Abstract: The Effect of Iodoacetic Acid and ATP Depletion on Isoaspartyl Damage in S. cerevisiae (2011 SACNAS National Conference)

Friday, October 28, 2011

Hall 1-2 (San Jose Convention Center)

Thuy Tran , Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA

Alexander Patananan , Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA

Steven Clarke, PhD , Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA

A prominent form of non-oxidative protein damage is the conversion of asparaginyl or aspartyl amino acids of any protein to abnormal isoaspartyl groups. This modification causes protein aggregation and can lead to cell death. In S. cerevisiae, ATP-dependent proton pumps are used to regulate cytosolic and vacuoler pH. Incubating S. cerevisiae in media buffered to pH 3 or 9 has been shown to increase isoaspartyl levels in cytosolic proteins compared to pH 6, suggesting a role for ATP levels in regulating isoaspartyl group formation. To test this hypothesis, yeast cells were incubated with 2 mM iodoacetic acid(IAA) to deplete ATP. Base labile volatility assays were used to quantify the total amount of isoaspartyls in cytosolic proteins. Furthermore, autoradiography showed specifically which proteins among them were damaged. Cells exhibited 100-fold decreases in ATP in both exponential and stationary phases as a result of the IAA treatment. Because these are preliminary results, further experiments are required to confirm ATP depletion, and the effectiveness of various concentrations of IAA.