title: Monitoring the process of HypF fibrillization and liposome permeabilization by protofibrils.
abstract: Much information has appeared in the last few years on the low resolution structure of amyloid fibrils and on their non-fibrillar precursors formed by a number of proteins and peptides associated with amyloid diseases. The fine structure and the dynamics of the process leading misfolded molecules to aggregate into amyloid assemblies are far from being fully understood. Evidence has been provided in the last five years that protein aggregation and aggregate toxicity are rather generic processes, possibly affecting all polypeptide chains under suitable experimental conditions. This evidence extends the number of model proteins one can investigate to assess the molecular bases and general features of protein aggregation and aggregate toxicity. We have used tapping mode atomic force microscopy to investigate the morphological features of the pre-fibrillar aggregates and of the mature fibrils produced by the aggregation of the hydrogenase maturation factor HypF N-terminal domain (HypF-N), a protein not associated to any amyloid disease. We have also studied the aggregate-induced permeabilization of liposomes by fluorescence techniques. Our results show that HypF-N aggregation follows a hierarchical path whereby initial globules assemble into crescents; these generate large rings, which evolve into ribbons, further organizing into differently supercoiled fibrils. The early pre-fibrillar aggregates were shown to be able to permeabilize synthetic phospholipid membranes, thus showing that this disease-unrelated protein displays the same amyloidogenic behaviour found for the aggregates of most pathological proteins and peptides. These data complement previously reported findings, and support the idea that protein aggregation, aggregate structure and toxicity are generic properties of polypeptide chains.
authors.affiliation: National Institute for the Physics of Matter and Department of Physics, University of Genoa, Genoa 16146, Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Relini
authors.forename: Silvia
authors.initials: S
authors.lastname: Torrassa
authors.forename: Ranieri
authors.initials: R
authors.lastname: Rolandi
authors.forename: Alessandra
authors.initials: A
authors.lastname: Gliozzi
authors.forename: Camillo
authors.initials: C
authors.lastname: Rosano
authors.forename: Claudio
authors.initials: C
authors.lastname: Canale
authors.forename: Martino
authors.initials: M
authors.lastname: Bolognesi
authors.forename: Georgia
authors.initials: G
authors.lastname: Plakoutsi
authors.forename: Monica
authors.initials: M
authors.lastname: Bucciantini
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Chiti
authors.forename: Massimo
authors.initials: M
authors.lastname: Stefani
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D008081:Liposomes / Q000378:metabolism*; D018625:Microscopy, Atomic Force; D010539:Permeability; D017434:Protein Structure, Tertiary
chemical_list: D001426:Bacterial Proteins; C108878:HypF protein, Bacteria; D008081:Liposomes