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CRS–MIS in Candida glabrata: sphingolipids modulate echinocandin–Fks interaction
Journal article   Open access   Peer reviewed

CRS–MIS in Candida glabrata: sphingolipids modulate echinocandin–Fks interaction

Kelley R Healey, Santosh K Katiyar, Shriya Raj and Thomas D Edlind
Molecular microbiology, v 86(2), pp 303-313
Oct 2012
PMID: 22909030
url
https://doi.org/10.1111/j.1365-2958.2012.08194.xView
Published, Version of Record (VoR) Open

Abstract

Summary Infections with the azole‐refractory yeast Candida glabrata are now commonly treated with the echinocandins caspofungin (CSF) or micafungin (MCF). True resistance (> 32‐fold decreased susceptibility) to these lipopeptide inhibitors of cell wall synthesis is rare and strictly associated with mutations in integral membrane proteins Fks1 or Fks2. In contrast, mutants exhibiting 4‐ to 32‐fold CSF reduced susceptibility (CRS) were readily selected in vitro, and surprisingly demonstrated 4‐ to 32‐fold MCF increased susceptibility (MIS). Sequencing and gene deletion demonstrated that CRS–MIS is Fks‐independent. To explore alternative mechanisms, we initially employed Saccharomyces cerevisiae, and observed that CRS was conferred by multiple mutations (fen1Δ, sur4Δ, cka2Δ and tsc10‐ts) disrupting sphingolipid biosynthesis. Following this lead, C. glabrata fen1Δ and cka2Δ deletants were constructed, and shown to exhibit CRS–MIS. Sphingolipid analysis of CRS–MIS laboratory mutants and clinical isolates demonstrated elevated dihydrosphingosine (DHS) and phytosphingosine (PHS) levels, and consistent with this sequencing revealed fen1, sur4, ifa38 and sur2 mutations. Moreover, exogenous DHS or PHS conferred a CRS–MIS phenotype on wild‐type C. glabrata. Exogenous PHS failed, however, to suppress CRS–MIS in a sur2 mutant blocked in conversion of DHS to PHS, implying that accumulation of these intermediates confers CRS–MIS. We conclude that membrane sphingolipids modulate echinocandin–Fks interaction.

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Web of Science research areas
Biochemistry & Molecular Biology
Microbiology
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