators. The velvet proteins constitute a large protein family of fungal transcription factors sharing a common velvet domain and play a key role in coordinating fungal secondary metabolism, developmental and differentiation processes. Our current understanding on velvet regulators is mostly from Ascomycota fungi; however, they remain largely unknown outside Ascomycota. Therefore, this study performed a taxonomic broad investigation of velvet proteins across the fungal kingdom and conducted a detailed analysis on velvet distribution, structure, diversity, and evolution. The results provide a holistic view of velvet regulatory system in the fungal kingdom.
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Affiliation(s)
- Wanping Chen
- School of Food Science and Biotechnology, Kyungpook National University, Daegu, South Korea
| | - Ye-Eun Son
- School of Food Science and Biotechnology, Kyungpook National University, Daegu, South Korea
| | - He-Jin Cho
- School of Food Science and Biotechnology, Kyungpook National University, Daegu, South Korea
| | - Dasol Choi
- Department of Bacteriology, University of Wisconsin, Madison, Wisconsin, USA
| | - Hee-Soo Park
- School of Food Science and Biotechnology, Kyungpook National University, Daegu, South Korea
- Department of Integrative Biology, Kyungpook National University, Daegu, South Korea
| | - Jae-Hyuk Yu
- Department of Bacteriology, University of Wisconsin, Madison, Wisconsin, USA
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Joehnk B, Ali N, Voorhies M, Walcott K, Sil A. Recyclable CRISPR/Cas9-mediated gene disruption and deletions in Histoplasma. mSphere 2023; 8:e0037023. [PMID: 37819140 PMCID: PMC10732100 DOI: 10.1128/msphere.00370-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Accepted: 07/17/2023] [Indexed: 10/13/2023] Open
Abstract
IMPORTANCE Histoplasma is a primary fungal pathogen with the ability to infect otherwise healthy mammalian hosts, causing systemic and sometimes life-threatening disease. Thus far, molecular genetic manipulation of this organism has utilized RNA interference, random insertional mutagenesis, and a homologous recombination protocol that is highly variable and often inefficient. Targeted gene manipulations have been challenging due to poor rates of homologous recombination events in Histoplasma. Interrogation of the virulence strategies of this organism would be highly accelerated by a means of efficiently generating targeted mutations. We have developed a recyclable CRISPR/Cas9 system that can be used to introduce gene disruptions in Histoplasma with high efficiency, thereby allowing disruption of multiple genes.
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Affiliation(s)
- Bastian Joehnk
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, California, USA
| | - Nebat Ali
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, California, USA
| | - Mark Voorhies
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, California, USA
| | - Keith Walcott
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, California, USA
| | - Anita Sil
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, California, USA
- Chan Zuckerberg Biohub–San Francisco, San Francisco, California, USA
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Joehnk B, Ali N, Voorhies M, Walcott K, Sil A. Recyclable CRISPR/Cas9 mediated gene disruption and deletions in Histoplasma. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.05.547774. [PMID: 37461713 PMCID: PMC10350005 DOI: 10.1101/2023.07.05.547774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 07/23/2023]
Abstract
Targeted gene disruption is challenging in the dimorphic fungal pathogen Histoplasma due to the low frequency of homologous recombination. Transformed DNA is either integrated ectopically into the genome or maintained extra chromosomally by de novo addition of telomeric sequences. Based on a system developed in Blastomyces, we adapted a CRISPR/Cas9 system to facilitate targeted gene disruption in Histoplasma with high efficiency. We express a codon-optimized version of Cas9 as well as guide RNAs from a single ectopic vector carrying a selectable marker. Once the desired mutation is verified, one can screen for isolates that have lost the Cas9 vector by simply removing the selective pressure. Multiple mutations can then be generated in the same strain by retransforming the Cas9 vector carrying different guides. We used this system to disrupt a number of target genes including RYP2 and SRE1 where loss-of-function mutations could be monitored visually by colony morphology or color, respectively. Interestingly, expression of two guide RNAs targeting the 5' and 3' ends of a gene allowed isolation of deletion mutants where the sequence between the guide RNAs was removed from the genome. Whole-genome sequencing showed that the frequency of off-target mutations associated with the Cas9 nuclease was negligible. Finally, we increased the frequency of gene disruption by using an endogenous Histoplasma regulatory sequence to drive guide RNA expression. These tools transform our ability to generate targeted mutations in Histoplasma.
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Affiliation(s)
- Bastian Joehnk
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, California, USA
| | - Nebat Ali
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, California, USA
| | - Mark Voorhies
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, California, USA
| | - Keith Walcott
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, California, USA
| | - Anita Sil
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, California, USA
- Chan Zuckerberg Biohub – San Francisco, San Francisco, CA 94158
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Chromosome-Level Genome Assembly of a Human Fungal Pathogen Reveals Synteny among Geographically Distinct Species. mBio 2022; 13:e0257421. [PMID: 35089059 PMCID: PMC8725592 DOI: 10.1128/mbio.02574-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Histoplasma capsulatum, a dimorphic fungal pathogen, is the most common cause of fungal respiratory infections in immunocompetent hosts. Histoplasma is endemic in the Ohio and Mississippi River Valleys in the United States and is also distributed worldwide. Previous studies have revealed at least eight clades, each specific to a geographic location: North American classes 1 and 2 (NAm 1 and NAm 2), Latin American groups A and B (LAm A and LAm B), Eurasian, Netherlands, Australian and African, and an additional distinct lineage (H81) comprised of Panamanian isolates. Previously assembled Histoplasma genomes are highly fragmented, with the highly repetitive G217B (NAm 2) strain, which has been used for most whole-genome-scale transcriptome studies, assembled into over 250 contigs. In this study, we set out to fully assemble the repeat regions and characterize the large-scale genome architecture of Histoplasma species. We resequenced five Histoplasma strains (WU24 [NAm 1], G217B [NAm 2], H88 [African], G186AR [Panama], and G184AR [Panama]) using Oxford Nanopore Technologies long-read sequencing technology. Here, we report chromosomal-level assemblies for all five strains, which exhibit extensive synteny among the geographically distant Histoplasma isolates. The new assemblies revealed that RYP2, a major regulator of morphology and virulence, is duplicated in G186AR. In addition, we mapped previously generated transcriptome data sets onto the newly assembled chromosomes. Our analyses revealed that the expression of transposons and transposon-embedded genes are upregulated in yeast phase compared to mycelial phase in the G217B and H88 strains. This study provides an important resource for fungal researchers and further highlights the importance of chromosomal-level assemblies in analyzing high-throughput data sets. IMPORTANCE Histoplasma species are dimorphic fungi causing significant morbidity and mortality worldwide. These fungi grow as mold in the soil and as budding yeast within the human host. Histoplasma can be isolated from soil in diverse regions, including North America, South America, Africa, and Europe. Phylogenetically distinct species of Histoplasma have been isolated and sequenced. However, for the commonly used strains, genome assemblies have been fragmented, leading to underutilization of genome-scale data. This study provides chromosome-level assemblies of the commonly used Histoplasma strains using long-read sequencing technology. Comparative analysis of these genomes shows largely conserved gene order within the chromosomes. Mapping existing transcriptome data on these new assemblies reveals clustering of transcriptionally coregulated genes. The results of this study highlight the importance of obtaining chromosome-level assemblies in understanding the biology of human fungal pathogens.
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Li B, Chen Y, Zhang Z, Qin G, Chen T, Tian S. Molecular basis and regulation of pathogenicity and patulin biosynthesis in
Penicillium expansum. Compr Rev Food Sci Food Saf 2020; 19:3416-3438. [DOI: 10.1111/1541-4337.12612] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 06/26/2020] [Accepted: 07/19/2020] [Indexed: 12/13/2022]
Affiliation(s)
- Boqiang Li
- Key Laboratory of Plant Resources, Institute of Botany, The Innovative Academy of Seed Design Chinese Academy of Sciences Beijing China
- Key Laboratory of Post‐Harvest Handing of Fruits Ministry of Agriculture Beijing China
| | - Yong Chen
- Key Laboratory of Plant Resources, Institute of Botany, The Innovative Academy of Seed Design Chinese Academy of Sciences Beijing China
| | - Zhanquan Zhang
- Key Laboratory of Plant Resources, Institute of Botany, The Innovative Academy of Seed Design Chinese Academy of Sciences Beijing China
| | - Guozheng Qin
- Key Laboratory of Plant Resources, Institute of Botany, The Innovative Academy of Seed Design Chinese Academy of Sciences Beijing China
- Key Laboratory of Post‐Harvest Handing of Fruits Ministry of Agriculture Beijing China
| | - Tong Chen
- Key Laboratory of Plant Resources, Institute of Botany, The Innovative Academy of Seed Design Chinese Academy of Sciences Beijing China
| | - Shiping Tian
- Key Laboratory of Plant Resources, Institute of Botany, The Innovative Academy of Seed Design Chinese Academy of Sciences Beijing China
- Key Laboratory of Post‐Harvest Handing of Fruits Ministry of Agriculture Beijing China
- University of Chinese Academy of Sciences Beijing China
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Abstract
Histoplasma capsulatum is a member of a group of fungal pathogens called thermally dimorphic fungi, all of which respond to mammalian body temperature by converting from an environmental mold form into a parasitic host form that causes disease. Histoplasma is a primary fungal pathogen, meaning it is able to cause disease in healthy individuals. We are beginning to understand how host temperature is utilized as a key signal to facilitate growth in the parasitic yeast form and promote production of virulence factors. In recent years, multiple regulators of morphology and virulence have been identified in Histoplasma. Mutations in these regulators render the pathogen unable to convert to the parasitic yeast form. Additionally, several virulence factors have been characterized for their importance in in vivo survival and pathogenesis. These virulence factors and regulators can serve as molecular handles for the development of effective drugs and therapeutics to counter Histoplasma infection.
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Affiliation(s)
- Sinem Beyhan
- Department of Infectious Diseases, J. Craig Venter Institute , La Jolla , CA , USA
| | - Anita Sil
- Department of Microbiology and Immunology, University of California , San Francisco , CA , USA
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9
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Restricting mycotoxins without killing the producers: a new paradigm in nano-fungal interactions. Appl Microbiol Biotechnol 2020; 104:2803-2813. [PMID: 32025763 DOI: 10.1007/s00253-020-10373-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 12/23/2019] [Accepted: 01/12/2020] [Indexed: 12/31/2022]
Abstract
Over the past several years, numerous studies have demonstrated the feasibility of using engineered nanoparticles as antifungals, especially against those fungal pathogens that produce mycotoxins and infect plants, animals, and humans. The high dosage of nanoparticles has been a concern in such antifungal applications due to the potential toxicological and ecotoxicological impacts. To address such concerns, we have recently introduced the idea of inhibiting mycotoxin biosynthesis using low doses of engineered nanoparticles. At such low doses these particles are minimally toxic to humans and the environment. From our studies we realize that for the effective use of nanotechnology to intervene in the biology of fungal pathogens and for an accurate evaluation of the impacts of the increasingly growing nanomaterials in the environment on fungi and their interacting biotic partners, there is a pressing need for a rigorous understanding of nano-fungal interactions, which is currently far from complete. In this minireview, we build on the available evidence from nano-bio interaction research and our recent interaction studies with Aspergillus cells and engineered silver nanoparticles to introduce a potential theoretical model for nano-fungal interactions. The aim of the proposed model is to provide an initial insight on how nanoparticle uptake and their transformation inside fungal cells, possibly influence the production of mycotoxins and other secondary metabolites of filamentous fungi .
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10
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Sil A. Molecular regulation of Histoplasma dimorphism. Curr Opin Microbiol 2019; 52:151-157. [PMID: 31739263 PMCID: PMC6910920 DOI: 10.1016/j.mib.2019.10.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 10/30/2019] [Indexed: 01/06/2023]
Abstract
Temperature serves as a fundamental signal in biological systems. In some microbial pathogens of humans, mammalian body temperature triggers establishment and maintenance of a developmental program that allows the microbe to survive and thrive in the host. Histoplasma capsulatum is one of a group of fungal pathogens called thermally dimorphic fungi, all of which respond to mammalian body temperature by converting from an environmental mold form that inhabits the soil into a parasitic form that causes disease in the host. It has been known for decades that temperature is a key signal that is sufficient to trigger the switch from the soil to host form (and vice versa) in the laboratory. Recent molecular studies have identified a number of key regulators that are required to specify each of the developmental forms in response to temperature. Here we review the regulatory circuits that govern temperature-dependent dimorphism in Histoplasma.
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Affiliation(s)
- Anita Sil
- Department of Microbiology & Immunology, University of California San Francisco, San Francisco, CA 94143, USA.
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11
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Denham ST, Wambaugh MA, Brown JCS. How Environmental Fungi Cause a Range of Clinical Outcomes in Susceptible Hosts. J Mol Biol 2019; 431:2982-3009. [PMID: 31078554 PMCID: PMC6646061 DOI: 10.1016/j.jmb.2019.05.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 04/18/2019] [Accepted: 05/01/2019] [Indexed: 12/11/2022]
Abstract
Environmental fungi are globally ubiquitous and human exposure is near universal. However, relatively few fungal species are capable of infecting humans, and among fungi, few exposure events lead to severe systemic infections. Systemic infections have mortality rates of up to 90%, cost the US healthcare system $7.2 billion annually, and are typically associated with immunocompromised patients. Despite this reputation, exposure to environmental fungi results in a range of outcomes, from asymptomatic latent infections to severe systemic infection. Here we discuss different exposure outcomes for five major fungal pathogens: Aspergillus, Blastomyces, Coccidioides, Cryptococcus, and Histoplasma species. These fungi include a mold, a budding yeast, and thermal dimorphic fungi. All of these species must adapt to dramatically changing environments over the course of disease. These dynamic environments include the human lung, which is the first exposure site for these organisms. Fungi must defend themselves against host immune cells while germinating and growing, which risks further exposing microbe-associated molecular patterns to the host. We discuss immune evasion strategies during early infection, from disruption of host immune cells to major changes in fungal cell morphology.
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Affiliation(s)
- Steven T Denham
- Division of Microbiology and Immunology, Pathology Department, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Morgan A Wambaugh
- Division of Microbiology and Immunology, Pathology Department, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Jessica C S Brown
- Division of Microbiology and Immunology, Pathology Department, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.
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Bayram ÖS, Dettmann A, Karahoda B, Moloney NM, Ormsby T, McGowan J, Cea-Sánchez S, Miralles-Durán A, Brancini GTP, Luque EM, Fitzpatrick DA, Cánovas D, Corrochano LM, Doyle S, Selker EU, Seiler S, Bayram Ö. Control of Development, Secondary Metabolism and Light-Dependent Carotenoid Biosynthesis by the Velvet Complex of Neurospora crassa. Genetics 2019; 212:691-710. [PMID: 31068340 PMCID: PMC6614901 DOI: 10.1534/genetics.119.302277] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 05/04/2019] [Indexed: 01/24/2023] Open
Abstract
Neurospora crassa is an established reference organism to investigate carotene biosynthesis and light regulation. However, there is little evidence of its capacity to produce secondary metabolites. Here, we report the role of the fungal-specific regulatory velvet complexes in development and secondary metabolism (SM) in N. crassa Three velvet proteins VE-1, VE-2, VOS-1, and a putative methyltransferase LAE-1 show light-independent nucleocytoplasmic localization. Two distinct velvet complexes, a heterotrimeric VE-1/VE-2/LAE-1 and a heterodimeric VE-2/VOS-1 are found in vivo The heterotrimer-complex, which positively regulates sexual development and represses asexual sporulation, suppresses siderophore coprogen production under iron starvation conditions. The VE-1/VE-2 heterodimer controls carotene production. VE-1 regulates the expression of >15% of the whole genome, comprising mainly regulatory and developmental features. We also studied intergenera functions of the velvet complex through complementation of Aspergillus nidulans veA, velB, laeA, vosA mutants with their N. crassa orthologs ve-1, ve-2, lae-1, and vos-1, respectively. Expression of VE-1 and VE-2 in A. nidulans successfully substitutes the developmental and SM functions of VeA and VelB by forming two functional chimeric velvet complexes in vivo, VelB/VE-1/LaeA and VE-2/VeA/LaeA, respectively. Reciprocally, expression of veA restores the phenotypes of the N. crassa ve-1 mutant. All N. crassa velvet proteins heterologously expressed in A. nidulans are localized to the nuclear fraction independent of light. These data highlight the conservation of the complex formation in N. crassa and A. nidulans However, they also underline the intergenera similarities and differences of velvet roles according to different life styles, niches and ontogenetic processes.
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Affiliation(s)
| | - Anne Dettmann
- Institute for Biology II, Molecular Plant Physiology, Albert-Ludwigs-University 79104 Freiburg, Germany
| | - Betim Karahoda
- Department of Biology, Maynooth University, Co. Kildare, W23 F2H6, Ireland
| | - Nicola M Moloney
- Department of Biology, Maynooth University, Co. Kildare, W23 F2H6, Ireland
| | - Tereza Ormsby
- Institute of Molecular Biology, University of Oregon, Eugene, 97403 Oregon
| | - Jamie McGowan
- Department of Biology, Maynooth University, Co. Kildare, W23 F2H6, Ireland
| | - Sara Cea-Sánchez
- Departmento de Genética, Facultad de Biologia, Universidad de Sevilla, 41012 Sevilla, Spain
| | | | - Guilherme T P Brancini
- Departmento de Genética, Facultad de Biologia, Universidad de Sevilla, 41012 Sevilla, Spain
| | - Eva M Luque
- Departmento de Genética, Facultad de Biologia, Universidad de Sevilla, 41012 Sevilla, Spain
| | | | - David Cánovas
- Departmento de Genética, Facultad de Biologia, Universidad de Sevilla, 41012 Sevilla, Spain
| | - Luis M Corrochano
- Departmento de Genética, Facultad de Biologia, Universidad de Sevilla, 41012 Sevilla, Spain
| | - Sean Doyle
- Department of Biology, Maynooth University, Co. Kildare, W23 F2H6, Ireland
| | - Eric U Selker
- Institute of Molecular Biology, University of Oregon, Eugene, 97403 Oregon
| | - Stephan Seiler
- Institute for Biology II, Molecular Plant Physiology, Albert-Ludwigs-University 79104 Freiburg, Germany
| | - Özgür Bayram
- Department of Biology, Maynooth University, Co. Kildare, W23 F2H6, Ireland
- Human Health Research Institute, Maynooth University, Co. Kildare, W23 F2H6, Ireland
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13
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Pandit SS, Lohmar JM, Ahmed S, Etxebeste O, Espeso EA, Calvo AM. UrdA Controls Secondary Metabolite Production and the Balance between Asexual and Sexual Development in Aspergillus nidulans. Genes (Basel) 2018; 9:E570. [PMID: 30477161 PMCID: PMC6316066 DOI: 10.3390/genes9120570] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 11/15/2018] [Accepted: 11/19/2018] [Indexed: 01/07/2023] Open
Abstract
The genus Aspergillus includes important plant pathogens, opportunistic human pathogens and mycotoxigenic fungi. In these organisms, secondary metabolism and morphogenesis are subject to a complex genetic regulation. Here we functionally characterized urdA, a gene encoding a putative helix-loop-helix (HLH)-type regulator in the model fungus Aspergillus nidulans. urdA governs asexual and sexual development in strains with a wild-type veA background; absence of urdA resulted in severe morphological alterations, with a significant reduction of conidial production and an increase in cleistothecial formation, even in the presence of light, a repressor of sex. The positive effect of urdA on conidiation is mediated by the central developmental pathway (CDP). However, brlA overexpression was not sufficient to restore wild-type conidiation in the ΔurdA strain. Heterologous complementation of ΔurdA with the putative Aspergillus flavus urdA homolog also failed to rescue conidiation wild-type levels, indicating that both genes perform different functions, probably reflected by key sequence divergence. UrdA also represses sterigmatocystin (ST) toxin production in the presence of light by affecting the expression of aflR, the activator of the ST gene cluster. Furthermore, UrdA regulates the production of several unknown secondary metabolites, revealing a broader regulatory scope. Interestingly, UrdA affects the abundance and distribution of the VeA protein in hyphae, and our genetics studies indicated that veA appears epistatic to urdA regarding ST production. However, the distinct fluffy phenotype of the ΔurdAΔveA double mutant suggests that both regulators conduct independent developmental roles. Overall, these results suggest that UrdA plays a pivotal role in the coordination of development and secondary metabolism in A. nidulans.
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Affiliation(s)
- Sandesh S Pandit
- Department of Biological Sciences, Northern Illinois University, 155 Castle Dr., Dekalb, IL 60115, USA.
| | - Jessica M Lohmar
- Department of Biological Sciences, Northern Illinois University, 155 Castle Dr., Dekalb, IL 60115, USA.
| | - Shawana Ahmed
- Department of Biological Sciences, Northern Illinois University, 155 Castle Dr., Dekalb, IL 60115, USA.
| | - Oier Etxebeste
- Department of Applied Chemistry, Faculty of Chemistry, University of the Basque Country (UPV/EHU), Manuel de Lardizabal, 3, 20018 San Sebastian, Spain.
| | - Eduardo A Espeso
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas (C.S.I.C.), Ramiro de Maeztu 9, 28040 Madrid, Spain.
| | - Ana M Calvo
- Department of Biological Sciences, Northern Illinois University, 155 Castle Dr., Dekalb, IL 60115, USA.
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Wu Y, Xu L, Yin Z, Dai Q, Gao X, Feng H, Voegele RT, Huang L. Two members of the velvet family, VmVeA and VmVelB, affect conidiation, virulence and pectinase expression in Valsa mali. MOLECULAR PLANT PATHOLOGY 2018; 19:1639-1651. [PMID: 29127722 PMCID: PMC6638101 DOI: 10.1111/mpp.12645] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 10/28/2017] [Accepted: 11/09/2017] [Indexed: 05/26/2023]
Abstract
Velvet protein family members are important fungal-specific regulators which are involved in conidial development, secondary metabolism and virulence. To gain a broader insight into the physiological functions of the velvet protein family of Valsa mali, which causes a highly destructive canker disease on apple, we conducted a functional analysis of two velvet protein family members (VmVeA and VmVelB) via a gene replacement strategy. Deletion mutants of VmVeA and VmVelB showed increased melanin production, conidiation and sensitivity to abiotic stresses, but exhibited reduced virulence on detached apple leaves and twigs. Further studies demonstrated that the regulation of conidiation by VmVeA and VmVelB was positively correlated with the melanin synthesis transcription factor VmCmr1. More importantly, transcript levels of pectinase genes were shown to be decreased in deletion mutants compared with those of the wild-type during infection. However, the expression of other cell wall-degrading enzyme genes, including cellulase, hemi-cellulase and ligninase genes, was not affected in the deletion mutants. Furthermore, the determination of pectinase activity and immunogold labelling of pectin demonstrated that the capacity for pectin degradation was attenuated as a result of deletions of VmVeA and VmVelB. Finally, the interaction of VmVeA with VmVelB was identified through co-immunoprecipitation assays. VmVeA and VmVelB play critical roles in conidiation and virulence, probably via the regulation of the melanin synthesis transcription factor VmCmr1 and their effect on pectinase gene expression in V. mali, respectively.
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Affiliation(s)
- Yuxing Wu
- State Key Laboratory of Crop Stress Biology for Arid Areas, China–Australia Joint Research Centre for Abiotic and Biotic Stress Management, College of Plant ProtectionNorthwest A&F UniversityShaanxiYangling 712100China
| | - Liangsheng Xu
- State Key Laboratory of Crop Stress Biology for Arid Areas, China–Australia Joint Research Centre for Abiotic and Biotic Stress Management, College of Plant ProtectionNorthwest A&F UniversityShaanxiYangling 712100China
| | - Zhiyuan Yin
- State Key Laboratory of Crop Stress Biology for Arid Areas, China–Australia Joint Research Centre for Abiotic and Biotic Stress Management, College of Plant ProtectionNorthwest A&F UniversityShaanxiYangling 712100China
| | - Qingqing Dai
- State Key Laboratory of Crop Stress Biology for Arid Areas, China–Australia Joint Research Centre for Abiotic and Biotic Stress Management, College of Plant ProtectionNorthwest A&F UniversityShaanxiYangling 712100China
| | - Xiaoning Gao
- State Key Laboratory of Crop Stress Biology for Arid Areas, China–Australia Joint Research Centre for Abiotic and Biotic Stress Management, College of Plant ProtectionNorthwest A&F UniversityShaanxiYangling 712100China
| | - Hao Feng
- State Key Laboratory of Crop Stress Biology for Arid Areas, China–Australia Joint Research Centre for Abiotic and Biotic Stress Management, College of Plant ProtectionNorthwest A&F UniversityShaanxiYangling 712100China
| | - Ralf T. Voegele
- Institut für Phytomedizin, Universität Hohenheim70599 StuttgartGermany
| | - Lili Huang
- State Key Laboratory of Crop Stress Biology for Arid Areas, China–Australia Joint Research Centre for Abiotic and Biotic Stress Management, College of Plant ProtectionNorthwest A&F UniversityShaanxiYangling 712100China
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15
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The role of the veA gene in adjusting developmental balance and environmental stress response in Aspergillus cristatus. Fungal Biol 2018; 122:952-964. [PMID: 30227931 DOI: 10.1016/j.funbio.2018.05.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 05/16/2018] [Accepted: 05/31/2018] [Indexed: 12/14/2022]
Abstract
veA belongs to the velvet regulatory system that regulates the development and secondary metabolism of many fungi. To identify the function of veA in Aspergillus cristatus, veA deletion mutants were constructed by homologous recombination via Agrobacterium tumefaciens-mediated transformation. Deletion of veA led to increased conidial production and reduced sexual sporulation. The regulatory role of veA in A. cristatus was not light-dependent, and this differed from its role in other Aspergilli. Furthermore, veA deletion mutants were more sensitive to environmental stressors, including salt, osmotic pressure, temperature and pH. In contrast, deletion of veA resulted in increased resistance to oxidative stress. veA also affected aerial vegetative growth. Transcriptomic analysis of the veA-null mutant and wild type indicated that most asexual and sexual development genes were upregulated and downregulated, respectively. These findings confirmed that veA has a positive effect on sexual development but represses conidial formation. Overall, these results suggested that the veA gene plays a critical role in maintaining a developmental balance between asexual and sexual sporulation and is involved in vegetative growth and environmental stress response in A. cristatus.
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16
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López-Díaz C, Rahjoo V, Sulyok M, Ghionna V, Martín-Vicente A, Capilla J, Di Pietro A, López-Berges MS. Fusaric acid contributes to virulence of Fusarium oxysporum on plant and mammalian hosts. MOLECULAR PLANT PATHOLOGY 2018; 19:440-453. [PMID: 28093838 PMCID: PMC6638071 DOI: 10.1111/mpp.12536] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 12/30/2016] [Accepted: 01/10/2017] [Indexed: 05/03/2023]
Abstract
Fusaric acid (FA) is amongst the oldest identified secondary metabolites produced by Fusarium species, known for a long time to display strong phytotoxicity and moderate toxicity to animal cells; however, the cellular targets of FA and its function in fungal pathogenicity remain unknown. Here, we investigated the role of FA in Fusarium oxysporum, a soil-borne cross-kingdom pathogen that causes vascular wilt on more than 100 plant species and opportunistic infections in humans. Targeted deletion of fub1, encoding a predicted orthologue of the polyketide synthase involved in FA biosynthesis in F. verticillioides and F. fujikuroi, abolished the production of FA and its derivatives in F. oxysporum. We further showed that the expression of fub1 was positively controlled by the master regulator of secondary metabolism LaeA and the alkaline pH regulator PacC through the modulation of chromatin accessibility at the fub1 locus. FA exhibited strong phytotoxicity on tomato plants, which was rescued by the exogenous supply of copper, iron or zinc, suggesting a possible function of FA as a chelating agent of these metal ions. Importantly, the severity of vascular wilt symptoms on tomato plants and the mortality of immunosuppressed mice were significantly reduced in fub1Δ mutants and fully restored in the complemented strains. Collectively, these results provide new insights into the regulation and mode of action of FA, as well as on the function of this phytotoxin during the infection process of F. oxysporum.
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Affiliation(s)
- Cristina López-Díaz
- Departamento de Genética, Facultad de Ciencias, Universidad de Córdoba, Campus de Excelencia Agroalimentario (ceiA3), Córdoba, E-14071, Spain
| | - Vahid Rahjoo
- Departamento de Genética, Facultad de Ciencias, Universidad de Córdoba, Campus de Excelencia Agroalimentario (ceiA3), Córdoba, E-14071, Spain
| | - Michael Sulyok
- Department for Agrobiotechnology (IFA-Tulln), University of Natural Resources and Life Sciences, Vienna (BOKU), Konrad Lorenz Str. 20, Tulln, 3430, Austria
| | - Veronica Ghionna
- Departamento de Genética, Facultad de Ciencias, Universidad de Córdoba, Campus de Excelencia Agroalimentario (ceiA3), Córdoba, E-14071, Spain
| | - Adela Martín-Vicente
- Mycology Unit, Medical School, Universitat Rovira i Virgili, IISPV, Reus, 43204, Spain
| | - Javier Capilla
- Mycology Unit, Medical School, Universitat Rovira i Virgili, IISPV, Reus, 43204, Spain
| | - Antonio Di Pietro
- Departamento de Genética, Facultad de Ciencias, Universidad de Córdoba, Campus de Excelencia Agroalimentario (ceiA3), Córdoba, E-14071, Spain
| | - Manuel S López-Berges
- Departamento de Genética, Facultad de Ciencias, Universidad de Córdoba, Campus de Excelencia Agroalimentario (ceiA3), Córdoba, E-14071, Spain
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17
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Shen Q, Rappleye CA. Differentiation of the fungus Histoplasma capsulatum into a pathogen of phagocytes. Curr Opin Microbiol 2017; 40:1-7. [PMID: 29096192 DOI: 10.1016/j.mib.2017.10.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 10/09/2017] [Indexed: 01/06/2023]
Abstract
Mammalian body temperature triggers differentiation of the fungal pathogen Histoplasma capsulatum into yeast cells. The Drk1 regulatory kinase and an interdependent network of Ryp transcription factors establish the yeast state. Beyond morphology, the differentiation-dependent expression program equips yeasts for invasion and survival within phagosomes. Yeast cells produce α-glucan and the Eng1 endoglucanase which hide yeasts from immune detection. Secretion of yeast phase-specific Sod3 and CatB detoxify phagocyte-derived reactive oxygen molecules. Histoplasma cells adapt to iron and zinc limitation in activated macrophages by production of siderophores and the Zrt2 transporter, respectively. Yeasts also respond to inflammation-associated hypoxia. Histoplasma pathogenicity thus relies on factors controlled by yeast differentiation as well as environment-dependent responses.
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Affiliation(s)
- Qian Shen
- Ohio State University, Columbus, OH 43210, USA
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18
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Feng X, Ramamoorthy V, Pandit SS, Prieto A, Espeso EA, Calvo AM. cpsA regulates mycotoxin production, morphogenesis and cell wall biosynthesis in the fungus Aspergillus nidulans. Mol Microbiol 2017; 105:1-24. [PMID: 28370587 PMCID: PMC5506848 DOI: 10.1111/mmi.13682] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 03/21/2017] [Accepted: 03/26/2017] [Indexed: 01/07/2023]
Abstract
The model fungus Aspergillus nidulans synthesizes numerous secondary metabolites, including sterigmatocystin (ST). The production of this toxin is positively controlled by the global regulator veA. In the absence of veA (ΔveA), ST biosynthesis is blocked. Previously, we performed random mutagenesis in a ΔveA strain and identified revertant mutants able to synthesize ST, among them RM1. Complementation of RM1 with a genomic library revealed that the mutation occurred in a gene designated as cpsA. While in the ΔveA genetic background cpsA deletion restores ST production, in a veA wild-type background absence of cpsA reduces and delays ST biosynthesis decreasing the expression of ST genes. Furthermore, cpsA is also necessary for the production of other secondary metabolites, including penicillin, affecting the expression of PN genes. In addition, cpsA is necessary for normal asexual and sexual development. Chemical and microscopy analyses revealed that CpsA is found in cytoplasmic vesicles and it is required for normal cell wall composition and integrity, affecting adhesion capacity and oxidative stress sensitivity. The conservation of cpsA in Ascomycetes suggests that cpsA homologs might have similar roles in other fungal species.
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Affiliation(s)
- Xuehuan Feng
- Department of Biological Sciences, Northern Illinois University, Dekalb, IL 60115, USA
| | - Vellaisamy Ramamoorthy
- Department of Biological Sciences, Northern Illinois University, Dekalb, IL 60115, USA,Dept. of Plant Pathology Agricultural College and Research Institute Killikulam, Vallanadu - 628 252 Thoothukudi District Tamil Nadu, India
| | - Sandesh S. Pandit
- Department of Biological Sciences, Northern Illinois University, Dekalb, IL 60115, USA
| | - Alicia Prieto
- Centro de Investigaciones Biológicas, CSIC, Madrid, Spain
| | | | - Ana M. Calvo
- Department of Biological Sciences, Northern Illinois University, Dekalb, IL 60115, USA,Author to whom correspondence should be addressed [telephone: (815) 753-0451]; fax (815) 753-0461; ]
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19
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Xie L, Li J, Deng W, Yu Z, Fang W, Chen M, Liao W, Xie J, Pan W. Proteomic analysis of lysine succinylation of the human pathogen Histoplasma capsulatum. J Proteomics 2017; 154:109-117. [PMID: 28063982 DOI: 10.1016/j.jprot.2016.12.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 12/28/2016] [Accepted: 12/30/2016] [Indexed: 01/02/2023]
Abstract
Histoplasma capsulatum, the causative agent of histoplasmosis (also called "Darling's disease"), can affect both immunocompetent and immunocompromised hosts. Post-translational protein modification by lysine succinylation (Ksuc) is a frequent occurrence in eukaryote and prokaryote. Recently, the roles of succinylation and its regulatory enzymes in regulating metabolic pathway in bacteria, mammalian and fungus were highlighted. Here, we report the first global profiling of lysine succinylation, with 463 modification sites in 202 proteins from H. capsulatum NAM1 identified, coupling immune-affinity enrichment using an anti-succinyllysine antibody with mass spectrometry. The bioinformatics results including GO functional and enrichment analysis showed that these succinylated proteins are mainly involved in central metabolism and protein synthesis, consistent with previous reports. 13 lysine succinylation sites on histones including H2A, H2B, H3 and H4 in H. capsulatum were firstly reported. The data is a good resource for further functional characterization of lysine succinylation in H. capsulatum. BIOLOGICAL SIGNIFICANCE H. capsulatum is the causative agent of lung disease histoplasmosis. The ability of H. capsulatum yeasts to infect and proliferate within macrophages as an intracellular pathogen can be contributed to several virulence factors and metabolic regulation. Lysine succinylation was recently shown to play a critical role in the metabolism regulation of Candida albicans. H. capsulatum succinylated proteins were firstly characterized in this work, and bioinformatics results showed that this modification may also be relevant with central metabolism in H. capsulatum. New succinylation sites on histones were reported. This represents an important resource to address the function of H. capsulatum lysine succinylation.
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Affiliation(s)
- Longxiang Xie
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource of the Three Gorges Area, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Beibei, Chongqing 400715, China
| | - Juan Li
- Shanghai Key Laboratory of Molecular Medical Mycology, Department of Dermatology, Changzheng Hospital, Second Military Medical University, Shanghai 200003, China
| | - Wanyan Deng
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource of the Three Gorges Area, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Beibei, Chongqing 400715, China
| | - Zhaoxiao Yu
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource of the Three Gorges Area, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Beibei, Chongqing 400715, China
| | - Wenjie Fang
- Shanghai Key Laboratory of Molecular Medical Mycology, Department of Dermatology, Changzheng Hospital, Second Military Medical University, Shanghai 200003, China
| | - Min Chen
- Shanghai Key Laboratory of Molecular Medical Mycology, Department of Dermatology, Changzheng Hospital, Second Military Medical University, Shanghai 200003, China
| | - Wanqing Liao
- Shanghai Key Laboratory of Molecular Medical Mycology, Department of Dermatology, Changzheng Hospital, Second Military Medical University, Shanghai 200003, China
| | - Jianping Xie
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource of the Three Gorges Area, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Beibei, Chongqing 400715, China.
| | - Weihua Pan
- Shanghai Key Laboratory of Molecular Medical Mycology, Department of Dermatology, Changzheng Hospital, Second Military Medical University, Shanghai 200003, China.
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rtfA, a putative RNA-Pol II transcription elongation factor gene, is necessary for normal morphological and chemical development in Aspergillus flavus. Appl Microbiol Biotechnol 2016; 100:5029-41. [PMID: 27020290 DOI: 10.1007/s00253-016-7418-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 02/22/2016] [Accepted: 02/24/2016] [Indexed: 01/05/2023]
Abstract
The filamentous fungus Aspergillus flavus is an agriculturally important opportunistic plant pathogen that produces potent carcinogenic compounds called aflatoxins. We identified the A. flavus rtfA gene, the ortholog of rtf1 in Saccharomyces cerevisiae and rtfA in Aspergillus nidulans. Interestingly, rtfA has multiple cellular roles in this mycotoxin-producing fungus. In this study, we show that rtfA regulates conidiation. The rtfA deletion mutant presented smaller conidiophores with significantly reduced conidial production compared to the wild-type strain. The absence of rtfA also resulted in a significant decrease or lack of sclerotial production under conditions that allowed abundant production of these resistance structures in the wild type. Importantly, the deletion of rtfA notably reduced the production of aflatoxin B1, indicating that rtfA is a regulator of mycotoxin biosynthesis in A. flavus. In addition, the deletion rtfA also altered the production of several unknown secondary metabolites indicating a broader regulatory scope. Furthermore, our study revealed that rtfA controls the expression of the global regulators veA and laeA, which further influence morphogenesis and secondary metabolism in A. flavus.
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21
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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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22
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Transcriptome Analysis of Aspergillus flavus Reveals veA-Dependent Regulation of Secondary Metabolite Gene Clusters, Including the Novel Aflavarin Cluster. EUKARYOTIC CELL 2015. [PMID: 26209694 DOI: 10.1128/ec.00092-15] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The global regulatory veA gene governs development and secondary metabolism in numerous fungal species, including Aspergillus flavus. This is especially relevant since A. flavus infects crops of agricultural importance worldwide, contaminating them with potent mycotoxins. The most well-known are aflatoxins, which are cytotoxic and carcinogenic polyketide compounds. The production of aflatoxins and the expression of genes implicated in the production of these mycotoxins are veA dependent. The genes responsible for the synthesis of aflatoxins are clustered, a signature common for genes involved in fungal secondary metabolism. Studies of the A. flavus genome revealed many gene clusters possibly connected to the synthesis of secondary metabolites. Many of these metabolites are still unknown, or the association between a known metabolite and a particular gene cluster has not yet been established. In the present transcriptome study, we show that veA is necessary for the expression of a large number of genes. Twenty-eight out of the predicted 56 secondary metabolite gene clusters include at least one gene that is differentially expressed depending on presence or absence of veA. One of the clusters under the influence of veA is cluster 39. The absence of veA results in a downregulation of the five genes found within this cluster. Interestingly, our results indicate that the cluster is expressed mainly in sclerotia. Chemical analysis of sclerotial extracts revealed that cluster 39 is responsible for the production of aflavarin.
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23
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Calvo AM, Cary JW. Association of fungal secondary metabolism and sclerotial biology. Front Microbiol 2015; 6:62. [PMID: 25762985 PMCID: PMC4329819 DOI: 10.3389/fmicb.2015.00062] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 01/18/2015] [Indexed: 11/13/2022] Open
Abstract
Fungal secondary metabolism and morphological development have been shown to be intimately associated at the genetic level. Much of the literature has focused on the co-regulation of secondary metabolite production (e.g., sterigmatocystin and aflatoxin in Aspergillus nidulans and Aspergillus flavus, respectively) with conidiation or formation of sexual fruiting bodies. However, many of these genetic links also control sclerotial production. Sclerotia are resistant structures produced by a number of fungal genera. They also represent the principal source of primary inoculum for some phytopathogenic fungi. In nature, higher plants often concentrate secondary metabolites in reproductive structures as a means of defense against herbivores and insects. By analogy, fungi also sequester a number of secondary metabolites in sclerotia that act as a chemical defense system against fungivorous predators. These include antiinsectant compounds such as tetramic acids, indole diterpenoids, pyridones, and diketopiperazines. This chapter will focus on the molecular mechanisms governing production of secondary metabolites and the role they play in sclerotial development and fungal ecology, with particular emphasis on Aspergillus species. The global regulatory proteins VeA and LaeA, components of the velvet nuclear protein complex, serve as virulence factors and control both development and secondary metabolite production in many Aspergillus species. We will discuss a number of VeA- and LaeA-regulated secondary metabolic gene clusters in A. flavus that are postulated to be involved in sclerotial morphogenesis and chemical defense. The presence of multiple regulatory factors that control secondary metabolism and sclerotial formation suggests that fungi have evolved these complex regulatory mechanisms as a means to rapidly adapt chemical responses to protect sclerotia from predators, competitors and other environmental stressors.
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Affiliation(s)
- Ana M Calvo
- Department of Biological Sciences, Northern Illinois University DeKalb, IL, USA
| | - Jeffrey W Cary
- Southern Regional Research Center, United States Department of Agriculture - Agricultural Research Service New Orleans, LA, USA
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24
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Karimi Aghcheh R, Németh Z, Atanasova L, Fekete E, Paholcsek M, Sándor E, Aquino B, Druzhinina IS, Karaffa L, Kubicek CP. The VELVET A orthologue VEL1 of Trichoderma reesei regulates fungal development and is essential for cellulase gene expression. PLoS One 2014; 9:e112799. [PMID: 25386652 PMCID: PMC4227869 DOI: 10.1371/journal.pone.0112799] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 10/15/2014] [Indexed: 11/25/2022] Open
Abstract
Trichoderma reesei is the industrial producer of cellulases and hemicellulases for biorefinery processes. Their expression is obligatorily dependent on the function of the protein methyltransferase LAE1. The Aspergillus nidulans orthologue of LAE1 - LaeA - is part of the VELVET protein complex consisting of LaeA, VeA and VelB that regulates secondary metabolism and sexual as well as asexual reproduction. Here we have therefore investigated the function of VEL1, the T. reesei orthologue of A. nidulans VeA. Deletion of the T. reesei vel1 locus causes a complete and light-independent loss of conidiation, and impairs formation of perithecia. Deletion of vel1 also alters hyphal morphology towards hyperbranching and formation of thicker filaments, and with consequently reduced growth rates. Growth on lactose as a sole carbon source, however, is even more strongly reduced and growth on cellulose as a sole carbon source eliminated. Consistent with these findings, deletion of vel1 completely impaired the expression of cellulases, xylanases and the cellulase regulator XYR1 on lactose as a cellulase inducing carbon source, but also in resting mycelia with sophorose as inducer. Our data show that in T. reesei VEL1 controls sexual and asexual development, and this effect is independent of light. VEL1 is also essential for cellulase gene expression, which is consistent with the assumption that their regulation by LAE1 occurs by the VELVET complex.
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Affiliation(s)
- Razieh Karimi Aghcheh
- Institute of Chemical Engineering, Research Division Biotechnology and Microbiology, Microbiology Group, Vienna University of Technology, 1060 Vienna, Austria
| | - Zoltán Németh
- Department of Biochemical Engineering, Faculty of Sciences and Technology, University of Debrecen, H-4032 Debrecen, Hungary
| | - Lea Atanasova
- Institute of Chemical Engineering, Research Division Biotechnology and Microbiology, Microbiology Group, Vienna University of Technology, 1060 Vienna, Austria
| | - Erzsébet Fekete
- Department of Biochemical Engineering, Faculty of Sciences and Technology, University of Debrecen, H-4032 Debrecen, Hungary
| | - Melinda Paholcsek
- Department of Human Genetics, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - Erzsébet Sándor
- Faculty of Agricultural and Food Science and Environmental Management, Institute of Food Science, H-4032 Debrecen, Hungary
| | - Benigno Aquino
- Institute of Chemical Engineering, Research Division Biotechnology and Microbiology, Microbiology Group, Vienna University of Technology, 1060 Vienna, Austria
| | - Irina S. Druzhinina
- Institute of Chemical Engineering, Research Division Biotechnology and Microbiology, Microbiology Group, Vienna University of Technology, 1060 Vienna, Austria
- Austrian Center of Industrial Biotechnology, c/o Institute of Chemical Engineering, Vienna University of Technology, 1060 Vienna, Austria
| | - Levente Karaffa
- Department of Biochemical Engineering, Faculty of Sciences and Technology, University of Debrecen, H-4032 Debrecen, Hungary
| | - Christian P. Kubicek
- Institute of Chemical Engineering, Research Division Biotechnology and Microbiology, Microbiology Group, Vienna University of Technology, 1060 Vienna, Austria
- Austrian Center of Industrial Biotechnology, 8010 Graz, Austria
- * E-mail:
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Coordinated and distinct functions of velvet proteins in Fusarium verticillioides. EUKARYOTIC CELL 2014; 13:909-18. [PMID: 24792348 DOI: 10.1128/ec.00022-14] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Velvet-domain-containing proteins are broadly distributed within the fungal kingdom. In the corn pathogen Fusarium verticillioides, previous studies showed that the velvet protein F. verticillioides VE1 (FvVE1) is critical for morphological development, colony hydrophobicity, toxin production, and pathogenicity. In this study, tandem affinity purification of FvVE1 revealed that FvVE1 can form a complex with the velvet proteins F. verticillioides VelB (FvVelB) and FvVelC. Phenotypic characterization of gene knockout mutants showed that, as in the case of FvVE1, FvVelB regulated conidial size, hyphal hydrophobicity, fumonisin production, and oxidant resistance, while FvVelC was dispensable for these biological processes. Comparative transcriptional analysis of eight genes involved in the ROS (reactive oxygen species) removal system revealed that both FvVE1 and FvVelB positively regulated the transcription of a catalase-encoding gene, F. verticillioides CAT2 (FvCAT2). Deletion of FvCAT2 resulted in reduced oxidant resistance, providing further explanation of the regulation of oxidant resistance by velvet proteins in the fungal kingdom.
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26
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Ahmed YL, Gerke J, Park HS, Bayram Ö, Neumann P, Ni M, Dickmanns A, Kim SC, Yu JH, Braus GH, Ficner R. The velvet family of fungal regulators contains a DNA-binding domain structurally similar to NF-κB. PLoS Biol 2013; 11:e1001750. [PMID: 24391470 PMCID: PMC3876986 DOI: 10.1371/journal.pbio.1001750] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2013] [Accepted: 11/18/2013] [Indexed: 12/20/2022] Open
Abstract
This study reveals an important family of fungal regulatory proteins to be transcription factors that contain a DNA-binding “velvet” domain structurally related to that of mammalian NFkB. Morphological development of fungi and their combined production of secondary metabolites are both acting in defence and protection. These processes are mainly coordinated by velvet regulators, which contain a yet functionally and structurally uncharacterized velvet domain. Here we demonstrate that the velvet domain of VosA is a novel DNA-binding motif that specifically recognizes an 11-nucleotide consensus sequence consisting of two motifs in the promoters of key developmental regulatory genes. The crystal structure analysis of the VosA velvet domain revealed an unforeseen structural similarity with the Rel homology domain (RHD) of the mammalian transcription factor NF-κB. Based on this structural similarity several conserved amino acid residues present in all velvet domains have been identified and shown to be essential for the DNA binding ability of VosA. The velvet domain is also involved in dimer formation as seen in the solved crystal structures of the VosA homodimer and the VosA-VelB heterodimer. These findings suggest that defence mechanisms of both fungi and animals might be governed by structurally related DNA-binding transcription factors. In many fungi, developmental processes and the synthesis of nonessential chemicals (secondary metabolites) are regulated by various external stimuli, such as light. Although fungi employ them for defensive purposes, secondary metabolites range from useful antibiotics to powerful toxins, so understanding the molecular processes that regulate their synthesis is of particular interest to us. In the mold Aspergillus nidulans the main regulators of these processes are the so-called “velvet” proteins VeA, VelB, and VosA, which share a 150-amino acid region known as the velvet domain. Velvet proteins interact with each other, alone (“homodimers”), in various combinations (“heterodimers”), and also with other proteins, but the molecular mechanism by which these proteins exert their regulatory function has been unclear. In this work we show that velvet proteins form a family of fungus-specific transcription factors that directly bind to target DNA, even though analysis of their amino acid sequence does not reveal any known DNA-binding domains or motifs. We determined the three-dimensional structure of the VosA-VosA homodimer and the VosA-VelB heterodimer and found that the structure of the velvet domain is strongly reminiscent of the N-terminal immunoglobulin-like domain found in the mammalian transcription factor NFκB-p50, despite the very low sequence similarity. We propose that, like NFκB, various homo- or heterodimers of velvet proteins modulate gene expression to drive development and defensive pathways in fungi.
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MESH Headings
- Aspergillus nidulans/genetics
- Aspergillus nidulans/physiology
- Consensus Sequence/genetics
- Consensus Sequence/physiology
- DNA, Fungal/genetics
- DNA, Fungal/physiology
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/physiology
- Gene Expression Regulation, Developmental/genetics
- Gene Expression Regulation, Developmental/physiology
- Gene Expression Regulation, Fungal/genetics
- Gene Expression Regulation, Fungal/physiology
- Genes, Fungal/genetics
- Genes, Fungal/physiology
- Genes, rel/genetics
- Genes, rel/physiology
- NF-kappa B/genetics
- NF-kappa B/physiology
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Affiliation(s)
- Yasar Luqman Ahmed
- Department of Molecular Structural Biology, Institute of Microbiology and Genetics, Georg-August University, Göttingen, Germany
| | - Jennifer Gerke
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Georg-August University, Göttingen, Germany
| | - Hee-Soo Park
- Departments of Bacteriology and Genetics, University of Wisconsin–Madison, Madison, Wisconsin, United States of America
| | - Özgür Bayram
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Georg-August University, Göttingen, Germany
| | - Piotr Neumann
- Department of Molecular Structural Biology, Institute of Microbiology and Genetics, Georg-August University, Göttingen, Germany
| | - Min Ni
- Departments of Bacteriology and Genetics, University of Wisconsin–Madison, Madison, Wisconsin, United States of America
| | - Achim Dickmanns
- Department of Molecular Structural Biology, Institute of Microbiology and Genetics, Georg-August University, Göttingen, Germany
| | - Sun Chang Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Dae-Jon, Republic of Korea
| | - Jae-Hyuk Yu
- Departments of Bacteriology and Genetics, University of Wisconsin–Madison, Madison, Wisconsin, United States of America
- * E-mail: (J.-H.Y.); (G.H.B.); (R.F.)
| | - Gerhard H. Braus
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Georg-August University, Göttingen, Germany
- * E-mail: (J.-H.Y.); (G.H.B.); (R.F.)
| | - Ralf Ficner
- Department of Molecular Structural Biology, Institute of Microbiology and Genetics, Georg-August University, Göttingen, Germany
- * E-mail: (J.-H.Y.); (G.H.B.); (R.F.)
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Ramamoorthy V, Dhingra S, Kincaid A, Shantappa S, Feng X, Calvo AM. The putative C2H2 transcription factor MtfA is a novel regulator of secondary metabolism and morphogenesis in Aspergillus nidulans. PLoS One 2013; 8:e74122. [PMID: 24066102 PMCID: PMC3774644 DOI: 10.1371/journal.pone.0074122] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2013] [Accepted: 07/28/2013] [Indexed: 01/07/2023] Open
Abstract
Secondary metabolism in the model fungus Aspergillus nidulans is controlled by the conserved global regulator VeA, which also governs morphological differentiation. Among the secondary metabolites regulated by VeA is the mycotoxin sterigmatocystin (ST). The presence of VeA is necessary for the biosynthesis of this carcinogenic compound. We identified a revertant mutant able to synthesize ST intermediates in the absence of VeA. The point mutation occurred at the coding region of a gene encoding a novel putative C2H2 zinc finger domain transcription factor that we denominated mtfA. The A. nidulans mtfA gene product localizes at nuclei independently of the illumination regime. Deletion of the mtfA gene restores mycotoxin biosynthesis in the absence of veA, but drastically reduced mycotoxin production when mtfA gene expression was altered, by deletion or overexpression, in A. nidulans strains with a veA wild-type allele. Our study revealed that mtfA regulates ST production by affecting the expression of the specific ST gene cluster activator aflR. Importantly, mtfA is also a regulator of other secondary metabolism gene clusters, such as genes responsible for the synthesis of terrequinone and penicillin. As in the case of ST, deletion or overexpression of mtfA was also detrimental for the expression of terrequinone genes. Deletion of mtfA also decreased the expression of the genes in the penicillin gene cluster, reducing penicillin production. However, in this case, over-expression of mtfA enhanced the transcription of penicillin genes, increasing penicillin production more than 5 fold with respect to the control. Importantly, in addition to its effect on secondary metabolism, mtfA also affects asexual and sexual development in A. nidulans. Deletion of mtfA results in a reduction of conidiation and sexual stage. We found mtfA putative orthologs conserved in other fungal species.
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Affiliation(s)
- Vellaisamy Ramamoorthy
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, United States of America
| | - Sourabh Dhingra
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, United States of America
| | - Alexander Kincaid
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, United States of America
| | - Sourabha Shantappa
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, United States of America
| | - Xuehuan Feng
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, United States of America
| | - Ana M. Calvo
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, United States of America,* E-mail:
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A temperature-responsive network links cell shape and virulence traits in a primary fungal pathogen. PLoS Biol 2013; 11:e1001614. [PMID: 23935449 PMCID: PMC3720256 DOI: 10.1371/journal.pbio.1001614] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 06/12/2013] [Indexed: 11/19/2022] Open
Abstract
Analysis of a transcriptional regulatory network in a fungal pathogen reveals that four interdependent transcription factors respond to human body temperature to trigger changes in cell shape and virulence gene expression. Survival at host temperature is a critical trait for pathogenic microbes of humans. Thermally dimorphic fungal pathogens, including Histoplasma capsulatum, are soil fungi that undergo dramatic changes in cell shape and virulence gene expression in response to host temperature. How these organisms link changes in temperature to both morphologic development and expression of virulence traits is unknown. Here we elucidate a temperature-responsive transcriptional network in H. capsulatum, which switches from a filamentous form in the environment to a pathogenic yeast form at body temperature. The circuit is driven by three highly conserved factors, Ryp1, Ryp2, and Ryp3, that are required for yeast-phase growth at 37°C. Ryp factors belong to distinct families of proteins that control developmental transitions in fungi: Ryp1 is a member of the WOPR family of transcription factors, and Ryp2 and Ryp3 are both members of the Velvet family of proteins whose molecular function is unknown. Here we provide the first evidence that these WOPR and Velvet proteins interact, and that Velvet proteins associate with DNA to drive gene expression. Using genome-wide chromatin immunoprecipitation studies, we determine that Ryp1, Ryp2, and Ryp3 associate with a large common set of genomic loci that includes known virulence genes, indicating that the Ryp factors directly control genes required for pathogenicity in addition to their role in regulating cell morphology. We further dissect the Ryp regulatory circuit by determining that a fourth transcription factor, which we name Ryp4, is required for yeast-phase growth and gene expression, associates with DNA, and displays interdependent regulation with Ryp1, Ryp2, and Ryp3. Finally, we define cis-acting motifs that recruit the Ryp factors to their interwoven network of temperature-responsive target genes. Taken together, our results reveal a positive feedback circuit that directs a broad transcriptional switch between environmental and pathogenic states in response to temperature. Microbial pathogens of humans display the ability to thrive at host temperature. So-called “thermally dimorphic” fungal pathogens, which include Histoplasma capsulatum, are a class of soil fungi that upon being inhaled into the human lung, undergo dramatic changes in cell shape and virulence gene expression in response to host temperature. The ability of these pathogens to cause disease is exquisitely coupled to temperature response. Here we elucidate the regulatory network that governs the ability of H. capsulatum to switch from a filamentous form in the soil environment to a pathogenic yeast form at body temperature. The circuit is driven by three transcription regulators (Ryp1, Ryp2, and Ryp3) that control yeast-phase growth. We show that these factors, which include two highly conserved proteins of the Velvet family of unknown function, bind to specific regulatory DNA elements and directly regulate expression of virulence genes. We identify and characterize Ryp4, a fourth regulator of this pathway, and define DNA motifs that recruit these transcription factors to their temperature-responsive target genes. Our results provide a molecular understanding of how changes in cell shape are linked to expression of virulence genes in thermally dimorphic fungi.
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Frequency and genetic diversity of the MAT1 locus of Histoplasma capsulatum isolates in Mexico and Brazil. EUKARYOTIC CELL 2013; 12:1033-8. [PMID: 23709181 DOI: 10.1128/ec.00012-13] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The MAT1-1 and MAT1-2 idiomorphs associated with the MAT1 locus of Histoplasma capsulatum were identified by PCR. A total of 28 fungal isolates, 6 isolates from human clinical samples and 22 isolates from environmental (infected bat and contaminated soil) samples, were studied. Among the 14 isolates from Mexico, 71.4% (95% confidence interval [95% CI], 48.3% to 94.5%) were of the MAT1-2 genotype, whereas 100% of the isolates from Brazil were of the MAT1-1 genotype. Each MAT1 idiomorphic region was sequenced and aligned, using the sequences of the G-217B (+ mating type) and G-186AR (- mating type) strains as references. BLASTn analyses of the MAT1-1 and MAT1-2 sequences studied correlated with their respective + and - mating type genotypes. Trees were generated by the maximum likelihood (ML) method to search for similarity among isolates of each MAT1 idiomorph. All MAT1-1 isolates originated from Brazilian bats formed a well-defined group; three isolates from Mexico, the G-217B strain, and a subgroup encompassing all soil-derived isolates and two clinical isolates from Brazil formed a second group; last, one isolate (EH-696P) from a migratory bat captured in Mexico formed a third group of the MAT1-1 genotype. The MAT1-2 idiomorph formed two groups, one of which included two H. capsulatum isolates from infected bats that were closely related to the G-186AR strain. The other group was formed by two human isolates and six isolates from infected bats. Concatenated ML trees, with internal transcribed spacer 1 (ITS1) -5.8S-ITS2 and MAT1-1 or MAT1-2 sequences, support the relatedness of MAT1-1 or MAT1-2 isolates. H. capsulatum mating types were associated with the geographical origin of the isolates, and all isolates from Brazil correlated with their environmental sources.
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López-Berges MS, Hera C, Sulyok M, Schäfer K, Capilla J, Guarro J, Di Pietro A. The velvet complex governs mycotoxin production and virulence of Fusarium oxysporum on plant and mammalian hosts. Mol Microbiol 2012; 87:49-65. [PMID: 23106229 DOI: 10.1111/mmi.12082] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/22/2012] [Indexed: 01/10/2023]
Abstract
Fungal pathogens provoke devastating losses in agricultural production, contaminate food with mycotoxins and give rise to life-threatening infections in humans. The soil-borne ascomycete Fusarium oxysporum attacks over 100 different crops and can cause systemic fusariosis in immunocompromised individuals. Here we functionally characterized VeA, VelB, VelC and LaeA, four components of the velvet protein complex which regulates fungal development and secondary metabolism. Deletion of veA, velB and to a minor extent velC caused a derepression of conidiation as well as alterations in the shape and size of microconidia. VeA and LaeA were required for full virulence of F. oxysporum on tomato plants and on immunodepressed mice. A critical contribution of velvet consists in promoting chromatin accessibility and expression of the biosynthetic gene cluster for beauvericin, a depsipeptide mycotoxin that functions as a virulence determinant. These results reveal a conserved role of the velvet complex during fungal infection on plants and mammals.
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Schumacher J, Pradier JM, Simon A, Traeger S, Moraga J, Collado IG, Viaud M, Tudzynski B. Natural variation in the VELVET gene bcvel1 affects virulence and light-dependent differentiation in Botrytis cinerea. PLoS One 2012; 7:e47840. [PMID: 23118899 PMCID: PMC3485325 DOI: 10.1371/journal.pone.0047840] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 09/21/2012] [Indexed: 12/14/2022] Open
Abstract
Botrytis cinerea is an aggressive plant pathogen causing gray mold disease on various plant species. In this study, we identified the genetic origin for significantly differing phenotypes of the two sequenced B. cinerea isolates, B05.10 and T4, with regard to light-dependent differentiation, oxalic acid (OA) formation and virulence. By conducting a map-based cloning approach we identified a single nucleotide polymorphism (SNP) in an open reading frame encoding a VELVET gene (bcvel1). The SNP in isolate T4 results in a truncated protein that is predominantly found in the cytosol in contrast to the full-length protein of isolate B05.10 that accumulates in the nuclei. Deletion of the full-length gene in B05.10 resulted in the T4 phenotype, namely light-independent conidiation, loss of sclerotial development and oxalic acid production, and reduced virulence on several host plants. These findings indicate that the identified SNP represents a loss-of-function mutation of bcvel1. In accordance, the expression of the B05.10 copy in T4 rescued the wild-type/B05.10 phenotype. BcVEL1 is crucial for full virulence as deletion mutants are significantly hampered in killing and decomposing plant tissues. However, the production of the two best known secondary metabolites, the phytotoxins botcinic acid and botrydial, are not affected by the deletion of bcvel1 indicating that other factors are responsible for reduced virulence. Genome-wide expression analyses of B05.10- and Δbcvel1-infected plant material revealed a number of genes differentially expressed in the mutant: while several protease- encoding genes are under-expressed in Δbcvel1 compared to the wild type, the group of over-expressed genes is enriched for genes encoding sugar, amino acid and ammonium transporters and glycoside hydrolases reflecting the response of Δbcvel1 mutants to nutrient starvation conditions.
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Affiliation(s)
- Julia Schumacher
- Institut für Biologie und Biotechnologie der Pflanzen (IBBP), Westfälische Wilhelms-Universität Münster, Münster, Germany
| | | | | | - Stefanie Traeger
- Institut für Biologie und Biotechnologie der Pflanzen (IBBP), Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Javier Moraga
- Organic Chemistry Department, Cádiz University, Puerto Real, Cádiz, Spain
| | | | - Muriel Viaud
- INRA, BIOGER, Grignon, France
- * E-mail: (MV); (BT)
| | - Bettina Tudzynski
- Institut für Biologie und Biotechnologie der Pflanzen (IBBP), Westfälische Wilhelms-Universität Münster, Münster, Germany
- * E-mail: (MV); (BT)
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VeA regulates conidiation, gliotoxin production, and protease activity in the opportunistic human pathogen Aspergillus fumigatus. EUKARYOTIC CELL 2012; 11:1531-43. [PMID: 23087369 DOI: 10.1128/ec.00222-12] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Invasive aspergillosis by Aspergillus fumigatus is a leading cause of infection-related mortality in immunocompromised patients. In this study, we show that veA, a major conserved regulatory gene that is unique to fungi, is necessary for normal morphogenesis in this medically relevant fungus. Although deletion of veA results in a strain with reduced conidiation, overexpression of this gene further reduced conidial production, indicating that veA has a major role as a regulator of development in A. fumigatus and that normal conidiation is only sustained in the presence of wild-type VeA levels. Furthermore, our studies revealed that veA is a positive regulator in the production of gliotoxin, a secondary metabolite known to be a virulent factor in A. fumigatus. Deletion of veA resulted in a reduction of gliotoxin production with respect to that of the wild-type control. This reduction in toxin coincided with a decrease in gliZ and gliP expression, which is necessary for gliotoxin biosynthesis. Interestingly, veA also influences protease activity in this organism. Specifically, deletion of veA resulted in a reduction of protease activity; this is the first report of a veA homolog with a role in controlling fungal hydrolytic activity. Although veA affects several cellular processes in A. fumigatus, pathogenicity studies in a neutropenic mouse infection model indicated that veA is dispensable for virulence.
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