RNA is a molecular messenger of the cell, essential to many cellular pathways and processes. In order to maintain functionality, RNA is processed and modified by protein complexes such as the exosome and associated proteins. The exosome-mediated RNA processing or degradation both require a Ski-2 like helicase to function. One such helicase is the Frequency-interacting RNA Helicase (FRH), an essential RNA helicase from Neurospora Crassa. FRH is homologous to the Saccharomyces cerevisiae Mtr4 from the Ski2-like family of RNA helicases. Sequence alignments between FRH and Ski2-like family helicases predicted FRH to share the helicase core domains and the inserted arch domain a characteristic of the Mtr4-like proteins in this protein family. FRH is also a main component of the circadian oscillation pathway in N. crassa. The participation of FRH in circadian oscillation is not a shared role across RNA helicases. FRH forms a link between two major cellular pathways providing a unique system to study RNA surveillance. Here we present the 3.51Å and 3.25Å crystal structures of FRH which supports structural prediction by maintaining the core architecture found in Ski2-like helicases. These similarities are accompanied by significant flexibility of the arch domain and revealed a unique homodimer. Other known Ski2-like helicases have not been observed to form dimers and function biologically as monomers. Furthermore, the initial characterization of helicase activity of FRH on a poly-adenylated RNA substrate is presented. Also explored is the evidence of a dimer through crosslinking and size exclusion chromatography assays.
| Identifer | oai:union.ndltd.org:UTAHS/oai:digitalcommons.usu.edu:etd-5710 |
| Date | 01 May 2016 |
| Creators | Johnson, Jacqueline M. |
| Publisher | DigitalCommons@USU |
| Source Sets | Utah State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | All Graduate Theses and Dissertations |
| Rights | Copyright for this work is held by the author. Transmission or reproduction of materials protected by copyright beyond that allowed by fair use requires the written permission of the copyright owners. Works not in the public domain cannot be commercially exploited without permission of the copyright owner. Responsibility for any use rests exclusively with the user. For more information contact Andrew Wesolek (andrew.wesolek@usu.edu). |
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