The Toxicity of a Novel Antifungal Compound Is Modulated by Endoplasmic Reticulum-Associated Protein Degradation (ERAD) Components

Shriya S Raj (1) , Karthik Krishnan (2) , David S Askew (2) , Olivier S Helynck (3) , Peggy Suzanne (4) , Aurélien Lesnard (4) , Sylvain Rault (4) , Ute S Zeidler (5) , Christophe d'Enfert (5) , Jean-Paul S Latgé (1) , Hélène Munier-Lehmann (3) , Cosmin Saveanu (6)

1 Aspergillus
2 UC - University of Cincinnati
3 Chimie et Biocatalyse
4 CERMN - Centre d'Etudes et de Recherche sur le Médicament de Normandie
5 BPF - Biologie et Pathogénicité fongiques
6 Génétique des Interactions macromoléculaires / Genetics of Macromolecular Interactions

In a search for new antifungal compounds, we screened a library of 4454 chemicals for toxicity against the human fungal pathogen Aspergillus fumigatus. We identified sr7575, a molecule that inhibits growth of the evolutionary distant fungi A. fumigatus and Saccharomyces cerevisiae but lacks acute toxicity for mammalian cells. To gain insight into the mode of inhibition, sr7575 was screened against 4885 S. cerevisiae mutants from the systematic collection of haploid deletion strains and 977 barcoded haploid DAmP strains in which the function of essential genes was perturbed by the introduction of a drug resistance cassette downstream of the coding sequence region. Comparisons with previously published chemogenomic screens revealed that the set of mutants conferring sensitivity to sr7575 was strikingly narrow, affecting components of the endoplasmic-associated protein degradation (ERAD) stress response and the ER membrane protein complex (EMC). ERAD-deficient mutants were hypersensitive to sr7575 in both S. cerevisiae and A. fumigatus, indicating a conserved mechanism of growth inhibition between yeast and filamentous fungi. Although the unfolded protein response (UPR) is linked to ERAD regulation, sr7575 did not trigger the UPR in A. fumigatus and UPR mutants showed no enhanced sensitivity to the compound. The data from this chemogenomic analysis demonstrate that sr7575 exerts its antifungal activity by disrupting ER protein quality control in a manner that requires ERAD intervention but bypasses the need for the canonical UPR. ER protein quality control is thus a specific vulnerability of fungal organisms that might be exploited for antifungal drug development.

Keywords: UPR; Aspergillus fumigatus; Antifungal Agents; ERAD; Chemogenomics; Saccharomyces cerevisiae; Yeast

Domains: Biochemistry [q-bio.BM]; Molecular biology; Genomics [q-bio.GN]

Shriya S Raj, Karthik Krishnan, David S Askew, Olivier S Helynck, Peggy Suzanne, et al.. The Toxicity of a Novel Antifungal Compound Is Modulated by Endoplasmic Reticulum-Associated Protein Degradation (ERAD) Components. Antimicrobial Agents and Chemotherapy, 2016, 60 (3), pp.1438-1449. ⟨10.1128/AAC.02239-15⟩. ⟨pasteur-01427574⟩