Desiccation Survival · Discovery of intrinsically disordered sequences conferring desiccation survival

Desiccation is a form of stress wherein extremely dry conditions cause intracellular proteins to unfold and aggregate irreversibly, resulting in cell-death. How do cells and organisms survive desiccation is a fundamental question in biology. Cytosolic Abundant Heat Soluble (CAHS) proteins, a family of intrinsically disordered proteins (IDPs) in tardigrades (a phylum of micro-animals), have been shown to be important for their survival during long periods of dryness. Under desiccation condition, CAHS proteins undergo glass-transition and gelation to form vitrified solids that protect intracellular proteins from unfolding and aggregation. However, the features of CAHS proteins that confer protection are unknown. Here, I aim to unravel the sequence determinants of CAHS protein functions, by addressing 3 specific questions:Aim 1: What are the sequence features that promote glass-transition and gelation in CAHS proteins?Aim 2: Can we discover new sequences that can rescue cells from desiccation?Aim 3: What is the sequence-to-function paradigm underlying IDP-mediated desiccation survival? I will (i) perform computational analysis of existing CAHS proteins to extract their sequence features to design a library for adequate sampling of the sequence space; (ii) screen the library with a high-throughput survival-based assay and validate the hits both in vitro and in vivo; (iii) analyse the results with machine learning algorithms to generate characteristic sequence features underlying protective glass-transition. The learned features will be tested by rationally designing and screening a new sequence library for desiccation survival. This project will provide fundamental sequence-level understanding of how IDPs promote stress response, specifically via glass-transition during desiccation. Moreover, the materials and pipeline generated and the findings of this study will aid in engineering functional biomaterials.