Date of Award

Winter 2022

Project Type

Thesis

Program or Major

Biochemistry

Degree Name

Master of Science

First Advisor

Estelle Hrabak

Second Advisor

Krisztina Varga

Third Advisor

Kelley Thomas

Abstract

Palmitoylation is a reversible post-translational modification that affects the location, activity, and stability of proteins. Arabidopsis thaliana contains 23 genes for palmitoyl acyltransferases (PATs), the enzymes that catalyze palmitoylation. Loss of PAT14 activity results in early senescence and diminished plant size when plants are grown on standard peat/perlite mixtures in pots and watered with a commercial fertilizer, but this phenotype is not observed when plants grown on agar plates containing a different nutrient solution. Here we show that neither the peat/perlite growth medium nor the commensal microbes present in the growth are the causative agents for phenotype development. However, the pat14-1 mutant early senescence phenotype could be partially rescued by supplementing commercial fertilizer with uric acid. XDH1 (xanthine dehydrogenase) is an enzyme that produces uric acid and is also predicted to be palmitoylated. An xdh1 mutant has a phenotype similar to the pat14 mutant, raising the possibility that XDH1 is a palmitoylation substrate of PAT14. Immunodetection of XDH1 showed that its subcellular localization was not affected in a pat14 background. However, there appeared to be a greater quantity of XDH1 in the cytosol of pat14 mutants, indicating that XDH1 expression or stability is altered.

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