Low ergosterol content in yeast adh1 mutant enhances chitin maldistribution and sensitivity to paraquat‐induced oxidative stress

Abstract

Alcohol dehydrogenases catalyse the reversible oxidation of alcohols to aldehydes or ketones, with concomitant reduction of NAD + or NADP + . Adh1p is responsible for the reduction of acetaldehyde to ethanol, while Adh2p catalyses the reverse reaction, the oxidation of ethanol to acetaldehyde. Lack of Adh1p shifts the cellular redox balance towards excess NADH/NADPH and acetaldehyde, while absence of Adh2p does the opposite. Yeast mutant adh1 had a slow growth rate, whereas adh2 grew like the isogenic wild-type (WT) during prediauxic shift fermentative metabolism. After 48 h WT and mutants reached the same number of viable cells. When exponentially growing (LOG) cells were exposed to calcofluor white, only mutant adh1 displayed an irregular deposition of chitin. Quantitative analyses of both LOG and stationaryphase cells showed that adh1 mutant contained significantly less ergosterol than cells of WT and adh2 mutant, whereas the erg3 mutant contained extremely low ergosterol pools. Both adh1 and adh2 mutants showed higher-than-WT resistance to heat shock and to H 2 O 2 but had WT resistance when exposed to ultraviolet (UV) light and the DNA cross-linking agent diepoxyoctane, indicating normal DNA repair capacity. Mutant adh1 was specifically sensitive to acetaldehyde and to membrane peroxidizing paraquat. Our results link the pleiotropic phenotype of adh1 mutants to low pools of ergosterol and to reductive stress, and introduce the two new phenotypes, resistance to heat shock and to H 2 O 2 , for the adh2 mutant, most probably related to increased ROS production in mitochondria, which leads to the induction of oxidative stress protection.

Antifungal Potential of Terpenes from Spondias Purpurea L. Leaf Extract against Moniliophthora Perniciosa that causes Witches Broom Disease of Theobroma Cacao

“…DHE-exposed M. perniciosa hyphae had shown a similar profile when subjected to a free radical-generating chemical treatment. Marisco et al [49] had shown similar results in the eukaryotic model in S. cerevisiae (yeast) using H 2 O 2 as pro oxidant. There is evidence for the role of endogenous ROS as a causative agent in mutagenesis and as a significant contributor in the mutational burden in microbes during periods of oxidative stress in which this response may be related to cytotoxicity [50].…”

Involvement of FgERG4 in ergosterol biosynthesis, vegetative differentiation and virulence in Fusarium graminearum

“…In addition, as the mutant showed an increased osmo‐sensitivity, paraquat and H 2 O 2 may penetrate the plasma membrane of the mutant more easily than that of the wild‐type, resulting in increased sensitivity of the mutant to these stress agents. In S. cerevisiae and C. albicans , the mutants with impaired ergosterol synthesis and a low content of ergosterol exhibited enhanced synthesis of chitin and abnormal distribution of chitin in their cell walls (Chiew et al ., ; Marisco et al ., ; Schmidt et al ., ). In this study, we found that the cell wall of ΔFgErg4‐2 was more resistant to the mixture of cellulase, lysozyme and snailase than was that of the wild‐type strain.…”

Development of a plasmid free CRISPR-Cas9 system for the genetic modification of Mucor circinelloides

“…In S . cerevisiae , low ergosterol level caused sensitivity to paraquat-induced oxidative stress 56 , 57 . In fact, membrane permeability plays important role in the adaptation to oxidative stress and the altered sterol production may result in higher sensitivity to inducers of oxidative stress 58 – 60 .…”