Toward the discovery of biological functions associated with the mechanosensor Mtl1p of Saccharomyces cerevisiae via integrative multi-OMICs analysis.

Functional analysis of the Mtl1 protein in Saccharomyces cerevisiae has revealed that this transmembrane sensor endows yeast cells with resistance to oxidative stress through a signaling mechanism called the cell wall integrity pathway (CWI). We observed upregulation of multiple heat shock proteins (HSPs), proteins associated with the formation of stress granules, and the phosphatase subunit of trehalose 6-phosphate synthase which suggests that mtl1Δ strains undergo intrinsic activation of a non-lethal heat stress response. Furthermore, quantitative global proteomic analysis conducted on TMT-labeled proteins combined with metabolome analysis revealed that mtl1Δ strains exhibit decreased levels of metabolites of carboxylic acid metabolism, decreased expression of anabolic enzymes and increased expression of catabolic enzymes involved in the metabolism of amino acids, with enhanced expression of mitochondrial respirasome proteins. These observations support the idea that Mtl1 protein controls the suppression of a non-lethal heat stress response under normal conditions while it plays an important role in metabolic regulatory mechanisms linked to TORC1 signaling that are required to maintain cellular homeostasis and optimal mitochondrial function.

Protein Interactions of the Mechanosensory Proteins Wsc2 and Wsc3 for Stress Resistance in Saccharomyces cerevisiae.

Antifungal drug discovery and design is very challenging because of the considerable similarities in genetic features and metabolic pathways between fungi and humans. However, cell wall composition represents a notable point of divergence. Therefore, a research strategy was designed to improve our understanding of the mechanisms for maintaining fungal cell wall integrity, and to identify potential targets for new drugs that modulate the underlying protein-protein interactions in Saccharomyces cerevisiae This study defines roles for Wsc2p and Wsc3p and their interacting protein partners in the cell wall integrity signaling and cell survival mechanisms that respond to treatments with fluconazole and hydrogen peroxide. By combined genetic and biochemical approaches, we report the discovery of 12 novel protein interactors of Wsc2p and Wsc3p Of these, Wsc2p interacting partners Gtt1p and Yck2p, have opposing roles in the resistance and sensitivity to fluconazole treatments respectively. The interaction of Wsc2p with Ras2p was confirmed by iMYTH and IP-MS approaches and is shown to play a dominant role in response to oxidative stress induced by hydrogen peroxide. Consistent with an earlier study, Ras2p was also identified as an interacting partner of Wsc1p and Mid2p cell wall integrity signaling proteins. Collectively, this study expands the interaction networks of the mechanosensory proteins of the Cell Wall Integrity pathway.

Fundamental Concepts of Azole Compounds and Triazole Antifungals: A Beginner's Review.

Azoles are the most widely used drugs in antifungal therapy. They have a wide spectrum of activity against pathogenic fungi that are clinically relevant. However, they have been associated with adverse reactions and toxicity, both of which can be significant in patients. Compared to diazoles, triazoles discriminate better between their intended molecular target, the fungal CYP51 enzyme, and several enzymes of the human CYP450 system. Over the years, this superior discrimination has led to the favoring of triazoles over diazoles in the treatment of systemic mycoses. Nevertheless, despite their being better able to discriminate between the fungal CYP51 and host CYP450 enzymes, they are still capable of inducing significant toxicity and adverse reactions in the host, especially when taken concomitantly with other therapeutic drugs by patients with compromised immune systems. In this writing, we review some of the fundamental concepts regarding the chemistry and mechanisms of action of azole compounds, as well as the spectrum of activity, pharmacokinetics, and adverse effects of triazole antifungals. In addition, we discuss some of the mechanisms that pathogenic fungi have developed to overcome the cytotoxic effects of therapeutic drugs, with an emphasis on triazoles.