Session: Undergraduate Research Posters: Biochemistry:

It is still unknown exactly how halophilic protein tolerates and function in an extreme ionic environment. It has been observed that these proteins have unique qualities like an increased number of acidic residues and a small hydrophobic core. The goal of this project is to answer two questions: how do halophilic proteins maintain activity in high ionic environments and to what extent can halophilic proteins bind salt. In an effort to elucidate the functionality and folding behaviors of these proteins under these extreme circumstances, peptides were developed to mimic many of the traits that are shown to stabilize the halophilic proteins under native conditions. All of these peptides were designed to have two alpha helices spanned by an unstructured region. Under hypersaline conditions, these alpha-helices should interact with each other due to the hydrophobic effects from tryptophan and alanine residues. As a result, the N and C termini should come within close proximity to each other. This provides an opportunity to utilize Förster Resonance Energy Transfer (FRET). By attaching fluorophores to the N and C termini, the salt-dependent folding behaviors can be directly observed. Our results indicate that the peptides exhibit behavior comparable to halophilic proteins. Under low salt conditions, the peptide adopts a loose structure but becomes more structured as salt concentration increases. This effect was sequence-dependent. Future work includes determining the degree to which these peptides can bind salt. By designing peptides based on our understanding of halophilic proteins, we hope to learn how proteins not only tolerate extremely ionic conditions but also how they could withstand other extremes as well.

Caryn Evilia

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