Localization of NAD⁺ Synthesis Enzymes in the Pathogenic Yeast Candida glabrata

Candida glabrata is an opportunistic yeast pathogen of humans and accounts for approximately 4% of all catheter associated urinary tract infection. It is normally controlled by the body's immune system and the body's bacteria flora, but can cause serious mucosal and systemic infecitons. C. glabrata is a nicotinamide adenine dinucleotide (NAD⁺) auxotroph, which depends on the environmental supply of NAD⁺ precursors using nicotinamide riboside (NR), nicotinic acid (NA), and nicotinamide (NAM) as NAD⁺ precursors. These precursors are used in a functional Preiss-Handler pathway to produce NAD⁺. We focused on the location of enzymes used in the Preiss-Handler pathway of C. glabrata under conditions replete for NAD⁺ precursors and under extreme conditions such as NAD⁺ precursor starvation. The C-terminus of the Npt1, Qns1, Nrk1 and Pnc1 was tagged with GFP to identify the location of the enzymes in the yeast before and after starvation of NA and NR. Under the fluorescent microscope, localization of enzymes was found in the cytoplasm before and after starvation. Therefore, within the limits of our assay, we conclude that localization of the Preiss-Handler pathway enzymes in C. glabrata is unaffected by environmental conditions. We intend to confirm and extend these results by exploring the subcellular localization of pathway enzymes using different tags for localization.