Journal article
Loss-of-Function ROX1 Mutations Suppress the Fluconazole Susceptibility of upc2A Δ Mutation in Candida glabrata, Implicating Additional Positive Regulators of Ergosterol Biosynthesis
mSphere, Vol.6(6), pp.e0083021-e0083021
12/22/2021
DOI: 10.1128/msphere.00830-21
PMCID: PMC8694151
PMID: 34935446
Abstract
Two of the major classes of antifungal drugs in clinical use target ergosterol biosynthesis. Despite its importance, our understanding of the transcriptional regulation of ergosterol biosynthesis genes in pathogenic fungi is essentially limited to the role of hypoxia and sterol-stress-induced transcription factors such as Upc2 and Upc2A as well as homologs of sterol response element binding (SREB) factors. To identify additional regulators of ergosterol biosynthesis in Candida glabrata, an important human fungal pathogen with reduced susceptibility to ergosterol biosynthesis inhibitors relative to other
spp., we used a serial passaging strategy to isolate suppressors of the fluconazole hypersusceptibility of a
Δ deletion mutant. This led to the identification of loss-of-function mutations in two genes:
, the homolog of a hypoxia gene transcriptional suppressor in Saccharomyces cerevisiae, and
, a transcription factor that is involved in the regulation of carbon dioxide response in C. glabrata. Here, we describe a detailed analysis of the genetic interaction of
and
. In the presence of fluconazole, loss of Rox1 function restores
expression to the
Δ mutant and inhibits the expression of
and
, leading to increased levels of ergosterol and decreased levels of the toxic sterol 14α methyl-ergosta-8,24(28)-dien-3β, 6α-diol, relative to the
Δ mutant. Our observations establish that Rox1 is a negative regulator of
gene biosynthesis and indicate that a least one additional positive transcriptional regulator of
gene biosynthesis must be present in C. glabrata.
Candida glabrata is one of the most important human fungal pathogens and has reduced susceptibility to azole-class inhibitors of ergosterol biosynthesis. Although ergosterol is the target of two of the three classes of antifungal drugs, relatively little is known about the regulation of this critical cellular pathway. Sterols are both essential components of the eukaryotic plasma membrane and potential toxins; therefore, sterol homeostasis is critical for cell function. Here, we identified two new negative regulators in C. glabrata of ergosterol (
) biosynthesis gene expression. Our results also indicate that in addition to Upc2A, the only known activator of
genes, additional positive regulators of this pathway must exist.
Details
- Title: Subtitle
- Loss-of-Function ROX1 Mutations Suppress the Fluconazole Susceptibility of upc2A Δ Mutation in Candida glabrata, Implicating Additional Positive Regulators of Ergosterol Biosynthesis
- Creators
- Tomye L Ollinger - Roy J. and Lucille A. Carver College of MedicineBao Vu - Roy J. and Lucille A. Carver College of MedicineDaniel Murante - Roy J. and Lucille A. Carver College of MedicineJosie E Parker - Swansea UniversityLucia Simonicova - Roy J. and Lucille A. Carver College of MedicineLaura Doorley - St. Jude Children's Research HospitalMark A Stamnes - Roy J. and Lucille A. Carver College of MedicineSteven L Kelly - Swansea UniversityP David Rogers - St. Jude Children's Research HospitalW Scott Moye-Rowley - Roy J. and Lucille A. Carver College of MedicineDamian J Krysan - Roy J. and Lucille A. Carver College of Medicine
- Resource Type
- Journal article
- Publication Details
- mSphere, Vol.6(6), pp.e0083021-e0083021
- DOI
- 10.1128/msphere.00830-21
- PMID
- 34935446
- PMCID
- PMC8694151
- NLM abbreviation
- mSphere
- ISSN
- 2379-5042
- eISSN
- 2379-5042
- Grant note
- P30 CA068485 / NCI NIH HHS T32 AI007474 / NIAID NIH HHS P30 DK058404 / NIDDK NIH HHS R01 AI131620 / NIAID NIH HHS T32 AI007281 / NIAID NIH HHS R01 AI152494 / NIAID NIH HHS
- Language
- English
- Date published
- 12/22/2021
- Academic Unit
- Molecular Physiology and Biophysics; Microbiology and Immunology; Stead Family Department of Pediatrics; Infectious Disease (Pediatrics); Internal Medicine
- Record Identifier
- 9984297426302771
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