Differences between Cryptococcus neoformans and Cryptococcus gattii in the molecular mechanisms governing utilization of D-amino acids as the sole nitrogen source

Yun C. ChangAmi Khanal LamichhaneJames BradleyLaura RodgersPopchai NgamskulrungrojKyung J. Kwon-ChungNational Institute of Allergy and Infectious DiseasesMahidol University2018-11-232018-11-232015-07-01PLoS ONE. Vol.10, No.7 (2015)193262032-s2.0-84938883780https://repository.li.mahidol.ac.th/handle/123456789/35135© 2015, Public Library of Science. All rights reserved. This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication. The ability to grow on media containing certain D-amino acids as a sole nitrogen source is widely utilized to differentiate Cryptococcus gattii from C. neoformans. We used the C. neoformans H99 and C. gattii R265 strains to dissect the mechanisms of D-amino acids utilization. We identified three putative D-amino acid oxidase (DAO) genes in both strains and showed that each DAO gene plays different roles in D-amino acid utilization in each strain. Deletion of DAO2 retarded growth of R265 on eleven D-amino acids suggesting its prominent role on D-amino acid assimilation in R265. All three R265 DAO genes contributed to growth on D-Asn and D-Asp. DAO3 was required for growth and detoxification of D-Glu by both R265 and H99. Although growth of H99 on most D-amino acids was poor, deletion of DAO1 or DAO3 further exacerbated it on four D-amino acids. Overexpression of DAO2 or DAO3 enabled H99 to grow robustly on several D-amino acids suggesting that expression levels of the native DAO genes in H99 were insufficient for growth on D-amino acids. Replacing the H99 DAO2 gene with a single copy of the R265 DAO2 gene also enabled its utilization of several D-amino acids. Results of gene and promoter swaps of the DAO2 genes suggested that enzymatic activity of Dao2 in H99 might be lower compared to the R265 strain. A reduction in virulence was only observed when all DAO genes were deleted in R265 but not in H99 indicating a pathobiologically exclusive role of the DAO genes in R265. These results suggest that C. neoformans and C. gattii divergently evolved in D-amino acid utilization influenced by their major ecological niches.Mahidol UniversityAgricultural and Biological SciencesBiochemistry, Genetics and Molecular BiologyMedicineDifferences between Cryptococcus neoformans and Cryptococcus gattii in the molecular mechanisms governing utilization of D-amino acids as the sole nitrogen sourceArticleSCOPUS10.1371/journal.pone.0131865