Defense Date

3-6-2013

Graduation Date

Spring 2013

Availability

Immediate Access

Submission Type

dissertation

Degree Name

PhD

Department

Biological Sciences

Committee Chair

Jana Patton-Vogt

Committee Member

Aaron Mitchell

Committee Member

Joseph McCormick

Committee Member

Nancy Trun

Committee Member

Partha Basu

Keywords

Glycerophosphodiesters, Metabolism, Phosphate, Transport

Abstract

Glycerophosphodiesters are products of phospholipase B-mediated hydrolysis of phospholipids. Their transport and metabolism is elaborated in the fungal pathogen, Candida albicans, as compared to the non-pathogenic Saccharomyces cerevisiae. C. albicans contains four ORFs (CaGIT1-4) predicted to encode transporters for glycerophosphodiesters, compared to one (ScGIT1) in S. cerevisiae. Here I have identified the gene products responsible for glycerophosphoinositol (GroPIns) and glycerophosphocholine (GroPCho) transport. C. albicans strain lacking ORF 19.34, which codes for CaGit1, is unable to transport intact GroPIns. Transport activity can be rescued by reintegration of one copy of CaGIT1 back into the genome. Similarly, a strain lacking CaGIT3 (ORF 19.1979) and CaGIT4 (ORF 19.1980) is unable to transport intact GroPCho into the cell. Reintegrating one copy of either CaGIT3 or CaGIT4 can rescue GroPCho transport activity. Initial transport assays and kinetic analyses indicate that CaGit3 is responsible for the majority of GroPCho transport activity. In addition, I present evidence that CaGDE1 (ORF 19.3936) codes for an enzyme with glycerophosphodiesterase activity against GroPCho. Homozygous deletion of CaGDE1 results in a buildup of internal GroPCho, which is restored to wild type accumulation by reintegration of one copy of CaGDE1 into the genome. The transcriptional regulator, CaPho4, was shown to positively regulate the expression of CaGIT1, CaGIT3, CaGIT4, and CaGDE1. Finally, glycerophosphodiester transport and metabolism was active under physiological relevant conditions that C. albicans may experience in the human host.

Format

PDF

Language

English

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