Identification and Characterization of Key Charged Residues in the Cofilin Protein Involved in Azole Susceptibility, Apoptosis, and Virulence of Aspergillus fumigatus [PublishAheadOfPrint]

Through some specific amino acid residues, Cofilin, a ubiquitous actin depolymoerization factor, can significantly affect mitochondrial function related to drug resistance and apoptosis in Saccharomyces cerevisiae; however, this modulation in a major fungal pathogen, A. fumigatus was still unclear. Hereby, it was found firstly that mutations on several charged residues in cofilin to alanine, D19A;R21A, E48A, and K36A increased the formation of reactive oxygen species and induced apoptosis along with typical hallmarks including mitochondrial membrane potential depolarization, the cytochrome c release, upregulation of metacaspases, and DNA cleavage in A. fumigatus. Two of these mutations (D19A;R21A and K36A) increased acetyl-coenzyme A and adenosine triphosphate (ATP) concentrations by triggering fatty acid β-oxidation. The upregulated acetyl-coenzyme A affected the ergosterol biosynthetic pathway, leading to overexpression of cyp51A and -B, while excess ATP fueled ATP-binding cassette transporters. Besides, these two mutations both reduced the susceptibility of A. fumigatus to azole drugs and enhanced the virulence of A. fumigatus in a Galleria mellonella infection model. Taken together, novel and key charged residues in cofilin were identified as essential modules regulating the mitochondrial function involved in azole susceptibility, apoptosis, and virulence of A. fumigatus.

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