Protein secretion is a remarkable folding process. First, secretory protein folding is temporarily delayed in the bacterial cytoplasm. Then, it occurs in a sub-cellular compartment other than that of synthesis. Nascent secretory proteins are synthesized with N-terminal signal peptides and are maintained non-folded in the cytoplasm, so that they can cross the membrane through a narrow channel. Non-folded secretory preproteins reduce aggregation risk by having optimized sequences to make them more disordered and soluble and by using chaperones.
These complexes end up on the membrane surface binding to the translocase, a dynamic machines that will process the non-folded secretory protein and drive its export. Traditional structural techniques cannot capture how these molecules shift in conformational space, when they interact with partners and when they interact with membranes.
Over the past 10 years we have developed a globally unique collection tools that offered us a glimpse in the dynamic life of these molecules. We combine primarily hydrogen deuterium exchange mass spectrometry (HDX-MS), single molecule FRET (smFRET), Molecular Dynamics simulations and advanced structural bioinformatics with several other biophysical tools (e.g. circular dichroism and laser light scattering).
Using these tools, we can monitor the kinetics of a secretory polypeptide as it undergoes folding transitions at single residue resolution and interacts with chaperones in solution or with the translocase at the membrane surface. We can also monitor the conformational changes that chaperones and the translocase undergo as they interact with their dynamic clients.
Combining these approaches, we can perform a synthesis of a complex and dynamic biological process.
Spreker: Tassos Economou, KU Leuven
Dit webinar vindt plaats op donderdag 22 april om 14:00