Identifying novel genetic determinants for oxidative stress tolerance in Candida glabrata via adaptive laboratory evolution

Abstract

Candida glabrata (C glabrata) is an important yeast of industrial and medical significance. Resistance to oxidative stress is an important trait affecting its robustness as a production host or virulence as a pathogenic agent, but current understanding of resistance mechanisms is still limited in this fungus. In this study, we rapidly evolved C glabrata population to adapt to oxidative challenge (from 80mM to 350mM of H O ) through short-term adaptive laboratory evolution. Adaptive mutants were isolated from evolved populations and subjected to phenotypic and omics analyses to identify potential mechanisms of tolerance to H O . Phenotypic characterizations revealed faster detoxification of H O and ability to initiate growth at a higher concentration of the oxidant in the isolated adaptive mutants compared with the wild type. Genome resequencing and genome-wide transcriptome analysis revealed multiple genetic determinants (eg, CAGL0E01243g, CAGL0F06831g, and CAGL0C00385g) that potentially contribute to enhanced H O resistance. Subsequent experimental verification confirmed that CgCth2 (CAGL0E01243g) and CgMga2 (CAGL0F06831g) are important in C glabrata tolerance to oxidative stress. Transcriptome profiling of adaptive mutants and bioinformatic analysis suggest that NADPH regeneration, modulation of membrane composition, cell wall remodeling, and/or global regulatory changes are involved in C glabrata tolerance to H O .

Adaptation of Desulfovibrio alaskensis G20 to perchlorate, a specific inhibitor of sulfate reduction

“…In this case, the precise mutation is important; parallelism may be due to constraints imposed by sat, which may not be able to tolerate many mutations. Perchlorate may also represent a simpler stress with fewer targets, unlike the more complex traits of salt or oxidative stress tolerance (Zhou et al, 2013;Huang and Kao, 2018). More likely, this parallelism hints at a rare pre-existing variant which becomes dominant under selection.…”

“…Paired with the ability of next-generation sequencing to rapidly and economically identify variants, ALE has greatly accelerated our understanding of the underlying mechanisms of adaptation, and has allowed us to link genomic changes to specific phenotypes (Dragosits and Mattanovich, 2013). Apart from basic insight into the adaptation process, ALE has allowed us to probe the mechanism of a variety of stressors and develop strains with industrially relevant phenotypes (Toprak et al, 2012;Wallace-Salinas and Gorwa-Grauslund, 2013;Reyes et al, 2014;Lenski, 2017;Huang and Kao, 2018). This experiment has yielded critical insight into the process of adaptation, its trajectory and replicability and its genetic basis.…”

“…This experiment has yielded critical insight into the process of adaptation, its trajectory and replicability and its genetic basis. Apart from basic insight into the adaptation process, ALE has allowed us to probe the mechanism of a variety of stressors and develop strains with industrially relevant phenotypes (Toprak et al, 2012;Wallace-Salinas and Gorwa-Grauslund, 2013;Reyes et al, 2014;Lenski, 2017;Huang and Kao, 2018). Most of this work has been in E. coli or S. cerevisiae, but current efforts are expanding to other microbes (Summers et al, 2012;Kurosawa et al, 2015;Zhou et al, 2015;2017).…”

Microevolution of the pathogenic yeasts Candida albicans and Candida glabrata during antifungal therapy and host infection

“…As shown by several genome-wide studies, regulation of the oxidative stress response is governed by the transcription factor Yap1 in vitro [136–139], however, Yap1 does not appear to be a virulence determinant and works in conjunction with other oxidative stress resistance (OSR) determinants to mediate phagocyte survival [137, 140]. The ability of C. glabrata to overcome oxidative stress was inspected by in vitro evolution during oxidative (H 2 O 2 ) challenge [141]. Individual C. glabrata populations were serially passaged in the presence of increasing concentrations of H 2 O 2 , resulting in a significant increase of MIC 50 of H 2 O 2 in comparison to the initial population.…”

The hypoxic transcription factor KlMga2 mediates the response to oxidative stress and influences longevity in the yeast Kluyveromyces lactis

“…Consistent with this hypothesis, adaptation to oxidative stress induced by hydrogen peroxide has been reported to involve transcription factors in S. cerevisiae, including Mga2, with correlations on fatty acids and ergosterol metabolism (Kelley and Ideker 2009). The involvement of Mga2 in response to the oxidative stress has also been reported in Candida glabrata (Huang and Kao 2018).…”