The Structure and Function of Reggie/Flotillin-like Proteins in Arabidopsis thaliana

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Reggies, discovered in C. Stuermer lab, are ubiquitous plasma membrane-associated intracellular proteins and characteristic markers of lipid raft microdomains. Metazoan Reggies have been implicated in axon regeneration, cell process and contact formation and in providing functional platforms for cell signaling. Although Reggie-like proteins are present in distant phyla, such as bacteria, fungi and higher plants, little is known about their physiological role in these organisms. We found three reggie-like genes (called here re-l1a, -l1b and -l2) in the genome of Arabidopsis thaliana and investigated their evolution, expression and function. We demonstrated that transcripts for Re-l1a and –l1b are upregulated during early stages of seedling development and later on during senescence as well as under light stress conditions. We succeeded to isolate a “knock-out” homozygous mutant line for Re-l2 that shows delayed development. The deletion of re-l1a gene seemed to be lethal. Here we propose to investigate the function and structural characteristics of Reggie-like proteins in plants, in order to compare them with their vertebrate and bacterial counterparts because of striking similarities of protein domain composition and lipid raft association. We will further examine the expression of Reggie-like transcripts and proteins under different physiological conditions, in various plant organs and tissues, to reveal their subcellular location laying emphasis on lipid raft association, search for interacting partners, and perform functional analysis using reverse genetics. An attempt will be made to solve the 3D structure of plant Reggie-like proteins.