Co-localization of Potential Nitrogen Catabolite Repression Transcription Factors in Cryptococcus Neoformans

Isabella Costanzo

Mentors: Julia Palmucci, Jennifer Tenor, Ph.D., John Perfect, M.D.

Department of Medicine, Division of Infectious Diseases

Cryptococcus neoformans, a ubiquitous infectious yeast, proliferates in cerebrospinal fluid (CSF) causing fungal meningitis in immunocompromised individuals. CSF is deficient in nitrogen, a necessary growth nutrient. To overcome this hostile growth environment and maximize fitness, many fungi employ nitrogen catabolite repression (NCR) in which genes required to break down unfavorable nitrogen sources are repressed when more favorable nitrogen sources are present. Other fungal genera like Saccharomyces and Aspergillus have well-studied NCR pathways, but NCR has not been thoroughly investigated in C. neoformans. Current research suggests that Tar1 and Ure3 in C. neoformans may be orthologous to NCR gene repressors in Aspergillus and Saccharomyces (NmrA and Ure2, respectively), and may regulate the GATA transcription factor Gat1—the master regulator of NCR. Tar1 and Ure3 proteins were fluorescently tagged with mCherry and transformed into both wild-type (H99) and Gat1::GFP backgrounds to determine the localization of these proteins during nitrogen replete and deplete conditions and co-localization with Gat1. Co-localization of Ure3 or Tar1 with Gat1 would indicate the C. neoformans NCR pathway is similar to Saccharomyces or Aspergillus, respectively. Negative results may indicate a unique regulatory system in C. neoformans. Further experimentation would examine additional NCR interactors and investigate its effect on C. neoformans on survival in CSF.

Leave a Reply

Your email address will not be published. Required fields are marked *