Bacterial amphiphiles as amyloid inducers: Effect of Rhamnolipid and Lipopolysaccharide on FapC fibrillation

Zahra Najarzadeh, Jannik Nedergaard Pedersen, Gunna Christiansen, Seyed Abbas Shojaosadati, Jan Skov Pedersen, Daniel E Otzen

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review


Pseudomonas species export the amyloid-forming protein FapC to strengthen bacterial biofilm. P. species also produce the biosurfactant rhamnolipid (Rhl) and its outer membrane contains lipopolysaccharide (LPS). Given the possible contacts between FapC, Rhl and LPS, we here investigate how Rhl and LPS affect FapC fibrillation compared with SDS, known to promote fibrillation of proteins at sub-micellar concentrations. Micelles of all three surfactants help FapC bypass the nucleation lag phase, leading to rapid fibrillation, which persists even at high concentrations of micelles and incorporates almost all available FapC monomers. Fibrils formed at high micellar concentrations of Rhl and SDS seed fibrillation at low surfactant concentrations while retaining the original fibril structure. FapC interacts strongly with SDS to form a dense network of narrow fibrils. Small angle X-ray scattering (SAXS) analyses reveal that surfactants reduce the population of intermediates in the fibrillation process and detect a fast aggregation step over the first 2-4 h which precedes the main fibrillation monitored by Thioflavin T. An additional SAXS-detected rearrangement of early aggregates occurs after 4-10 h. At high Rhl concentrations, the micelles are decorated with protein fibrils. SDS induces FapC fibrillation so efficiently that epigallocatechin-3-gallate (EGCG) is unable to inhibit this process. However, EGCG stimulates FapC oligomer formation and inhibits fibrillation both on its own and in the presence of Rhl and LPS. This oligomer could be modelled as a compact core with a flexible shell. This suggests that EGCG can override the natural amyloid-stimulatory properties of these biosurfactants and thus target biofilm.

Original languageEnglish
Article number140263
JournalB B A - Proteins and Proteomics
Publication statusPublished - 1 Nov 2019


  • FapC protein
  • Functional amyloid
  • Pseudomonas aeruginosa
  • Rhamnolipid
  • Surfactant


Dive into the research topics of 'Bacterial amphiphiles as amyloid inducers: Effect of Rhamnolipid and Lipopolysaccharide on FapC fibrillation'. Together they form a unique fingerprint.

Cite this