When proteins are folded incorrectly in living cells there is a possibility of abnormal protein clumping, which can lead to undesirable consequences for the organism. Protein aggregation is associated with diseases such as Alzheimer’s and Parkinson’s. To prevent misfolding, proteins are guided into correct conformations by chaperones. The chaperone-like protein NAC or Nascent Polypeptide Associated Complex has been found to bind to ribosomes near the exit site of the newly forming protein. The NAC is composed of alpha and beta subunits. It has been shown that a removal of beta-NAC, the subunit that comes into contact with the ribosome during translation, hinders yeast cells in a noticeable way. Mutations of the NAC and the chaperone SSB (stress 70B) leads to protein aggregation. To protect itself from unfolded proteins, the cell initiates the unfolded protein response (UPR). The UPR is a series of events that leads to the degradation or repair of misfolded proteins. In the eukaryotic model Saccharomyces cerevisiae, commonly known as baker’s yeast, transmembrane proteins sense the increased levels of unfolded proteins in the ER lumen and initiate a process that leads to the upregulation of the transcription of specific genes. When the UPR is not sufficient to solve the problem, the cell resorts to autophagy, in which whole sections of the cytoplasm are degraded. To better understand these important cellular processes, the role of yeast beta-NAC in cell stress response and longevity will be investigated. The potential connection between the NAC, autophagy, and the UPR will be studied by obtaining mutants in the NAC genes.

Additional Abstract Information

Student(s): Bejan A. Rasoul

Department: Biology

Faculty Advisor: Dr. Kimberly H. Slekar

Type: Oral

Year: 2013

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