Mutations in complex components involved in mRNA polyadenylation and factors involved in its folding affect 5-FC susceptibility in Aspergillus fumigatus

Author:

Teppei Arai (JP)

Abstract:

Background: Invasive aspergillosis is one of fungal infections with the poorest prognosis. Clinically, antifungals belonging to three classes -azoles, polyenes, and echinocandins- are used to treat this disease. The nucleoside analogue 5-fluorocytosine (5-FC) is another class antifungal agent, but is rarely used to treat this disease because of its low in vitro susceptibility to A. fumigatus. The mechanism of resistance of A. fumigatus to 5-FC remains unclear. In this study, we report that mutations in components of the complex involved in mRNA polyadenylation and in factors involved in its retention affect 5-FC susceptibility in A. fumigatus.

Methods: To find novel factors associated with altered susceptibility to 5-FC, we performed comparative genomic analysis of A. fumigatus strains with different susceptibilities to 5-FC (MIC >16 and =8) isolated from a same patient. Antifungal susceptibility testing was performed according to CLSI-M38. To investigate the association between newly discovered genetic variants and altered susceptibility to 5-FC, mutant alleles in clinical isolates were replaced with wild-type alleles by the CRISPR-Cas9 system.

Results: Comparative genomic analysis of the two strains identified mutations in Ysh1, a component of the mRNA cleavage and polyadenylation factor (CPF) complex, and CCT7, a member of protein-folding complex called Chaperonin-Containing TCP-1 (CCT), in the strain with increased susceptibility to 5-FC. Replacing the mutant ysh1 and cct7 with the wild-type genes in the strain reduced susceptibility to 5-FC.

Conclusions: This study identified novel genetic changes that influence 5-FC sensitivity.　 These results suggest that mutations in Ysh1 and CCT7 caused the altered susceptibility to 5-FC observed in this study.

Abstract Number: 51

Conference Year: 2024

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