Exploring the Biophysical Properties of Human Golgi Reassembly and Stacking Protein 55 in Solution and Its Interaction with Model Membranes

Abstract

Golgi Reassembly and Stacking Proteins (GRASPs) play a significant role in a variety of functions including the formation of ribbon-like Golgi apparatus and secretion of unconventional proteins. The molecular mechanism underlying the functional properties of GRASPs remains unaddressed. Our project mainly focuses on exploring the biochemical and biophysical characterization of the human full-length GRASP 55 in solution and its interaction with model membranes. Although various crystal structures of GRASPs have been reported, there is a lack of data in understanding the structure-activity relationship. In the present project, we aim to address two major aspects of the mechanistic basis of GRASP 55 function. (1) Although GRASPs (such as GRASP 55) are involved in various functions, the comprehensive understanding of structure, size, oligomerization, and intrinsically disordered protein (IDP) behavior are not known. (2) GRASPs are involved in tethering of Golgi membranes, however, there are no reports so far on the interaction of GRASPs with Golgi membranes. To carry out these studies, we propose to use a combination of biochemical and biophysical methods such as proteolysis assays, circular dichroism and fluorescence spectroscopy, small angle X-ray scattering, differential scanning calorimetry, solution nuclear magnetic resonance, electron spin resonance, and isothermal titration calorimetry. We envision that insights from our experiments would help in extending our present understanding of the structural aspects of GRASP 55 and its interaction with model membranes which are crucial for its function.