The Positively Charged Cluster in the N-terminal Disordered Region may Affect Prion Protein Misfolding: Cryo-EM Structure of Hamster PrP(23-144) Fibrils

Chih-Hsuan Lee; Jing-Ee Saw; Eric H-L Chen; Chun-Hsiung Wang; Takayuki Uchihashi; Rita P-Y Chen

doi:10.1016/j.jmb.2024.168576

The Positively Charged Cluster in the N-terminal Disordered Region may Affect Prion Protein Misfolding: Cryo-EM Structure of Hamster PrP(23-144) Fibrils

J Mol Biol. 2024 Apr 18;436(11):168576. doi: 10.1016/j.jmb.2024.168576. Online ahead of print.

Authors

Chih-Hsuan Lee¹, Jing-Ee Saw², Eric H-L Chen¹, Chun-Hsiung Wang¹, Takayuki Uchihashi³, Rita P-Y Chen⁴

Affiliations

¹ Institute of Biological Chemistry, Academia Sinica, No. 128, Sec. 2, Academia Rd, Nankang, Taipei 115, Taiwan.
² Institute of Biological Chemistry, Academia Sinica, No. 128, Sec. 2, Academia Rd, Nankang, Taipei 115, Taiwan; Institute of Biochemical Sciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd, Taipei 106, Taiwan.
³ Department of Physics, Nagoya University, Nagoya 464-8602, Japan; Institute for Glyco-core Research (iGCORE), Nagoya University, Nagoya 464-8602, Japan; Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan.
⁴ Institute of Biological Chemistry, Academia Sinica, No. 128, Sec. 2, Academia Rd, Nankang, Taipei 115, Taiwan; Institute of Biochemical Sciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd, Taipei 106, Taiwan; Neuroscience Program of Academia Sinica, Academia Sinica, No. 128, Sec. 2, Academia Rd, Nankang, Taipei 115, Taiwan. Electronic address: pyc@gate.sinica.edu.tw.

PMID: 38641239
DOI: 10.1016/j.jmb.2024.168576

Abstract

Prions, the misfolding form of prion proteins, are contagious proteinaceous macromolecules. Recent studies have shown that infectious prion fibrils formed in the brain and non-infectious fibrils formed from recombinant prion protein in a partially denaturing condition have distinct structures. The amyloid core of the in vitro-prepared non-infectious fibrils starts at about residue 160, while that of infectious prion fibrils formed in the brain involves a longer sequence (residues ∼90-230) of structural conversion. The C-terminal truncated prion protein PrP(23-144) can form infectious fibrils under certain conditions and cause disease in animals. In this study, we used cryogenic electron microscopy (cryo-EM) to resolve the structure of hamster sHaPrP(23-144) fibrils prepared at pH 3.7. This 2.88 Å cryo-EM structure has an amyloid core covering residues 94-144. It comprises two protofilaments, each containing five β-strands arranged as a long hairpin plus an N-terminal β-strand. This N-terminal β-strand resides in a positively charged cluster region (named PCC2; sequence 96-111), which interacts with the turn region of the opposite protofilaments' hairpin to stabilize the fibril structure. Interestingly, this sHaPrP(23-144) fibril structure differs from a recently reported structure formed by the human or mouse counterpart at pH 6.5. Moreover, sHaPrP(23-144) fibrils have many structural features in common with infectious prions. Whether this structure is infectious remains to be determined. More importantly, the sHaPrP(23-144) structure is different from the sHaPrP(108-144) fibrils prepared in the same fibrillization buffer, indicating that the N-terminal disordered region, possibly the positively charged cluster, influences the misfolding pathway of the prion protein.

Keywords: amyloid fibril; cryoEM; hamster; prion; protein misfolding.