Characterization and function of the RNA interference machinery of Aspergillus fumigatus

Author:

Abdulrahman Kelani 1, Matthew G. Blango 1, Flora Rivieccio 1, Florian Mock 2,
Manja Marz 2, Axel A. Brakhage 1,2

Author address:

1 Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, Jena, Germany;
2 Friedrich Schiller University Jena, Jena, Germany

Full conference title:

15th European Conference on Fungal Genetics 2020

Date: 20 June 2020

Abstract:

Aspergillus fumigatus is a ubiquitous fungus of high abundance in natural environments and able to thrive in very diverse environments, ranging from compost piles to even mammalian lungs in some cases. RNA interference (RNAi) is a conserved molecular mechanism in eukaryotes, which uses small RNA (sRNA) molecules to suppress gene expression through sequence-specific messenger RNA (mRNA) degradation. RNAi has been shown to be important for fungal development, physiology, and defense against invading nucleic acids. sRNAs from some pathogens can even be used as effectors to modulate host defense and influence pathogenesis. In this study, we hypothesized that A. fumigatus RNAi is important for gene regulation, stress resistance, and survival of the fungus in human hosts. To test this hypothesis, we created single and double knockouts of key components of the RNAi machinery, including orthologs of the dicer, argonaute, and RNA-dependent RNA polymerase proteins in A. fumigatus. Only the deletion of both argonaute proteins resulted in a sporulation defect. To gain insight into the active mechanisms of silencing in A. fumigatus and characterize the observed phenotypes, we are currently analyzing the contribution of each protein to silencing mediated by an inverted repeat transgene (IRT)-containing plasmid. So far, our results suggest that only one of the A. fumigatus argonaute proteins contributes to IRT-dependent silencing of target mRNA. We next performed RT-qPCR to measure transcript levels of RNAi genes, which revealed high relative expression in conidia and fungal hyphae under starvation conditions. This was followed by sRNA sequencing in these conditions to predict potential sRNAs, which are currently being analyzed. This study has revealed that A. fumigatus RNAi regulates several physiological processes, and we hope to fully characterize the A. fumigatus RNAi pathway and provide a platform to study RNAi mediated interactions during infection.

Link to conference website:

Link Conference abstract:

ECFG 15