The Cryptococcus neoformans monocarboxylate transporter Jen4 is responsible for increased 3-bromopyruvate sensitivity

In the last decades, 3-bromopyruvate (3BP) has been intensively studied as a promising anticancer and antimicrobial agent. The transport of this drug inside the cell is a critical step for its toxicity in cancer and microorganisms. The Cryptococcus neoformans is the most sensitive species of microorganisms toward 3BP. Its cells exhibit the highest uptake rate of 3BP among all tested fungal strains. In Saccharomyces cerevisiae cells, the Jen1 transporter was found to be responsible for 3BP sensitivity. The deletion of Jen1 resulted in the abolishment of 3BP mediated transport. We functionally characterized the Jen4 protein, a Jen1 homologue of C. neoformans, and its role in the phenotypic 3BP sensitivity. The deletion of the CNAG_04704 gene, which encodes Jen4, was found to impair the mediated transport of 3BP and decrease 3BP sensitivity. Further heterologous expression of Jen4 in the S. cerevisiae jen1 Delta ady2 Delta strain restored the mediated transport of 3BP. The application of a green fluorescent protein fusion tag with the CNAG_04704, revealed the Jen4 labeled on the plasma membrane. The identification of 3BP transporters in pathogen cells is of great importance for understanding the mechanisms of 3BP action and to anticipate the application of this compound as an antimicrobial drug.

This work was supported by the Ministry of Science and Higher Education (Poland) via 'Statutory Research 2018/S/IGM', the strategic program UID/BIA/04050/2013 (POCI-01-0145-FEDER-007569) and was also co-financed by the Polish National Science Center (grant number 2015/19/N/NZ7/00956), by the project PTDC/BIAMIC/5184/2014 funded by national funds through the Fundacao para a Ciencia e Tecnologia (FCT) I.P. and by the European Regional Development Fund (ERDF) through the COMPETE 2020-Programa Operacional Competitividade e Internacionalizacao (POCI). DR acknowledges FCT for the SFRH/BD/96 166/2013 PhD grant.