Development of an Efficient Gene-targeting System for Elucidating Infection Mechanisms of the Fungal Pathogen Trichosporon Asahii

Abstract

Trichosporon asahii is a pathogenic fungus that causes severe, deep-seated fungal infections in neutropenic patients. Elucidating the infection mechanisms of T. asahii based on genetic studies requires a specific gene-targeting system. Here, we established an efficient gene-targeting system in a highly pathogenic T. asahii strain identified using the silkworm infection model. By comparing the pathogenicity of T. asahii clinical isolates in a silkworm infection model, T. asahii MPU129 was identified as a highly pathogenic strain. Using an Agrobacterium tumefaciens-mediated gene transfer system, we obtained a T. asahii MPU129 mutant lacking the ku70 gene, which encodes the Ku70 protein involved in the non-homologous end-joining repair of DNA double-strand breaks. The ku70 gene-deficient mutant showed higher gene-targeting efficiency than the wild-type strain for constructing a mutant lacking the cnb1 gene, which encodes the beta-subunit of calcineurin. The cnb1 gene-deficient mutant showed reduced pathogenicity against silkworms compared with the parental strain. These results suggest that an efficient gene-targeting system in a highly pathogenic T. asahii strain is a useful tool for elucidating the molecular mechanisms of T. asahii infection.

JMM Profile: Trichosporon yeasts: from superficial pathogen to threat for haematological-neutropenic patients

“…Melanin production, expression of glucuronoxylomannan, and production and secretion of enzymes such as proteases, lipases and phospholipases play a critical role in infection development. In T. asahii, the calcineurin pathway may be involved in its pathogenicity [1,11,33,34].…”