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Ianiri G, LeibundGut-Landmann S, Dawson TL. Malassezia: A Commensal, Pathogen, and Mutualist of Human and Animal Skin. Annu Rev Microbiol 2022; 76:757-782. [PMID: 36075093 DOI: 10.1146/annurev-micro-040820-010114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Identified in the late nineteenth century as a single species residing on human skin, Malassezia is now recognized as a diverse genus comprising 18 species inhabiting not only skin but human gut, hospital environments, and even deep-sea sponges. All cultivated Malassezia species are lipid dependent, having lost genes for lipid synthesis and carbohydrate metabolism. The surging interest in Malassezia results from development of tools to improve sampling, culture, identification, and genetic engineering, which has led to findings implicating it in numerous skin diseases, Crohn disease, and pancreatic cancer. However, it has become clear that Malassezia plays a multifaceted role in human health, with mutualistic activity in atopic dermatitis and a preventive effect against other skin infections due to its potential to compete with skin pathogens such as Candida auris. Improved understanding of complex microbe-microbe and host-microbe interactions will be required to define Malassezia's role in human and animal health and disease so as to design targeted interventions.
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Affiliation(s)
- Giuseppe Ianiri
- Department of Agricultural, Environmental, and Food Sciences, University of Molise, Campobasso, Italy
| | - Salomé LeibundGut-Landmann
- Section of Immunology, Faculty of Vetsuisse, and Institute of Experimental Immunology, University of Zürich, Zürich, Switzerland
| | - Thomas L Dawson
- Skin Research Institute of Singapore, Agency for Science, Technology and Research (A*STAR), Singapore; .,Department of Drug Discovery, College of Pharmacy, Medical University of South Carolina, Charleston, South Carolina, USA
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Ehemann K, Mantilla MJ, Mora-Restrepo F, Rios-Navarro A, Torres M, Celis Ramírez AM. Many ways, one microorganism: Several approaches to study Malassezia in interactions with model hosts. PLoS Pathog 2022; 18:e1010784. [PMID: 36074792 PMCID: PMC9455852 DOI: 10.1371/journal.ppat.1010784] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Malassezia, a lipophilic and lipid-dependent yeast, is a microorganism of current interest to mycobiologists because of its role as a commensal or pathogen in health conditions such as dermatological diseases, fungemia, and, as discovered recently, cancer and certain neurological disorders. Various novel approaches in the study of Malassezia have led to increased knowledge of the cellular and molecular mechanisms of this yeast. However, additional efforts are needed for more comprehensive understanding of the behavior of Malassezia in interactions with the host. This article reviews advances useful in the experimental field for Malassezia.
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Affiliation(s)
- Kevin Ehemann
- Grupo de Investigación Celular y Molecular de Microorganismos Patógenos (CeMoP), Departamento de Ciencias Biológicas, Universidad de los Andes, Bogotá, Colombia
| | - María Juliana Mantilla
- Grupo de Investigación Celular y Molecular de Microorganismos Patógenos (CeMoP), Departamento de Ciencias Biológicas, Universidad de los Andes, Bogotá, Colombia
| | - Felipe Mora-Restrepo
- Grupo de Investigación Celular y Molecular de Microorganismos Patógenos (CeMoP), Departamento de Ciencias Biológicas, Universidad de los Andes, Bogotá, Colombia
| | - Andrea Rios-Navarro
- Grupo de Investigación Celular y Molecular de Microorganismos Patógenos (CeMoP), Departamento de Ciencias Biológicas, Universidad de los Andes, Bogotá, Colombia
| | - Maritza Torres
- Grupo de Investigación Celular y Molecular de Microorganismos Patógenos (CeMoP), Departamento de Ciencias Biológicas, Universidad de los Andes, Bogotá, Colombia
| | - Adriana Marcela Celis Ramírez
- Grupo de Investigación Celular y Molecular de Microorganismos Patógenos (CeMoP), Departamento de Ciencias Biológicas, Universidad de los Andes, Bogotá, Colombia
- * E-mail:
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Hobi S, Cafarchia C, Romano V, Barrs VR. Malassezia: Zoonotic Implications, Parallels and Differences in Colonization and Disease in Humans and Animals. J Fungi (Basel) 2022; 8:jof8070708. [PMID: 35887463 PMCID: PMC9324274 DOI: 10.3390/jof8070708] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 06/29/2022] [Accepted: 06/30/2022] [Indexed: 12/13/2022] Open
Abstract
Malassezia spp. are commensals of the skin, oral/sinonasal cavity, lower respiratory and gastrointestinal tract. Eighteen species have been recovered from humans, other mammals and birds. They can also be isolated from diverse environments, suggesting an evolutionary trajectory of adaption from an ecological niche in plants and soil to the mucocutaneous ecosystem of warm-blooded vertebrates. In humans, dogs and cats, Malassezia-associated dermatological conditions share some commonalities. Otomycosis is common in companion animals but is rare in humans. Systemic infections, which are increasingly reported in humans, have yet to be recognized in animals. Malassezia species have also been identified as pathogenetic contributors to some chronic human diseases. While Malassezia species are host-adapted, some species are zoophilic and can cause fungemia, with outbreaks in neonatal intensive care wards associated with temporary colonization of healthcare worker’s hands from contact with their pets. Although standardization is lacking, susceptibility testing is usually performed using a modified broth microdilution method. Antifungal susceptibility can vary depending on Malassezia species, body location, infection type, disease duration, presence of co-morbidities and immunosuppression. Antifungal resistance mechanisms include biofilm formation, mutations or overexpression of ERG11, overexpression of efflux pumps and gene rearrangements or overexpression in chromosome 4.
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Affiliation(s)
- Stefan Hobi
- Department of Veterinary Clinical Sciences, Jockey Club College of Veterinary Medicine and Life Sciences, City University, Tat Chee Avenue, Kowloon, Hong Kong, China
- Correspondence: (S.H.); (V.R.B.)
| | - Claudia Cafarchia
- Department of Veterinary Medicine, University of Bari, Str. prov. per Casamassima Km 3, Valenzano, (Bari), 70010, Italy; (C.C.); (V.R.)
| | - Valentina Romano
- Department of Veterinary Medicine, University of Bari, Str. prov. per Casamassima Km 3, Valenzano, (Bari), 70010, Italy; (C.C.); (V.R.)
| | - Vanessa R. Barrs
- Department of Veterinary Clinical Sciences, Jockey Club College of Veterinary Medicine and Life Sciences, City University, Tat Chee Avenue, Kowloon, Hong Kong, China
- Centre for Animal Health and Welfare, City University of Hong Kong, Kowloon Tong, Hong Kong, China
- Correspondence: (S.H.); (V.R.B.)
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Fu J, Brockman NE, Wickes BL. Optimizing Transformation Frequency of Cryptococcus neoformans and Cryptococcus gattii Using Agrobacterium tumefaciens. J Fungi (Basel) 2021; 7:jof7070520. [PMID: 34209781 PMCID: PMC8305055 DOI: 10.3390/jof7070520] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 06/23/2021] [Accepted: 06/25/2021] [Indexed: 11/25/2022] Open
Abstract
The transformation of Cryptococcus spp. by Agrobacterium tumefaciens has proven to be a useful genetic tool. A number of factors affect transformation frequency. These factors include acetosyringone concentration, bacterial cell to yeast cell ratio, cell wall damage, and agar concentration. Agar concentration was found to have a significant effect on the transformant number as transformants increased with agar concentration across all four serotypes. When infection time points were tested, higher agar concentrations were found to result in an earlier transfer of the Ti-plasmid to the yeast cell, with the earliest transformant appearing two h after A. tumefaciens contact with yeast cells. These results demonstrate that A. tumefaciens transformation efficiency can be affected by a variety of factors and continued investigation of these factors can lead to improvements in specific A. tumefaciens/fungus transformation systems.
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Wang Y, Yang X, Chen P, Yang S, Zhang H. Homologous overexpression of genes in Cordyceps militaris improves the production of polysaccharides. Food Res Int 2021; 147:110452. [PMID: 34399454 DOI: 10.1016/j.foodres.2021.110452] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 05/03/2021] [Accepted: 05/23/2021] [Indexed: 11/15/2022]
Abstract
The maximum yield of EPS produced by mutant CM-pgm-H was 4.63 ± 0.23 g/L, whereas the yield of wild-type strain was 3.43 ± 0.26 g/L. In addition, the data obtained in the present study indicated that the yield of EPS produced by the engineered strain treated with the co-overexpression of phosphoglucomutase and UDP-glucose 6-dehydrogenase genes achieved 6.11 ± 0.21 g/L, which was increased by 78.13% compared with that by the wild-type strain. CM-pgm-H obtained the highest EPS content than that of gk, ugp, and ugdh mutants. This result indicated that the content of protein phosphoglucomutase was an important influencing factor on the CP production of C. militaris. Furthermore, the EPS production of CM-ugdh-pgm-M was significantly improved by 1.78-fold by co-overexpression. Therefore, our engineering strategies will play an important role in the development of C. militaris for the sustainable production of Cordyceps polysaccharides.
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Affiliation(s)
- Yifeng Wang
- The College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China
| | - Xi Yang
- The College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China
| | - Ping Chen
- The College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China
| | - Shengli Yang
- The College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China.
| | - Hui Zhang
- School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou 310023, People's Republic of China.
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Abstract
Malassezia are emerging fungal pathogens causing opportunistic skin and severe systemic infection. Nosocomial outbreaks are associated with azole resistance and understanding of the underlying mechanisms are limited to knowledge from other fungal species. Herein, we identified distinct antifungal susceptibility patterns in 26 Malassezia furfur isolates derived from healthy and diseased individuals. A Y67F CYP51 mutation was identified in five isolates of M. furfur However, this mutation alone was insufficient to induce reduce azole susceptibility in the wild type strain. RNA-seq and differential gene analysis of healthy and disease derived strains exposed to clotrimazole in vitro identified several key metabolic pathways and transporter proteins which are involved in reduce azole susceptibility. The pleiotropic drug transporter PDR10 was the single most highly upregulated transporter gene in multiple strains of M. furfur after azole treatment and increased expression of PDR10 is associated with reduced azole susceptibility in some systemic disease isolates of M. furfur Deletion of PDR10 in a pathogenic M. furfur strain with reduced susceptibility reduced MIC values to the level of that in susceptible isolates. The current dearth of antifungal technologies, globally emerging multi-azole resistance, and broad agriculture and consumer care use of azoles means improved understanding of the mechanisms underlying intrinsic and acquired azole resistance in Malassezia is crucial for development of antibiotic stewardship and antifungal treatment strategies.
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Fungal Genetics & Genomics: a call for manuscript submissions. G3 GENES|GENOMES|GENETICS 2021; 11:6131402. [PMID: 33585876 PMCID: PMC8022971 DOI: 10.1093/g3journal/jkaa040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 12/09/2020] [Indexed: 11/12/2022]
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Fungal Genetics & Genomics: a call for manuscript submissions. Genetics 2021. [DOI: 10.1093/genetics/iyaa032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Arazoe T. CRISPR-based pathogenic fungal genome editing for control of infection and disease. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2021; 179:161-196. [PMID: 33785176 DOI: 10.1016/bs.pmbts.2020.12.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Fungi play important roles in many aspects of human life, such as in various food, beverage, agricultural, chemical, and pharmaceutical industries. Meanwhile, some fungal species cause several severe diseases in plants, humans and animals. Fungal and fungal-like diseases pose a severe threat to human health, food security, and ecosystem health worldwide. This chapter introduces CRISPR-based genome editing technologies for pathogenic fungi and their application in controlling fungal diseases.
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Affiliation(s)
- Takayuki Arazoe
- Faculty of Science and Technology, Department of Applied Biological Science, Tokyo University of Science, Noda-shi, Chiba, Japan.
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Vijaya Chandra SH, Srinivas R, Dawson TL, Common JE. Cutaneous Malassezia: Commensal, Pathogen, or Protector? Front Cell Infect Microbiol 2021; 10:614446. [PMID: 33575223 PMCID: PMC7870721 DOI: 10.3389/fcimb.2020.614446] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 12/04/2020] [Indexed: 12/19/2022] Open
Abstract
The skin microbial community is a multifunctional ecosystem aiding prevention of infections from transient pathogens, maintenance of host immune homeostasis, and skin health. A better understanding of the complex milieu of microbe-microbe and host-microbe interactions will be required to define the ecosystem's optimal function and enable rational design of microbiome targeted interventions. Malassezia, a fungal genus currently comprising 18 species and numerous functionally distinct strains, are lipid-dependent basidiomycetous yeasts and integral components of the skin microbiome. The high proportion of Malassezia in the skin microbiome makes understanding their role in healthy and diseased skin crucial to development of functional skin health knowledge and understanding of normal, healthy skin homeostasis. Over the last decade, new tools for Malassezia culture, detection, and genetic manipulation have revealed not only the ubiquity of Malassezia on skin but new pathogenic roles in seborrheic dermatitis, psoriasis, Crohn's disease, and pancreatic ductal carcinoma. Application of these tools continues to peel back the layers of Malassezia/skin interactions, including clear examples of pathogenicity, commensalism, and potential protective or beneficial activities creating mutualism. Our increased understanding of host- and microbe-specific interactions should lead to identification of key factors that maintain skin in a state of healthy mutualism or, in turn, initiate pathogenic changes. These approaches are leading toward development of new therapeutic targets and treatment options. This review discusses recent developments that have expanded our understanding of Malassezia's role in the skin microbiome, with a focus on its multiple roles in health and disease as commensal, pathogen, and protector.
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Affiliation(s)
| | - Ramasamy Srinivas
- Skin Research Institute of Singapore, Agency for Science, Technology and Research, Singapore, Singapore
| | - Thomas L Dawson
- Skin Research Institute of Singapore, Agency for Science, Technology and Research, Singapore, Singapore
- Department of Drug Discovery, College of Pharmacy, Medical University of South Carolina, Charleston, SC, United States
| | - John E Common
- Skin Research Institute of Singapore, Agency for Science, Technology and Research, Singapore, Singapore
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Ianiri G, Heitman J. Approaches for Genetic Discoveries in the Skin Commensal and Pathogenic Malassezia Yeasts. Front Cell Infect Microbiol 2020; 10:393. [PMID: 32850491 PMCID: PMC7426719 DOI: 10.3389/fcimb.2020.00393] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 06/25/2020] [Indexed: 12/21/2022] Open
Abstract
Malassezia includes yeasts belong to the subphylum Ustilaginomycotina within the Basidiomycota. Malassezia yeasts are commonly found as commensals on human and animal skin. Nevertheless, Malassezia species are also associated with several skin disorders, such as dandruff/seborrheic dermatitis, atopic eczema, pityriasis versicolor, and folliculitis. More recently, associations of Malassezia with Crohn's disease, pancreatic ductal adenocarcinoma, and cystic fibrosis pulmonary exacerbation have been reported. The increasing availability of genomic and molecular tools have played a crucial role in understanding the genetic basis of Malassezia commensalism and pathogenicity. In the present review we report genomics advances in Malassezia highlighting unique features that potentially impacted Malassezia biology and host adaptation. Furthermore, we describe the recently developed protocols for Agrobacterium tumefaciens-mediated transformation in Malassezia, and their applications for random insertional mutagenesis or targeted gene replacement strategies.
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Affiliation(s)
- Giuseppe Ianiri
- Department of Agricultural, Environmental and Food Sciences, Università degli Studi del Molise, Campobasso, Italy
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, United States
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Abstract
Cordyceps is a parasitic edible fungus with a variety of metabolically active ingredients. The main active ingredient, extracellular polysaccharide (EPS), shows favourable application prospects in prevention and treatment of certain diseases. EPS extracted from different parts of various Cordyceps species can be used in health foods or medicinal preparations because of the structural diversity and multiple bioactivities. In terms of the complexity of composition and structure, researchers have speculated on the anabolic pathways of EPSs and the genes involved in the synthesis process. Studies to increase the yield of polysaccharides are limited because the synthesis pathways and anabolic regulation mechanisms of Cordyceps exopolysaccharide remain unknown. This review summarises the current researches in the yield of Cordyceps polysaccharides. A mechanism for the biosynthesis of Cordyceps polysaccharides was proposed by referring to the polysaccharide synthesis in other species. Furthermore, we also discuss the future perspective and ongoing challenges of EPS in uses of health foods and pharmaceutics.
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Affiliation(s)
- Shengli Yang
- College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, China
| | - Xi Yang
- College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, China
| | - Hui Zhang
- School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou, China
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Rhimi W, Theelen B, Boekhout T, Otranto D, Cafarchia C. Malassezia spp. Yeasts of Emerging Concern in Fungemia. Front Cell Infect Microbiol 2020; 10:370. [PMID: 32850475 PMCID: PMC7399178 DOI: 10.3389/fcimb.2020.00370] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 06/16/2020] [Indexed: 12/23/2022] Open
Abstract
Malassezia spp. are lipid-dependent yeasts, inhabiting the skin and mucosa of humans and animals. They are involved in a variety of skin disorders in humans and animals and may cause bloodstream infections in severely immunocompromised patients. Despite a tremendous increase in scientific knowledge of these yeasts during the last two decades, the epidemiology of Malassezia spp. related to fungemia remains largely underestimated most likely due to the difficulty in the isolation of these yeasts species due to their lipid-dependence. This review summarizes and discusses the most recent literature on Malassezia spp. infection and fungemia, its occurrence, pathogenicity mechanisms, diagnostic methods, in vitro susceptibility testing and therapeutic approaches.
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Affiliation(s)
- Wafa Rhimi
- Dipartimento di Medicina Veterinaria, Università degli Studi "Aldo Moro", Bari, Italy
| | - Bart Theelen
- Yeast Research, Westerdijk Fungal Biodiversity Institute, Utrecht, Netherlands
| | - Teun Boekhout
- Yeast Research, Westerdijk Fungal Biodiversity Institute, Utrecht, Netherlands.,The Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, Amsterdam, Netherlands.,Shanghai Key Laboratory of Molecular Medical Mycology, Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - Domenico Otranto
- Dipartimento di Medicina Veterinaria, Università degli Studi "Aldo Moro", Bari, Italy.,Faculty of Veterinary Sciences, Bu-Ali Sina University, Hamedan, Iran
| | - Claudia Cafarchia
- Dipartimento di Medicina Veterinaria, Università degli Studi "Aldo Moro", Bari, Italy
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Goh JPZ, Ianiri G, Heitman J, Dawson TL. Expression of a Malassezia Codon Optimized mCherry Fluorescent Protein in a Bicistronic Vector. Front Cell Infect Microbiol 2020; 10:367. [PMID: 32793513 PMCID: PMC7387403 DOI: 10.3389/fcimb.2020.00367] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 06/15/2020] [Indexed: 12/29/2022] Open
Abstract
The use of fluorescent proteins allows a multitude of approaches from live imaging and fixed cells to labeling of whole organisms, making it a foundation of diverse experiments. Tagging a protein of interest or specific cell type allows visualization and studies of cell localization, cellular dynamics, physiology, and structural characteristics. In specific instances fluorescent fusion proteins may not be properly functional as a result of structural changes that hinder protein function, or when overexpressed may be cytotoxic and disrupt normal biological processes. In our study, we describe application of a bicistronic vector incorporating a Picornavirus 2A peptide sequence between a NAT antibiotic selection marker and mCherry. This allows expression of multiple genes from a single open reading frame and production of discrete protein products through a cleavage event within the 2A peptide. We demonstrate integration of this bicistronic vector into a model Malassezia species, the haploid strain M. furfur CBS 14141, with both active selection, high fluorescence, and proven proteolytic cleavage. Potential applications of this technology can include protein functional studies, Malassezia cellular localization, and co-expression of genes required for targeted mutagenesis.
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Affiliation(s)
- Joleen P. Z. Goh
- Skin Research Institute of Singapore, Agency of Science, Technology and Research, Singapore, Singapore
| | - Giuseppe Ianiri
- Department of Agricultural, Environmental and Food Sciences, University of Molise, Campobasso, Italy
- Department of Molecular Genetics and Microbiology, Duke University Medical Centre, Durham, NC, United States
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Centre, Durham, NC, United States
| | - Thomas L. Dawson
- Skin Research Institute of Singapore, Agency of Science, Technology and Research, Singapore, Singapore
- Department of Drug Discovery, School of Pharmacy, Medical University of South Carolina, Charleston, SC, United States
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HGT in the human and skin commensal Malassezia: A bacterially derived flavohemoglobin is required for NO resistance and host interaction. Proc Natl Acad Sci U S A 2020; 117:15884-15894. [PMID: 32576698 DOI: 10.1073/pnas.2003473117] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The skin of humans and animals is colonized by commensal and pathogenic fungi and bacteria that share this ecological niche and have established microbial interactions. Malassezia are the most abundant fungal skin inhabitant of warm-blooded animals and have been implicated in skin diseases and systemic disorders, including Crohn's disease and pancreatic cancer. Flavohemoglobin is a key enzyme involved in microbial nitrosative stress resistance and nitric oxide degradation. Comparative genomics and phylogenetic analyses within the Malassezia genus revealed that flavohemoglobin-encoding genes were acquired through independent horizontal gene transfer events from different donor bacteria that are part of the mammalian microbiome. Through targeted gene deletion and functional complementation in Malassezia sympodialis, we demonstrated that bacterially derived flavohemoglobins are cytoplasmic proteins required for nitric oxide detoxification and nitrosative stress resistance under aerobic conditions. RNA-sequencing analysis revealed that endogenous accumulation of nitric oxide resulted in up-regulation of genes involved in stress response and down-regulation of the MalaS7 allergen-encoding genes. Solution of the high-resolution X-ray crystal structure of Malassezia flavohemoglobin revealed features conserved with both bacterial and fungal flavohemoglobins. In vivo pathogenesis is independent of Malassezia flavohemoglobin. Lastly, we identified an additional 30 genus- and species-specific horizontal gene transfer candidates that might have contributed to the evolution of this genus as the most common inhabitants of animal skin.
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Abstract
Fungal pathogens represent a major human threat affecting more than a billion people worldwide. Invasive infections are on the rise, which is of considerable concern because they are accompanied by an escalation of antifungal resistance. Deciphering the mechanisms underlying virulence traits and drug resistance strongly relies on genetic manipulation techniques such as generating mutant strains carrying specific mutations, or gene deletions. However, these processes have often been time-consuming and cumbersome in fungi due to a number of complications, depending on the species (e.g., diploid genomes, lack of a sexual cycle, low efficiency of transformation and/or homologous recombination, lack of cloning vectors, nonconventional codon usage, and paucity of dominant selectable markers). These issues are increasingly being addressed by applying clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 mediated genetic manipulation to medically relevant fungi. Here, we summarize the state of the art of CRISPR-Cas9 applications in four major human fungal pathogen lineages: Candida spp., Cryptococcus neoformans, Aspergillus fumigatus, and Mucorales. We highlight the different ways in which CRISPR has been customized to address the critical issues in different species, including different strategies to deliver the CRISPR-Cas9 elements, their transient or permanent expression, use of codon-optimized CAS9, and methods of marker recycling and scarless editing. Some approaches facilitate a more efficient use of homology-directed repair in fungi in which nonhomologous end joining is more commonly used to repair double-strand breaks (DSBs). Moreover, we highlight the most promising future perspectives, including gene drives, programmable base editors, and nonediting applications, some of which are currently available only in model fungi but may be adapted for future applications in pathogenic species. Finally, this review discusses how the further evolution of CRISPR technology will allow mycologists to tackle the multifaceted issue of fungal pathogenesis.
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