Determining Chaperone Requirements for the Propagation of Heterologous Poly‐Glutamine Aggregates in Saccharomyces cerevisiae

Abstract

Amyloid‐based yeast prions are heritable aggregates of misfolded protein that can be passed on to daughter cells following fragmentation by chaperone proteins including Hsp70, Hsp104, and the Hsp40 Sis1. Yeast prions usually exhibit an amyloid structure, forming cross‐beta sheets of protein sections known as the prion‐forming domain, or PrD. In vivo, long tracts of glutamine have been shown to form amyloid structures. Previously Alexandrov et al. created a set of polyQ sequences with a single heterologous amino acid interspersed every fifth residue (QQQXQ), fused to the MC regions of yeast Sup35 (responsible for the prion [PSI+]) and expressed in a sup35‐ΔN strain of Saccharomyces cerevisiae. These polyQX sequences replace the PrD of Sup35, and form amyloid aggregates in vivo that propagate in an Hsp104‐dependent manner. Here we report our efforts to test the J‐protein chaperone requirements of these aggregates, first by repressing levels of Sis1 to determine if any polyQX aggregates are maintained without Sis1. Preliminary results suggest several QX constructs are dependent upon Sis1 for propagation, demonstrating that these aggregates propagate in an Hsp40/Hsp70‐dependent manner. Subsequent replacement of wild‐type Sis1 expression with several well‐studied Sis1 variants will allow the determination of the importance of specific regions of Sis1 for the propagation of these aggregates. We anticipate that this line of investigation will provide significant insight into the ways in which amino acid content of a PrD affects the interaction of the resulting prion with chaperone proteins.Support or Funding InformationThis work was supported by the National Institute of General Medical Sciences of the National Institutes of Health under Award Number R15GM110606. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.