Cited by 42Antifungal resistance and susceptibilityFungal and yeast genetics researchBacterial biofilms and quorum sensing

A common mechanism involving the TORC1 pathway can lead to amphotericin B-persistence in biofilm and planktonic Saccharomyces cerevisiae populations

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Bojsen, Rasmus, Regenberg, Birgitte, Gresham, David, Folkesson, Anders·2016·Scientific Reports

Abstract

Fungal infections are an increasing clinical problem. Decreased treatment effectiveness is associated with biofilm formation and drug recalcitrance is thought to be biofilm specific. However, no systematic investigations have tested whether resistance mechanisms are shared between biofilm and planktonic populations. We performed multiplexed barcode sequencing (Bar-seq) screening of a pooled collection of gene-deletion mutants cultivated as biofilm and planktonic cells. Screening for resistance to the ergosterol-targeting fungicide amphotericin B (AmB) revealed that the two growth modes had significant overlap in AmB-persistent mutants. Mutants defective in sterol metabolism, ribosome biosynthesis and the TORC1 and Ras pathways showed increased persistence when treated with AmB. The ras1, ras2 and tor1 mutants had a high-persister phenotype similar to wild-type biofilm and planktonic cells exposed to the TORC1 pathway inhibitor rapamycin. Inhibition of TORC1 with rapamycin also increased the proportion of persisters in Candida albicans and Candida glabrata. We propose that decreased TORC1-mediated induction of ribosome biosynthesis via Ras can lead to formation of AmB-persister cells regardless of whether the cells are in planktonic or biofilm growth mode. Identification of common pathways leading to growth mode-independent persister formation is important for developing novel strategies for treating fungal infections.

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Crossref · 10.1038/srep21874

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  • The TORC1/Ras ribosome biosynthesis mechanism extends to the clinical pathogenic fungi C. albicans and N. glabratus.

    “Further, this study extended this mechanism to the clinical pathogenic fungi C. albicans and N. glabratus [62].”

    From Antifungal persistence: Clinical relevance and mechanisms (2025) · cites this paper as [62]

    The Results section reports that TORC1 inhibition increased amphotericin B persisters in C. albicans and C. glabrata. The Discussion proposes a TORC1–Ras–ribosome synthesis mechanism for S. cerevisiae, but the paper does not establish that the full mechanism operates in either Candida species. The source calls the second species C. glabrata, not N. glabratus; no page numbers are available in our copy. (LLM, conf=0.88)

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  • In S. cerevisiae, reducing induction of TORC1-mediated ribosome biosynthesis through the Ras pathway can lead to formation of AmB-tolerant persisters, independent of growth mode and occurring in both biofilm and planktonic cells.

    “Moreover, in a study of Saccharomyces cerevisiae, reducing the induction of the target of rapamycin complex 1(TORC1)-mediated ribosome biosynthesis through Ras pathway can lead to the formation of AmB-tolerant persisters, which is independent of the growth mode and occurs in both biofilm and planktonic.”

    From Antifungal persistence: Clinical relevance and mechanisms (2025) · cites this paper as [62]

  • Although calcineurin promoted tolerance to echinocandins and azoles, it did not seem to alter the biphasic kinetics of survival during exposure to amphotericin B in C. glabrata, C. albicans, or S. cerevisiae.

    “Although calcineurin promoted tolerance to echinocandins and azoles, it did not seem to alter the biphasic kinetics of survival during exposure to amphotericin B in C. glabrata, C. albicans, or S. cerevisiae (64).”

    From Echinocandin tolerance and persistence <i>in vitro</i> are regulated by calcineurin signaling in <i>Candida glabrata</i> (2026) · cites this paper as [64]

    The Results section on TORC1 inhibition reports amphotericin B-tolerant persister cells in C. albicans, C. glabrata, and S. cerevisiae, but it does not test calcineurin. Searches for calcineurin, echinocandin/azole tolerance, and biphasic survival kinetics found no passage addressing the claimed effects of calcineurin. (LLM, conf=0.77)

    Experimental — accuracy not yet measured
  • ras1, ras2, and tor1 mutants had a high-persister phenotype compared to wild-type biofilm and planktonic cells exposed to rapamycin, and TORC1 inhibition with rapamycin improved the proportion of persisters in C. glabrata.

    “The ras1, ras2, and tor1 mutants had a high-persister phenotype compared to wild-type biofilm and planktonic cells exposed to the TORC1 pathway inhibitor rapamycin, and, on the other hand, the inhibition of TORC1 with rapamycin similarly improved the proportion of persisters in C. glabrata.”

    From Candida glabrata Biofilms: How Far Have We Come? (2017) · cites this paper as [167]

  • Mutants defective in sterol metabolism, ribosome biosynthesis, TORC1, and Ras pathways displayed amplified persistence when treated with amphotericin B.

    “Also, the authors were able to demonstrate that the mutants defective in sterol metabolism, ribosome biosynthesis, and in the TORC1 (ubiquitin binding activity, role in cellular response to starvation, regulation of cell growth, etc.) and in the Ras pathways (protein signal transduction) displayed an amplified persistence when treated with amphotericin B.”

    From Candida glabrata Biofilms: How Far Have We Come? (2017) · cites this paper as [167]

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Authors
Bojsen, R., Regenberg, B., Gresham, D., & Folkesson, A.
Affiliations
  • Technical University of Denmark (DK)
  • University of Copenhagen (DK)
  • New York University (US)
Corresponding author
  • Bojsen, Rasmus
  • Folkesson, Anders
Venue
Scientific Reports
Published
2016-02-23
Volume
6
Issue
1
Pages
21874-21874
ISSN
2045-2322 (ISSN-L)
OpenAlex
W2296574497
Cited by
42
References
51
Citations by year
2026: 2 · 2025: 6 · 2024: 5 · 2023: 3 · 2022: 3 · 2021: 3 · 2020: 2 · 2019: 5 · 2018: 6 · 2017: 4 · 2016: 3
FWCI
5.54
Type
journal article
Language
en
Open access
Locations
  • Scientific Reports (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • Research at the University of Copenhagen (University of Copenhagen) (publishedVersion, cc-by)
  • Technical University of Denmark, DTU Orbit (Technical University of Denmark, DTU) (submittedVersion, other-oa)
Funders
  • University of Toronto
  • National Institutes of Health
  • National Institute of General Medical Sciences (R01GM107466)
Topics
  • Health Sciences › Medicine › Infectious Diseases › Antifungal resistance and susceptibility
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Fungal and yeast genetics research
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Bacterial biofilms and quorum sensing
Keywords
amphotericin B resistance, persister cells, biofilm, planktonic growth, Ras signaling, ribosome biogenesis, sterol metabolism, ergosterol, Saccharomyces cerevisiae, Candida albicans, Candida glabrata, rapamycin, antifungal resistance, fungal infection
MeSH terms
Amphotericin B, Antifungal Agents, Candida albicans, Ergosterol, Mutation, Plankton, Ribosomes, Saccharomyces cerevisiae, Transcription Factors, Signal Transduction, Gene Expression Regulation, Fungal, Sequence Analysis, DNA, Biofilms, ras Proteins, Phosphatidylinositol 3-Kinases, Sirolimus, Drug Resistance, Fungal, Saccharomyces cerevisiae Proteins, Candida glabrata

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