Nucleation-dependent amyloid fibrillation of human GRASP55 in aqueous solution

Author(s)

Reddy, S. Thirupathi ^[1] ; Uversky, Vladimir N. ^{[2, 3]} ; Costa-Filho, Antonio Jose ^[1]

Affiliation

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

^[2] Univ S Florida, Morsani Coll Med, USF Hlth Byrd Alzheimers Res Inst, Dept Mol Med, Tampa, FL 33620 - USA

^[3] Russian Acad Sci, Inst Biol Instrumentat, Lab New Methods Biol, Pushchino - Russia

• Document type: Journal article
• Source: EUROPEAN BIOPHYSICS JOURNAL WITH BIOPHYSICS LETTERS; v. 49, n. 2, p. 133-143, MAR 2020.
• Web of Science Citations: 0

Abstract

GRASP55, one of the two human GRASP proteins, has been implicated in the organization of Golgi stacks and in unconventional protein secretion. However, the detailed molecular mechanisms supporting GRASP55 participation in those processes remain mostly unclear. We have shown that GRASP55 exists as monomers in solution, which transitions to amorphous aggregates with increasing temperatures. Here, we further investigated the formation of higher order structures of GRASP55 by exploring its amyloid fibrillation at 37 degrees C. Sequence-based AGGRESCAN analysis revealed that GRASP55 has ten aggregation ``hot spots{''}, preferentially concentrated in its N-terminal half. Congo Red, ThT, and circular dichroism assays suggested GRASP55 formed amyloid-like fibrils in a time-dependent manner at 37 degrees C. Dynamic light scattering showed the mean hydrodynamic radius of GRASP55 amyloid-like fibrils increased with increasing incubation times at 37 degrees C. Transmission electron microscopy and intrinsic fluorescence lifetime imaging showed that, upon increasing incubation time at 37 degrees C, GRASP55 yielded amyloid-like fibrils in a nucleation-dependent process via a sequence of events: lag-phase (monomers to oligomers), growth phase (oligomers to organized protofibrils), and plateau phase (protofibrils to amyloid-like fibrils). The insights gained herein may help in better understanding the mechanisms of GRASP55 amyloid fibrillation in vivo and its potential association with neurological disorders. (AU)

• 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
• 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: 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