UPC2 gene deletion modifies sterol homeostasis and susceptibility to metabolic inhibitors in Kluyveromyces lactis

Abstract

Kluyveromyces lactis Upc2p is an ortholog of Upc2p/Ecm22p transcription factors involved in regulation of sterol import and sterol homeostasis in Saccharomyces cerevisiae. In this work, we investigated the role of Upc2p in K. lactis. The absence of KlUpc2p significantly reduced the tolerance of mutant cells to antifungal azoles and Li + cations. Reduced expression of genes from the late ergosterol pathway results in a decreased ergosterol content and altered plasma membrane-associated functions in Klupc2 mutant cells-the plasma membrane is hyperpolarized, and its fluidity is reduced. KlUpc2p contributes to transcriptional upregulation of KlENA1, KlPMA1 and KlYAP1 under azole stress. Our study demonstrates that KlUpc2p is involved in the regulation of ergosterol homeostasis in K. lactis. The analysis of KlPMA1 and KlPDR12 transcripts in wild-type and Klupc2Δ mutant strains showed that KlUpc2p acts as an activator or as a repressor depending upon its target.

Genomic Variation-Mediating Fluconazole Resistance in Yeast

“…The PDR12 promoter contains a cis-regulatory element for Upc2 binding. Isolates without UPC2 exhibit abnormal sterols accumulation and membrane permeability, as well as increased susceptibility to fluconazole [ 13 ]. While the C-terminal modification of PDR1 with FLAG tag enables a decreased mRNA concentration by about 50%, the N-terminal modification leads to a 2-fold increase in mRNA concentration.…”