Prof. Dr. Stefan Raunser

The power of cryo-EM to elucidate biological mechanisms

Max-Planck-Institut für molekulare Physiologie

Muscular movement plays an essential role not only in our lives. Muscle contraction is initiated by the release of calcium from the sarcoplasmic reticulum into the cytoplasm of myocytes through ryanodine receptors. Calcium binds to troponin, which releases tropomyosin from its blocking position allowing myosin filaments to move along actin filaments resulting in the contraction of the muscle. Upon infection with bacterial pathogens, F-actin, which is not only the major component of muscles but also the cytoskeleton, is attacked by Tc toxin complexes. Tripartite Tc toxin complexes perforate the host membrane by forming channels that translocate toxic enzymes into the host, including humans.The underlying mechanism of Tc toxin action and the function and regulation of muscle contraction are complex but poorly understood. In my talk I will present our recent published and unpublished findings revealing important molecular details of both processes.