Protein folding

We are examining protein folding and unfolding characteristics by the use of fluorescent markers.

In collaboration with Prof. Hartl, we examine the functionality of chaperonin-assisted protein folding in detail. The GroEL/GroES system from E. coli works as a container (GroEL) with a lid (GroES). In a current project, Maltose binding protein (MBP) was chosen as a substrate and labeled with two fluorescent dyes at carefully selected labeling positions. In spFRET experiments the folding state of MBP and the influence of the chaperonin-system were observed by monitoring the FRET efficiency. Different mutants of the GroEL/GroES system were examined to clarify its working mechanism.

In collaboration with the group of Prof. Buchner, we study the folding and unfolding pathways of different immunoglobulin (Ig) antibody domains and their interaction with each other. By labeling a protein with two different fluorescent dyes at different labeling positions, the dyes will undergo FRET. The FRET efficiency E depends on the spatial distance of the dyes, thus indicating the folding state of the protein. At the same time, a third fluorescent marker attached to a different Ig-domain enables us to determine the colocalization and thereby the fusion of the domains using PIE-FCCS.