Date of Award

Spring 2012

Document Type

Restricted Thesis

Terms of Use

© 2012 Laura H. Rodgers. All rights reserved. Access to this work is restricted to users within the Swarthmore College network and may only be used for non-commercial, educational, and research purposes. Sharing with users outside of the Swarthmore College network is expressly prohibited. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts

Department

Biology Department

First Advisor

Amy Cheng Vollmer

Abstract

During host invasion, the opportunistic pathogenic fungi Cryptococcus neoformans and Cryptococcus gattii rely on trehalose, an essential disaccharide, for stress and heat tolerance. In this study, we investigated the trehalose biosynthesis pathway in these sister species through genetic and biochemical analyses. Previous work from the Perfect laboratory at Duke University described phenotypic differences between C. neoformans and C. gattii trehalose-6-phosphate synthase (TPS1) mutant strains. Using allelic exchange, we determined that the polymorphisms between the TPS1 alleles in C. neoformans and C. gattii were not responsible for the phenotypic differences between the tps1 mutant strains. We therefore examined the localization patterns of the native Tps1 and Tps2 (trehalose-6-phosphate phosphatase) enzymes in the trehalose pathway in both C. neoformans and C. gattii. Preliminary localization data suggest that, in both species, Tps1 localized to the cytoplasm and endoplasmic reticulum. Tps2 in both species localized to the cytoplasm and either the plasma membrane or the cell wall. Tps2 also showed unusual localization patterns in a currently unspecified internal location in the cell. These localization patterns suggest that in C. neoformans and C. gattii Tps1 and Tps2 colocalize in the cytoplasm where trehalose biosynthesis occurs. The data also suggest a novel function for the Tps1 and Tps2 enzymes other than in trehalose biosynthesis.

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