Fundamental dynamics of protein folding:

Nanosecond measurements reveal local dynamics in α-Helices

Moving the spectroscopic labels through the helix sequence allows position dependent measurements of helix dynamics.

27.01.2009, Press releases

Researchers at the Technische Universitaet Muenchen developed a method to observe protein dynamics on the nanoseconds to microseconds timescale. Applying this approach to study α-helix formation, an elementary process in protein folding, they obtained fundamental information about how proteins fold or change their structure. The research results have been published in the Early Online Edition of PNAS.

A protein consists of a chain of amino acids, which has to adopt a defined three dimensional structure during the folding process to fulfill its biological function. If this process is perturbed, misfolded proteins can form aggregates in cells, which may lead to diseases as Altzheimer’s disease, Creutzfeldt-Jakob diesase or Parkinson’s disease. The native structure of a protein is flexible and can adopt different conformations which interconvert rapidly. Such conformational transitions are often required for protein function. It is thus of fundamental importance to understand the dynamics of polypeptide chains in detail.

Elementary conformational transitions in proteins occur within nanoseconds to microseconds. Until recently, experimental access to this timescale has been very restricted. Applying a new electron-transfer based method, developed in the laboratory of Thomas Kiefhaber at the TU Munich, Beat Fierz, Andreas Reiner and Thomas Kiefhaber were able to observe conformational transitions in proteins. The method allows position-dependent measurements of protein dynamics with sub-nanosecond time resolution through site specific introduction of spectroscopic probes into the protein followed by measurements of their relative motions.

The research team chose to study dynamics of an α-helix, the most common and most basic structural element in proteins. Due to the high folding rate and kinetic complexity of the system the α-helix folding mechanism was still not well understood. The new results, published in PNAS, allow now a deeper insight into the dynamics of α-helices. The study shows that an α-helix does not fold or unfold as a whole but that many different states are in fast equilibrium. Local conformational transitions are position dependent and occur on the 250 nano- to 1.5 microseconds timescale, whereas dynamics are faster at the helix termini than in the center. Using helix-coil theory and computer simulations, these results could be rationalized. The results of this study are of fundamental importance for a deeper understanding of function, folding and misfolding of proteins.

Original publication:

Beat Fierz, Andreas Reiner, and Thomas Kiefhaber: Local conformational dynamics in α-helices measured by fast triplet transfer
PNAS, published online before print January 8, 2009 | doi: 10.1073/pnas.0808581106

Contact:

Kontakt: presse@tum.de