Deletion of thePDR16gene influences the plasma membrane properties of the yeastKluyveromyces lactis

Abstract

The plasma membrane is the first line of cell defense against changes in external environment, thus its integrity and functionality are of utmost importance. The plasma membrane properties depend on both its protein and lipid composition. The PDR16 gene is involved in the control of Kluyveromyces lactis susceptibility to drugs and alkali metal cations. It encodes the homologue of the major K. lactis phosphatidylinositol transfer protein Sec14p. Sec14p participates in protein secretion, regulation of lipid synthesis, and turnover in vivo. We report here that the plasma membrane of the Klpdr16Δ mutant is hyperpolarized and its fluidity is lower than that of the parental strain. In addition, protoplasts prepared from the Klpdr16Δ cells display decreased stability when subjected to hypo-osmotic conditions. These changes in membrane properties lead to an accumulation of radiolabeled fluconazole and lithium cations inside mutant cells. Our results point to the fact that the PDR16 gene of K. lactis (KlPDR16) influences the plasma membrane properties in K. lactis that lead to subsequent changes in susceptibility to a broad range of xenobiotics.

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

“…Several reports in C. albicans showed that Ca Upc2p positively regulates the expression of MDR1 gene, encoding a multidrug transporter of the major facilitator superfamily that exports azoles (Dunkel et al, 2008; Flowers et al, 2012; Znaidi et al, 2008). The observed azole sensitivity of the yeast Klupc2 deletion mutants can be the result of increased passive diffusion of azoles across the modified plasma membrane (Culakova, Dzugasova, Perzelova, Gbelska, & Subik, 2013; Goffa et al, 2014; Toth Hervay et al, 2015; van den Hazel et al, 1999) or decreased efflux of azoles from cells. On the other hand, the fact that these phenotypes are suppressed by UFAs suggests that the observed defects could be the result of altered membrane functions.…”

“…The excitation wavelength was 360 nm, and the emission wavelength was 430 nm. Anisotropy ( r s ) was calculated from polarized intensities as described in Toth Hervay et al (2015). For statistical analyses, the one‐way analysis of variance and post‐hoc Dunnett multiple comparisons with control were used.…”

“…Fluorescence emission spectra of the stained cell suspensions with the potentiometric fluorescent probe diS‐C 3 (3) (3,3′‐dipropylthiacarboxycyanine, 1.5 × 10 −7 mol/L) (Fluka) were measured as described previously (Toth Hervay et al, 2015). The difference in the fluorescence maxima ( Δλ max ) was determined as a difference between the maximum of steady‐state emission wavelength and the maximum emission wavelength at the beginning of the measurement.…”

“…Several reports in C. albicans showed that CaUpc2p positively regulates the expression of MDR1 gene, encoding a multidrug transporter of the major facilitator superfamily that exports azoles (Dunkel et al, 2008;Flowers et al, 2012;Znaidi et al, 2008). The observed azole sensitivity of the yeast Klupc2 deletion mutants can be the result of increased passive diffusion of azoles across the modified plasma membrane (Culakova, Dzugasova, Perzelova, Gbelska, & Subik, 2013;Goffa et al, 2014;Toth Hervay et al, 2015;van den Hazel et al, 1999) Upc2p and its paralog, Ecm22p, initially identified in S. cerevisiae, regulate ergosterol biosynthesis, sterol uptake and yeast adaptation to anaerobic growth (Abramova et al, 2001;Branco et al, 2017;Crowley, Leak, Shianna, Tove, & Parks, 1998;Jiang et al, 2016;MacPherson et al, 2005;Nagi et al, 2011;Silver, Oliver, & White, 2004;Vik & Rine, 2001). Phylogenetic analysis showed that these Zn 2 Cys 6 transcription factors are specific for Saccharomycotina clade (Maguire et al, 2014).…”