Structural dynamics of the non-folded, translocation-competent secretome

Secretory proteins have adapted unique structural and sequence characteristics that distinguish them as a novel and unique structural class. This involves a strong propensity for elevated disorder, higher than that of cytoplasmic protein but less than that of IDPs; and flexibility to maintain polypeptides in kinetically trapped, loosely folded states in the cytoplasm so that they remain export-competent. Understanding the main components and the underlying “code” of these internal factors and the potential interaction with external factors will advance our knowledge of both folding and of the protein secretion process. Structural and conformational analysis will be applied on our unique collection of secretory proteins with and without their signal peptide and contains sets of structurally matched pairs between cytoplasmic and periplasmic variants. From this collection, we want to identify protein pairs with HDX-MS and smFRET that can be used as model sets with highly differentiated folding kinetics, to study differences between structural and conformational dynamics during folding and predict important residues that establish this ‘non-folding’ code to test in the cytoplasmic structural counterparts.