Stress Adaptation

Abstract

Fungal species display an extraordinarily diverse range of lifestyles. Nevertheless, the survival of each species depends on its ability to sense and respond to changes in its natural environment. Environmental changes such as fluctuations in temperature, water balance or pH, or exposure to chemical insults such as reactive oxygen and nitrogen species exert stresses that perturb cellular homeostasis and cause molecular damage to the fungal cell. Consequently, fungi have evolved mechanisms to repair this damage, detoxify chemical insults, and restore cellular homeostasis. Most stresses are fundamental in nature, and consequently, there has been significant evolutionary conservation in the nature of the resultant responses across the fungal kingdom and beyond. For example, heat shock generally induces the synthesis of chaperones that promote protein refolding, antioxidants are generally synthesized in response to an oxidative stress, and osmolyte levels are generally increased following a hyperosmotic shock. In this article we summarize the current understanding of these and other stress responses as well as the signaling pathways that regulate them in the fungi. Model yeasts such as Saccharomyces cerevisiae are compared with filamentous fungi, as well as with pathogens of plants and humans. We also discuss current challenges associated with defining the dynamics of stress responses and with the elaboration of fungal stress adaptation under conditions that reflect natural environments in which fungal cells may be exposed to different types of stresses, either sequentially or simultaneously.

Proteomic and Metabolomic Characteristics of Extremophilic Fungi Under Simulated Mars Conditions

“…Interestingly, exposed to ionizing radiation C. sphaerospermum, Wangiella dermatitidis , and Cryptococcus neoformans showed increased growth when compared to unexposed controls due to electronic changes in melanin (Dadachova et al, 2007), however, in our study only ISSFT-021-30 seemed to follow that pattern, revealing up-regulation of translation-related proteins. Observed opposite expression patterns of translation-related proteins, which underlay species-related unique defense system, may have been shaped by the varying environmental origins of each isolate (Gasch, 2007; Heitman et al, 2017). This discrepancy suggests that different species of filamentous fungi alter their growth and development in response to adverse environmental conditions in a species/strain-specific manner.…”

Stress-Activated Protein Kinases in Human Fungal Pathogens

“…Stress responses are essential for pathogenic fungi to survive hostile environments encountered in the host (Brown et al, 2017), and it is apparent that stress-activated protein kinase (SAPK) pathways are central in mediating such responses and virulence in many fungal pathogens. SAPKs were first identified in the model yeast Saccharomyces cerevisiae where the High Osmolarity Glycerol (HOG) pathway was shown to regulate the cellular response to osmotic stress (Brewster et al, 1993).…”

Signal peptide peptidase activity connects the unfolded protein response to plant defense suppression by Ustilago maydis

“…Microbial cells modulate conserved signaling pathways to adjust their intracellular physiology to constantly changing environmental conditions [1–3]. The smut fungus Ustilago maydis is a highly adapted biotrophic pathogen of its host plant maize that establishes a compatible fungal/plant interaction without evoking obvious plant defense responses [4].…”