RNAi is conserved across 300 sequenced A. fumigatus strains. (A) Structural domains of A. fumigatus RNAi proteins were analyzed using UniProt (www.uniprot.org/). DclA and DclB both contain a DExH-helicase followed by a helicase-C, a Dicer-dsRNA binding fold that mediates binding with other proteins (Qin et al. 2010), a P-element-induced wimpy testis (PIWI)–Argonaute–Zwille (PAZ) domain for binding the 3′ end of the dsRNA, and two RNase III domains necessary for cleavage of bound dsRNA (Schauer et al. 2002; Mukherjee et al. 2013; Song and Rossi 2017). Both argonaute orthologs (PpdA/B) have the characteristic PAZ domain and a PIWI domain present in all eukaryotic argonautes (Jinek and Doudna 2009; Ender and Meister 2010). (B) Calculation of the ratio of nonsynonymous to synonymous base changes (dN/dS) for each of the core RNAi components and peripheral factors using 300 genomes from Barber et al. (2021). Ratios under one indicate that each gene is under neutral-to-purifying selection.
