Taf1: a class II transposon of Aspergillus fumigatus.

Aspergillus fumigatus is an important medical pathogen that lacks a known sexual cycle. Transposons may provide an important mechanism for the generation of genetic diversity in this organism. Here, we describe Taf1, the first class II transposon to be identified in A. fumigatus. Taf1, a member of the mariner superfamily and pogo family of transposons, is distinguished by the presence of extremely long (89 bp) inverted repeats that flank the transposase coding sequence. Taf1 is present in different locations and copy number among clinical strains of A. fumigatus and is transcribed. Analysis of multiple insertion sequences within a single strain suggests that Taf1 elements undergo inactivation by a repeat induced polymorphism-like mechanism. Taf1 insertion patterns were extremely stable despite multiple stressors including heat shock, serial passage, and infection in mice. Thus Taf1 may be useful for strain identification and molecular typing.