Poster: Cytoskeleton structure & dynamics

Abs # 688: Overexpression of FRC2, A Katanin-Like Protein

Presenter:	Stacey, Jeffries R, jeffr004@ufl.edu
Authors	Stacey, Jeffries R (A)   Paris, Grey  (A)   Oppenheimer, David  (A)
Affiliations:	(A): University of Florida

Arabidopsis trichomes are an excellent model in which to study cell shape determination. Using this system, the frc2 mutation was isolated in a screen to identify genes involved in trichome branch initiation. Mutations in FRC2 results in trichomes with two and three branches. FRC2 has been shown to be allelic to FRA2, ERH3, BOT1, and LEU1, which encode a katanin-like protein (1,2,3,5). Katanins have been extensively studied in animal model systems. They are regulatory proteins responsible for ATPase dependent microtubule severing. Biochemical analysis of animal katanin reveals it is a heterodimer, composed of p60 and p80 kD subunits. The p80 subunit is believed to target the katanin to the centrosomes in animals, while the p60 subunit has been attributed with the actual severing of microtubules. Their most prominent function in animal cells is in severing of microtubules during mitosis and meiosis. However, in Arabidopsis, katanin does not seem to have an important microtubule severing activity during cell division. The katanin of Arabidopsis seem to play a more prominent role during interphase, in processes such as cell wall biosynthesis, cell expansion, cell identity, and hormone responses (1,2,3,5). Genetic evidence suggests that FRC2 is partially redundant to ZWI. To directly test this hypothesis, we have PCR amplified the genomic clone from BAC F5I6, and are overexpressing it in zwi mutant backgrounds, as well as other mutant backgrounds. Overexpression was accomplished by using a modified gateway plasmid containing the GL2 promoter. GL2 is highly expressed in developing trichomes (4). Therefore, we expect the FRC2 gene to be highly expressed in developing trichomes and to rescue the zwi mutant phenotype.