Investigating liquid-liquid phase separation behaviour of histidine-rich squid beak protein variants

Abstract

Squid beak protein, in particular, HBP (D.gigas histidine-rich protein) is an intrinsically disordered protein capable of self coacervate via liquid-liquid separation process (LLPS).

Here, we are investigating how the change of repetitive regions affects the solubility of the HBPs. By analysing four repeats connected to HBP we strongly believe that proteins with more hydrophobic repeats show solid-like characteristics. The four repeats used in this study are GHGLYx10, GAGFA x2, GAGFA x4 and GAGFA x6.

We are looking at their expression, integrity, the morphology of droplets formed and the impact of external environmental conditions to LLPS. A novel purification method named salt extraction was done for the first with success. We were able to show that subtle differences in repeats in HBP result in changes in droplets material state.

The knowledge provided by this study helps to understand the properties of the repeats, thus contributing to engineering bottom-to-top of biomaterials inspired by the squid beak‘s material properties.