Publication
Hyperactivation of L-lactate oxidase by liquid-liquid phase separation
Publisher:
Cold Spring Harbor Laboratory
Date:
09-12-2020
DOI:
10.1101/2020.12.08.416958
Abstract: Liquid droplets formed by liquid-liquid phase separation are attracting attention as functional states of proteins in living cells. Liquid droplets are thought to activate enzymatic reactions by assembling the required molecules. Thus, liquid droplets usually increase the affinity of an enzyme to its substrates, leading to decreased K M values. In this study, we demonstrate a new mechanism of enzyme activation in the droplets using Llactate oxidase (LOX). In the presence of poly-L-lysine (PLL), LOX formed droplets with diameters of hundreds of nanometers to tens of micrometers, stabilized by electro-static interaction. The enzyme activity of LOX in the droplets was significantly enhanced by a fourfold decrease in K M and a tenfold increase in k cat . To our knowledge, this represents the first report for increasing k cat by the formation of the liquid droplet. Interestingly, the conformation of LOX changed in the liquid droplet, probably leading to increased k cat value. Understanding enzyme activation in the droplets provides essential information about enzyme function in living cells in addition to biotechnology applications.