Antifungal azoles trigger a xenobiotic detoxification pathway and chitin synthesis in Neurospora crassa.

The presence of antifungal drugs is prompting the fungal microorganisms to react by mechanisms broader than the resistance. The fungi evolved mechanisms, by which they respond to various stress conditions, including the presence of antifungal compounds. In this work, we studied the response of model filamentous fungus Neurospora crassa to azole antifungals in the broader context of the adaptation mechanisms. We demonstrated the increase in expression of filamentous fungi-specific genes encoding cytochrome enzymes of CYP65 clan and plasma membrane-localized ABCC transporters. Azoles appear not to conjugate with glutathione. Surprisingly, the azoles caused changes in the hyphae organization and the amount of chitin in cell wall by the same manner that was thought to be echinocandin-specific. The response to individual azoles appeared to be influenced by the structure of azole compound (prochloraz - main outlier). Taken together, these findings demonstrate the importance of study of stress response mechanisms, specifically in filamentous fungi. Many aspects of the reaction within azoles seem to be similar, though specificities are occurring.

Peptaibol-Containing Extracts of Trichoderma atroviride and the Fight against Resistant Microorganisms and Cancer Cells.

Fighting resistance to antibiotics and chemotherapeutics has brought bioactive peptides to the fore. Peptaibols are short α-aminoisobutyric acid-containing peptides produced by Trichoderma species. Here, we studied the production of peptaibols by Trichoderma atroviride O1 and evaluated their antibacterial and anticancer activity against drug-sensitive and multidrug-resistant bacterium and cancer cell lines. This was substantiated by an analysis of the activity of the peptaibol synthetase-encoding gene. Atroviridins, 20-residue peptaibols were detected using MALDI-TOF mass spectrometry. Gram-positive bacteria were susceptible to peptaibol-containing extracts of T. atroviride O1. A synergic effect of extract constituents was possible, and the biolo-gical activity of extracts was pronounced in/after the peak of peptaibol synthetase activity. The growth of methicillin-resistant Staphylococcus aureus was reduced to just under 10% compared to the control. The effect of peptaibol-containing extracts was strongly modulated by the lipoteichoic acid and only slightly by the horse blood serum present in the cultivation medium. Peptaibol-containing extracts affected the proliferation of human breast cancer and human ovarian cancer cell lines in a 2D model, including the multidrug-resistant sublines. The peptaibols influenced the size and compactness of the cell lines in a 3D model. Our findings indicate the molecular basis of peptaibol production in T. atroviride O1 and the potential of its peptaibol-containing extracts as antimicrobial/anticancer agents.

An update on ABC transporters of filamentous fungi - from physiological substrates to xenobiotics.

The superfamily of ATP-binding cassette (ABC) transporters is a large family of proteins with a wide substrate repertoire and range of functions. The main role of these proteins is in the transportation of different molecules across biological membranes. Due to the broad range of substrates, ABC transporters can transport not only natural metabolites but also various xenobiotics, including antifungal compounds, which makes some ABC transporters key players in antifungal resistance. Alternatively, ABC proteins without transport function seem to be essential for fungal cell viability. In this work, we review the individual subfamilies of ABC transporters in filamentous fungi regarding physiological substrates, clinical and agricultural significance. Subfamilies are defined using well-studied transporters in yeast, which may help to clarify their role in filamentous fungi.

Signalling mechanisms involved in stress response to antifungal drugs.

The emergence of antifungal resistance is a serious threat in the treatment of mycoses. The primary susceptible fungal cells may evolve a resistance after longer exposure to antifungal agents. The exposure itself causes stress condition, to which the fungus needs to adapt. This review provides detailed description of evolutionary conserved molecular mechanisms contributing to the adaptation response to stress caused by antifungal agents as well as their interconnection. The knowledge may help us to find new ways to delay the emergence of drug resistance as the same mechanisms are used regardless of what antifungal compound causes stress.

Synergy Over Monotherapy.

Pathogenic fungi, as an increasing global threat to human health, represent a sizable risk. However, significant attention should also be paid to the yeast biofilms. One promising strategy for combating resistant microbes, as well as fungal biofilms, is to extend the lifespan and efficacy of our currently employed drugs by using combination therapy. Since the application of combined therapy of fungal infections is currently accepted, we have decided to verify the efficacy of derivative H in combination with fluconazole on C. albicans biofilm. The main advantage of synergy over monotherapy lies in reducing or even completely preventing the induction of resistance of fungal cells. We have decided to verify the derivative H (1,4-dihydropyridine-2,3,5-tricarboxylate), an intermediate of nilvadipine synthesis, in the resistance of C. albicans to fluconazole. Therefore, we have focused on the influence of derivative H on the gene expression of the main C. albicans adhesin (ALS3), which is important for the tissue colonization during the infection process. Our results show that the newly synthesized derivative H had an impact on biofilm eradication. The effect of biofilm diminution could, therefore, be explained as derivative H preventing the adherence of C. albicans cells. This study supports even more the attractiveness of this substance as a potential agent that could be used in synergy with commonly used azoles to treat various fungal infections.