Belmont University Research Symposium (BURS)

Publication Date

Spring 2024

College

Sciences and Mathematics, College of

Department

Biology, Department of

BURS Faculty Advisor

Rebecca Adams

Presentation Type

Poster Presentation

Abstract

Eukaryotic proteins are synthesized through the steps of transcription of RNA in the nucleus and translation of RNA into protein in the cytoplasm. Between these two steps, the mRNA must export from the nucleus through nuclear pore complexes (NPCs), selective doorways embedded in the nuclear envelope. To facilitate this process, Mex67 binds to the transcript to ferry it across the NPC. Once in the cytoplasm, an enzyme called Dpb5 removes Mex67 to prevent reentry into the nucleus. In addition to Mex67, the transcript is also bound by other RNA binding proteins that are not removed in the cytoplasm, and an unanswered question is how Dbp5 specifically removes Mex67 and no other proteins. We hypothesize that Dbp5 transiently binds to Mex67, recruiting Dpb5 to the specific region of the transcript for Mex67 removal. Indeed, we have uncovered four evolutionarily conserved charged amino acids on the surface of S. cerevisiae Dbp5 that are not associated with known binding partners, suggesting that these residues underlie a novel binding interface, potentially with Mex67. Therefore, this project has aimed to introduce mutations to change the charge of these residues (K443D, R463E, D467K, and E471R) via site-directed mutagenesis. Following my successful generation of one of these mutants, the resulting plasmid was transformed into a yeast strain that lacks endogenous Dbp5 to assess whether they can functionally replace wild-type Dbp5. If the resulting strains are not viable, it suggests that the mutation has disrupted Dbp5 function, and subsequent studies will be aimed at testing if the Dbp5-Mex67 interaction is disrupted in these mutants.

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