# In Silico Analysis and Expression Profiling of Adhesin-Like Flocculins in Trichosporon asahii

## TL;DR

This study explores adhesion-related genes in Trichosporon asahii, a yeast that causes infections, and finds that these genes are more active in biofilms and during specific growth forms.

## Contribution

The study identifies and characterizes adhesin-like flocculin genes in T. asahii and their expression patterns in different morphologies and biofilms.

## Key findings

- T. asahii flocculins show high similarity to Cryptococcus neoformans adhesins and bind to human proteins.
- Flocculin gene expression varies by strain and is highest in biofilms and hyphal forms.
- Clinical strain L2585 shows highest expression of the CFL1 flocculin gene.

## Abstract

Trichosporon asahii is an opportunistic basidiomycetous yeast increasingly recognized as a cause of invasive infections in immunocompromised individuals, often associated with high morbidity and mortality. Its ability to adhere to host tissues and abiotic surfaces is considered a critical virulence factor, yet the molecular mechanisms underlying this adhesion remain poorly understood.

To characterize gene sequences in T. asahii belonging to the flocculin family with potential adhesive functions.

The homologous flocculin genes DHA1, DHA2, CPL1, and CFL1, previously described in Cryptococcus neoformans as being involved in cell adhesion, were identified within the T. asahii predicted proteome. Four T. asahii strains were analyzed: two reference strains (CBS2479 and CBS7631) and two clinical strains (L2585 and L773). Cells were grown in planktonic morphology and biofilms in RPMI + MOPS medium with 2% glucose. The predominant morphology of the cells was observed using bright-field optical microscopy, and total RNA was extracted. The relative expression of the four flocculin genes was analyzed by qRT-PCR and normalized using the 2-ΔΔCt method and the actin gene.

The flocculin proteins showed high similarity and common domains with C. neoformans flocculins and other adhesins. The strains exhibited a variety of morphologies, with the T. asahii CBS2479 strain predominantly displaying yeast forms, while the T. asahii L2585 strain presented a higher quantity of hyphae. All flocculins bound to human proteins in the PriaA/Cpl1_fungi domain and/or to the Cpl1-like domain. T. asahii flocculins were downregulated when compared to the reference strain CBS2479, while the clinical strain L2585 exhibited the highest expression of the flocculin CFL1. During biofilm formation, DHA1 and CFL1 were highly expressed.

Flocculins were expressed according to specific yeast/hyphal morphology and were also more expressed in biofilms, indicating their association with biofilm maintenance and development.

The online version contains supplementary material available at 10.1007/s11046-025-01045-2.