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 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 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 Mitochondrial perturbation reduces susceptibility to xenobiotics through altered efflux in Candida albicans

Genetics ◽  
2021 ◽  
Author(s):  
Saif Hossain ◽  
Amanda O Veri ◽  
Zhongle Liu ◽  
Kali R Iyer ◽  
Teresa R O’Meara ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Mitochondrial Function ◽  
Efflux Pump ◽  
Systemic Disease ◽  
Filamentous Growth ◽  
Hsp90 Inhibitor ◽  
Homozygous Deletion ◽  
Hsp90 Inhibitors ◽  
Hsp90 Inhibition ◽  
Conditional Expression

Abstract Candida albicans is a leading human fungal pathogen, which can cause superficial infections or life-threatening systemic disease in immunocompromised individuals. The ability to transition between yeast and filamentous forms is a major virulence trait of C. albicans, and a key regulator of this morphogenetic transition is the molecular chaperone Hsp90. To explore the mechanisms governing C. albicans morphogenesis in response to Hsp90 inhibition, we performed a functional genomic screen using the gene replacement and conditional expression (GRACE) collection to identify mutants that are defective in filamentation in response to the Hsp90 inhibitor, geldanamycin. We found that transcriptional repression of genes involved in mitochondrial function blocked filamentous growth in response to the concentration of Hsp90 inhibitor used in the screen, and this was attributable to increased resistance to the compound. Further exploration revealed that perturbation of mitochondrial function reduced susceptibility to two structurally distinct Hsp90 inhibitors, geldanamycin and radicicol, such that filamentous growth was restored in the mitochondrial mutants by increasing the compound concentration. Deletion of two representative mitochondrial genes, MSU1 and SHY1, enhanced cellular efflux and reduced susceptibility to diverse intracellularly acting compounds. Additionally, screening a C. albicans efflux pump gene deletion library implicated Yor1 in efflux of geldanamycin and Cdr1, in efflux of radicicol. Deletion of these transporter genes restored sensitivity to Hsp90 inhibitors in MSU1 and SHY1 homozygous deletion mutants, thereby enabling filamentation. Taken together, our findings suggest that mitochondrial dysregulation elevates cellular efflux and consequently reduces susceptibility to xenobiotics in C. albicans.

scholarly journals Disruption of the Candida albicans TPS2 Gene Encoding Trehalose-6-Phosphate Phosphatase Decreases Infectivity without Affecting Hypha Formation

2002 ◽  
Vol 70 (4) ◽  
pp. 1772-1782 ◽  
Author(s):  
Patrick Van Dijck ◽  
Larissa De Rop ◽  
Karolina Szlufcik ◽  
Elke Van Ael ◽  
Johan M. Thevelein
Keyword(s):  
Candida Albicans ◽  
High Throughput Screening ◽  
Deletion Mutant ◽  
Systemic Infection ◽  
Homozygous Deletion ◽  
Antifungal Drugs ◽  
Gene Encoding ◽  
Complete Inactivation ◽  
Hypha Formation ◽  
Stress Protectant

ABSTRACT Deletion of trehalose-6-phosphate phosphatase, encoded by TPS2, in Saccharomyces cerevisiae results in accumulation of trehalose-6-phosphate (Tre6P) instead of trehalose under stress conditions. Since trehalose is an important stress protectant and Tre6P accumulation is toxic, we have investigated whether Tre6P phosphatase could be a useful target for antifungals in Candida albicans. We have cloned the C. albicans TPS2 (CaTPS2) gene and constructed heterozygous and homozygous deletion strains. As in S. cerevisiae, complete inactivation of Tre6P phosphatase in C. albicans results in 50-fold hyperaccumulation of Tre6P, thermosensitivity, and rapid death of the cells after a few hours at 44°C. As opposed to inactivation of Tre6P synthase by deletion of CaTPS1, deletion of CaTPS2 does not affect hypha formation on a solid glucose-containing medium. In spite of this, virulence of the homozygous deletion mutant is strongly reduced in a mouse model of systemic infection. The pathogenicity of the heterozygous deletion mutant is similar to that of the wild-type strain. CaTPS2 is a new example of a gene not required for growth under standard conditions but required for pathogenicity in a host. Our results suggest that Tre6P phosphatase may serve as a potential target for antifungal drugs. Neither Tre6P phosphatase nor its substrate is present in mammals, and assay of the enzymes is simple and easily automated for high-throughput screening.

Deletion of the Candida albicans G-protein-coupled receptor, encoded by orf19.1944 and its allele orf19.9499, produces mutants defective in filamentous growth

2004 ◽  
Vol 50 (12) ◽  
pp. 1081-1085 ◽  
Author(s):  
Quentin L Sciascia ◽  
Patrick A Sullivan ◽  
Peter C Farley
Keyword(s):  
Candida Albicans ◽  
G Protein ◽  
Transmembrane Domain ◽  
Single Copy ◽  
Filamentous Growth ◽  
Homozygous Deletion ◽  
Tube Formation ◽  
G Protein Coupled Receptor ◽  
Environmental Signals ◽  
G Protein Coupled

Filamentous growth of Candida albicans occurs in response to a variety of environmental signals. The C. albicans gene orf19.1944 and its allele orf19.9499 are identical and are predicted to encode an 823-residue, 7-transmembrane-domain protein that has all the expected features of a G-protein-coupled receptor. The protein is 20.9% identical to the Saccharomyces cerevisiae Gpr1p receptor that signals both glucose availability and nitrogen limitation. Deletion of both copies of the gene in C. albicans abolished filamentation by colonies embedded in rich media (YPS, YPGal, and YPGlu), whereas mutants carrying a single copy of the gene were indistinguishable from the parental strain under these conditions. On medium containing low concentrations of ammonia (SLAD and SLAM media), surface colonies of both the homozygous deletion mutants and the mutants carrying a single copy of the gene were defective in filamentation. Serum-induced germ tube formation was unaffected by deletion of this gene, as was filamentation of the mutants growing on the surface of solid Spider medium at 37 °C or embedded in solid Spider medium at 25 °C. The protein encoded by orf19.1944 and orf19.9499 has a role in filamentation by both surface and embedded colonies, presumably as a sensor of environmental cues.Key words: Candida albicans, G-protein-coupled receptor, orf19.1944, embedded agar, filamentation.

scholarly journals Role of Candida albicans Transcription Factor Upc2p in Drug Resistance and Sterol Metabolism

2004 ◽  
Vol 3 (6) ◽  
pp. 1391-1397 ◽  
Author(s):  
Peter M. Silver ◽  
Brian G. Oliver ◽  
Theodore C. White
Keyword(s):  
Drug Resistance ◽  
Transcription Factor ◽  
Candida Albicans ◽  
Transmembrane Domain ◽  
Homozygous Deletion ◽  
Antifungal Drugs ◽  
Deletion Strain ◽  
Ergosterol Biosynthesis ◽  
Heterozygous Deletion ◽  
Nuclear Localization Signals

ABSTRACT In Candida albicans, drug resistance to clinically important antifungal drugs may be regulated through the action of transcription factors in a manner that may or may not be similar to regulation in Saccharomyces cerevisiae. A search of the C. albicans genome identified a single homolog of the S. cerevisiae transcription factor genes UPC2 (ScUPC2) and ECM22 (ScECM22) that have been associated with regulation of ergosterol biosynthesis. Sequence analysis of this C. albicans UPC2 (CaUPC2) gene identifies two domains, an anchoring transmembrane domain and a transcription factor region containing multiple nuclear localization signals and a fungal Zn(2)-Cys(6) binuclear cluster domain. Heterozygous deletion, homozygous deletion, and reconstructed strains of CaUPC2 as well as the parental strain were tested against several antifungal drugs, including ergosterol biosynthesis inhibitors. The CaUPC2 homozygous deletion strain showed marked hypersusceptibility to most drugs, compared to the parental and reconstructed strains. The deletion strains accumulate significantly less radiolabeled cholesterol, suggesting reduced ergosterol scavenging in those strains. When grown under azole drug pressure, the parental, heterozygous deletion and reconstructed strains of CaUPC2 upregulate the ERG2 and ERG11 ergosterol biosynthesis genes, while the homozygous deletion strain shows no such upregulation. Consistent with these results, CaUPC2 deletion strains show reduced ergosterol levels, which may explain the increased susceptibilities of the CaUPC2 deletion strains. Thus, it appears that CaUPC2 acts as a transcription factor involved in the regulation of ergosterol biosynthetic genes and as a regulator of sterol uptake across the plasma membrane.

scholarly journals Inactivation of Sterol Δ5,6-Desaturase Attenuates Virulence in Candida albicans

2005 ◽  
Vol 49 (9) ◽  
pp. 3646-3651 ◽  
Author(s):  
Andrew S. Chau ◽  
Maya Gurnani ◽  
Robyn Hawkinson ◽  
Michel Laverdiere ◽  
Anthony Cacciapuoti ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Deletion Mutant ◽  
Desaturase Activity ◽  
Systemic Infection ◽  
Homozygous Deletion ◽  
Infection Model ◽  
Wild Type ◽  
Competitive Disadvantage ◽  
Ergosterol Synthesis ◽  
High Level

ABSTRACT Two clinical Candida albicans isolates that exhibited high-level resistance to azoles and modest decreases in susceptibility to amphotericin B were cultured from unrelated patients. Both isolates harbored homozygous nonsense mutations in ERG3, which encodes an enzyme, sterol Δ5,6-desaturase, involved in ergosterol synthesis. Extraction and analysis of the sterols from both isolates confirmed the absence of sterol Δ5,6-desaturase activity. Although the loss of sterol Δ5,6-desaturase activity is known to confer resistance to azoles, this mechanism of resistance has rarely been seen in clinical isolates, suggesting that such mutants are at a competitive disadvantage. To test this hypothesis, the virulence of the erg3 mutants was assayed by using a mouse systemic infection model. The mutants were significantly less virulent than the wild-type comparator strains. However, the kidney fungal burdens in mice infected with the erg3 mutants were similar to those in mice infected with the wild-type strains. Similar results were obtained by using a laboratory-generated homozygous erg3 deletion mutant (D. Sanglard et al., Antimicrob. Agents Chemother. 47:2404-2412, 2003). Reintroduction of a wild-type ERG3 allele into the homozygous deletion mutant restored virulence, ergosterol synthesis, and susceptibility to azoles, confirming that these phenotypic changes were solely due to the inactivation of Erg3p.

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