Disruption of mitochondrial iron-Sulfur cluster biosynthesis: a novel mechanism of action for two plant-derived antifungal aporphinoid alkaloids

Authors: TRIPATHI, SIDDHARTH - University Of Mississippi; XU, TAO - University Of Mississippi; FENG, QIN - University Of Mississippi; AVULA, BHARATHI - University Of Mississippi; SHI, XIAOMIN - Baylor College Of Medicine; PAN, XUEWEN - Baylor College Of Medicine; Mask, Melanie; Baerson, Scott; JACOB, MELISSA - University Of Mississippi; RAVU, RANGA - University Of Mississippi; KHAN, SHABANA - University Of Mississippi; LI, XING-CONG - University Of Mississippi; KHAN, IKHLAS - University Of Mississippi; CLARK, ALICE - University Of Mississippi; AGARWAL, AMEETA - University Of Mississippi

Submitted to: Journal of Biological Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/18/2017
Publication Date: 10/6/2017
Citation: Tripathi, S.K., Xu, T., Feng, Q., Avula, B., Shi, X., Pan, X., Mask, M.M., Baerson, S.R., Jacob, M.R., Ravu, R.R., Khan, S.I., Li, X., Khan, I.A., Clark, A.M., Agarwal, A.K. 2017. Disruption of mitochondrial iron-Sulfur cluster biosynthesis: a novel mechanism of action for two plant-derived antifungal aporphinoid alkaloids. Journal of Biological Chemistry. 292(40):16578-16593.

Interpretive Summary: This article describes studies performed on analogs of the structurally-related naturally-occurring antifungal compounds eupolauridine and liriodenine in order to understand how they inhibit the growth of fungal pathogens. The results described indicate that these compounds interfere with iron-sulfur cluster synthesis in mitochondria, which perform critical energy generating functions within cells. The work described in this study lays the foundation for future studies that can pin-point the exact molecular target of eupolauridine and liriodenine in fungal pathogens. This type of work is important for the development of candidate antifungal compounds, and also could lead to the discovery other compounds exhibiting similar biological and chemical properties.

Technical Abstract: Eupolauridine and liriodenine are plant-derived aporphinoid alkaloids that exhibit potent inhibitory activity against the opportunistic fungal pathogens Candida albicans and Cryptococcus neoformans. In this study, we show that eupolauridine 9591 (E9591), a synthetic analog of eupolauridine, and liriodenine methiodide (LMT), a methiodide salt of liriodenine, mediate their antifungal activities by disrupting mitochondrial iron-sulfur (Fe-S) cluster synthesis. Several lines of evidence supported this conclusion. First, E9591 and LMT elicited a transcriptional response indicative of iron imbalance, causing the induction of genes that are required for iron uptake and for the maintenance of cellular iron homeostasis. Second, a genome-wide fitness profile analysis showed that yeast mutants with deletions in iron homeostasis-related genes were hypersensitive to E9591 and LMT. Third, treatment of wild-type yeast cells with E9591 and LMT generated cellular defects that mimicked deficiencies in mitochondrial Fe-S cluster synthesis including an increase in mitochondrial iron levels, a decrease in mitochondrial aconitase activity, a decrease in respiratory function, and an increase in oxidative stress. Collectively, our results demonstrate that E9591 and LMT perturb mitochondrial Fe-S cluster biosynthesis, thus targeting a novel cellular pathway that is distinct from the pathways targeted by clinically used antifungal drugs. The identification of this pathway as a target for antifungal compounds has potential applications in the development of new antifungal therapies.