Presentation Title

Use and abuse of functional amyloid: how to control and direct protein self-assembly

Presentation Abstract

In contrast to the pathological amyloid associated with neurodegenerative diseases, functional amyloid are a showcase of protein self-assembly occurring with great efficiency and usefulness in many different organisms. They are particularly widespread in bacteria (FuBA) where work in particular on the E. coli curli and Pseudomonas Fap operons have uncovered simple and robust principles for controlled amyloid biogenesis. Fibrils, largely composed of one protein (E. coli CsgA or Pseudomonas FapC), extend from the surface of the outer membrane, assembled by transport through a dedicated export channel with associated anchoring proteins, periplasmic aggregation inhibitors and surface nucleators and increasing the mechanical strength of the bacterial biofilm. Their repetitive surfaces also make them potentially interesting protein-based catalysts although research on that topic is still at an early stage. FuBA are optimized for aggregation through imperfect repeats, each of which can form one layer in a β-helix and lead to a fast-track fibrillation involving nucleation and elongation. Each of these steps involves essentially the same level of folding at the monomer level. Removal of the repeats increases the tendency to fragment and destabilize the fibrils1. The amyloid structure is recapitulated and enhanced when the protein is presented with a structured surface such as graphene which is covered in a very comprehensive and highly regular fashion by the amyloid2. FUBA’s robustness notwithstanding, they are sensitive to inhibition, not only by generic amyloid blockers such as the polyphenol EGCG3 and protein chaperones4, but also by designed peptides which divert the amyloidogenic proteins towards more amorphous and weakly organized aggregates5. This inhibition reduces biofilm formation and opens up for more efficient intervention against bacterial growth in combination with more conventional antibiotics6.


(1) Rasmussen, C., Christiansen, G., Vad, B. S., Enghild, J. J., Lynggaard, C., Andreasen, M. & Otzen, D. E. Imperfect repeats in the functional amyloid protein FapC reduce the tendency to secondary nucleation and fragmentation during fibrillation Prot. Sci. 28, 633-642 (2019).
(2) Sønderby, T. V., Zou, Y., Wang, P., Wang, C. & Otzen, D. E. Molecular-level insights into the surface-induced assembly of functional bacterial amyloid. Biophys J 121, 3422-3434,(2022).
(3) Najarzadeh, Z., Mohammad-Beigi, H., Nedergaard Pedersen, J., Christiansen, G., Sønderby, T. V., Shojaosadati, S. A., Morshedi, D., Stromgaard, K., Meisl, G., Sutherland, D., Skov Pedersen, J. & Otzen, D. E. Plant Polyphenols Inhibit Functional Amyloid and Biofilm Formation in Pseudomonas Strains by Directing Monomers to Off-Pathway Oligomers. Biomolecules 9, 659, doi:10.3390/biom9110659 (2019).
(4) Nagaraj, M., Najarzadeh, Z., Pansieri, J., Biverstål, H., Musteikyte, G., Smirnovas, V., Matthews, S., Emanuelsson, C., Johansson, J., Buxbaum, J. N., Morozova-Roche, L. & Otzen, D. E. Chaperones mainly suppress primary nucleation during formation of functional amyloid required for bacterial biofilm formation. Chemical science 13, 536-553, doi:10.1039/D1SC05790A (2022). 10.1039/D1SC05790A.
(5) Sønderby, T. V., Lourios, N. N., Khodaparast, L., Khodaparast, L., Jhaf, D., Nagaraj, M., Strømgaard, K., Rousseau, F., Schymkowitz, J. & Otzen, D. E. Sequence-targeted peptides divert functional bacterial amyloid towards destabilized aggregates and reduce biofilm formation. J. Mol. Biol. In press (2023).
(6) Sønderby, T. V., Najarzadeh, Z. & Otzen, D. E. Functional Bacterial Amyloids: Understanding Fibrillation, Regulating Biofilm Fibril Formation and Organizing Surface Assemblies. Molecules 27, 4080, doi:10.3390/molecules27134080 (2022).

About Daniel

Daniel Otzen is Professor of Nanobiotechnology at the Interdisciplinary Nanoscience Center (iNANO) at Aarhus University. He has an MSc degree (1992) in Molecular Biology from Aarhus University and a PhD (1995) in protein biophysics from the lab of Sir Alan Fersht at Cambridge University, jointly with Aarhus University. He has worked with protein stability, folding and misfolding his whole career. After 2 years as research chemist (1995-1997) at Novozymes A/S (which stimulated his interest in the impact of surfactants on protein stability and structure), he returned to academia, first as a postdoc at University of Lund (1997-2000) with Mikael Oliveberg and subsequently as Associate Professor and Professor (2000-2007) at the Department of Life and Environmental Sciences at Aalborg University. He joined iNANO as Professor in 2007. His group combines different spectroscopic, calorimetric and structural techniques (scattering and electron microscopy) to address the mechanisms and thermodynamics of protein aggregation and self assembly in health and disease, folding in membranes and micelles and – recently – activity and stability of cold-active and plastic-degrading enzymes. He has authored > 360 peer-reviewed articles.

He is married with two children and uses his spare time to keep the weeds at bay in the garden while listening to podcasts about history.

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