Investigation of the Roles of RNA-Binding Proteins in Arabidopsis thaliana
Authors:Aubrie De La Cruz, Maureen Hummel
Mentor:Julia Bailey-Serres, Professor of Genetics, University of California Riverside
There are very few existing investigations of the functions of RNA-binding proteins (RBPs) in Arabidopsis thaliana. Over 1200 RBP domains have been identified in the organism, but only one-third of their functions have been characterized. These compounds play major roles in post-transcriptional RNA modification, and it is crucial to explore how these roles might affect stress responses in Arabidopsis. To determine the localization of two of these proteins (RBPa and RBPb) within the cell, Arabidopsis Col-0 (WT) protoplasts were transfected with vectors that contained an RBP-mCherry construct and then viewed using a confocal microscope to detect fluorescence within the cell. To see how rbp mutants responded to different stresses, mutant lines rbpa and rbpb, and Col-0 were grown on several different media including 300 mM sucrose, 2 µM Abscisic acid (ABA), 2 µM Paclobutrazol (PAC), 300 mM sorbitol and 0.01% DMSO. Mutant seedlings were then monitored for differences in % germination, % greening, and root length compared to Col-0. To determine how abundantly RBPb was expressed in Col-0, rbpb-1 and rbpb-2 cells, immunopurification (IP) and Western Blotting were conducted using a specific α-RBPb antibody. Results of all these studies showed that both RBPa and RBPb localized in the cytoplasm. When grown on PAC for 8 days, rbpa mutants had a lower % germination and lower % greening, compared to Col-0. When grown on PAC for 7 days, rbpb-2 mutants maintained a high % germination and % greening in comparison to Col-0. When grown on a high sucrose level for 14 days, rbpa mutants exhibited shorter roots compared to Col-0. The Western blot showed that α-RBPb could likely detect RBPb. Future experiments will focus on improving the RBPb immunopurification, and examining possible non-cytoplasmic localization of the RBPs in Arabidopsis.