Speaker
Description
Transposable elements (TEs) play an important role in genome evolution. TEs drive genomic instability, gene expression and gene evolution, frequently leading to phenotypic changes. The impact of novel TE insertions is likely deleterious; thus, ongoing TE activity is limited by purifying selection and diverse defense mechanisms, including the fungal specific repeat-induced point mutations. However, in rare cases novel TE insertions are adaptive. We recently argued that some fungal species make a “Devil’s bargain”, where a moderate activity of TEs is tolerated to create novelty. In these cases, most TEs are located in TE-rich regions containing effectors but lacking any essential genes. Other fungal species, including the Saccharomycotina, contain only few TE families with each just a handful of copies. Consequently, Saccharomycotina species have very gene-dense genomes, and the impact of a novel TE insertion is very likely deleterious, indicating that strong purifying selection against TE activity. The loss of a TE copy can likely mean the loss of the whole family, and it would be expected that over time, all TE copies would be lost. However, no Saccharomycotina species with a complete lack of TEs has been described so far. We recently found that TE-derived domains are more likely to be domesticated in Saccharomycotina, compared to other fungal species. Despite this, full-length TE copies with the potential to be active are still detected. We observed small bursts of TEs in clinical isolates of Candida albicans, preferred location of TEs in the subtelomeric region in C. auris,as well as individual specific location of the 1-3 copies of the only TE family in C. glabrata. Using both short-and long read sequencing, we described pangenome-wide structural variants and the activity of TEs over all known clades of C. albicans and C. auris.
