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Amyloid fibrils are formed from polypeptide chains assembled into an organized fibrillar structure. Now, it has been shown that such fibrillar structures can also bind metal ions and catalyse chemical reactions.

Even an ordinary globular protein can assume a rogue guise if conditions are right.

Here the authors perform the reconstruction and analysis of pathological ALys amyloid fibrils extracted from fat tissue from a patient carrying the D87G variant. They reveal an intact amyloid fibril with no evidence of proteolysis and four intact disulphide bonds.

This study reports the cryo-EM structures of AA amyloid fibrils from two patients with vascular AA amyloidosis. The findings imply that different disease variants in systemic amyloidosis are associated with different fibril structures.

Systemic AL amyloidosis is one of the most frequently diagnosed forms of systemic amyloidosis. Here the authors analyse the structures of AL amyloid fibrils with different light chain mutations and show that the mutations contribute to defining the fibril structure in different patients.

Systemic AL amyloidosis is a protein misfolding disease caused by the aggregation and fibrillation of immunoglobulin light chains (LCs). Here, the authors present the cryo-EM structures of λ3 LC-derived amyloid fibrils that were isolated from patient tissue and they observe structural breaks, where the two different fibril structures co-exist at different z-axial positions within the same fibril.

Systemic AL amyloidosis is caused by misfolding of immunoglobulin light chains (LCs) but how post-translational modifications (PTMs) of LCs influence amyloid formation is not well understood. Here, the authors present the cryo-EM structure of an AL amyloid fibril derived from the heart tissue of a patient that is partially pyroglutamylated, N-glycosylated and contains an intramolecular disulfide bond. Based on their structure and biochemical experiments the authors conclude that the mutational changes, disulfide bond and glycosylation determine the fibril protein fold and that glycosylation protects the fibril core from proteolytic degradation.

Systemic AA amyloidosis is a protein misfolding disease caused by the formation of amyloid fibrils from serum amyloid A (SAA) protein. Here, the authors present the cryo-EM structures of AA amyloid fibrils isolated from mouse tissue and in vitro formed fibrils, which differ in their structures and they also show that the ex vivo fibrils are more resistant to proteolysis than the in vitro fibrils and propose that pathogenic amyloid fibrils might originate from proteolytic selection.

Here, the authors present the cryo-EM structure of in vitro amyloid fibrils from recombinant SAA1.1 protein that were formed by seeding with fibrils purified from systemic AA amyloidosis tissue. This in vitro fibril structure resembles the structure of the ex vivo fibrils but differs from unseeded in vitro fibrils. These findings show that fibril morphologies can be propagated in vitro by seeding.

This study presents the cryo-EM structures of polymorphic TDP-43-derived amyloid fibrils that share a common fibril protein conformation constituting an amyloid key motif. The obtained results provide a possible mechanistic explanation for the formation of this motif in amyloid fibrils.

Alzheimer’s disease is characterised by the deposition of Aβ amyloid fibrils and tau protein neurofibrillary tangles. Here the authors use cryo-EM to structurally characterise brain derived Aβ amyloid fibrils and find that they are polymorphic and right-hand twisted, which differs from in vitro generated Aβ fibrils.

Systemic AL amyloidosis is caused by misfolding of immunoglobulin light chains and is one of the most frequently occurring forms of systemic amyloidosis. Here the authors present the 3.3 Å cryo-EM structure of a λ1 AL amyloid fibril that was isolated from an explanted human heart.

Systemic amyloidosis of the ATTR is one of the most abundant forms of systemic amyloidosis and caused by misfolding of the circulating blood protein transthyretin (TTR). Here the authors present the cryo-EM structure of patient-derived Val30Met ATTR amyloid fibrils which reveals that the protofilament consists of an N-terminal and a C-terminal TTR fragment and discuss implications for the mechanism of misfolding.

Hereditary ATTR amyloidosis has diverse disease manifestations. Using cryo-EM it was possible to reveal, that the phenotypic variations arise from the circumstances under which the amyloid fibrils are formed, rather than from different fibril morphologies.

In this work, the authors report the Cryo-EM structure of PNF-18, a biotechnologically engineered peptide fibril that enhances retroviral infectivity. The peptide fibrils mature into polymorphic amyloid structures in a time-dependent manner. The structure provides insights into the molecular basis of peptide nanofibrils as retroviral transduction enhancers.

Semen-derived peptides can form amyloid fibrils that boost HIV infection in vitro, but the existence of such fibrils in semen remained to be demonstrated. Here, the authors show that human semen contains amyloid fibrils, which can bind HIV particles and increase their infectiveness.

Systemic AA amyloidosis is caused by misfolding of the acute phase protein serum amyloid A1. Here the authors present the cryo-EM structures of murine and human AA amyloid fibrils that were isolated from tissue samples and describe how the fibrils differ in their fundamental structural properties.

Amyloid fibril structures can display polymorphism. Here the authors reveal the cryo-EM structures of several different fibril morphologies of a peptide derived from an amyloidogenic immunoglobulin light chain and present a mathematical analysis of physical factors that influence fibril polymorphism.

An orcein-related small molecule can drive polymerization of amyloid-β, implicated in Alzheimer's disease, without remodeling oligomeric or fibril forms but by stabilizing a seeding-competent protofilament state and shortening the lag phase of spontaneous polymerization.