Date of Award

8-2014

Degree Name

Master of Science

Department

Chemistry

First Advisor

Dr. Blair R. Szymczyna

Second Advisor

Dr. Ramakrishna Guda

Third Advisor

Dr. David Huffman

Keywords

PWI motif, nucleic acids, RNA processing, NMR, flurescence

Access Setting

Masters Thesis-Open Access

Abstract

The PWI motif is a highly conserved domain that contains a Proline-Tryptophan-Isoleucine (PWI) tripeptide sequence, for which it is named. Proteins that contain a PWI motif are known to be involved in the constitutive and alternative splicing and the 3'-end processing of messenger RNA transcripts. The hypothesized role of the PWI motif is to nonspecifically interact with nucleic acids. The PWI motif is capable of binding both doublestranded and single stranded forms of DNA and RNA. The structure of the highly conserved core of the PWI motif reveals that it adopts a four-helix bundle fold. The structured core domain, however, has little to no affinity for nucleic acids. Optimal nucleic acid binding of the PWI motifs from SRm160, Prp3 and RBM25 requires both the structured core domain and an adjacent flanking basic region. The mechanism by which the PWI domain and the adjacent basic region cooperate to bind nucleic acids is still unknown. In order to study the role of protein dynamics in nucleic acid binding, nuclear magnetic resonance spectroscopy was used to identify a soluble protein construct containing the PWI motif of the RBM25 protein. The stoichiometry of the protein-nucleic acid complex that contains the PWI motif from Prp3 was assessed using intrinsic tryptophan fluorescence.

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