StuDy
SARCOMERE
We are an international consortium of four research groups, supported by a Synergy Grant from the European Research Council (ERC) to study the nanostructure of muscles and the causes of muscular diseases.
The Project
Sarcomeres are small repeating subunits of myofibrils, the long cylinders that bundle together to make the muscle fibres. Inside the sarcomeres, filaments of the proteins myosin and actin interact to generate muscle contraction and relaxation.
The high-resolution structure of sarcomeres is unknown, yet a precise molecular understanding of how the entire sarcomere machine forms and functions is required to understand its role in health, disease and ageing. With the support by the European Research council we will solve the structure of the sarcomere at near atomic resolution, unravel the fundamentals of its force-driven assembly and turnover in health and ageing, and develop the foundations for future basic and translational research including the design and development of new agents to mitigate muscle disease and ageing.
"Electron cryo-tomography will allows us to obtain detailed and artefact-free 3D images of the frozen muscle.”
Stefan Raunser
What we have achieved so far
Using cryo-tomography a team led by Stefan Raunser in collaboration with Mathias Gautel has obtained the first high-resolution 3D image of nebulin, a giant actin-binding protein that is an essential component of skeletal muscle. This discovery has brought to light the chance to better understand the role of nebulin, as its functions have remained largely nebulous due to its large size and the difficulty in extracting nebulin in a native state from muscle. Their findings could lead to novel therapeutic approaches to treat muscular diseases, as genetic mutations in nebulin are accompanied by a dramatic loss in muscle force known as nemaline myopathy.
Wang Z, Grange M, Pospich S, Wagner T, Kho A.L, Gautel M, Raunser S (02/2022). Structures from intact myofibrils reveal mechanism of thin filament regulation through nebulin. Science
Insect flight muscles have a particular sarcomere architecture to power wing oscillations at 200 Hz. In this collaboration between the Jungmann, Görlich and Schnorrer groups we have revealed the precise titin nanoarchitecture in these special muscles. We combined DNA-PAINT super-resolution microscopy with our newly development titin nanobody toolbox and showed that two titin homologs display a staggered organisation at the I-band/A-band interface that may be critical for efficient force transduction of flight muscles.
Schueder F, Mangeol P, Chan EH, Rees R, Schünemann, J, Jungmann R*, Görlich D*, Schnorrer F*. (04/2021). Nanobodies combined with DNA-PAINT super-resolution reveal a staggered titin nano-architecture in flight muscles. bioRxiv
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The group of Stefan Raunser from the Max Planck Institute in Dortmund, in collaboration with Mathias Gautel at the the King's College London, has produced the first high-resolution 3D image of the sarcomere, the basic contractile unit of skeletal and heart muscle cells, by using electron cryo-tomography (cryo-ET).
Wang Z, Grange M, Wagner T, Khoo AL, Gautel M, Raunser S (03/2021). The molecular basis for sarcomere organization in vertebrate skeletal muscle. Cell
Titin is the largest protein in mammalian muscle and determines the length of the mammalian sarcomere. A new collaborative effort between the Görlich and Schnorrer groups has generated a toolbox of small and highly specific nanobodies to study the precise location of the titin homologs in the different muscles of the fruit fly Drosophila melanogaster. These tools revealed a precise organisation of the two Drosophila titin homologs in the sarcomeres of the different muscle types, with the surprising finding that a fly titin can be longer than the mammalian titin.
Loreau V, Rees R, Chan EH, Taxer W, Gregor K, Mußil B, Pitaval C, Luis NM, Mageol P, Schnorrer F*, Görlich D*. (04/2022). A nanobody toolbox to investigate localisation and dynamics of Drosophila titins. bioRxiv
