Sequence determinants of thermoresponsive prion-like domain
S. Pathak, L.C. Strader
Department of Biology, Duke University, Durham, NC 27008, USA

Temperature perception is important in timing the developmental processes of plants. Due to global warming, plants are being exposed to extreme temperature fluctuations which will be affecting plant survival and developmental programs. Biomolecular condensates are membrane less organelles formed by the interaction of proteins and nucleic acids. The saturation concentration at which condensates are formed is highly dependent on temperature. Proteins containing prion-like domains (PLDs) frequently form biomolecular condensates, as driven by multivalent interaction sites provided by these intrinsically disordered domains. Indeed, at least on PLD-containing protein, ELF3, has been shown to act as a direct thermosensor, such that flowering is tied to temperature. Small-scale protoplast transient screening of PLD-containing proteins of Arabidopsis thaliana under varying temperature conditions revealed that approximately 70% of the proteins are thermoresponsive at LCST (Lower Critical Solution Temperature). Sequence analysis of the PLDs in these thermoresponsive proteins indicates high enrichment of proline and hydrophobic residues. This suggests that a combination of proline and hydrophobic residues might serve as signature residues in creating a thermoresponsive prion-like domain. Understanding how sequence tunes PLDs to form condensates at specific temperatures will allow not only a deeper understanding of this process, but also tools that will allow engineering of plants better adapted to new temperature regimes.