Document Type

Master's Research

Degree Name

Master of Science




George S. Mourad

Date of Award



The use and importance of nucleobases and nucleosides can never be understated due to their plethora of contribution to the vitality of all organisms. Their de novo synthesis and salvage is compartmentalized within cells, and their transport intercellular transport serves the biochemical needs of distant cells. This intra- and inter-cellular type of communication is mediated by nucleobase/nucleoside transporters, which are ubiquitous in life. The necessity of transporters is reflected in all genomes, which can code up to 10% of proteins involved with transport. In Arabidiopsis thaliana alone, there are six families have been shown to code for transporters of nucleobases, and the families also overlap in solute specificity. This study will focus on the Nucleobase Cation Symporter-1 (NCS1). The sole of the NCS1 family in A. thaliana (AtNCS1) has recently been shown to transport adenine, guanine, and uracil (Mourad et al., 2012). The objective of this study is to characterize an NCS1 protein in Nicotiana sylvestris (NsNCS1), which has been found to have high amino acid similarity to AtNCS1. Using heterologous complementation in Saccharomyces cerevisiae, this study will demonstrate that NsNCS1 has similar solute specificities as AtNCS1 by being able to transport adenine, guanine, and uracil. In addition to this, competition studies will show the ability of NsNCS1 to bind to other solutes. Overall this study will contribute to an understanding of how NCS1 has evolved in the plant kingdom.