Neurofilament Proteins Act as Shock Absorbers

October 17, 2016

Neurofilament Proteins Act as Shock Absorbers

Neurofilament Proteins

A study by physicists at Tel Aviv University has revealed how some neurofilament proteins act as shock absorbers to protect the nervous system of humans and animals. Neurofilament proteins form a filamentous network that mechanically support nerve cells, and are critical for proper neural function and structure. These proteins are exposed to large compression stress from the transport of cellular organelles through the network. It was not clear how neurofilament proteins could balance that much stress until Roy Beck and other physicists measured and modeled the compression response of neurofilament proteins. They showed that these proteins function like shock absorbers. 

How They Figured This Out

The physicists used X-ray diffraction and computer models to study the disordered protein structures that are responsible for absorbing compressive forces in neurons cells. The proteins are composed of long filaments with tails sticking out, giving them the shape of a bottlebrush. The proteins differ in their charge distribution and the length of their tails. The physicists compressed the filamentous network and determined its structure using a small angle x-ray scattering technique. Their results revealed that the network’s mechanical and structural properties were governed by the tails’ molecular composition protruding from the main filament backbone and the surrounding environment. 

Stress Levels 

The physicists made conclusions. When the filaments were exposed to low compressive forces such as low mechanical stress, the filaments were held together in a network by an attractive interaction between the tails. As the compression increases and the proteins experienced large amounts of stress, the interaction between the tails became repulsive and was very effective at absorbing the compressive force. Beck and physicists modeled the interactions between the tails using a single fitting parameter that showed the proteins stayed intact with each other. About one half of all human protein structures contain disordered regions  and this study could open doors on the physics of these systems. 

Rebecca Reilly