Mutations in the Second Alternative Oxidase Gene: A New Approach to Group Strains.

Alternative oxidase is a terminal oxidase in the branched mitochondrial electron transport chain of most fungi including (subgenus Circumdati, section Nigri). A second, paralogous gene () is extant in some isolates but also present in two divergent species of the subgenus Nidulantes- and -as well as in . Black aspergilli are cosmopolitan opportunistic fungi that can cause diverse mycoses and acute aspergillosis in immunocompromised individuals. Amongst the approximately 75 genome-sequenced strains, features considerable sequence variation. Five mutations were identified that rationally affect transcription or function or terminally modify the gene product. One mutant allele that occurs in CBS 513.88 and neotype strain CBS 554.65 involves a chromosomal deletion that removes exon 1 and intron 1 from . Another allele results from retrotransposon integration. Three other alleles result from point mutations: a missense mutation of the start codon, a frameshift, and a nonsense mutation. strain ATCC 1015 has a full-length gene. The complex can thus be subdivided into six taxa according to extant allele, which may facilitate rapid and accurate identification of individual species.