Abstract

Our bodies contain some 100,000 proteins that enable or regulate essentially every biochemical process on which our lives depend. To maintain healthy proteostasis, cells have evolved intricate quality control networks that identify aberrant and damaged components and destroy them. For this to occur, cells need to spatially organise their components to promote specific reactions and processes. The rapid formation and dissolution of membraneless, biomolecular condensates (BCs) is key to many biological roles, including autophagy, the cell’s waste disposal machinery. BCs contain an array of different biomolecules and, depending on their biological function, they can be very fluid in nature or they can have a more gel-like composition; therefore the dynamics and physical attributes of BCs appear to be closely linked with their biological roles. But how does the cell control the phase boundaries within live cells and how do they know when to form droplets in the right place at the right time? Here we are exploring the design of novel proteins comprising molecular adhesive peptides to drive liquid-liquid-phase separation (LLPS) and consensus tetratricopeptide repeat units (CTPR) to endow the droplets with functional capabilities in order to create well defined BCs. We want to characterise the physico-chemical properties of these LLPS -CTPR designs in vitro and relate these attributes to their ability to induce autophagosome formation and subsequent protein degradation in cells. We hope to establish a structure-function relationship that will enable rational design of artificial phase-separating molecules that can drive the removal of disease-causing proteins from the cell.