Evolutionary Conservation of Variant‐dependent Prion‐promoting Hsp40 Functions in Plants

Abstract

The J‐protein (Hsp40) Sis1 is required for the propagation of yeast prions and for the efficient curing of the prion [PSI+] by overexpression of the disaggregase Hsp104. Interestingly, some of the prion‐supporting functions of Sis1 are conserved in homologs from higher organisms: Sis1 homologs from fruit flies and humans have been shown to substitute for Sis1 in yeast in the propagation of some, but not all, yeast prions. The number and diversity of J‐proteins is greatest in the cytosol and the number of J‐protein genes in the eukaryotic genome generally scales with the overall biochemical complexity of the organism and genome size. As such, yeast has 23 J‐proteins, humans have 41, and we recently reported that the model plant Arabidopsis thaliana has 106. Not surprisingly, at least 6 functional homologs of Sis1 have been identified in A. thaliana. Here we present the results of our ongoing investigation, using yeast complementation assays and multiple prions, to examine which prion‐maintaining functions of Sis1 are conserved in various plant Sis1 homologs. Most notably, preliminary results indicate that these homologs give rise to distinct patterns of prion maintenance, indicating that the diversification of Sis1‐homolog structure has created alternative combinations of functions that affect prion‐propagation. In addition to providing information about J‐protein evolution, our investigation is expected to lead to a greater understanding of how the amino acid sequences of various J‐proteins allow for prion‐specific interactions in yeast.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.