Electrostatic interactions drive phase separation in Pup protein.

The similarities in the liquid-liquid phase separation (LLPS) phenomenon between membrane-less organelles (MLOs) and coacervates make them an ideal platform for studying the nature of life. Herein, we have developed a peptide-protein coacervative system between the positively charged poly-L-lysine peptide and negatively charged intrinsically disordered Pup protein to model the electrostatic nature of MLOs, providing insights into their mechanisms and potential therapeutic targets. We have constructed a phase diagram for coacervate formation at different concentrations of the Pup-PLL system, determined by turbidity measurements and optical microscopy.

Single-Molecule Optical Tweezers As a Tool for Delineating the Mechanisms of Protein-Processing Mechanoenzymes.

Mechanoenzymes convert chemical energy from the hydrolysis of nucleotide triphosphates to mechanical energy for carrying out cellular functions ranging from DNA unwinding to protein degradation. Protein-processing mechanoenzymes either remodel the protein structures or translocate them across cellular compartments in an energy-dependent manner. Optical-tweezer-based single-molecule force spectroscopy assays have divulged information on details of chemo-mechanical coupling, directed motion, as well as mechanical forces these enzymes are capable of generating.