The chromatin remodeling factor Arp9 modulates drug-resistance and plays a key role in aflatoxins biosynthesis under mammalian-physiological-temperature in Aspergillus flavus

Aspergillus flavus is the second most prevalent species of Aspergillus causing invasive aspergillosis, but its treatment efforts had been hindered by the continuous emergence of drug-resistant fungal strains, while the underlying mechanisms remain largely unexplored. In this study, we investigated the role of the chromatin remodeling factor Arp9 in A. flavus drug-resistant. We show that Arp9 up-regulates the chromatin accessibility of the Erg3 and Erg6 promoters, thereby increasing their transcription levels and enhancing ergosterol synthesis. Therefore, the absence of Arp9 enhances A. flavus sensitivity to amphotericin B (AMB). Additionally, by down-regulating chromatin accessibility of Erg11A gene promoter, Arp9 leads to the decrease of its transcription level and subsequently reduces A. flavus resistance to voriconazole (VOR). Co-immunoprecipitation analysis revealed that Arp9 exists in both SWI/SNF and RSC complex. Drug susceptibility test results indicated that the drug sensitivity response induced by Arp9 may be unique to Arp9, as neither SWP82 of the SWI/SNF nor Sth1 of the RSC is required. The role of Arp9 in drug-resistance was also confirmed using the Galleria mellonella model. Furthermore, we found that VOR induces aflatoxin B1 (AFB1) biosynthesis in an Arp9-dependent manner at 35°C and 37°C, and the effect is dramatically magnified in the VOR-resistant A. flavus strain. This study demonstrates that Arp9 plays a critical role in regulating fungal drug-resistance in vitro and in vivo and revealed that Arp9 is an important factor in enhancing AFB1 biosynthesis under Mammalian physiological temperatures. This study provides potential new insights for the control of the infections caused by filamentous pathogenic fungi.