An interchangeable prion-like domain is required for Ty1 retrotransposition

• Type of Material: Article
• Authors: Sean L. Beckwith, University of Georgia; Emily J. Nomberg, University of Georgia; Abigail C. Newman, University of Georgia; Jeannette V. Taylor, Emory University; Ricardo C. Guerrero-Ferreira, Emory University; David J. Garfinkel, University of Georgia
• Language: English
• Date: 2023
• Publisher: National Academy of Sciences
• Publication Version: Final Published Version
• Copyright Statement: © 2023 the Author(s). Published by PNAS.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1073/pnas.2303358120
• Title of Journal or Parent Work: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• Volume: 120
• Issue: 30
• Grant/Funding Information: This work was supported by an NIH grant to D.J.G. (R01GM124216) and an NIH Postdoctoral Fellowship to S.L.B. (F32GM139247). This study was also supported by the Robert P. Apkarian Integrated Electron Microscopy Core (RPAIEMC), which is subsidized by the Emory University School of Medicine and the Emory College of Arts and Sciences. Additional support was provided by the Georgia Clinical and Translational Science Alliance of the NIH under award number UL1TR000454. Some of the data reported here were collected on the JEOL JEM1400 Transmission Electron Microscope supported by the NIH Grant S10 RR025679.
• Keywords: Saccharomyces cerevisiae; virus-like particle; retrotransposon; prion-like domain
• Research Categories: Biology, Virology

Abstract

Retrotransposons and retroviruses shape genome evolution and can negatively impact genome function. Saccharomyces cerevisiae and its close relatives harbor several families of LTR-retrotransposons, the most abundant being Ty1 in several laboratory strains. The cytosolic foci that nucleate Ty1 virus-like particle (VLP) assembly are not well understood. These foci, termed retrosomes or T-bodies, contain Ty1 Gag and likely Gag-Pol and the Ty1 mRNA destined for reverse transcription. Here, we report an intrinsically disordered N-terminal prion-like domain (PrLD) within Gag that is required for transposition. This domain contains amino acid composition similar to known yeast prions and is sufficient to nucleate prionogenesis in an established cell-based prion reporter system. Deleting the Ty1 PrLD results in dramatic VLP assembly and retrotransposition defects but does not affect Gag protein level. Ty1 Gag chimeras in which the PrLD is replaced with other sequences, including yeast and mammalian prionogenic domains, display a range of retrotransposition phenotypes from wild type to null. We examine these chimeras throughout the Ty1 replication cycle and find that some support retrosome formation, VLP assembly, and retrotransposition, including the yeast Sup35 prion and the mouse PrP prion. Our interchangeable Ty1 system provides a useful, genetically tractable in vivo platform for studying PrLDs, complete with a suite of robust and sensitive assays. Our work also invites study into the prevalence of PrLDs in additional mobile elements.