Student of the Month (November 2008)
Name: Sherry Hildreth (shildret at vt.edu)
Research project: Investigating a Putative Nicotine Metabolic Channel in Nicotiana Tabacum
Advisor: John Jelesko
Departmental affiliation: PPWS
Anticipated defense date: 2009
Project description:
Posters at international meetings:
Publications:
Secondary metabolites such as the alkaloid nicotine are important plant chemical defense compounds. For example, consumption of nicotine by insect herbivores causes hyperstimulation of insect acetylcholine receptors. This hyperstimulation results in paralysis of the insect thereby reducing feeding by the herbivore. Nicotine was the first commercial insecticide, but use was discontinued due to its neurotoxic effects on humans. Biosynthesis of nicotine, specifically biosynthesis of the N-methylpyrrolinium ring, has several steps in common with tropane alkaloid biosynthesis. Tropane alkaloids, produced in some other members of the Solanaceae, are important human pharmacologicals. Thus, much can be learned by the study of nicotine biosynthesis that is relevant to other high value plant medicinals as well as to our understanding of plant defense mechanisms. The goal of my research is answer two specific questions regarding nicotine biosynthesis.
1) Are direct interactions between proteins occurring among nicotine biosynthetic enzymes to form a nicotine metabolic channel?
2) Where does nicotine biosynthesis enzymes occur in the plant root?
I am using complementary approaches to investigate protein-protein interactions. The classic biochemical technique co-immunoprecipitation is being used to investigate direct protein interactions in tobacco root extract. Additionally, I am using the yeast two-hybrid assay to conduct a broader screen to identify interacting proteins. Nicotine biosynthesis occurs exclusively in the root tissue, but specifically in what cell types is still unknown. To answer this question I am using microscopy together with molecular biology techniques to localize mRNA transcripts and proteins involved in nicotine biosynthesis.