Lake Forest College, Biology, Lake Forest College, IL 60045
Parkinson’s disease (PD) is a devastating and incurable neurodegenerative disorder that afflicts over one million Americans. The universal PD pathology is the presence of aggregated α-synuclein within dying midbrain substantia nigra neurons. The role these α- synuclein aggregates play in cell death is unclear, but debate rages about whether these aggregates are neuroprotective or harmful to cells. The α-synuclein found within these aggregates is heavily phosphorylated at serine residue 129. Scientists found that rats espressing alpha-synuclein with a mutation that prevents phosphorylation at serine-129 (S129A) had a decrease in the amount of substantia nigra neurons compared to rats expressing wild type protein (Gorbatyuk et al. 2007). Our lab tested the hypothesis that lack of phosphorylation exacerbates a-synuclein toxicity by expressing two phosphorylation deficient a-synuclein mutants (S87A & S129A) in budding and fission yeast. We found that the phosphorylation deficient mutant S129A increased toxicity in budding yeast (BY4741), and that both mutants altered the localization patterns of the protein in a second budding yeast strain(TSY623). Unintentionally, these alpha-synuclein constructs were created with a substitution at the 140th amino acid (A140G). In a previous study by another lab, an accidental point mutation that occurred in the sequence of their alpha-synuclein construct ended up shedding light on the properties of the protein, and thus we compared our work with the A140G protein to the corrected protein.
[Abstract (DOC)]