Unraveling the multi-functionality and the interaction partners of proteins is a key question for modern protein science. Answering these questions requires development and use of novel biophysical techniques that are able to capture the dynamics and function of proteins and protein complexes in vitro as well as in vivo. In particular, single molecule methods have revolutionized our possibilities to study the function of proteins. These methods allow direct observation of functional heterogeneities, transiently populated states as well as mechanistic pathways which are often masked in ensemble measurements. The initiative will strengthen the many ongoing research collaborations as well as foster the formation of new teams to tackle protein science challenges in a multi-faceted approach. The Protein Biophysics subgroup will form the technological and biophysical backbone of the initiative. Four nationally and internationally leading groups will team up with chemists, biochemists and biologists to develop and apply cutting edge biophysical techniques to unravel protein function on all levels starting from the single molecule level to protein networks and cells finally up to the whole organism level. The Protein biophysics and Imaging groups will offer ultrasensitive dynamic in vitro and in vivo methods covering timescales from femtoseconds to seconds with spatial resolution from submolecular to whole organisms. Special emphasis will be given to mechanical and optical techniques including ultrafast IR spectroscopy. The Munich area has an exceptionally high international reputation in all of these fields:

• Munich research groups have pioneered the field of protein mechanics. A number of internationally leading research groups (Prof. Dr. Hermann Gaub, Prof. Dr. Matthias Rief) including promising junior groups (Dr. Jens Michaelis and Dr. Thorsten Hugel) form a unique setting for the application and development of mechanical single molecule methods for protein research (AFM, optical traps). Within this cluster a strong focus will be dedicated to elucidate mechanisms and mechanical processes in proteins ranging from folding to supra-molecular machines.

• Over the last years the Bräuchle group has made several signifcant contributions to the development of ultrasensitive microscopy as well as live cell imaging that have attracted much international attention. The optical microscopy groups provide expertise in a large range of ultra-sensitive fluorescence techniques ranging from single molecule FRET and single fluorophore tracking to live cell imaging.

• The Zinth group is one of the world-leading groups in ultrafast IR spectroscopy techniques covering the whole timescale ranging from femtoseconds to milliseconds. In the present project, they will apply ultrafast IR techniques to the study of native proteins and newly synthesized peptide systems, where structural changes can be induced on the sub-picosecond time scale.