The first man to hold both the 100 metres and 200 metres world records, no one is faster than Usain Bolt. The 1,95 metre tall Jamaican can outrun any competition with ease and his trademark lightening bolt arrow pose has become legendary. But what is his secret? Does it lie in the sprinter’s height or is it his running technique? Scientists from the Max Planck Institute of Molecular Physiology in Dortmund looked for the answer. Using cryo-electron microscopy, they analysed muscle proteins and watched them at work.
Observing muscle proteins
“With cryo-electron microscopy we can observe the natural changes in the interplay of muscle proteins. It would also enable us to discover whether this interplay differs in Usain Bolt’s muscles from that in other people’s muscles,” explains Stefan Raunser, head of the department of Structural Biochemistry at the Max Planck Institute of Molecular Physiology. As Raunser’s team reported in the Science journal Nature (2016 online publication), they focused their attention on the two main players in muscle contraction – the proteins actin and myosin.
It’s known that certain constellations in the interaction of these muscle proteins can develop strength and makes world champions out of athletes like Usain Bolt. “All top athletes probably have genes that enable them to achieve top performances,” says Raunser. In addition, given that skeletal muscle contains both fast muscle fibres capable of rapid bursts of power and slow ones that are suitable for enduring activity, Bolt’s musculature may be composed of a particularly effective combination of fibres.
Understanding the cause of muscle diseases
The protagonists of muscle movement are the protein actin, which accounts for 20 percent of the weight of the musculature, and the motor protein myosin, which converts chemical energy into actual movement. The actin forms long thread-like fibres: “The actin uses myosin molecules like a track,” explains Julian von der Ecken, a doctoral student in Stefan Raunser’s Group. “When several million myosin molecules move along this track simultaneously, the muscle contracts.”
With genetic muscle diseases, the actin and myosin no longer work adequately together and the musculature is weakened as a result. It is not known why the proteins interact less effectively with each other in such cases, as it was not possible for scientists to study the proteins at the necessary level of detail up to now.
“We are in the very early stages of our research, as muscle contraction is a process that unfolds extremely rapidly. For this reason, we have to subdivide the entire process into numerous individual stages. Nevertheless, our findings could be used as a basis for research on new drugs,” says Raunser.