Scientists have discovered that the world's most generally used class of antifungals causes pathogens to self-destruct. Research led by the University of Exeter could help improve food safety and ways to guard human life.
Fungal diseases account for 1 / 4 of the world's crop losses. They also pose a threat to humans and will be fatal to individuals with weakened immune systems.
Azole fungicides are our strongest “weapon” against fungal plant diseases. These chemical products account for 1 / 4 of the worldwide agricultural fungicide market, value greater than £3 billion a yr. Antifungal azoles are also widely used as therapeutics against pathogenic fungi that will be fatal to humans, increasing their importance in our efforts to manage fungal disease.
Azoles goal enzymes within the pathogen cell that produce a cholesterol-like molecule, called ergosterol. Ergosterol is a vital component of cellular biomembranes. Azoles deplete ergosterol, leading to pathogen cell death. However, despite the importance of azoles, scientists know little concerning the actual reason for pathogen death.
In a recent study published in , University of Exeter scientists have uncovered the cellular mechanism by which azoles kill pathogenic fungi.
Funded by the BBSRC, the team of researchers, led by Professor Jero Steinberg, combined live-cell imaging approaches and molecular genetics to grasp how ergosterol (Why inhibition of synthesis leads to cell death in crop pathogenic fungi). This fungus causes septoria leaf spot in wheat, a serious disease in temperate climates, estimated to cost over £250 million annually in crop losses and fungicide sprays within the UK alone. .
The Exeter team observed living cells, treated them with agricultural azoles and analyzed cellular responses. They showed that the previously accepted concept that azoles kill pathogen cells by causing perforation of the outer cell membrane. Instead, they found that the azole-induced reduction of ergosterol increases the activity of cellular mitochondria, the cell's “powerhouse,” which is required to provide the cellular “fuel” that fuels all metabolic processes in pathogenic cells. Runs the method. Although producing more “fuel” will not be harmful in itself, the method results in the formation of more toxic byproducts. These byproducts initiate a “suicide” program within the pathogen cell, termed apoptosis. In addition, decreased ergosterol levels also activate one other “self-destruct” pathway, which causes the cell to “eat” its nucleus and other vital organelles — a process often called called macroautophagy. The authors show that each cell death pathways influence the lethal activity of azoles. They conclude that azoles drive the fungal pathogen to “suicide” by initiating self-destruction.
The authors found an analogous mechanism for the way azoles kill pathogen cells within the rice blast fungus. Disease brought on by this fungus kills as much as 30 percent of rice, a necessary food for greater than 3.5 billion people worldwide. The team also tested other clinically relevant antifungal drugs that focus on ergosterol biosynthesis, including Terbinafine, Tolfonate and Fluconazole. All initiated an analogous response within the pathogen cell, suggesting that cell suicide is a general consequence of ergosterol biosynthesis inhibitors.
Lead writer Professor Jero Steinberg, who holds the Chair in Cell Biology and Director of the Bioimaging Center on the University of Exeter, said: “Our findings rewrite the final understanding of how azoles kill fungal pathogens. The program, which leads to this cellular response after two days of treatment, suggests that a while after exposure to the azoles, it gives the pathogen time to develop resistance to the azoles, which explains This explains why fungal pathogens have gotten increasingly immune to azoles, meaning they usually tend to fail to kill disease in crops and humans.
“Our work sheds light on the activity of our most widely used chemical control agents in crop and human pathogens around the world. We hope our findings will be useful for improving control strategies that save lives.” can save and secure food security for the long run.”