Sire Kassama
Faculty Advisor: Klaas Van Wijk
Year: 2017

“Proteins of Obscure Function in the Plastoglobule”

Project Summary:

Plastoglobules (PGs) are highly dynamic lipoprotein particles in all plastid types, and have important roles in plastid biogenesis/homeostasis, senescence, and abiotic stress responses. Their specialized proteome consists of ~30 proteins and a metabolome enriched for prenyl lipids, such as vitamin E and various quinones, under normal growth conditions. The proteome includes six atypical ABC1 kinases (K1,3,5,6,7,9), tocopheral cyclase (VTE1), and various proteins with unknown functions that strongly coexpress, suggesting that PGs are a regulatory hub of many plastid pathways.

This study focuses on four such unknown proteins, two flavin reductase-related proteins (FRed-1 and FRed-2), and two plastoglobule methyltransferase proteins (PGMT-1 and PGMT-2). These proteins have been previously identified as part of plant abiotic stress response.  T-DNA insertion mutants of A. thaliana were collected from SALK and Gabi-KAT and were grown in salinity and oxidative stress conditions. Phenotypic data was collected on the length, diameter, and surface area of the roots of the plants; this data established that the target proteins confer a root phenotype. Chlorophyll and carotenoid concentration measurements were also taken but showed no significant difference in mutant plants. Exploration into conserved domains between the target proteins and potential ancestral proteins revealed key information into the function of FRed-1 and -2, as well as PGMT-1 and -2. This relationship illustrated a strong phylogenetic relationship and helped to gain insight on the role of FRed-1 and -2, and PGMT-1 and -2.

My Experience:

As a PGRP intern, I was given the opportunity to gain first-hand experience in the path to scientific discovery. With the aid of my mentor and the van Wijk lab, I had the chance to expand my knowledge and skills in the plant biology field. The program helped me to build relationships within the scientific community and beyond. I was taught how to handle criticism, experiments that may fail, and grow confidence as a researcher in plant biology. One of the most valuable lessons of the internship was given to me from my mentor, which was the importance of a work-life balance. In the future, I will be pursuing a graduate degree in the plant sciences field.