1
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O'Meara MJ, Rapala JR, Nichols CB, Alexandre AC, Billmyre RB, Steenwyk JL, Alspaugh JA, O'Meara TR. CryptoCEN: A Co-Expression Network for Cryptococcus neoformans reveals novel proteins involved in DNA damage repair. PLoS Genet 2024; 20:e1011158. [PMID: 38359090 PMCID: PMC10901339 DOI: 10.1371/journal.pgen.1011158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 02/28/2024] [Accepted: 01/30/2024] [Indexed: 02/17/2024] Open
Abstract
Elucidating gene function is a major goal in biology, especially among non-model organisms. However, doing so is complicated by the fact that molecular conservation does not always mirror functional conservation, and that complex relationships among genes are responsible for encoding pathways and higher-order biological processes. Co-expression, a promising approach for predicting gene function, relies on the general principal that genes with similar expression patterns across multiple conditions will likely be involved in the same biological process. For Cryptococcus neoformans, a prevalent human fungal pathogen greatly diverged from model yeasts, approximately 60% of the predicted genes in the genome lack functional annotations. Here, we leveraged a large amount of publicly available transcriptomic data to generate a C. neoformans Co-Expression Network (CryptoCEN), successfully recapitulating known protein networks, predicting gene function, and enabling insights into the principles influencing co-expression. With 100% predictive accuracy, we used CryptoCEN to identify 13 new DNA damage response genes, underscoring the utility of guilt-by-association for determining gene function. Overall, co-expression is a powerful tool for uncovering gene function, and decreases the experimental tests needed to identify functions for currently under-annotated genes.
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Affiliation(s)
- Matthew J O'Meara
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Jackson R Rapala
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Connie B Nichols
- Departments of Medicine and Molecular Genetics/Microbiology; and Cell Biology, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - A Christina Alexandre
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - R Blake Billmyre
- Departments of Pharmaceutical and Biomedical Sciences/Infectious Disease, College of Pharmacy/College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
| | - Jacob L Steenwyk
- Howard Hughes Medical Institute and the Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, United States of America
| | - J Andrew Alspaugh
- Departments of Medicine and Molecular Genetics/Microbiology; and Cell Biology, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Teresa R O'Meara
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, United States of America
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2
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Ueno K, Nagamori A, Honkyu NO, Kataoka M, Shimizu K, Chang YC, Kwon-Chung KJ, Miyazaki Y. Cryptococcus neoformans requires the TVF1 gene for thermotolerance and virulence. Med Mycol 2023; 61:myad101. [PMID: 37818721 PMCID: PMC10565887 DOI: 10.1093/mmy/myad101] [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: 07/11/2023] [Revised: 09/13/2023] [Accepted: 09/26/2023] [Indexed: 09/29/2023] Open
Abstract
Cryptococcus neoformans is the primary causative agent of cryptococcosis. Since C. neoformans thrives in environments and its optimal growth temperature is 25-30°C, it needs to adapt to heat stress in order to cause infection in mammalian hosts. In this study, we aimed to investigate the role of an uncharacterized gene, CNAG_03308. Although the CNAG_03308 deletion strain grew as well as the parent strain KN99, it produced yeast cells with abnormal morphology at 37°C and failed to propagate at 39°C. Furthermore, the deletion strain exhibited slower growth at 37°C in the presence of congo red, which is a cell wall stressor. When cultured at 39°C, the deletion strain showed strong staining with fluorescent probes for cell wall chitin and chitosan, including FITC-labeled wheat germ agglutinin, Eosin Y, and calcofluor white. The transmission electron microscopy of the deletion strain revealed a thickened inner layer of the cell wall containing chitin and chitosan under heat stress. This cell-surface altered deletion strain induced dendritic cells to secrete more interleukin (IL)-6 and IL-23 than the control strains under heat stress. In a murine infection study, C57BL/6 mice infected with the deletion strain exhibited lower mortality and lower fungal burden in the lungs and brain compared to those infected with the control strains. Based on these findings, we concluded that CNAG_03308 gene is necessary for C. neoformans to adapt to heat stress both in vitro and in the host environment. Therefore, we designated the CNAG_03308 gene as TVF1, which stands for thermotolerance and virulence-related factor 1.
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Affiliation(s)
- Keigo Ueno
- Department of Fungal Infection, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
| | - Akiko Nagamori
- Department of Fungal Infection, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
| | - Nahoko Oniyama Honkyu
- Department of Fungal Infection, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
| | - Michiyo Kataoka
- Department of Pathology, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
| | - Kiminori Shimizu
- Department of Biological Science and Technology, Tokyo University of Science, Tokyo 125-8585, Japan
| | - Yun C Chang
- Molecular Microbiology Section, Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Kyung J Kwon-Chung
- Molecular Microbiology Section, Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Yoshitsugu Miyazaki
- Department of Fungal Infection, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
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3
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O’Meara MJ, Rapala JR, Nichols CB, Alexandre C, Billmyre RB, Steenwyk JL, Alspaugh JA, O’Meara TR. CryptoCEN: A Co-Expression Network for Cryptococcus neoformans reveals novel proteins involved in DNA damage repair. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.17.553567. [PMID: 37645941 PMCID: PMC10462067 DOI: 10.1101/2023.08.17.553567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Elucidating gene function is a major goal in biology, especially among non-model organisms. However, doing so is complicated by the fact that molecular conservation does not always mirror functional conservation, and that complex relationships among genes are responsible for encoding pathways and higher-order biological processes. Co-expression, a promising approach for predicting gene function, relies on the general principal that genes with similar expression patterns across multiple conditions will likely be involved in the same biological process. For Cryptococcus neoformans, a prevalent human fungal pathogen greatly diverged from model yeasts, approximately 60% of the predicted genes in the genome lack functional annotations. Here, we leveraged a large amount of publicly available transcriptomic data to generate a C. neoformans Co-Expression Network (CryptoCEN), successfully recapitulating known protein networks, predicting gene function, and enabling insights into the principles influencing co-expression. With 100% predictive accuracy, we used CryptoCEN to identify 13 new DNA damage response genes, underscoring the utility of guilt-by-association for determining gene function. Overall, co-expression is a powerful tool for uncovering gene function, and decreases the experimental tests needed to identify functions for currently under-annotated genes.
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Affiliation(s)
- Matthew J. O’Meara
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, USA
| | - Jackson R. Rapala
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI, USA
| | - Connie B. Nichols
- Departments of Medicine and Molecular Genetics/Microbiology; and Cell Biology, Duke University School of Medicine, Durham, North Carolina, USA
| | - Christina Alexandre
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI, USA
| | - R. Blake Billmyre
- Departments of Pharmaceutical and Biomedical Sciences/Infectious Disease, College of Pharmacy/College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
| | - Jacob L Steenwyk
- Howards Hughes Medical Institute and the Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - J. Andrew Alspaugh
- Departments of Medicine and Molecular Genetics/Microbiology; and Cell Biology, Duke University School of Medicine, Durham, North Carolina, USA
| | - Teresa R. O’Meara
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI, USA
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4
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Chaudhary A, Singh D. In-silico analysis of the regulatory region of effector protein genes in Verticillium dahliae. GENE REPORTS 2022. [DOI: 10.1016/j.genrep.2022.101533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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5
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Pianalto KM, Billmyre RB, Telzrow CL, Alspaugh JA. Roles for Stress Response and Cell Wall Biosynthesis Pathways in Caspofungin Tolerance in Cryptococcus neoformans. Genetics 2019; 213:213-227. [PMID: 31266771 PMCID: PMC6727808 DOI: 10.1534/genetics.119.302290] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Accepted: 06/24/2019] [Indexed: 12/14/2022] Open
Abstract
Limited antifungal diversity and availability are growing problems for the treatment of fungal infections in the face of increasing drug resistance. The echinocandins, one of the newest classes of antifungal drugs, inhibit production of a crucial cell wall component. However, these compounds do not effectively inhibit the growth of the opportunistic fungal pathogen Cryptococcus neoformans, despite potent inhibition of the target enzyme in vitro Therefore, we performed a forward genetic screen to identify cellular processes that mediate the relative tolerance of this organism to the echinocandin drug caspofungin. Through these studies, we identified 14 genetic mutants that enhance caspofungin antifungal activity. Rather than directly affecting caspofungin antifungal activity, these mutations seem to prevent the activation of various stress-induced compensatory cellular processes. For example, the pfa4Δ mutant has defects in the palmitoylation and localization of many of its target proteins, including the Ras1 GTPase and the Chs3 chitin synthase, which are both required for caspofungin tolerance. Similarly, we have confirmed the link between caspofungin treatment and calcineurin signaling in this organism, but we suggest a deeper mechanism in which caspofungin tolerance is mediated by multiple pathways downstream of calcineurin function. In summary, we describe here several pathways in C. neoformans that contribute to the complex caspofungin tolerance phenotype in this organism.
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Affiliation(s)
- Kaila M Pianalto
- Department of Medicine, Duke University School of Medicine, Durham, North Carolina 27710
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina 27710
| | - R Blake Billmyre
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina 27710
| | - Calla L Telzrow
- Department of Medicine, Duke University School of Medicine, Durham, North Carolina 27710
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina 27710
| | - J Andrew Alspaugh
- Department of Medicine, Duke University School of Medicine, Durham, North Carolina 27710
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina 27710
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6
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de Oliveira HC, Trevijano-Contador N, Garcia-Rodas R. Cryptococcal Pathogenicity and Morphogenesis. CURRENT FUNGAL INFECTION REPORTS 2019. [DOI: 10.1007/s12281-019-00340-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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7
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Hühn J, Musielak M, Schmitz HP, Heinisch JJ. Fungal homologues of human Rac1 as emerging players in signal transduction and morphogenesis. Int Microbiol 2019; 23:43-53. [PMID: 31020478 DOI: 10.1007/s10123-019-00077-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 03/28/2019] [Accepted: 04/02/2019] [Indexed: 02/06/2023]
Abstract
A wealth of data is accumulating on the physiological functions of human Rac1, a member of the Rho GTPase family of molecular switches and substrate of botulinum toxin, which was first identified as a regulator of cell motility through its effect on the actin cytoskeleton. Later on, it was found to be involved in different diseases like cancers, cardiac function, neuronal disorders, and apoptotic cell death. Despite the presence of Rac1 homologues in most fungi investigated so far, including Rho5 in the genetically tractable model yeast Saccharomyces cerevisiae, knowledge on their physiological functions is still scarce, let alone the details of the molecular mechanisms of their actions and interactions. Nevertheless, all functions proposed for human Rac1 seem to be conserved in one or the other fungus. This includes the regulation of MAPK cascades, polarized growth, and actin dynamics. Moreover, both the production and response to reactive oxygen species, as well as the reaction to nutrient availability, can be affected. We here summarize the studies performed on fungal Rac1 homologues, with a special focus on S. cerevisiae Rho5, which may be of use in drug development in medicine and agriculture.
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Affiliation(s)
- Julia Hühn
- Department of Biology and Chemistry, Genetics group, University of Osnabrück, Barbarastrasse 11, 49076, Osnabrück, Germany
| | - Marius Musielak
- Department of Biology and Chemistry, Genetics group, University of Osnabrück, Barbarastrasse 11, 49076, Osnabrück, Germany
| | - Hans-Peter Schmitz
- Department of Biology and Chemistry, Genetics group, University of Osnabrück, Barbarastrasse 11, 49076, Osnabrück, Germany
| | - Jürgen J Heinisch
- Department of Biology and Chemistry, Genetics group, University of Osnabrück, Barbarastrasse 11, 49076, Osnabrück, Germany.
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8
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Martin-Vicente A, Souza ACO, Al Abdallah Q, Ge W, Fortwendel JR. SH3-class Ras guanine nucleotide exchange factors are essential for Aspergillus fumigatus invasive growth. Cell Microbiol 2019; 21:e13013. [PMID: 30698898 PMCID: PMC6522298 DOI: 10.1111/cmi.13013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 12/11/2018] [Accepted: 01/22/2019] [Indexed: 01/23/2023]
Abstract
Proper hyphal morphogenesis is essential for the establishment and progression of invasive disease caused by filamentous fungi. In the human pathogen Aspergillus fumigatus, signalling cascades driven by Ras and Ras‐like proteins orchestrate a wide variety of cellular processes required for hyphal growth. For activation, these proteins require interactions with Ras‐subfamily‐specific guanine nucleotide exchange factors (RasGEFs). Although Ras‐protein networks are essential for virulence in all pathogenic fungi, the importance of RasGEF proteins is largely unexplored. A. fumigatus encodes four putative RasGEFs that represent three separate classes of RasGEF proteins (SH3‐, Ras guanyl nucleotide‐releasing protein [RasGRP]–, and LTE‐class), each with fungus‐specific attributes. Here, we show that the SH3‐class and RasGRP‐class RasGEFs are required for properly timed polarity establishment during early growth and branch emergence as well as for cell wall stability. Further, we show that SH3‐class RasGEF activity is essential for polarity establishment and maintenance, a phenotype that is, at least, partially independent of the major A. fumigatus Ras proteins, RasA and RasB. Finally, loss of both SH3‐class RasGEFs resulted in avirulence in multiple models of invasive aspergillosis. Together, our findings suggest that RasGEF activity is essential for the integration of multiple signalling networks to drive invasive growth in A. fumigatus.
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Affiliation(s)
- Adela Martin-Vicente
- Department of Clinical Pharmacy and Translational Science, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Ana Camila Oliveira Souza
- Department of Clinical Pharmacy and Translational Science, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Qusai Al Abdallah
- Department of Clinical Pharmacy and Translational Science, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Wenbo Ge
- Department of Clinical Pharmacy and Translational Science, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Jarrod R Fortwendel
- Department of Clinical Pharmacy and Translational Science, University of Tennessee Health Science Center, Memphis, Tennessee, USA
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9
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Rahim K, Huo L, Li C, Zhang P, Basit A, Xiang B, Ting B, Hao X, Zhu X. Identification of a basidiomycete-specific Vilse-like GTPase activating proteins (GAPs) and its roles in the production of virulence factors in Cryptococcus neoformans. FEMS Yeast Res 2019; 17:4644832. [PMID: 29177429 DOI: 10.1093/femsyr/fox089] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 11/20/2017] [Indexed: 12/25/2022] Open
Abstract
Cryptococcus neoformans is a basidiomycetous pathogenic yeast that causes fatal infections in both immunocompetent and immunocompromised patients. Regulation on the production of its virulence factors is not fully understood. Here we reported the characterization of a gene, named CVH1(CNA06260), encoding a Drosophila Vilse-like RhoGAP homolog, which is hallmarked by three conserved functional domains: WW, MyTH4 and RhoGAP. Phylogenetic analysis suggests that CVH1 is highly conserved from protists to mammals and interestingly in basidiomycetes, but absent in plants or Ascomycota and other lower fungi. This phylogenetic distribution indicates an evolutionary link among these groups of organisms. Functional analyses demonstrated that CVH1 was involved in stress tolerance and virulence factor production. By disrupting CVH1, we created a second mutant cvh1Δ with the CRISPR-Cas9 editing tool. The mutant strain exhibited hypersensitivity to osmotic stress by 2 M sorbitol and NaCl, suggesting defects in the HOG signaling pathway and an interaction of Cvh1 with the HOG pathway. Hypersensitivity of cvh1Δ to 1% Congo red and 0.01% SDS suggests that the cell wall integrity was impaired in the mutant. And cvh1Δ hardly produced the pigment melanin and capsule. Our study for the first time demonstrates that the fungal Vilse-like RhoGAP CVH1 is an important regulator of multiple biological processes in C. neoformans, and provides novel insights into the regulatory circuit of stress resistance/cell wall integrity, and laccase and capsule synthesis in C. neoformans.
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Affiliation(s)
- Kashif Rahim
- Beijing Key Laboratory of Genetic Engineering Drug and Biotechnology, Institute of Biochemistry and Biotechnology, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Liang Huo
- Beijing Key Laboratory of Genetic Engineering Drug and Biotechnology, Institute of Biochemistry and Biotechnology, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Chenxi Li
- Beijing Key Laboratory of Genetic Engineering Drug and Biotechnology, Institute of Biochemistry and Biotechnology, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Ping Zhang
- Beijing Key Laboratory of Genetic Engineering Drug and Biotechnology, Institute of Biochemistry and Biotechnology, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Abdul Basit
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Biyun Xiang
- Beijing Key Laboratory of Genetic Engineering Drug and Biotechnology, Institute of Biochemistry and Biotechnology, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Bie Ting
- Beijing Key Laboratory of Genetic Engineering Drug and Biotechnology, Institute of Biochemistry and Biotechnology, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Xiaoran Hao
- Beijing Key Laboratory of Genetic Engineering Drug and Biotechnology, Institute of Biochemistry and Biotechnology, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Xudong Zhu
- Beijing Key Laboratory of Genetic Engineering Drug and Biotechnology, Institute of Biochemistry and Biotechnology, College of Life Sciences, Beijing Normal University, Beijing 100875, China
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10
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Genome-Wide Identification of circRNAs in Pathogenic Basidiomycetous Yeast Cryptococcus neoformans Suggests Conserved circRNA Host Genes over Kingdoms. Genes (Basel) 2018; 9:genes9030118. [PMID: 29495353 PMCID: PMC5867839 DOI: 10.3390/genes9030118] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 02/09/2018] [Accepted: 02/19/2018] [Indexed: 12/15/2022] Open
Abstract
Circular RNAs (circRNAs), a novel class of ubiquitous and intriguing noncoding RNA, have been found in a number of eukaryotes but not yet basidiomycetes. In this study, we identified 73 circRNAs from 39.28 million filtered RNA reads from the basidiomycete Cryptococcus neoformans JEC21 using next-generation sequencing (NGS) and the bioinformatics tool circular RNA identification (CIRI). Furthermore, mapping of newly found circRNAs to the genome showed that 73.97% of the circRNAs originated from exonic regions, whereas 20.55% were from intergenic regions and 5.48% were from intronic regions. Enrichment analysis of circRNA host genes was conducted based on the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway databases. The results reveal that host genes are mainly responsible for primary metabolism and, interestingly, ribosomal protein production. Furthermore, we uncovered a high-level circRNA that was a transcript from the guanosine triphosphate (GTP)ase gene CNM01190 (gene ID: 3255052) in our yeast. Coincidentally, YPT5, CNM01190's ortholog of the GTPase in Schizosaccharomyces pombe, protists, and humans, has already been proven to generate circRNAs. Additionally, overexpression of RNA debranching enzyme DBR1 had varied influence on the expression of circRNAs, indicating that multiple circRNA biosynthesis pathways exist in C. neoformans. Our study provides evidence for the existence of stable circRNAs in the opportunistic human pathogen C. neoformans and raises a question regarding their role related to pathogenesis in this yeast.
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11
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Pentland DR, Piper-Brown E, Mühlschlegel FA, Gourlay CW. Ras signalling in pathogenic yeasts. MICROBIAL CELL 2017; 5:63-73. [PMID: 29417055 PMCID: PMC5798406 DOI: 10.15698/mic2018.02.612] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The small GTPase Ras acts as a master regulator of growth, stress response and cell death in eukaryotic cells. The control of Ras activity is fundamental, as highlighted by the oncogenic properties of constitutive forms of Ras proteins. Ras also plays a crucial role in the pathogenicity of fungal pathogens where it has been found to regulate a number of adaptions required for virulence. The importance of Ras in fungal disease raises the possibility that it may provide a useful target for the development of new treatments at a time when resistance to available antifungals is increasing. New findings suggest that important regulatory sequences found within fungal Ras proteins that are not conserved may prove useful in the development of new antifungals. Here we review the roles of Ras protein function and signalling in the major human yeast pathogens Candida albicans and Cryptococcus neoformans and discuss the potential for targeting Ras as a novel approach to anti-fungal therapy.
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Affiliation(s)
- Daniel R Pentland
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury, Kent, United Kingdom, CT2 7NJ
| | - Elliot Piper-Brown
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury, Kent, United Kingdom, CT2 7NJ
| | - Fritz A Mühlschlegel
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury, Kent, United Kingdom, CT2 7NJ.,Laboratoire national de santé, 1, Rue Louis Rech, L-3555 Dudelange, Luxembourg
| | - Campbell W Gourlay
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury, Kent, United Kingdom, CT2 7NJ
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12
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Malachowski AN, Yosri M, Park G, Bahn YS, He Y, Olszewski MA. Systemic Approach to Virulence Gene Network Analysis for Gaining New Insight into Cryptococcal Virulence. Front Microbiol 2016; 7:1652. [PMID: 27833589 PMCID: PMC5081415 DOI: 10.3389/fmicb.2016.01652] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Accepted: 10/04/2016] [Indexed: 11/13/2022] Open
Abstract
Cryptococcus neoformans is pathogenic yeast, responsible for highly lethal infections in compromised patients around the globe. C. neoformans typically initiates infections in mammalian lung tissue and subsequently disseminates to the central nervous system where it causes significant pathologies. Virulence genes of C. neoformans are being characterized at an increasing rate, however, we are far from a comprehensive understanding of their roles and genetic interactions. Some of these reported virulence genes are scattered throughout different databases, while others are not yet included. This study gathered and analyzed 150 reported virulence associated factors (VAFs) of C. neoformans. Using the web resource STRING database, our study identified different interactions between the total VAFs and those involved specifically in lung and brain infections and identified a new strain specific virulence gene, SHO1, involved in the mitogen-activated protein kinase signaling pathway. As predicted by our analysis, SHO1 expression enhanced C. neoformans virulence in a mouse model of pulmonary infection, contributing to enhanced non-protective immune Th2 bias and progressively enhancing fungal growth in the infected lungs. Sequence analysis indicated 77.4% (116) of total studied VAFs are soluble proteins, and 22.7% (34) are transmembrane proteins. Motifs involved in regulation and signaling such as protein kinases and transcription factors are highly enriched in Cryptococcus VAFs. Altogether, this study represents a pioneering effort in analysis of the virulence composite network of C. neoformans using a systems biology approach.
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Affiliation(s)
- Antoni N Malachowski
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical School, Ann ArborMI, USA; VA Ann Arbor Healthcare System Research Service (11R), Ann ArborMI, USA
| | - Mohamed Yosri
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical School, Ann ArborMI, USA; VA Ann Arbor Healthcare System Research Service (11R), Ann ArborMI, USA; The Regional Center for Mycology and Biotechnology, Al-Azhar UniversityCairo, Egypt
| | - Goun Park
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University Seoul, South Korea
| | - Yong-Sun Bahn
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University Seoul, South Korea
| | - Yongqun He
- Unit for Laboratory Animal Medicine, University of Michigan Medical School, Ann ArborMI, USA; Department of Microbiology and Immunology, University of Michigan Medical School, Ann ArborMI, USA; Center for Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann ArborMI, USA
| | - Michal A Olszewski
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical School, Ann ArborMI, USA; VA Ann Arbor Healthcare System Research Service (11R), Ann ArborMI, USA
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13
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Relative Contributions of Prenylation and Postprenylation Processing in Cryptococcus neoformans Pathogenesis. mSphere 2016; 1:mSphere00084-15. [PMID: 27303728 PMCID: PMC4894686 DOI: 10.1128/msphere.00084-15] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 03/03/2016] [Indexed: 12/01/2022] Open
Abstract
Cryptococcus neoformans is an important human fungal pathogen that causes disease and death in immunocompromised individuals. The growth and morphogenesis of this fungus are controlled by conserved Ras-like GTPases, which are also important for its pathogenicity. Many of these proteins require proper subcellular localization for full function, and they are directed to cellular membranes through a posttranslational modification process known as prenylation. These studies investigate the roles of one of the prenylation enzymes, farnesyltransferase, as well as the postprenylation processing enzymes in C. neoformans. We demonstrate that the postprenylation processing steps are dispensable for the localization of certain substrate proteins. However, both protein farnesylation and the subsequent postprenylation processing steps are required for full pathogenesis of this fungus. Prenyltransferase enzymes promote the membrane localization of their target proteins by directing the attachment of a hydrophobic lipid group at a conserved C-terminal CAAX motif. Subsequently, the prenylated protein is further modified by postprenylation processing enzymes that cleave the terminal 3 amino acids and carboxymethylate the prenylated cysteine residue. Many prenylated proteins, including Ras1 and Ras-like proteins, require this multistep membrane localization process in order to function properly. In the human fungal pathogen Cryptococcus neoformans, previous studies have demonstrated that two distinct forms of protein prenylation, farnesylation and geranylgeranylation, are both required for cellular adaptation to stress, as well as full virulence in animal infection models. Here, we establish that the C. neoformans RAM1 gene encoding the farnesyltransferase β-subunit, though not strictly essential for growth under permissive in vitro conditions, is absolutely required for cryptococcal pathogenesis. We also identify and characterize postprenylation protease and carboxyl methyltransferase enzymes in C. neoformans. In contrast to the prenyltransferases, deletion of the genes encoding the Rce1 protease and Ste14 carboxyl methyltransferase results in subtle defects in stress response and only partial reductions in virulence. These postprenylation modifications, as well as the prenylation events themselves, do play important roles in mating and hyphal transitions, likely due to their regulation of peptide pheromones and other proteins involved in development. IMPORTANCECryptococcus neoformans is an important human fungal pathogen that causes disease and death in immunocompromised individuals. The growth and morphogenesis of this fungus are controlled by conserved Ras-like GTPases, which are also important for its pathogenicity. Many of these proteins require proper subcellular localization for full function, and they are directed to cellular membranes through a posttranslational modification process known as prenylation. These studies investigate the roles of one of the prenylation enzymes, farnesyltransferase, as well as the postprenylation processing enzymes in C. neoformans. We demonstrate that the postprenylation processing steps are dispensable for the localization of certain substrate proteins. However, both protein farnesylation and the subsequent postprenylation processing steps are required for full pathogenesis of this fungus.
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Arkowitz RA, Bassilana M. Regulation of hyphal morphogenesis by Ras and Rho small GTPases. FUNGAL BIOL REV 2015. [DOI: 10.1016/j.fbr.2015.02.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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15
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Tian H, Zhou L, Guo W, Wang X. Small GTPase Rac1 and its interaction partner Cla4 regulate polarized growth and pathogenicity in Verticillium dahliae. Fungal Genet Biol 2014; 74:21-31. [PMID: 25475370 DOI: 10.1016/j.fgb.2014.11.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Revised: 11/20/2014] [Accepted: 11/25/2014] [Indexed: 12/21/2022]
Abstract
Rac1 is a small GTPase coordinating diverse cellular functions such as cell polarity, vesicular trafficking, the cell cycle and transcriptional dynamics in many organisms. In this study, we investigate the biological functions of VdRac1, a Rac1 homolog in the soil-borne, wilt-causing fungus Verticillium dahliae. The VdRac1 gene was deleted in a V. dahliae virulence strain Vd8 isolated from a local cotton cultivar. ΔVdrac1 mutants display drastic reduction in colony expansion and form compact, convoluted colonies, show hyper-branching, loss of polarity and ability to penetrate, leading to severely reduced virulence. The p21-activated kinase Cla4 (named as VdCla4 in V. dahliae) null mutants ΔVdcla4 share identical phenotypes with ΔVdrac1. Yeast two-hybrid studies prove that VdCla4 is an effector of VdRac1. Localizations of actin and reactive oxygen species (ROS) in ΔVdrac1 and ΔVdcla4 compared with the corresponding wild-type strain reveal that VdRac1 and VdCla4 play a primary role in polarized hyphal growth via organization of ROS and play only a minor role in the organization of actin. The Vdrac1 and Vdcla4 null mutants are defective in conidiation and trace elements can partially compensate for the defect. Our data demonstrate that VdRac1 regulates polarized growth and pathogenicity by interacting with its effector VdCla4 in V. dahliae.
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Affiliation(s)
- Hui Tian
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, PR China
| | - Lei Zhou
- The State Key Laboratory of Crop Genetics & Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, PR China
| | - Wangzhen Guo
- The State Key Laboratory of Crop Genetics & Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, PR China
| | - Xinyu Wang
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, PR China.
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Abstract
Morphogenesis in fungi is often induced by extracellular factors and executed by fungal genetic factors. Cell surface changes and alterations of the microenvironment often accompany morphogenetic changes in fungi. In this review, we will first discuss the general traits of yeast and hyphal morphotypes and how morphogenesis affects development and adaptation by fungi to their native niches, including host niches. Then we will focus on the molecular machinery responsible for the two most fundamental growth forms, yeast and hyphae. Last, we will describe how fungi incorporate exogenous environmental and host signals together with genetic factors to determine their morphotype and how morphogenesis, in turn, shapes the fungal microenvironment.
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Affiliation(s)
- Xiaorong Lin
- Department of Biology, Texas A&M University, College Station, Texas 77843-3258
| | - J Andrew Alspaugh
- Department of Medicine, Division of Infectious Diseases, Duke University Medical Center, Durham, North Carolina 27710
| | - Haoping Liu
- Department of Biological Chemistry, University of California, Irvine, California 92697
| | - Steven Harris
- Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, Nebraska 68588
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Ras GTPase activating protein CoIra1 is involved in infection-related morphogenesis by regulating cAMP and MAPK signaling pathways through CoRas2 in Colletotrichum orbiculare. PLoS One 2014; 9:e109045. [PMID: 25275394 PMCID: PMC4183519 DOI: 10.1371/journal.pone.0109045] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 08/29/2014] [Indexed: 11/19/2022] Open
Abstract
Colletotrichum orbiculare is the causative agent of anthracnose disease on cucurbitaceous plants. Several signaling pathways, including cAMP–PKA and mitogen-activating protein kinase (MAPK) pathways are involved in the infection-related morphogenesis and pathogenicity of C. orbiculare. However, upstream regulators of these pathways for this species remain unidentified. In this study, CoIRA1, encoding RAS GTPase activating protein, was identified by screening the Agrobacterium tumefaciens-mediated transformation (AtMT) mutant, which was defective in the pathogenesis of C. orbiculare. The coira1 disrupted mutant showed an abnormal infection-related morphogenesis and attenuated pathogenesis. In Saccharomyces cerevisiae, Ira1/2 inactivates Ras1/2, which activates adenylate cyclase, leading to the synthesis of cAMP. Increase in the intracellular cAMP levels in coira1 mutants and dominant active forms of CoRAS2 introduced transformants indicated that CoIra1 regulates intracellular cAMP levels through CoRas2. Moreover, the phenotypic analysis of transformants that express dominant active form CoRAS2 in the comekk1 mutant or a dominant active form CoMEKK1 in the coras2 mutant indicated that CoRas2 regulates the MAPK CoMekk1–Cmk1 signaling pathway. The CoRas2 localization pattern in vegetative hyphae of the coira1 mutant was similar to that of the wild-type, expressing a dominant active form of RFP–CoRAS2. Moreover, we demonstrated that bimolecular fluorescence complementation (BiFC) signals between CoIra1 and CoRas2 were detected in the plasma membrane of vegetative hyphae. Therefore, it is likely that CoIra1 negatively regulates CoRas2 in vegetative hyphae. Furthermore, cytological analysis of the localization of CoIraI and CoRas2 revealed the dynamic cellular localization of the proteins that leads to proper assembly of F-actin at appressorial pore required for successful penetration peg formation through the pore. Thus, our results indicated that CoIra1 is involved in infection-related morphogenesis and pathogenicity by proper regulation of cAMP and MAPK signaling pathways through CoRas2.
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Rho GTPase-phosphatidylinositol phosphate interplay in fungal cell polarity. Biochem Soc Trans 2014; 42:206-11. [PMID: 24450653 DOI: 10.1042/bst20130226] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Rho G-proteins and phosphatidylinositol phosphates, which are important for exocytosis, endocytosis and cytoskeleton organization, are key regulators of polarized growth in a range of organisms. The aim of the present brief review is to highlight recent findings and their implications with respect to the functions and interplay between Rho G-proteins and phosphatidylinositol phosphates in highly polarized fungal filamentous growth.
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Hogan D, Wheeler RT. The complex roles of NADPH oxidases in fungal infection. Cell Microbiol 2014; 16:1156-67. [PMID: 24905433 DOI: 10.1111/cmi.12320] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 05/27/2014] [Accepted: 05/29/2014] [Indexed: 12/21/2022]
Abstract
NADPH oxidases play key roles in immunity and inflammation that go beyond the production of microbicidal reactive oxygen species (ROS). The past decade has brought a new appreciation for the diversity of roles played by ROS in signalling associated with inflammation and immunity. NADPH oxidase activity affects disease outcome during infections by human pathogenic fungi, an important group of emerging and opportunistic pathogens that includes Candida, Aspergillus and Cryptococcus species. Here we review how alternative roles of NADPH oxidase activity impact fungal infection and how ROS signalling affects fungal physiology. Particular attention is paid to roles for NADPH oxidase in immune migration, immunoregulation in pulmonary infection, neutrophil extracellular trap formation, autophagy and inflammasome activity. These recent advances highlight the power and versatility of spatiotemporally controlled redox regulation in the context of infection, and point to a need to understand the molecular consequences of NADPH oxidase activity in the cell.
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Affiliation(s)
- Deborah Hogan
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
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Restricted substrate specificity for the geranylgeranyltransferase-I enzyme in Cryptococcus neoformans: implications for virulence. EUKARYOTIC CELL 2013; 12:1462-71. [PMID: 24014765 DOI: 10.1128/ec.00193-13] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Proper cellular localization is required for the function of many proteins. The CaaX prenyltransferases (where CaaX indicates a cysteine followed by two aliphatic amino acids and a variable amino acid) direct the subcellular localization of a large group of proteins by catalyzing the attachment of hydrophobic isoprenoid moieties onto C-terminal CaaX motifs, thus facilitating membrane association. This group of enzymes includes farnesyltransferase (Ftase) and geranylgeranyltransferase-I (Ggtase-1). Classically, the variable (X) amino acid determines whether a protein will be an Ftase or Ggtase-I substrate, with Ggtase-I substrates often containing CaaL motifs. In this study, we identify the gene encoding the β subunit of Ggtase-I (CDC43) and demonstrate that Ggtase-mediated activity is not essential. However, Cryptococcus neoformans CDC43 is important for thermotolerance, morphogenesis, and virulence. We find that Ggtase-I function is required for full membrane localization of Rho10 and the two Cdc42 paralogs (Cdc42 and Cdc420). Interestingly, the related Rac and Ras proteins are not mislocalized in the cdc43Δ mutant even though they contain similar CaaL motifs. Additionally, the membrane localization of each of these GTPases is dependent on the prenylation of the CaaX cysteine. These results indicate that C. neoformans CaaX prenyltransferases may recognize their substrates in a unique manner from existing models of prenyltransferase specificity. It also suggests that the C. neoformans Ftase, which has been shown to be more important for C. neoformans proliferation and viability, may be the primary prenyltransferase for proteins that are typically geranylgeranylated in other species.
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Ballou ER, Kozubowski L, Nichols CB, Alspaugh JA. Ras1 acts through duplicated Cdc42 and Rac proteins to regulate morphogenesis and pathogenesis in the human fungal pathogen Cryptococcus neoformans. PLoS Genet 2013; 9:e1003687. [PMID: 23950731 PMCID: PMC3738472 DOI: 10.1371/journal.pgen.1003687] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Accepted: 06/17/2013] [Indexed: 02/07/2023] Open
Abstract
Proliferation and morphogenesis in eukaryotic cells depend on the concerted activity of Rho-type GTPases, including Ras, Cdc42, and Rac. The sexually dimorphic fungus Cryptococcus neoformans, which encodes paralogous, non-essential copies of all three, provides a unique model in which to examine the interactions of these conserved proteins. Previously, we demonstrated that RAS1 mediates C. neoformans virulence by acting as a central regulator of both thermotolerance and mating. We report here that ras1Δ mutants accumulate defects in polarized growth, cytokinesis, and cell cycle progression. We demonstrate that the ras1Δ defects in thermotolerance and mating can be largely explained by the compromised activity of four downstream Rho-GTPases: the Cdc42 paralogs, Cdc42 and Cdc420; and the Rac paralogs, Rac1 and Rac2. Further, we demonstrate that the separate GTPase classes play distinct Ras-dependent roles in C. neoformans morphogenesis and pathogenesis. Cdc42 paralogs primarily control septin localization and cytokinesis, while Rac paralogs play a primary role in polarized cell growth. Together, these duplicate, related signaling proteins provide a robust system to allow microbial proliferation in the presence of host-derived cell stresses.
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Affiliation(s)
- Elizabeth Ripley Ballou
- Department of Medicine, Duke University School of Medicine, Durham, North Carolina, United States of America
- Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Lukasz Kozubowski
- Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Connie B. Nichols
- Department of Medicine, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - J. Andrew Alspaugh
- Department of Medicine, Duke University School of Medicine, Durham, North Carolina, United States of America
- Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina, United States of America
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