Off-pathway aggregation can inhibit fibrillation at high protein concentrations.

Published

Journal Article

Ribosomal protein S6 fibrillates readily at slightly elevated temperatures and acidic pH. We find that S6 fibrillation is retarded rather than favored when the protein concentration is increased above a threshold concentration of around 3.5mg/mL. We name this threshold concentration C(FR), the concentration at which fibrillation is retarded. Our data are consistent with a model in which this inhibition is due to the formation of an off-pathway oligomeric species with native-like secondary structure. The oligomeric species dominates at high protein concentrations but exists in dynamic equilibrium with the monomer so that seeding with fibrils can overrule oligomer formation and favors fibrillation under C(FR) conditions. Thus, fibrillation competes with formation of off-pathway oligomers, probably due to a monomeric conversion step that is required to commit the protein to the fibrillation pathway. The S6 oligomer is resistant to pepsin digestion. We also report that S6 forms different types of fibrils dependent on protein concentration. Our observations highlight the multitude of conformational states available to proteins under destabilizing conditions.

Full Text

Cited Authors

  • Deva, T; Lorenzen, N; Vad, BS; Petersen, SV; Thørgersen, I; Enghild, JJ; Kristensen, T; Otzen, DE

Published Date

  • March 2013

Published In

Volume / Issue

  • 1834 / 3

Start / End Page

  • 677 - 687

PubMed ID

  • 23313095

Pubmed Central ID

  • 23313095

Electronic International Standard Serial Number (EISSN)

  • 1878-2434

International Standard Serial Number (ISSN)

  • 0006-3002

Digital Object Identifier (DOI)

  • 10.1016/j.bbapap.2012.12.020

Language

  • eng