scholarly journals mSphere of Influence: a Systematic Approach To Dissect Virulence Traits in Candida albicans

mSphere ◽  
2019 ◽  
Vol 4 (3) ◽  
Author(s):  
J. Christian Pérez
Keyword(s):  
Candida Albicans ◽  
Systematic Approach ◽  
Genetic Manipulation ◽  
Homozygous Deletion ◽  
Mammalian Host ◽  
Genetic Screens ◽  
Content Type ◽  
Link Type ◽  
Virulence Traits ◽  
Deletion Library

ABSTRACT J. Christian Pérez studies the interplay between Candida albicans and the mammalian host. In this mSphere of Influence article, he reflects on how “Systematic screens of a Candida albicans homozygous deletion library decouple morphogenetic switching and pathogenicity” (S. M. Noble, S. French, L. A. Kohn, V. Chen, et al., Nat Genet 42:590–598, 2010, https://doi.org/10.1038/ng.605) provided tools and a blueprint for open-ended genetic screens in an organism that had been a challenge for genetic manipulation.

scholarly journals mSphere of Influence: Start with an Interesting Biological Phenomenon

mSphere ◽  
2019 ◽  
Vol 4 (3) ◽  
Author(s):  
Teresa O’Meara
Keyword(s):  
Candida Albicans ◽  
Single Cell Analysis ◽  
Homozygous Deletion ◽  
Functional Genomic ◽  
Cell Analysis ◽  
Biological Phenomenon ◽  
Content Type ◽  
Link Type ◽  
New Biology ◽  
Deletion Library

ABSTRACT Teresa O'Meara works in the field of functional genomics of Candida albicans, with a focus on host-pathogen interactions. In this mSphere of Influence article, she reflects on how papers entitled "Systematic Screens of a Candida albicans Homozygous Deletion Library Decouple Morphogenetic Switching and Pathogenicity" by S. M. Noble, S. French, L. A. Kohn, V. Chen, and A. D. Johnson (Nat Genet 42:590–598, 2010, https://doi.org/10.1038/ng.605) and "Exploring Quantitative Yeast Phenomics with Single-Cell Analysis of DNA Damage Foci" by E. B. Styles et al. (Cell Syst 3:264–277.e10, 2016, https://doi.org/10.1016/j.cels.2016.08.008) impacted her research and thinking through pioneering functional genomic screens. These articles show the power of combining defined mutant libraries with screens for interesting phenotypes to understand new biology.

scholarly journals Candida albicans Gene Deletion with a Transient CRISPR-Cas9 System

mSphere ◽  
2016 ◽  
Vol 1 (3) ◽  
Author(s):  
Kyunghun Min ◽  
Yuichi Ichikawa ◽  
Carol A. Woolford ◽  
Aaron P. Mitchell
Keyword(s):  
Drug Resistance ◽  
Candida Albicans ◽  
Genetic Analysis ◽  
Genome Editing ◽  
Drug Targets ◽  
Gene Deletion ◽  
Genetic Manipulation ◽  
Content Type ◽  
Biological Features ◽  
Link Type

ABSTRACT The fungus Candida albicans is a major pathogen. Genetic analysis of this organism has revealed determinants of pathogenicity, drug resistance, and other unique biological features, as well as the identities of prospective drug targets. The creation of targeted mutations has been greatly accelerated recently through the implementation of CRISPR genome-editing technology by Vyas et al. [Sci Adv 1(3):e1500248, 2015, http://dx.doi.org/10.1126/sciadv.1500248 ]. In this study, we find that CRISPR elements can be expressed from genes that are present only transiently, and we develop a transient CRISPR system that further accelerates C. albicans genetic manipulation. Clustered regularly interspaced short palindromic repeat (CRISPR) and CRISPR-associated gene 9 (CRISPR-Cas9) systems are used for a wide array of genome-editing applications in organisms ranging from fungi to plants and animals. Recently, a CRISPR-Cas9 system has been developed for the diploid fungal pathogen Candida albicans; the system accelerates genetic manipulation dramatically [V. K. Vyas, M. I. Barrasa, and G. R. Fink, Sci Adv 1(3):e1500248, 2015, http://dx.doi.org/10.1126/sciadv.1500248 ]. We show here that the CRISPR-Cas9 genetic elements can function transiently, without stable integration into the genome, to enable the introduction of a gene deletion construct. We describe a transient CRISPR-Cas9 system for efficient gene deletion in C. albicans. Our observations suggest that there are two mechanisms that lead to homozygous deletions: (i) independent recombination of transforming DNA into each allele and (ii) recombination of transforming DNA into one allele, followed by gene conversion of the second allele. Our approach will streamline gene function analysis in C. albicans, and our results indicate that DNA can function transiently after transformation of this organism. IMPORTANCE The fungus Candida albicans is a major pathogen. Genetic analysis of this organism has revealed determinants of pathogenicity, drug resistance, and other unique biological features, as well as the identities of prospective drug targets. The creation of targeted mutations has been greatly accelerated recently through the implementation of CRISPR genome-editing technology by Vyas et al. [Sci Adv 1(3):e1500248, 2015, http://dx.doi.org/10.1126/sciadv.1500248 ]. In this study, we find that CRISPR elements can be expressed from genes that are present only transiently, and we develop a transient CRISPR system that further accelerates C. albicans genetic manipulation.

scholarly journals mSphere of Influence: the Power of Yeast Genetics Still Going Strong!

mSphere ◽  
2019 ◽  
Vol 4 (5) ◽  
Author(s):  
Felipe H. Santiago-Tirado
Keyword(s):  
Genetic Analysis ◽  
Fungal Pathogen ◽  
Cell Biology ◽  
Genetic Manipulation ◽  
Chemical Genetics ◽  
Yeast Genetics ◽  
Content Type ◽  
Human Fungal Pathogen ◽  
Link Type ◽  
Fungal Meningitis

ABSTRACT Felipe Santiago-Tirado studies the cell biology of cryptococcal infections. In this mSphere of Influence article, he reflects on how the papers “Systematic Genetic Analysis of Virulence in the Human Fungal Pathogen Cryptococcus neoformans” (https://doi.org/10.1016/j.cell.2008.07.046) and “Unraveling the Biology of a Fungal Meningitis Pathogen Using Chemical Genetics” (https://doi.org/10.1016/j.cell.2014.10.044) by the Noble and Madhani groups influenced his thinking by showcasing the various modern applications of yeast genetics in an organism where genetic manipulation was difficult.

scholarly journals The Quorum-Sensing Molecules Farnesol/Homoserine Lactone and Dodecanol Operate via Distinct Modes of Action in Candida albicans

2011 ◽  
Vol 10 (8) ◽  
pp. 1034-1042 ◽  
Author(s):  
Rebecca A. Hall ◽  
Kara J. Turner ◽  
James Chaloupka ◽  
Fabien Cottier ◽  
Luisa De Sordi ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Quorum Sensing ◽  
Signaling Pathway ◽  
Homoserine Lactone ◽  
Burkholderia Cenocepacia ◽  
Camp Signaling ◽  
Mammalian Host ◽  
Content Type ◽  
Hyphal Development ◽  
Natural Flora

ABSTRACTLiving as a commensal,Candida albicansmust adapt and respond to environmental cues generated by the mammalian host and by microbes comprising the natural flora. These signals have opposing effects onC. albicans, with host cues promoting the yeast-to-hyphal transition and bacteria-derived quorum-sensing molecules inhibiting hyphal development. Hyphal development is regulated through modulation of the cyclic AMP (cAMP)/protein kinase A (PKA) signaling pathway, and it has been postulated that quorum-sensing molecules can affect filamentation by inhibiting the cAMP pathway. Here, we show that both farnesol and 3-oxo-C12-homoserine lactone, a quorum-sensing molecule secreted byPseudomonas aeruginosa, block hyphal development by affecting cAMP signaling; they both directly inhibited the activity of theCandidaadenylyl cyclase, Cyr1p. In contrast, the 12-carbon alcohol dodecanol appeared to modulate hyphal development and the cAMP signaling pathway without directly affecting the activity of Cyr1p. Instead, we show that dodecanol exerted its effects through a mechanism involving theC. albicanshyphal repressor, Sfl1p. Deletion ofSFL1did not affect the response to farnesol but did interfere with the response to dodecanol. Therefore, quorum sensing inC. albicansis mediated via multiple mechanisms of action. Interestingly, our experiments raise the possibility that theBurkholderia cenocepaciadiffusible signal factor, BDSF, also mediates its effects via Sfl1p, suggesting that dodecanol's mode of action, but not farnesol or 3-oxo-C12-homoserine lactone, may be used by other quorum-sensing molecules.

scholarly journals Host Carbon Dioxide Concentration Is an Independent Stress for Cryptococcus neoformans That Affects Virulence and Antifungal Susceptibility

mBio ◽  
2019 ◽  
Vol 10 (4) ◽  
Author(s):  
Damian J. Krysan ◽  
Bing Zhai ◽  
Sarah R. Beattie ◽  
Kara M. Misel ◽  
Melanie Wellington ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Cryptococcus Neoformans ◽  
Carbon Dioxide Concentration ◽  
Antifungal Drugs ◽  
Clinical Isolates ◽  
Mammalian Host ◽  
Environmental Isolates ◽  
Capsule Formation ◽  
Content Type ◽  
Virulence Traits

ABSTRACT The ability of Cryptococcus neoformans to cause disease in humans varies significantly among strains with highly related genotypes. In general, environmental isolates of pathogenic species such as Cryptococcus neoformans var. grubii have reduced virulence relative to clinical isolates, despite having no differences in the expression of the canonical virulence traits (high-temperature growth, melanization, and capsule formation). In this observation, we report that environmental isolates of C. neoformans tolerate host CO2 concentrations poorly compared to clinical isolates and that CO2 tolerance correlates well with the ability of the isolates to cause disease in mammals. Initial experiments also suggest that CO2 tolerance is particularly important for dissemination of C. neoformans from the lung to the brain. Furthermore, CO2 concentrations affect the susceptibility of both clinical and environmental C. neoformans isolates to the azole class of antifungal drugs, suggesting that antifungal testing in the presence of CO2 may improve the correlation between in vitro azole activity and patient outcome. IMPORTANCE A number of studies comparing either patient outcomes or model system virulence across large collections of Cryptococcus isolates have found significant heterogeneity in virulence even among strains with highly related genotypes. Because this heterogeneity cannot be explained by variations in the three well-characterized virulence traits (growth at host body temperature, melanization, and polysaccharide capsule formation), it has been widely proposed that additional C. neoformans virulence traits must exist. The natural niche of C. neoformans is in the environment, where the carbon dioxide concentration is very low (∼0.04%); in contrast, mammalian host tissue carbon dioxide concentrations are 125-fold higher (5%). We have found that the ability to grow in the presence of 5% carbon dioxide distinguishes low-virulence strains from high-virulence strains, even those with a similar genotype. Our findings suggest that carbon dioxide tolerance is a previously unrecognized virulence trait for C. neoformans.

scholarly journals Three Related Enzymes in Candida albicans Achieve Arginine- and Agmatine-Dependent Metabolism That Is Essential for Growth and Fungal Virulence

mBio ◽  
2020 ◽  
Vol 11 (4) ◽  
Author(s):  
Katja Schaefer ◽  
Jeanette Wagener ◽  
Ryan M. Ames ◽  
Stella Christou ◽  
Donna M. MacCallum ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Amino Acid ◽  
Galleria Mellonella ◽  
Fungal Growth ◽  
Open Reading Frames ◽  
Mammalian Host ◽  
No Production ◽  
Triple Mutant ◽  
Fungal Virulence ◽  
Content Type

ABSTRACT Amino acid metabolism is crucial for fungal growth and development. Ureohydrolases produce amines when acting on l-arginine, agmatine, and guanidinobutyrate (GB), and these enzymes generate ornithine (by arginase), putrescine (by agmatinase), or GABA (by 4-guanidinobutyrase or GBase). Candida albicans can metabolize and grow on arginine, agmatine, or guanidinobutyrate as the sole nitrogen source. Three related C. albicans genes whose sequences suggested that they were putative arginase or arginase-like genes were examined for their role in these metabolic pathways. Of these, Car1 encoded the only bona fide arginase, whereas we provide evidence that the other two open reading frames, orf19.5862 and orf19.3418, encode agmatinase and guanidinobutyrase (Gbase), respectively. Analysis of strains with single and multiple mutations suggested the presence of arginase-dependent and arginase-independent routes for polyamine production. CAR1 played a role in hyphal morphogenesis in response to arginine, and the virulence of a triple mutant was reduced in both Galleria mellonella and Mus musculus infection models. In the bloodstream, arginine is an essential amino acid that is required by phagocytes to synthesize nitric oxide (NO). However, none of the single or multiple mutants affected host NO production, suggesting that they did not influence the oxidative burst of phagocytes. IMPORTANCE We show that the C. albicans ureohydrolases arginase (Car1), agmatinase (Agt1), and guanidinobutyrase (Gbu1) can orchestrate an arginase-independent route for polyamine production and that this is important for C. albicans growth and survival in microenvironments of the mammalian host.

scholarly journals Systematic screens of a Candida albicans homozygous deletion library decouple morphogenetic switching and pathogenicity

2010 ◽  
Vol 42 (7) ◽  
pp. 590-598 ◽  
Author(s):  
Suzanne M Noble ◽  
Sarah French ◽  
Lisa A Kohn ◽  
Victoria Chen ◽  
Alexander D Johnson
Keyword(s):  
Candida Albicans ◽  
Homozygous Deletion ◽  
Deletion Library

scholarly journals Physiologic Expression of the Candida albicans Pescadillo Homolog Is Required for Virulence in a Murine Model of Hematogenously Disseminated Candidiasis

2012 ◽  
Vol 11 (12) ◽  
pp. 1552-1556 ◽  
Author(s):  
Priya Uppuluri ◽  
Ashok K. Chaturvedi ◽  
Niketa Jani ◽  
Read Pukkila-Worley ◽  
Carlos Monteagudo ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Murine Model ◽  
Critical Role ◽  
Growth Defect ◽  
Mammalian Host ◽  
Developmental Cycle ◽  
Yeast Growth ◽  
Content Type ◽  
Disseminated Candidiasis

ABSTRACT Morphogenetic conversions contribute to the pathogenesis of Candida albicans invasive infections. Many studies to date have convincingly demonstrated a link between filamentation and virulence; however, relatively little is known regarding the role of the filament-to-yeast transition during the pathogenesis of invasive candidiasis. We previously identified the C. albicans pescadillo homolog ( PES1 ) as essential during yeast growth and growth of lateral yeast on hyphae but not during hyphal growth. Furthermore, we demonstrated that PES1 is required for virulence in vivo in a Galleria mellonella larva model of candidiasis. Here, we have used a regulatable tetO-PES1 / pes1 strain to assess the contribution of C. albicans PES1 to pathogenesis in the commonly used and clinically relevant murine model of hematogenously disseminated candidiasis. Our results indicate that a physiologically controlled level of PES1 expression is required for full virulence in this animal model, with virulence defects observed both when PES1 is overexpressed and and when it is depleted. The pathogenetic defect of cells depleted of PES1 is not due to a general growth defect, as demonstrated by the fact that PES1 -depleted cells still kill Caenorhabditis elegans as efficiently as the wild type due to hyphal outgrowth through worm tissues. Our results suggest a critical role of lateral yeast growth in the ability of C. albicans to normally proliferate within tissues, as well as a pivotal role for Pes1 in the normal developmental cycle of C. albicans within the mammalian host during infection.

scholarly journals Simulating the evolutionary trajectories of metabolic pathways for insect symbionts in the genus Sodalis

2020 ◽  
Vol 6 (7) ◽  
Author(s):  
Rebecca J. Hall ◽  
Stephen Thorpe ◽  
Gavin H. Thomas ◽  
A. Jamie Wood
Keyword(s):  
Type Species ◽  
Genetic Manipulation ◽  
Balance Model ◽  
Ecological Change ◽  
Content Type ◽  
Link Type ◽  
Starting Point ◽  
Evolutionary Trajectories ◽  
Insect Symbionts

Insect–bacterial symbioses are ubiquitous, but there is still much to uncover about how these relationships establish, persist and evolve. The tsetse endosymbiont Sodalis glossinidius displays intriguing metabolic adaptations to its microenvironment, but the process by which this relationship evolved remains to be elucidated. The recent chance discovery of the free-living species of the genus Sodalis , Sodalis praecaptivus , provides a serendipitous starting point from which to investigate the evolution of this symbiosis. Here, we present a flux balance model for S. praecaptivus and empirically verify its predictions. Metabolic modelling is used in combination with a multi-objective evolutionary algorithm to explore the trajectories that S. glossinidius may have undertaken from this starting point after becoming internalized. The order in which key genes are lost is shown to influence the evolved populations, providing possible targets for future in vitro genetic manipulation. This method provides a detailed perspective on possible evolutionary trajectories for S. glossinidius in this fundamental process of evolutionary and ecological change.

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