ABSTRACT
The SPFH (stomatin, prohibitin, flotillin, and HflK/HflC) protein superfamily is conserved across all domains of life. Fungal SPFH proteins are required for respiration, stress adaptation, and membrane scaffolding. In the yeast
Candida albicans
, stomatin-like protein 3 (Slp3) forms punctate foci at the plasma membrane, and
SLP3
overexpression causes cell death following exposure to the surfactant, SDS, and the oxidative stressor, H
2
O
2
. Here, we sought to determine the cellular localization and functionally characterize stomatin-like protein 2 (Slp2), prohibitin-1 (Phb1), prohibitin-2 (Phb2), and prohibitin-12 (Phb12) in
C. albicans
. Cytological and western blotting results showed that Slp2-Gfp/Rfp and prohibitin-Gfp fusion proteins localize to the mitochondrion in yeast cells. Growth assay results did not identify any respiration defects in a panel of stomatin and prohibitin mutant strains, suggesting that SPFH respiratory function has diverged in
C. albicans
from other model eukaryotes. However, a
slp2Δ
/
Δ
/
slp3Δ
/
Δ
double mutant strain grew poorly in the presence of 0.08% SDS, accumulated intracellular reactive oxidative species, and displayed aberrant ergosterol distribution in the plasma membrane. These phenotypes were not observed in
slp2Δ
/
Δ
or
slp3Δ
/
Δ
single mutants, indicating a possible indirect genetic interaction between
SLP2
and
SLP3
. In addition,
slp2Δ
/
Δ
and
slp2Δ
/
Δ
/
slp3Δ
/
Δ
mutant strains were slightly resistant to the antifungal drug, fluconazole. Collectively, these findings reveal the cellular localization of Slp2, Phb1, Phb2, and Phb12, highlight the significance of stomatins in
C. albicans
SDS stress tolerance, and, for the first time, associate stomatins with antifungal resistance.
IMPORTANCE
Stomatins and prohibitins coordinate respiration and stress adaptation in fungi. Invasive mycoses caused by
Candida albicans
are a significant cause of morbidity, and candidemia patients show high mortality rates worldwide. Mitochondria are essential for
C. albicans
commensalism and virulence, and mitochondrial proteins are targets for antifungal interventions.
C. albicans
encodes five SPFH proteins: two stomatin-like proteins and three prohibitins. We have previously shown that Slp3 is important for
C. albicans
adaptation to various types of environmental stress. Moreover, synthetic compounds that bind to mammalian prohibitins inhibit
C. albicans
filamentation and are fungicidal. However, there is limited information available regarding the remaining SPFH proteins. Our findings show that mitochondrial localization of SPFH proteins is conserved in
C. albicans
. In addition, we demonstrate the importance of stomatins in plasma membrane and mitochondrial stress tolerance.