Getting a Grip on Slippery Cell Membranes
Within each of our cells is a distribution system that uses molecular motors and filaments to move proteins, organelles, and other tiny bits of cargo along its inner framework, or cytoskeleton. To achieve this feat, the motors and filaments must tug on flexible membranes that surround the cargo packages, but these membranes, made of fatty molecules called lipids, are extremely slippery. Scientists have long wondered how the molecular transport machinery is able to maintain its grip.
The work is important because knowledge of the basic science of molecular motors and membrane mechanics can translate into a better understanding of cell and tissue development, wound healing, and the responses of the immune system--and how cancer cells can spread from a single tumor to other areas of the body.
The research team is using laboratory experiments and computational modeling to study the interactions between the motors (made from a protein called myosin-1), the filaments (made from the protein actin), and the membranes. Their findings are reported in the paper "Force Generation by Membrane-Associated Myosin-1" published online by Nature Scientific Reports.
Serapion Pyrpassopoulos, Göker Arpağ, Elizabeth A. Feeser, Henry Shuman, Erkan Tüzel, E. Michael Ostap. Force Generation by Membrane-Associated Myosin-I. Scientific Reports, 2016; 6: 25524 DOI: 10.1038/srep25524
To study the forces generated by myosin-1 motors on oily membranes, researchers at Worcester Polytechnic Institute (WPI) and the University of Pennsylvania (Penn) strung a motor attached to an actin filament between two fluorescent beads, with the motor's tail resting on a sphere covered with lipids. The filament was moved side-to-side with the help of an optical trap. As the myosin-1 molecules stretched and slipped on the sphere, the researchers measured the forces applied to the sphere by the molecule. Credit: Worcester Polytechnic Institute and University of Pennsylvania
