Biophysics

On the pH-dependence of α-synuclein amyloid polymorphism and the role of secondary nucleation in seed-based amyloid propagation

1. Lukas Frey
2. Dhiman Ghosh
3. Bilal M Qureshi
4. David Rhyner
5. Ricardo Guerrero-Ferreira
6. Aditya Pokharna
7. Witek Kwiatkowski
8. Tetiana Serdiuk
9. Paola Picotti
10. Roland Riek
11. Jason Greenwald

• Curated by eLife

  eLife assessment

  This study presents important findings on the different polymorphs of alpha-synuclein filaments that form at various pH's during in vitro assembly reactions with purified recombinant protein. Of particular note is the discovery of two new polymorphs (1M and 5A) that form in PBS buffer at pH 7. The strength of the evidence presented is convincing. The work will be of interest to biochemists and biophysicists working on protein aggregation and amyloids.

Reviewed by eLife

Direct single-molecule detection and super-resolution imaging with a low-cost portable smartphone-based microscope

1. Morgane Loretan
2. Mariano Barella
3. Nathan Fuchs
4. Samet Kocabey
5. Karol Kołątaj
6. Fernando D. Stefani
7. Guillermo P. Acuna

Reviewed by preLights

Emergence of ion-channel-mediated electrical oscillations in Escherichia coli biofilms

1. Emmanuel Akabuogu
2. Victor Carneiro da Cunha Martorelli
3. Rok Krašovec
4. Ian S Roberts
5. Thomas A Waigh

• Curated by eLife

  eLife Assessment

  This potentially valuable study presents claims of evidence for coordinated membrane potential oscillations in E. coli biofilms that can be linked to a putative K+ channel and that may serve to enhance photo-protection. The finding of waves of membrane potential would be of interest to a wide audience from molecular biology to microbiology and physical biology. Unfortunately, a major issue is that it is unclear whether the dye used can act as a Nernstian membrane potential dye in E. coli. The arguments of the authors, who largely ignore previously published contradictory evidence, are not adequate in that they do not engage with the fact that the dye behaves in their hands differently than in the hands of others. In addition, the lack of proper validation of the experimental method including key control experiments leaves the evidence incomplete.

Reviewed by eLife

Structural characterization and dynamics of AdhE ultrastructures from Clostridium thermocellum show a containment strategy for toxic intermediates

1. Samantha J Ziegler
2. Brandon C Knott
3. Josephine N Gruber
4. Neal N Hengge
5. Qi Xu
6. Daniel G Olson
7. Eduardo E Romero
8. Lydia-Marie Joubert
9. Yannick J Bomble

• Curated by eLife

  eLife assessment

  This work presents valuable information on the structure of the spirosome's native extended conformation as the active form of the aldehyde-alcohol dehydrogenase (AdhE) enzyme. The evidence is solid, although the work does not provide a mechanistic understanding of the function and dynamics of AdhE.

Reviewed by eLife

A scale-invariant log-normal droplet size distribution below the critical concentration for protein phase separation

1. Tommaso Amico
2. Samuel Toluwanimi Dada
3. Andrea Lazzari
4. Michaela Brezinova
5. Antonio Trovato
6. Michele Vendruscolo
7. Monika Fuxreiter
8. Amos Maritan

• Curated by eLife

  eLife assessment

  In this valuable study, the authors analyze droplet size distributions of multiple protein condensates and their fit to a scaling ansatz, highlighting that they exhibit features of first- and second-order phase transitions. The experimental evidence is solid, and it prompts further research into the nature of the link between percolation and phase separation.

Reviewed by eLife

Mapping spatial patterns to energetic benefits in groups of flow-coupled swimmers

1. Sina Heydari
2. Haotian Hang
3. Eva Kanso

• Curated by eLife

  eLife assessment

  This fundamental study provides a modeling regime that provides new insight into the energy-preservation parameters among schooling fish. The strength of the evidence supporting observations such as distilled dynamics between leading and lagging schooling fish which are derived from emergent properties is compelling. Overall, the study provides exciting insights into energetic coupling with respect to group swimming dynamics.

Reviewed by eLife

Decoupling of the onset of anharmonicity between a protein and its surface water around 200 K

1. Lirong Zheng
2. Bingxin Zhou
3. Banghao Wu
4. Yang Tan
5. Juan Huang
6. Madhusudan Tyagi
7. Victoria García Sakai
8. Takeshi Yamada
9. Hugh O'Neill
10. Qiu Zhang
11. Liang Hong

• Curated by eLife

  eLife assessment

  The study answers the important question of whether the conformational dynamics of proteins are slaved by the motion of solvent water or are intrinsic to the polypeptide. The results from neutron scattering experiments, involving isotopic labelling, carried out on a set of four structurally different proteins are convincing, showing that protein motions are not coupled to the solvent. A strength of this work is the study of a set of proteins using spectroscopy covering a range of resolutions. The work is of broad interest to researchers in the fields of protein biophysics and biochemistry.

Reviewed by eLife

The geometric basis of epithelial convergent extension

1. Fridtjof Brauns
2. Nikolas H Claussen
3. Matthew F Lefebvre
4. Eric F Wieschaus
5. Boris I Shraiman

• Curated by eLife

  eLife assessment

  This important study analyzes in an original way how tension pattern dynamics can reveal the contribution of active versus passive intercalation during tissue elongation. The authors develop a compelling, elegant analytical framework (isogonal tension decomposition) to disentangle the passive (adjacent tissues pulling) and active (local tension anisotropy) contributions to intercalation events. This allows the generation of global maps of tissue mechanics that will be extremely helpful in the field of biomechanics.

Reviewed by eLife

Structure of the human heparan-α-glucosaminide N-acetyltransferase (HGSNAT)

1. Vikas Navratna
2. Arvind Kumar
3. Jaimin K Rana
4. Shyamal Mosalaganti

• Curated by eLife

  eLife assessment

  This important study presents the structure of human heparan-alpha-glucosaminide N-acetyltransferase (HGSNAT) in the acetyl-CoA bound state, providing the first description of the architecture of this family of integral membrane enzymes, and revealing the mode of acetyl-CoA binding. The structural work is convincing, with a high resolution and isotropic single-particle cryoEM map and an atomic model that is well-justified by the density map, with strong density for the acetyl-CoA ligand. However, experimental support for the molecular mechanism of the HS acetylation reaction and the impact of disease-causing mutations is incomplete. This work will be of interest to biochemists and structural biologists studying the structure and function of integral membrane enzymes, as well as those interested in genetic diseases resulting from mutations in this family of enzymes, such as mucopolysaccharidosis IIIC (MPS III-C).

Reviewed by eLife

Detecting directed motion and confinement in single-particle trajectories using hidden variables

1. François Simon
2. Guillaume Ramadier
3. Inès Fonquernie
4. Janka Zsok
5. Sergiy Patskovsky
6. Michel Meunier
7. Caroline Boudoux
8. Elisa Dultz
9. Lucien E Weiss

• Curated by eLife

  eLife assessment

  In this valuable contribution, the authors present a novel and versatile probabilistic tool for classifying tracking behaviors and understanding parameters for different types of single-particle motion. The tool will be broadly applicable to single-particle tracking studies. While some reviewers feel that the methodology has been convincingly tested by computational comparisons and experimental data, others feel that the mathematical foundation needs to be strengthened and clearly defined.

Reviewed by eLife