The physical dimensions of amyloid aggregates control their infective potential as prion particles

Atomic force microscopy 3D structural reconstruction of individual particles in the study of amyloid protein assemblies

Recent developments in atomic force microscopy (AFM) image analysis have made three-dimensional (3D) structural reconstruction of individual particles observed on 2D AFM height images a reality. Here, we review the emerging contact point reconstruction AFM (CPR-AFM) methodology and its application in 3D reconstruction of individual helical amyloid filaments in the context of the challenges presented by the structural analysis of highly polymorphous and heterogeneous amyloid protein structures. How individual particle-level structural analysis can contribute to resolving the amyloid polymorph structure-function relationships, the environmental triggers leading to protein misfolding and aggregation into amyloid species, the influences by the conditions or minor fluctuations in the initial monomeric protein structure on the speed of amyloid fibril formation, and the extent of the different types of amyloid species that can be formed, are discussed. Future perspectives in the capabilities of AFM-based 3D structural reconstruction methodology exploiting synergies with other recent AFM technology advances are also discussed to highlight the potential of AFM as an emergent general, accessible and multimodal structural biology tool for the analysis of individual biomolecules.

MIL-CELL: a tool for multi-scale simulation of yeast replication and prion transmission

The single-celled baker's yeast, Saccharomyces cerevisiae, can sustain a number of amyloid-based prions, the three most prominent examples being [URE3], [PSI+], and [PIN+]. In the laboratory, haploid S. cerevisiae cells of a single mating type can acquire an amyloid prion in one of two ways (i) spontaneous nucleation of the prion within the yeast cell, and (ii) receipt via mother-to-daughter transmission during the cell division cycle. Similarly, prions can be lost due to (i) dissolution of the prion amyloid by its breakage into non-amyloid monomeric units, or (ii) preferential donation/retention of prions between the mother and daughter during cell division. Here we present a computational tool (Monitoring Induction and Loss of prions in Cells; MIL-CELL) for modelling these four general processes using a multiscale approach describing both spatial and kinetic aspects of the yeast life cycle and the amyloid-prion behavior. We describe the workings of the model, assumptions upon which it is based and some interesting simulation results pertaining to the wave-like spread of the epigenetic prion elements through the yeast population. MIL-CELL is provided as a stand-alone GUI executable program for free download with the paper. MIL-CELL is equipped with a relational database allowing all simulated properties to be searched, collated and graphed. Its ability to incorporate variation in heritable properties means MIL-CELL is also capable of simulating loss of the isogenic nature of a cell population over time. The capability to monitor both chronological and reproductive age also makes MIL-CELL potentially useful in studies of cell aging.

ATP modulates self-perpetuating conformational conversion generating structurally distinct yeast prion amyloids that limit autocatalytic amplification

Prion-like self-perpetuating conformational conversion of proteins into amyloid aggregates is associated with both transmissible neurodegenerative diseases and non-Mendelian inheritance. The cellular energy currency ATP is known to indirectly regulate the formation, dissolution, or transmission of amyloid-like aggregates by providing energy to the molecular chaperones that maintain protein homeostasis. In this work, we demonstrate that ATP molecules, independent of any chaperones, modulate the formation and dissolution of amyloids from a yeast prion domain (NM domain of Saccharomyces cerevisiae Sup35) and restricts autocatalytic amplification by controlling the amount of fragmentable and seeding-competent aggregates. ATP, at (high) physiological concentrations in the presence of Mg²⁺, kinetically accelerates NM aggregation. Interestingly, ATP also promotes phase-separation-mediated aggregation of a human protein harboring a yeast prion-like domain. We also show that ATP disaggregates preformed NM fibrils in a dose-independent manner. Our results indicate that ATP-mediated disaggregation, unlike the disaggregation by the disaggregase Hsp104, yields no oligomers that are considered one of the critical species for amyloid transmission. Furthermore, high concentrations of ATP delimited the number of seeds by giving rise to compact, ATP-bound NM fibrils that exhibited nominal fragmentation by either free ATP or Hsp104 disaggregase to generate lower molecular weight amyloids. Additionally, (low) pathologically relevant ATP concentrations restricted autocatalytic amplification by forming structurally distinct amyloids which are found seeding-inefficient due to their reduced β-content. Our results provide key mechanistic underpinnings of concentration-dependent chemical chaperoning by ATP against prion-like transmissions of amyloids.

Phase separation and other forms of α-Synuclein self-assemblies

α-Synuclein (α-Syn) is a natively unstructured protein, which self-assembles into higher-order aggregates possessing serious pathophysiological implications. α-Syn aberrantly self-assembles into protein aggregates, which have been widely implicated in Parkinson’s disease (PD) pathogenesis and other synucleinopathies. The self-assembly of α-Syn involves the structural conversion of soluble monomeric protein into oligomeric intermediates and eventually fibrillar aggregates of amyloids with cross-β-sheet rich conformation. These aggregated α-Syn species majorly constitute the intraneuronal inclusions, which is a hallmark of PD neuropathology. Self-assembly/aggregation of α-Syn is not a single-state conversion process as unfolded protein can access multiple conformational states through the formation of metastable, transient pre-fibrillar intermediate species. Recent studies have indicated that soluble oligomers are the potential neurotoxic species responsible for cell death in PD pathogenesis. The heterogeneous and transient nature of oligomers formed during the early stage of aggregation pathway limit their detailed study in understanding the structure–toxicity relationship. Moreover, the precise molecular events occurring in the early stage of α-Syn aggregation process majorly remain unsolved. Recently, liquid–liquid phase separation (LLPS) of α-Syn has been designated as an alternate nucleation mechanism, which occurs in the early lag phase of the aggregation pathway leading to the formation of dynamic supramolecular assemblies. The stronger self-association among the protein molecules triggers the irreversible liquid-to-solid transition of these supramolecular assemblies into the amyloid-like hydrogel, which may serve as a reservoir entrapping toxic oligomeric intermediates and fibrils. This review strives to provide insights into different modes of α-Syn self-assemblies including LLPS-mediated self-assembly and its recent advancements.

Direct Demonstration of Seed Size-Dependent α-Synuclein Amyloid Amplification

The size of amyloid seeds is known to modulate their autocatalytic amplification and cellular toxicity. However, the seed size-dependent secondary nucleation mechanism, toxicity, and disease-associated biological processes mediated by α-synuclein (α-Syn) fibrils are largely unknown. Using the cellular model and in vitro reconstitution, we showed that the size of α-Syn fibril seeds dictates not only their cellular internalization and associated cell death but also the distinct mechanisms of fibril amplification pathways involved in the pathological conformational change of α-Syn. Specifically, small fibril seeds showed elongation possibly through monomer addition at the fibril termini, whereas longer fibrils template the fibril amplification by surface-mediated nucleation as demonstrated by super-resolution microscopy. The distinct mechanism of fibril amplification and cellular uptake along with toxicity suggest that breakage of fibrils into seeds of different sizes determines the underlying pathological outcome of synucleinopathies.

Sub-stoichiometric Hsp104 regulates the genesis and persistence of self-replicable amyloid seeds of Sup35 prion domain

Prion-like self-perpetuating conformational conversion of proteins is involved in both transmissible neurodegenerative diseases in mammals and non-Mendelian inheritance in yeast. The transmissibility of amyloid-like aggregates is dependent on the stoichiometry of chaperones such as heat shock proteins (Hsps), including disaggregases. To provide the mechanistic underpinnings of the formation and persistence of prefibrillar amyloid seeds, we investigated the role of substoichiometric Hsp104 on the in vitro amyloid aggregation of the prion domain (NM-domain) of Saccharomyces cerevisiae Sup35. At low substoichiometric concentrations, we show Hsp104 exhibits a dual role: it considerably accelerates the formation of prefibrillar species by shortening the lag phase but also prolongs their persistence by introducing unusual kinetic halts and delaying their conversion into mature amyloid fibers. Additionally, Hsp104-modulated amyloid species displayed a better seeding capability compared to NM-only amyloids. Using biochemical and biophysical tools coupled with site-specific dynamic readouts, we characterized the distinct structural and dynamical signatures of these amyloids. We reveal that Hsp104-remodeled amyloidogenic species are compositionally diverse in prefibrillar aggregates and are packed in a more ordered fashion compared to NM-only amyloids. Finally, we show these Hsp104-remodeled, conformationally distinct NM aggregates display an enhanced autocatalytic self-templating ability that might be crucial for phenotypic outcomes. Taken together, our results demonstrate that substoichiometric Hsp104 promotes compositional diversity and conformational modulations during amyloid formation, yielding effective prefibrillar seeds that are capable of driving prion-like Sup35 propagation. Our findings underscore the key functional and pathological roles of substoichiometric chaperones in prion-like propagation.

Comparative Analysis of the Relative Fragmentation Stabilities of Polymorphic Alpha-Synuclein Amyloid Fibrils

The division of amyloid fibril particles through fragmentation is implicated in the progression of human neurodegenerative disorders such as Parkinson's disease. Fragmentation of amyloid fibrils plays a crucial role in the propagation of the amyloid state encoded in their three-dimensional structures and may have an important role in the spreading of potentially pathological properties and phenotypes in amyloid-associated diseases. However, despite the mechanistic importance of fibril fragmentation, the relative stabilities of different types or different polymorphs of amyloid fibrils toward fragmentation remain to be quantified. We have previously developed an approach to compare the relative stabilities of different types of amyloid fibrils toward fragmentation. In this study, we show that controlled sonication, a widely used method of mechanical perturbation for amyloid seed generation, can be used as a form of mechanical perturbation for rapid comparative assessment of the relative fragmentation stabilities of different amyloid fibril structures. This approach is applied to assess the relative fragmentation stabilities of amyloid formed in vitro from wild type (WT) α-synuclein and two familial mutant variants of α-synuclein (A30P and A53T) that generate morphologically different fibril structures. Our results demonstrate that the fibril fragmentation stabilities of these different α-synuclein fibril polymorphs are all highly length dependent but distinct, with both A30P and A53T α-synuclein fibrils displaying increased resistance towards sonication-induced fibril fragmentation compared with WT α-synuclein fibrils. These conclusions show that fragmentation stabilities of different amyloid fibril polymorph structures can be diverse and suggest that the approach we report here will be useful in comparing the relative stabilities of amyloid fibril types or fibril polymorphs toward fragmentation under different biological conditions.

Amyloid particles facilitate surface-catalyzed cross-seeding by acting as promiscuous nanoparticles

Amyloid seeds are nanometer-sized protein particles that accelerate amyloid assembly as well as propagate and transmit the amyloid protein conformation associated with a wide range of protein misfolding diseases. However, seeded amyloid growth through templated elongation at fibril ends cannot explain the full range of molecular behaviors observed during cross-seeded formation of amyloid by heterologous seeds. Here, we demonstrate that amyloid seeds can accelerate amyloid formation via a surface catalysis mechanism without propagating the specific amyloid conformation associated with the seeds. This type of seeding mechanism is demonstrated through quantitative characterization of the cross-seeded assembly reactions involving two nonhomologous and unrelated proteins: the human Aβ42 peptide and the yeast prion-forming protein Sup35NM. Our results demonstrate experimental approaches to differentiate seeding by templated elongation from nontemplated amyloid seeding and rationalize the molecular mechanism of the cross-seeding phenomenon as a manifestation of the aberrant surface activities presented by amyloid seeds as nanoparticles.

Aggregation Condition-Structure Relationship of Mouse Prion Protein Fibrils

Prion diseases are associated with conformational conversion of cellular prion protein into a misfolded pathogenic form, which resembles many properties of amyloid fibrils. The same prion protein sequence can misfold into different conformations, which are responsible for variations in prion disease phenotypes (prion strains). In this work, we use atomic force microscopy, FTIR spectroscopy and magic-angle spinning NMR to devise structural models of mouse prion protein fibrils prepared in three different denaturing conditions. We find that the fibril core region as well as the structure of its N- and C-terminal parts is almost identical between the three fibrils. In contrast, the central part differs in length of β-strands and the arrangement of charged residues. We propose that the denaturant ionic strength plays a major role in determining the structure of fibrils obtained in a particular condition by stabilizing fibril core interior-facing glutamic acid residues.

Insights into the dynamic trajectories of protein filament division revealed by numerical investigation into the mathematical model of pure fragmentation

The dynamics by which polymeric protein filaments divide in the presence of negligible growth, for example due to the depletion of free monomeric precursors, can be described by the universal mathematical equations of ‘pure fragmentation’. The rates of fragmentation reactions reflect the stability of the protein filaments towards breakage, which is of importance in biology and biomedicine for instance in governing the creation of amyloid seeds and the propagation of prions. Here, we devised from mathematical theory inversion formulae to recover the division rates and division kernel information from time-dependent experimental measurements of filament size distribution. The numerical approach to systematically analyze the behaviour of pure fragmentation trajectories was also developed. We illustrate how these formulae can be used, provide some insights on their robustness, and show how they inform the design of experiments to measure fibril fragmentation dynamics. These advances are made possible by our central theoretical result on how the length distribution profile of the solution to the pure fragmentation equation aligns with a steady distribution profile for large times.

Amyloid fibrils are fibrillar protein structures involved in many neurodegenerative illnesses, such as Parkinson’s disease or Alzheimer’s disease. To propagate in disease, these misfolded protein aggregates must grow and divide to proliferate. Therefore, the intrinsic characteristics of their division, including the division rate and the pattern of division in terms of whether the fibrils are likely to break in the middle or at the edges, impact the disease aetiology. Here, we discovered mathematical formulae that can be used to directly extract the fibril division characteristics from recent experiments data obtained from time-dependent fibril length distribution measurements. We explain how these formulae can be used, and prove the robustness of the division rate formula where small errors in the measurement leads to small errors in the division rate. We also demonstrate that the mathematical formula is not robust enough to precisely decipher the pattern of division in the data, and suggest instead new future experimental design with short time measurements in experiments starting with fibril suspensions where all fibrils have similar size, which would be suitable to provide improved estimates.

On the Structural Diversity and Individuality of Polymorphic Amyloid Protein Assemblies

The prediction of highly ordered three-dimensional structures of amyloid protein fibrils from the amino acid sequences of their monomeric self-assembly precursors constitutes a challenging and unresolved aspect of the classical protein folding problem. Because of the polymorphic nature of amyloid assembly whereby polypeptide chains of identical amino acid sequences under identical conditions are capable of self-assembly into a spectrum of different fibril structures, the prediction of amyloid structures from an amino acid sequence requires a detailed and holistic understanding of its assembly free energy landscape. The full extent of the structure space accessible to the cross-β molecular architecture of amyloid must also be resolved. Here, we review the current understanding of the diversity and the individuality of amyloid structures, and how the polymorphic landscape of amyloid links to biology and disease phenotypes. We present a comprehensive review of structural models of amyloid fibrils derived by cryo-EM, ssNMR and AFM to date, and discuss the challenges ahead for resolving the structural basis and the biological consequences of polymorphic amyloid assemblies.

Protein aggregation and the evolution of stress resistance in clinical yeast

Protein aggregation, particularly in its prion-like form, has long been thought to be detrimental. However, recent studies have identified multiple instances where protein aggregation is important for normal physiological functions. Combining mass spectrometry and cell biological approaches, we developed a strategy for the identification of protein aggregates in cell lysates. We used this approach to characterize prion-based traits in pathogenic strains of the yeast Saccharomyces cerevisiae isolated from immunocompromised human patients. The proteins that we found, including the metabolic enzyme Cdc19, the translation elongation factor Yef3 and the fibrillarin homologue Nop1, are known to assemble under certain physiological conditions. Yet, such assemblies have not been reported to be stable or heritable. Our data suggest that some proteins which aggregate in response to stress have the capacity to acquire diverse assembled states, certain ones of which can be propagated across generations in a form of protein-based epigenetics. This article is part of the theme issue 'How does epigenetics influence the course of evolution?'

Entropic Bristles Tune the Seeding Efficiency of Prion-Nucleating Fragments

Prions of lower eukaryotes are self-templating protein aggregates with cores formed by parallel in-register beta strands. Short aggregation-prone glutamine (Q)- and asparagine (N)-rich regions embedded in longer disordered domains have been proposed to act as nucleation sites that initiate refolding of soluble prion proteins into highly ordered fibrils, termed amyloid. We demonstrate that a short Q/N-rich peptide corresponding to a proposed nucleation site in the prototype Saccharomyces cerevisiae prion protein Sup35 is sufficient to induce infectious cytosolic prions in mouse neuroblastoma cells ectopically expressing the soluble Sup35 NM prion domain. Embedding this nucleating core in a non-native N-rich sequence that does not form amyloid but acts as an entropic bristle quadruples seeding efficiency. Our data suggest that large disordered sequences flanking an aggregation core in prion proteins act as not only solubilizers of the monomeric protein but also breakers of the formed amyloid fibrils, enhancing infectivity of the prion seeds.

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A short peptide derived from Sup35 (p103–113) forms rigid amyloid fibrils

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p103–113 fibrils can induce infectious Sup35 NM prions in mammalian cells

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Embedding p103–113 in an N-rich sequence increases fibril brittleness

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Increased fibril brittleness enhances prion-inducing capacity

Tumor suppressor protein p53 expressed in yeast can remain diffuse, form a prion, or form unstable liquid-like droplets

Mutations in the p53 tumor suppressor are frequent causes of cancer. Because p53 aggregates appear in some tumor cells, it has been suggested that p53 could also cause cancer by forming self-replicating protein aggregates (prions). Here, using yeast, we show that transient p53 overexpression induced the formation of p53 prion aggregates that were transmitted for >100 generations, found in lysate pellets, stained with Thioflavin T, and transmitted by cytoplasmic transfer, or transfection with lysates of cells carrying the prion or with p53 amyloid peptide. As predicted for a prion, transient interruption of p53 expression caused permanent p53 prion loss. Importantly, p53 transcription factor activity was reduced by prion formation suggesting that prion aggregation could cause cancer. p53 has also been found in liquid-like nuclear droplets in animal cell culture. In yeast, we found that liquid-like p53 foci appear in response to stress and disappear with stress removal.

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A published yeast model of functional nuclear human p53 tumor suppressor was used

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Upon transient overexpression p53 loses its transcription function and aggregates

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These p53 aggregates are cytoplasmic and behave like stable heritable prions

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Stress induces p53 to form liquid-like droplets that are unstable and not prion-like

Amyotrophic Lateral Sclerosis: Proteins, Proteostasis, Prions, and Promises

Amyotrophic lateral sclerosis (ALS) is characterized by the progressive degeneration of the motor neurons that innervate muscle, resulting in gradual paralysis and culminating in the inability to breathe or swallow. This neuronal degeneration occurs in a spatiotemporal manner from a point of onset in the central nervous system (CNS), suggesting that there is a molecule that spreads from cell-to-cell. There is strong evidence that the onset and progression of ALS pathology is a consequence of protein misfolding and aggregation. In line with this, a hallmark pathology of ALS is protein deposition and inclusion formation within motor neurons and surrounding glia of the proteins TAR DNA-binding protein 43, superoxide dismutase-1, or fused in sarcoma. Collectively, the observed protein aggregation, in conjunction with the spatiotemporal spread of symptoms, strongly suggests a prion-like propagation of protein aggregation occurs in ALS. In this review, we discuss the role of protein aggregation in ALS concerning protein homeostasis (proteostasis) mechanisms and prion-like propagation. Furthermore, we examine the experimental models used to investigate these processes, including in vitro assays, cultured cells, invertebrate models, and murine models. Finally, we evaluate the therapeutics that may best prevent the onset or spread of pathology in ALS and discuss what lies on the horizon for treating this currently incurable disease.

The Division of Amyloid Fibrils: Systematic Comparison of Fibril Fragmentation Stability by Linking Theory with Experiments

The division of amyloid protein fibrils is required for the propagation of the amyloid state and is an important contributor to their stability, pathogenicity, and normal function. Here, we combine kinetic nanoscale imaging experiments with analysis of a mathematical model to resolve and compare the division stability of amyloid fibrils. Our theoretical results show that the division of any type of filament results in self-similar length distributions distinct to each fibril type and the conditions applied. By applying these theoretical results to profile the dynamical stability toward breakage for four different amyloid types, we reveal particular differences in the division properties of disease-related amyloid formed from α-synuclein when compared with non-disease associated model amyloid, the former showing lowered intrinsic stability toward breakage and increased likelihood of shedding smaller particles. Our results enable the comparison of protein filaments' intrinsic dynamic stabilities, which are key to unraveling their toxic and infectious potentials.

Quantification of amyloid fibril polymorphism by nano-morphometry reveals the individuality of filament assembly

Amyloid fibrils are highly polymorphic structures formed by many different proteins. They provide biological function but also abnormally accumulate in numerous human diseases. The physicochemical principles of amyloid polymorphism are not understood due to lack of structural insights at the single-fibril level. To identify and classify different fibril polymorphs and to quantify the level of heterogeneity is essential to decipher the precise links between amyloid structures and their functional and disease associated properties such as toxicity, strains, propagation and spreading. Employing gentle, force-distance curve-based AFM, we produce detailed images, from which the 3D reconstruction of individual filaments in heterogeneous amyloid samples is achieved. Distinctive fibril polymorphs are then classified by hierarchical clustering, and sample heterogeneity is objectively quantified. These data demonstrate the polymorphic nature of fibril populations, provide important information regarding the energy landscape of amyloid self-assembly, and offer quantitative insights into the structural basis of polymorphism in amyloid populations.

Protein-based inheritance

Epigenetic mechanisms of inheritance have come to occupy a prominent place in our understanding of living systems, primarily eukaryotes. There has been considerable and lively discussion of the possible evolutionary significance of transgenerational epigenetic inheritance. One particular type of epigenetic inheritance that has not figured much in general discussions is that based on conformational changes in proteins, where proteins with altered conformations can act as templates to propagate their own structure. An increasing number of such proteins - prions and prion-like - are being discovered. Phenotypes due to the structurally altered proteins are transmitted along with their structures. This review discusses the properties and implications of "classical" amyloid-forming prions, as well as the broader class of proteins with intrinsically disordered domains, which are proving to have fascinating properties that appear to play important roles in cell organisation and function, especially during stress responses.

Imaging aquatic animal cells and associated pathogens by atomic force microscopy in air

Atomic force microscopy (AFM) is a sophisticated imaging tool with nanoscale resolution that is widely used in structural biology, cell biology, and material science, among other fields. However, to date it has rarely been applied to the study of aquatic animals, especially on one of the main cultured species, shrimp. One reason for this is that no shrimp cell line established until now, primary cell is fragile and difficult to be studied under AFM. In this study, we used AFM to image three different types of biological material from shrimp (Litopenaeus vannamei) in air, including hemocytes and two associated pathogens. Without obvious deformations when the cells were imaged in air and in the case for the haemocytes and the cells were fixed as well. The result suggests hydrophobic glass coverslips are a suitable substrate for adhesion of these samples. The method described here can be applied to the preparation of other fragile biological samples from aquatic animals for high-resolution analyses of host-pathogen interactions and other basic physiological processes.

A new approach for the separation, characterization and testing of potential prionoid protein aggregates through hollow-fiber flow field-flow fractionation and multi-angle light scattering

Protein misfolding and aggregation are the common mechanisms in a variety of aggregation-dependent diseases. The compromised proteins often assemble into toxic, accumulating amyloid-like structures of various lengths and their toxicity can also be transferred both in vivo and in vitro a prion-like behavior. The characterization of protein interactions, degradation and conformational dynamics in biological systems still represents an analytical challenge in the prion-like protein comprehension. In our work, we investigated the nature of a transferable cytotoxic agent, presumably a misfolded protein, through the coupling of a multi-detector, non-destructive separation platform based on hollow-fiber flow field-flow fractionation with imaging and downstream in vitro tests. After purification with ion exchange chromatography, the transferable cytotoxic agentwas analyzed with Atomic Force Microscopy and statistical analysis, showing that the concentration of protein dimers and low n-oligomer forms was higher in the cytotoxic sample than in the control preparation. To assess whether the presence of these species was the actual toxic and/or self-propagating factor, we employed HF5 fractionation, with UV and Multi-Angle Light Scattering detection, to define proteins molar mass distribution and abundance, and fractionate the sample into size-homogeneous fractions. These fractions were then tested individually in vitro to investigate the direct correlation with cytotoxicity. Only the later-eluted fraction, which contains high-molar mass aggregates, proved to be toxic onto cell cultures. Moreover, it was observed that the selective transfer of toxicity also occurs for one lower-mass fraction, suggesting that two different mechanisms, acute and later induced toxicity, are in place. These results strongly encourage the efficacy of this platform to enable the identification of protein toxicants.

Modulation of the Aggregation of the Prion-like Protein RepA-WH1 by Chaperones in a Cell-Free Expression System and in Cytomimetic Lipid Vesicles

The accumulation of aggregated forms of proteins as toxic species is associated with fatal diseases such as amyloid proteinopathies. With the purpose of deconstructing the molecular mechanisms of these type of diseases through a Synthetic Biology approach, we are working with a model bacterial prion-like protein, RepA-WH1, expressed in a cell-free system. Our findings show that the Hsp70 chaperone from Escherichia coli, together with its Hsp40 and nucleotide exchange factor cochaperones, modulates the aggregation of the prion-like protein in the cell-free system. Moreover, we observe the same effect by reconstructing the aggregation process inside lipid vesicles. Chaperones reduce the number of aggregates formed, matching previous findings in vivo. We expect that the in vitro approach reported here will help to achieve better understanding and control of amyloid proteinopathies.