The yeast GRASP Grh1 displays a high polypeptide backbone mobility along with an amyloidogenic behavior

Abstract

AbstractGRASPs are proteins involved in cell processes that seem paradoxical, such as being responsible for shaping the Golgi cisternae and also involved in unconventional secretion mechanisms that bypass the Golgi, among other functions in the cell. Despite its involvement in several relevant cell processes, there is still a considerable lack of studies on full-length GRASPs. Our group has previously reported an unexpected behavior of the full-length GRASP from the fungus C. neoformans: its intrinsically-disordered characteristic. Here, we generalize this finding by showing that is also observed in the GRASP from the yeast S. cerevisae (Grh1), which strongly suggests it may be a general property within the GRASP family. Furthermore, Grh1 is also able to form amyloid fibrils either upon heating or when submitted to changes in the dielectric constant of its surroundings, a condition that is experienced by the protein when in close contact with membranes of cell compartments, such as the Golgi apparatus. Intrinsic disorder and amyloid fibril formation can thus be two structural properties exploited by GRASP during its functional cycle.