title: Differences between Cryptococcus neoformans and Cryptococcus gattii in the Molecular Mechanisms Governing Utilization of D-Amino Acids as the Sole Nitrogen Source.
abstract: 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.
authors.affiliation: Molecular Microbiology Section, Laboratory of Clinical Infectious Diseases, NIAID, NIH, Bethesda, MD, United States of America.
authors.forename: Yun C
authors.initials: YC
authors.lastname: Chang
authors.affiliation: Molecular Microbiology Section, Laboratory of Clinical Infectious Diseases, NIAID, NIH, Bethesda, MD, United States of America.
authors.forename: Ami
authors.initials: A
authors.lastname: Khanal Lamichhane
authors.affiliation: Molecular Microbiology Section, Laboratory of Clinical Infectious Diseases, NIAID, NIH, Bethesda, MD, United States of America.
authors.forename: James
authors.initials: J
authors.lastname: Bradley
authors.affiliation: Molecular Microbiology Section, Laboratory of Clinical Infectious Diseases, NIAID, NIH, Bethesda, MD, United States of America.
authors.forename: Laura
authors.initials: L
authors.lastname: Rodgers
authors.affiliation: Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Popchai
authors.initials: P
authors.lastname: Ngamskulrungroj
authors.affiliation: Molecular Microbiology Section, Laboratory of Clinical Infectious Diseases, NIAID, NIH, Bethesda, MD, United States of America.
authors.forename: Kyung J
authors.initials: KJ
authors.lastname: Kwon-Chung
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D003453:Cryptococcosis / Q000382:microbiology; D056285:Cryptococcus gattii / Q000378:metabolism* / Q000472:pathogenicity; D003455:Cryptococcus neoformans / Q000378:metabolism* / Q000472:pathogenicity; D003605:D-Amino-Acid Oxidase / Q000235:genetics / Q000378:metabolism; D051379:Mice; D009584:Nitrogen / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D014774:Virulence
chemical_list: D000596:Amino Acids; D003605:D-Amino-Acid Oxidase; D009584:Nitrogen