The cryptococcus neoformans saga (#182)
Christina Stephenson
1
- SCMB, School of Chemistry and Molecular Biology , Brisbane, QLD, Australia
- neoformans is optimistic pathogenic fungus which poses a constant threat to the global immunocompromised population. Upon infection this pathogen induces a plethora of virulence traits which enable it to evade host immune systems and navigate across the blood brain barrier, causing meningoencephalitis and death. The virulence traits that make this possible are highly regulated by a complex interplay between the environment, transcriptional machinery and genomic elements. Therefore, any mechanism which can interfere or block these pathways are areas of significant interest that could enhance our understanding of the process of pathogenesis. Transcriptional regulatory proteins which have a widespread impact on gene regulation make ideal candidates for drug therapies as they can interfere in numerous pathways. A primary candidate for this level of pleiotropic regulation is the SAGA complex, a 20-protein coactivator conserved across eukaryotes. Interactions between this complex and transcriptional regulation has widely been established in S. cerevisiae. The complex interfaces between the DNA, histones, and additional transcriptional machinery through a combination of five protein modules. Intriguingly a handful of SAGA studies have been conducted within C. neoformans which demonstrated a diverse and non-predictive phenotypic effect on virulence, creating both hyper and hypovirulent strains. This study identified previously uncharacterised candidate genes for UBP8, SFG73, SUS1 and SGF11 of the DeUBiquitination module of SAGA in C. neoformans. Each gene was deleted from the H99O type strain background and successfully complemented, with the reinsertion of the original gene at the Safe Haven locus. The phenotypes observed from a series of in vitro assays indicted that DUB mutants exhibit a change in the expression of subsets of genes related to the organisms associated virulence. These changes in virulence were studied further using an in vivo murine inhalation model of infection.