Exploring structural aspects of the human Golgi matrix protein GRASP55 in solution

Author(s)

Thirupathi Reddy, S. ^[1] ; Santos Mendes, Luis Felipe ^[1] ; Fontana, Natalia Aparecida ^[1] ; Costa-Filho, Antonio Jose ^[1]

Affiliation

^[1] Univ Sao Paulo, Dept Phys, Ribeirao Preto Sch Philosophy Sci & Literature, Av Bandeirantes 3900, BR-14040901 Ribeirao Preto, SP - Brazil

• Document type: Journal article
• Source: International Journal of Biological Macromolecules; v. 135, p. 481-489, AUG 15 2019.
• Web of Science Citations: 0

Abstract

In mammals, the Golgi apparatus is the central hub for intracellular trafficking, sorting and post-translational modifications of proteins and lipids. Golgi reassembly and stacking proteins (GRASPs) are somehow involved in Golgi stacking, which is relevant for its proper function, and also in unconventional protein secretion. However, the structural details on how GRASPs accomplish those tasks are still elusive. Here, we have explored the biochemical and biophysical properties of human full-length GRASP55 in solution. Sequence-based analyses and circular dichroism spectroscopy suggest that GRASP55 presents multiple intrinsically disordered sites, although keeping considerable contents of regular secondary structure. Size exclusion chromatography and multiple-angle light scattering show that GRASP55 are monomers in solution. Urea denaturation of GRASP55 suggests the transition to the unfolded state is a cooperative process. Differential scanning calorimetry analysis displays two endothermic transitions for GRASP55, indicating the existence of an intermediate state prior to unfolding. Thioflavin T fluorescence suggests GRASP55 intermediate can be aggregates/fibrils. Transmission electron microscopy and fluorescence lifetime imaging microscopy prove GRASP55 forms large amorphous aggregates but not amyloid-like fibrils in the intermediate state. These results could be helpful in discussing the proper function of human GRASP55 in the Golgi organization as well as unconventional secretion of proteins. (C) 2019 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 16/23863-2 - Molecular interactions of the Golgi Reassembly and Stacking Protein (GRASP) form Saccharomyces cerevisiae
• Grantee: Natália Aparecida Fontana
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• FAPESP's process: 17/12146-0 - Exploring the Biophysical Properties of Human Golgi Reassembly and Stacking Protein 55 in Solution and Its Interaction with Model Membranes
• Grantee: Thirupathi Reddy Soudherpally
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 17/24669-8 - Unraveling the molecular bases of the early protein secretory pathway in humans using biophysical techniques
• Grantee: Luis Felipe Santos Mendes
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 15/16812-0 - Multi-User Equipment approved in grant 2014/15546-1: SEC-MALS
• Grantee: Richard Charles Garratt
• Support Opportunities: Multi-user Equipment Program
• FAPESP's process: 15/50366-7 - Resolving mechanistic details of peptide transport across membranes using crystallographic and non-crystallographic structural biology approaches
• Grantee: Antonio José da Costa Filho
• Support Opportunities: Regular Research Grants
• FAPESP's process: 12/20367-3 - Structural and functional studies of the Golgi Re-Assembly and Stacking Protein (GRASP) from Cryptococcus neoformans
• Grantee: Antonio José da Costa Filho
• Support Opportunities: Regular Research Grants