Protein aggregation

  • Article
    | Open Access

    Molecular chaperones from the Hsp70 family can break up protein aggregates, including amyloids. Here, the authors utilize microfluidic diffusional sizing to assess the mechanism of α-synuclein (αS) disaggregation by the Hsc70–DnaJB1–Apg2 system, and show that single αS molecules are removed directly from the fibril ends.

    • Matthias M. Schneider
    • , Saurabh Gautam
    •  & Tuomas P. J. Knowles
  • Article
    | Open Access

    Protein binding by the Hsp70/J-domain protein (JDP) chaperones prevents aggregation of the client protein. Here, the authors show that DnaJC7 binds preferentially to natively folded wild-type tau, via a β-turn element in tau that contains the known amyloid motif, while aggregation-prone tau mutants are recognized with reduced affinity.

    • Zhiqiang Hou
    • , Pawel M. Wydorski
    •  & Lukasz A. Joachimiak
  • Article
    | Open Access

    Aβ oligomers (AβO) are thought to represent the main toxic species in Alzheimer’s disease but very high Aβ concentrations are required to study them in vitro and it remains unknown what role these off-pathway oligomers play in vivo. Here, the authors use a dimeric variant of Aβ termed dimAβ, where two Aβ40 units are linked, which facilitates to study AβO formation kinetics and they observe that Aβ off-pathway oligomer formation is strongly accelerated at endo-lysosomal pH, while amyloid fibril formation is delayed. Furthermore, the authors demonstrate that dimAβ is a disease-relevant model construct for pathogenic AβO formation by showing that dimAβ AβOs target dendritic spines and induce AD-like somatodendritic Tau missorting.

    • Marie P. Schützmann
    • , Filip Hasecke
    •  & Wolfgang Hoyer
  • Article
    | Open Access

    Huntingtin exon-1 (HTTex1) consists of a N-terminal N17 domain, the disease causing polyQ domain and a C-terminal proline-rich domain (PRD). Here, the authors combine electron paramagnetic resonance (EPR), solid-state NMR with other biophysical method to characterise the structural differences of various HTTex1 fibril types with different toxicity and find that the dynamics and entanglement of the PRD domain differs among them and that the HTTex1 fibrils can be interconverted.

    • J. Mario Isas
    • , Nitin K. Pandey
    •  & Ansgar B. Siemer
  • Article
    | Open Access

    Amyloid aggregation of mutant p53 contributes to its loss of tumor suppressor function and oncogenic gain-of-function. Here, the authors use a protein mimetic to abrogate mutant p53 aggregation and rescue p53 function, which inhibits cancer cell proliferation in vitro and halts tumor growth in vivo.

    • L. Palanikumar
    • , Laura Karpauskaite
    •  & Mazin Magzoub
  • Article
    | Open Access

    α-Synuclein (αS) aggregation is a driver of several neurodegenerative disorders. Here, the authors identify a class of peptides that bind toxic αS oligomers and amyloid fibrils but not monomeric functional protein, and prevent further αS aggregation and associated cell damage.

    • Jaime Santos
    • , Pablo Gracia
    •  & Salvador Ventura
  • Article
    | Open Access

    Wobble uridine (U34) tRNA modifications are important for the decoding of AA-ending codons. Here the authors show that while the U34-codon content of mRNAs are predictive of changes in ribosome translation elongation, the resulting outcome in protein expression also relies on specific hydrophilic motifs-dependent protein aggregation and clearance.

    • Francesca Rapino
    • , Zhaoli Zhou
    •  & Pierre Close
  • Article
    | Open Access

    The self-assembly of α-synuclein (αS) is a pathological feature of Parkinson’s disease. The αS species responsible for neuronal damage are not well characterized. Here, the authors show that αS fibrils release soluble prefibrillar oligomeric species responsible for neurotoxicity in vitro.

    • Roberta Cascella
    • , Serene W. Chen
    •  & Cristina Cecchi
  • Article
    | Open Access

    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.

    • Akanksha Bansal
    • , Matthias Schmidt
    •  & Marcus Fändrich
  • Article
    | Open Access

    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.

    • Lynn Radamaker
    • , Julian Baur
    •  & Marcus Fändrich
  • Article
    | Open Access

    Our understanding of the molecular mechanisms underlying pathological protein aggregation remains incomplete. Here, single molecule infrared nanospectroscopy (AFM-IR) offers insight into the structure of Aβ42 oligomeric and fibrillar species and their interaction with an aggregation inhibitor, paving the way for single molecule drug discovery studies.

    • Francesco Simone Ruggeri
    • , Johnny Habchi
    •  & Tuomas P. J. Knowles
  • Article
    | Open Access

    α1-Antitrypsin (AAT) is a 52 kDa serum glycoprotein, the misfolding and polymerisation of which is associated with COPD and liver disease. Here the authors demonstrate the use of high-resolution multidimensional solution-state NMR spectroscopy to characterise the structure and dynamics in solution of Z AAT purified directly from clinical patients.

    • Alistair M. Jagger
    • , Christopher A. Waudby
    •  & David A. Lomas
  • Article
    | Open Access

    Identifying factors that enable cells to induce a potent stress response to amyloid-like aggregation can provide further insight into the mechanism of stress regulation. Here, the authors express polyglutamine-expanded Huntingtin as a model disease protein in yeast cells and perform a genetic screen for chaperone factors that allow yeast cells to activate a potent stress response. They identify Sis1, an essential Hsp40 co-chaperone of Hsp70, as a critical sensor of proteotoxic stress and further show that both Sis1 and its mammalian homolog DnaJB6 regulate the magnitude of the cellular heat stress response, indicating that this mechanism is conserved.

    • Courtney L. Klaips
    • , Michael H. M. Gropp
    •  & F. Ulrich Hartl
  • Article
    | Open Access

    Detection of amyloid beta deposits is often performed with fluorescent compounds that bind plaques. Here the authors develop turn-on chemiluminescent probes that bind amyloid beta plaques in vivo, and amplify the signal via chemiluminescence resonance energy transfer to the plaque-binding fluorescent molecule CRANAD-3.

    • Jing Yang
    • , Wei Yin
    •  & Chongzhao Ran
  • Article
    | Open Access

    ALS is a neurodegenerative disease characterized by loss of motor neurons. Here, the authors showed that reduced levels of the VSP35 subunit in the retromer complex is a conserved ALS feature and identified a new lead compound increasing retromer stability ameliorating the disease phenotype.

    • Luca Muzio
    • , Riccardo Sirtori
    •  & Gianvito Martino
  • Article
    | Open Access

    Rift Valley fever virus (RVFV) can cause severe diseases in humans, including encephalitis. Here the authors show that NSs, the major virulence factor of RVFV, is an amyloidogenic protein forming fibrils in infected mouse brains and causing increased mortality in mice.

    • Psylvia Léger
    • , Eliana Nachman
    •  & Pierre-Yves Lozach
  • Article
    | Open Access

    Nonsense-mediated mRNA decay (NMD) is a translation-coupled process that eliminates mRNAs containing premature translation-termination codons. Here the authors identify a role for the NMD factor UPF1 in protein quality control, whereby truncated misfolded polypeptides are cleared through autophagy.

    • Yeonkyoung Park
    • , Joori Park
    •  & Yoon Ki Kim
  • Article
    | Open Access

    The unfolded protein response (UPR) is a stress response pathway implicated in numerous diseases and chemotherapy resistance. Here, the authors define the UPR regulon with a multi-omics strategy, uncovering changes to mitochondrial one-carbon metabolism and concomitant resistance to folate-based therapeutics.

    • Stefan Reich
    • , Chi D. L. Nguyen
    •  & Jan Medenbach
  • Article
    | Open Access

    Tau plays an important role in tauopathies and undergoes liquid-liquid phase separation (LLPS). The authors show that disease-related P301L mutant and phosphomimic (S199E/S202E/T205E) tau enhance LLPS in vitro at physiological levels, and using specific antibodies, that tau LLPS leads to pathological conformations such as N-terminal exposure and oligomeric species.

    • Nicholas M. Kanaan
    • , Chelsey Hamel
    •  & Benjamin Combs
  • Article
    | Open Access

    Protein aggregation remains a significant challenge for manufacturing of protein biopharmaceuticals. Here, the authors demonstrate the use of directed evolution and an assay for in vivo innate protein aggregation-propensity to generate aggregation-resistant scFv fragments.

    • Jessica S. Ebo
    • , Janet C. Saunders
    •  & David J. Brockwell
  • Article
    | Open Access

    Galectin-3 consists of an unstructured N-terminal domain (NTD) and a structured carbohydrate-recognition domain and agglutinates neutrophils and glycosylated molecules in the extracellular milieu. Here the authors combine biophysical and biochemical experiments with NMR measurements and show that the galectin-3 NTD undergoes liquid-liquid phase separation (LLPS) and agglutinates other molecules through this process.

    • Yi-Ping Chiu
    • , Yung-Chen Sun
    •  & Jie-rong Huang
  • Article
    | Open Access

    It is not yet clear how ubiquitously-expressed proteins can cause the selective degeneration of particular populations of neurons, such as in spinocerebellar ataxia type 17, SCA17, which results from a CAG trinucleotide repeat expansion in the ubiquitously expressed transcription factor TBP. Here, the authors show that mutant TBP suppresses the cerebellum-enriched transcription of Inpp5a and link altered levels of INPP5A to the selective degeneration of cerebellar neurons.

    • Qiong Liu
    • , Shanshan Huang
    •  & Shihua Li
  • Article
    | Open Access

    Tau fibril formation is a hallmark of Alzheimer’s disease. Here the authors reveal an aggregation-dependent protein interaction pattern of Tau and further show that π-stacking of the arginine side-chains drives aberrant protein binding to Tau fibrils.

    • Luca Ferrari
    • , Riccardo Stucchi
    •  & Stefan G. D. Rüdiger
  • Article
    | Open Access

    Single-molecule in vitro assays require dedicated confocal microscopes equipped with fluorescence correlation spectroscopy (FCS) modules. Here the authors present a compact, cheap and open-source 3D-printed confocal microscope for single photon counting and FCS measurements, and use it to detect α-synuclein aggregation.

    • James W. P. Brown
    • , Arnaud Bauer
    •  & Yann Gambin
  • Article
    | Open Access

    While the cellular recycling process autophagy has been linked to aging, the impact of selective autophagy on lifespan remains unclear. Here Kumsta et al. show that the autophagy receptor p62/SQSTM1 is required for hormetic benefits and p62/SQSTM1 overexpression is sufficient to extend C. elegans lifespan and improve proteostasis.

    • Caroline Kumsta
    • , Jessica T. Chang
    •  & Malene Hansen
  • Article
    | Open Access

    Chiral inversion of amino acids is thought to modulate the structure and function of amyloid beta (Aβ) but these processes are poorly understood. Here, the authors develop an ion mobility-mass spectrometry based approach to study chirality-regulated structural features of Aβ fragments and their influence on receptor recognition.

    • Gongyu Li
    • , Kellen DeLaney
    •  & Lingjun Li
  • Article
    | Open Access

    Deposition of tau protein aggregates occurs during aging and Alzheimer disease. Here, the authors show that tau burden in the anterior-temporal memory network is associated with disrupted fMRI connectivity and functional isolation of the hippocampus from other memory network components.

    • Theresa M. Harrison
    • , Anne Maass
    •  & William J. Jagust
  • Article
    | Open Access

    The sequestration of misfolded proteins into large assemblies by sequestrases is now considered as the third pillar in protein quality control besides chaperones and proteases. Here the authors characterise the functions of the sequestrases Hsp42 and Btn2 in the proteostasis network of S. cerevisiae and find that they protect cells from too exhaustive depletion of the Hsp70 system.

    • Chi-ting Ho
    • , Tomas Grousl
    •  & Axel Mogk
  • Article
    | Open Access

    Processing bodies are membrane less organelles that contain enzymes involved in mRNA turnover, among them enhancer of decapping 3 (Edc3). Here the authors use solid- and solution-state NMR spectroscopy to characterize the structural organization and dynamics of Edc3 and find that its interactions with RNA and between the different Edc3 domains are largely preserved in the phase-separated state.

    • Reinier Damman
    • , Stefan Schütz
    •  & Marc Baldus
  • Article
    | Open Access

    Accumulation of abnormal tau protein drives neurodegeneration in Alzheimer’s disease and related dementia disorders. Here, the authors demonstrate the endoplasmic reticulum unfolded protein response mediator XBP-1 controls pathological tau accumulation and the resultant neurodegeneration in a transgenic C. elegans model.

    • Sarah M. Waldherr
    • , Timothy J. Strovas
    •  & Brian C. Kraemer
  • Article
    | Open Access

    The Src-homology 3 domain of phosphatidyl-inositol-3-kinase (PI3K-SH3) is a model system for studying amyloid fibril formation. Here the authors present the 3.4 Å cryo-EM structure of the PI3K-SH3 amyloid fibril, which allows them to rationalize the effects of mutations on the kinetics of fibril formation.

    • Christine Röder
    • , Nicola Vettore
    •  & Gunnar F. Schröder
  • Article
    | Open Access

    Proteins have been used in the synthesis of magnetic nanoparticles but issues with aggregation limit this application. Here, the authors report on the synthesis of coiled proteins that display the active loop of the natural proteins to avoid aggregation and investigate the application in nanoparticle synthesis.

    • Andrea E. Rawlings
    • , Lori A. Somner
    •  & Sarah S. Staniland
  • Article
    | Open Access

    Bacterial ClpB is a disaggregase that solubilizes protein aggregates. Here the authors present the 2.9 Å cryo-EM structure of a hyperactive variant of ClpB bound to the substrate casein in active translocation states and discuss its polypeptide translocation mechanism.

    • Alexandrea N. Rizo
    • , JiaBei Lin
    •  & Daniel R. Southworth
  • Article
    | Open Access

    Genes encoding protein complex subunits are often dispersed in the genome of eukaryotes, raising the question how these protein complexes assemble. Here, the authors provide evidence that mammalian nuclear transcription complexes are formed co-translationally to ensure specific and functional interactions.

    • Ivanka Kamenova
    • , Pooja Mukherjee
    •  & László Tora
  • Article
    | Open Access

    Prion-forming proteins have been found in animals, plants, fungi, and bacteria. Here, Nan et al. report that a baculovirus-encoded protein behaves as prion in a yeast system and forms aggregates at high multiplicity of infection in insect cells that affect baculovirus replication.

    • Hao Nan
    • , Hongying Chen
    •  & Xiaodong Xu
  • Article
    | Open Access

    Small molecule metabolites like phenylalanine can form amyloid-like structures but so far this has only been demonstrated in vitro. Here the authors generate a yeast in vivo model of adenine self-assembly and characterize the adenine assemblies in cells by indicative amyloid dye and anti-adenine assemblies antibodies.

    • Dana Laor
    • , Dorin Sade
    •  & Ehud Gazit
  • Article
    | Open Access

    Impaired kidney function can lead to an increase of β2-microglobulin (β2m) serum levels, which can cause β2m aggregation and amyloid fibril formation. Here the authors combine cryo-EM and magic angle spinning NMR measurements to determine the structure of a β2m fibril and they also present the low resolution model of a β2m fibril with a different morphology.

    • Matthew G. Iadanza
    • , Robert Silvers
    •  & Sheena E. Radford
  • Article
    | Open Access

    Manual sample deposition on a substrate can introduce artifacts in quantitative AFM measurements. Here the authors present a microfluidic spray device for reliable deposition of subpicoliter droplets which dry out in milliseconds after landing on the surface, thereby avoiding protein self-assembly.

    • Francesco Simone Ruggeri
    • , Jerome Charmet
    •  & Tuomas P. J. Knowles