Date of Award

Spring 2012

Document Type

Restricted Thesis

Terms of Use

© 2012 Melissa A. Frick. All rights reserved. Access to this work is restricted to users within the Swarthmore College network and may only be used for non-commercial, educational, and research purposes. Sharing with users outside of the Swarthmore College network is expressly prohibited. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts

Department

Biology Department

First Advisor

Nicholas J. Kaplinsky

Abstract

Molecular chaperones and proteasomes are required for the normal development of plants via their role in the folding and degradation of cellular proteins. Using a genetic screen, we identified a genetic interaction between BOBBER1—a NudC domain containing Arabidopsis small heat shock protein with both developmental and thermotolerance functions—and RPT2a, an AAA-ATPase subunit of the 26S proteasome. This interaction suggests a connection between the pathways of protein folding and degradation in plant development. We used a series of genetic, molecular, and pharmacological approaches to better understand the relationship between these genes, and how they collectively contribute to development. The results of these experiments have shown that bom and bob1-3 do not interact physically and that knockouts of other 26SP subunits produce synergistic phenotypes like those observed in bom;bob1-3 mutants. This suggests that the genetic interaction observed between bom and bob1-3 is due to a general decrease in proteasome function and not a specific interaction with bom. Additionally, we demonstrate that born behaves like the null allele rpt2a-2 in response to proteasome inhibition even though it differs from the wild type allele by a single point mutation. We also show that no epistatic relationship exists between bom and bobl-3 in response to proteasome inhibition and suggests that these genes do not operate in a simple linear genetic pathway. Finally, we have identified and characterized a heritable mutant phenotype within the mutagenized AT87 family and have demonstrated that it is BOB1 dependent. Next-generation sequencing of the AT87 mapping population was unable to identify a causal genetic basis for the AT87 developmental phenotype.

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