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

Through some specific amino acid residues, cofilin, a ubiquitous actin depolymerization factor, can significantly affect mitochondrial function related to drug resistance and apoptosis inSaccharomyces cerevisiae ; however, this modulation in a major fungal pathogen,Aspergillus fumigatus , was still unclear. Hereby, it was found, first, 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, cytochromec release, upregulation of metacaspases, and DNA cleavage, inA. fumigatus . Two of these mutations (D19A-R21A and K36A) increased acetyl coenzyme A and ATP concentrations by triggering fatty acid β-oxidation. The upregulated acetyl coenzyme A affected the ergosterol biosynthetic pathway, leading to overexpression ofcyp51A and -B , while excess ATP fueled ATP-binding cassette transporters. Besides, both of these mutations reduced the susceptibility ofA. fumigatus to azole drugs and enhanced the virulence ofA. fumigatus in aGalleria mellonella infection model. Taken together, novel and key charged residues in cofilin were identified to be essential modules regulating the mitochondrial function involved in azole susceptibility, apoptosis, and virulence ofA. fumigatus .