Biophysics

  • Article
    | Open Access

    Multifocal imaging suffers from a number of limitations. Here the authors report an open-source 3D reconstruction algorithm to enable label-free tracking of spherical and filamentous structures which they use to characterise fluid flow and flagellar beating of human and sea urchin sperm.

    • Jan N. Hansen
    • , An Gong
    •  & Luis Alvarez
  • Article
    | Open Access

    Mitochondrial transport toward both the plus- and minus-ends of microtubules is mediated by motor proteins linked to mitochondria by TRAK adaptor proteins. Here the authors investigate the role of TRAK2 as a bidirectional motor adaptor, and propose a model where TRAK2 coordinates the activities of opposing kinesin-1 and cytoplasmic dynein motors as a single interdependent motor complex.

    • Adam R. Fenton
    • , Thomas A. Jongens
    •  & Erika L. F. Holzbaur
  • Article
    | Open Access

    Cytokinetic ring constriction during cell division requires actin but curiously is independent of myosin in many organisms. Here, the authors show that anillin, a protein enriched in the contractile ring, is a non-motor actin crosslinker that generates contractile force in lieu of a molecular motor.

    • Ondřej Kučera
    • , Valerie Siahaan
    •  & Zdenek Lansky
  • Article
    | Open Access

    Environmental and genetic risk factors affect the distal airway epithelium in idiopatic pulmonary fibrosis (IPF) but the role of the epithelium in IPF remains unclear. Here the authors show that pathologic activation of the ERBB-YAP axis induces dynamic and structural dysfunction in the distal airway epithelium eliciting a pro-fibrotic phenotype in mesenchymal cells.

    • Ian T. Stancil
    • , Jacob E. Michalski
    •  & David A. Schwartz
  • Article
    | Open Access

    The nucleation mechanisms of biological protein phase separation are poorly understood. Here, the authors perform time-resolved SAXS experiments with the low-complexity domain (LCD) of hnRNPA1 and uncover multiple kinetic regimes on the micro- to millisecond timescale. Initially, individual proteins collapse. Nucleation then occurs via two steps distinguished by their protein cluster size distributions.

    • Erik W. Martin
    • , Tyler S. Harmon
    •  & Tanja Mittag
  • Article
    | Open Access

    Plant sulfate transporters mediate absorption and distribution of sulfate. Here the authors present functional assays and a cryo-EM structure of the Arabidopsis SULTR4;1 transporter identifying key domains for dimerization, substrate binding and coupling of transport activity to a proton gradient.

    • Lie Wang
    • , Kehan Chen
    •  & Ming Zhou
  • Article
    | Open Access

    In the basal body of the bacterial flagellum, the LP ring acts as a bushing supporting the distal rod for its rapid and stable rotation. Here, Yamaguchi et al. present the electron cryomicroscopy structure of the LP ring around the rod, shedding light into potential mechanisms involved in stability and assembly of the structure.

    • Tomoko Yamaguchi
    • , Fumiaki Makino
    •  & Keiichi Namba
  • Article
    | Open Access

    The length of single-particle tracking experiments are limited due to photobleaching. Here the authors achieve long-term single-particle tracking with continuous fluorophore exchange in DNA-PAINT and use this to observe DNA origami on lipid bilayers for tens of minutes.

    • Florian Stehr
    • , Johannes Stein
    •  & Petra Schwille
  • Article
    | Open Access

    DNA origami can be used to control the movement of nanoscale assemblies. Here the authors construct multiple-micrometer-long hollow DNA filaments through which DNA pistons move with micrometer-per-second speeds.

    • Pierre Stömmer
    • , Henrik Kiefer
    •  & Hendrik Dietz
  • Article
    | Open Access

    DNA probes used in next generation sequencing (NGS) have variable hybridisation kinetics, resulting in non-uniform coverage. Here, the authors develop a deep learning model to predict NGS depth using DNA probe sequences and apply to human and non-human sequencing panels.

    • Jinny X. Zhang
    • , Boyan Yordanov
    •  & David Yu Zhang
  • Article
    | Open Access

    High-speed atomic force microscopy height spectroscopy and single channel electrophysiology recordings are used to correlate conformational and functional dynamics of the model membrane protein, outer membrane protein G (OmpG). These techniques show that both states coexist and rapidly interchange in all conditions supported by molecular dynamics simulations.

    • Raghavendar Reddy Sanganna Gari
    • , Joel José Montalvo‐Acosta
    •  & Simon Scheuring
  • Article
    | Open Access

    Pleckstrin homology (PH) domains are presumed to bind phosphoinositides (PIPs) but only few specific interactions are known. Using TIRF microscopy based assays, functional studies and an experimentally validated prediction algorithm, the authors show that specific PIP binding is widespread among human PH domains.

    • Nilmani Singh
    • , Adriana Reyes-Ordoñez
    •  & Jie Chen
  • 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

    Fly Dicer-2 is thought to use two distinct – processive or distributive – modes of cleavage by distinguishing the terminal structures of double-stranded RNA (dsRNA) substrates with the help of its cofactor LoquaciousPD (Loqs-PD). Here the authors show by single-molecule imaging that dsRNA terminal structures and Loqs-PD change the probability for Dicer to initiate processive cleavage but not the mode of cleavage action per se.

    • Masahiro Naganuma
    • , Hisashi Tadakuma
    •  & Yukihide Tomari
  • Article
    | Open Access

    The folding of outer membrane proteins (OMPs) is catalyzed by the βbarrel assembly machinery (BAM). Here, structural and functional analyses of BAM stabilized in distinct conformations elucidate the roles of lateral gate opening and interactions of BAM with the lipid bilayer in OMP assembly.

    • Paul White
    • , Samuel F. Haysom
    •  & Sheena E. Radford
  • Article
    | Open Access

    Cells can modify their environment by depositing biochemical signals or mechanically remodelling the extracellular matrix; the impact of such self-induced environmental perturbations on cell trajectories at various scales remains unexplored. Here authors show that motile cells leave long-lived physicochemical footprints along their way, which determine their future path.

    • Joseph d’Alessandro
    • , Alex Barbier--Chebbah
    •  & Benoît Ladoux
  • Article
    | Open Access

    The cryo-EM structure of pentameric green-light absorbing proteorhodopsin together with molecular dynamics simulations and functional studies provides insights into the proton translocation pathway and oligomerization, and a protonation-dependent mechanism for intracellular half channel hydration.

    • Stephan Hirschi
    • , David Kalbermatter
    •  & Dimitrios Fotiadis
  • Article
    | Open Access

    The intracellular compartment is a crowded environment. Here, the authors use molecular dynamics (MD) simulations to assess inhibitor binding to c-Src kinase and show how ligand binding pathways differ in crowded and dilute protein solutions, highlighting the role of c-Src Tyr82 sidechain.

    • Kento Kasahara
    • , Suyong Re
    •  & Yuji Sugita
  • Article
    | Open Access

    Emerging evidence suggests that exit from pluripotency is a regulated, rather than passive process. Here the authors identify a requirement for SS18-mediated Brg/Brahma-associated factors (BAF) chromatin remodeling complex assembly during exit from pluripotency, and that SS18 promotes BAF assembly through liquidliquid phase separation.

    • Junqi Kuang
    • , Ziwei Zhai
    •  & Duanqing Pei
  • Article
    | Open Access

    The permeability barrier of nuclear pore complexes blocks passage of inert macromolecules but allows rapid, receptor-mediated, and RanGTPase-driven transport of cargoes up to ribosome size. The authors now show that such a barrier can be faithfully recapitulated by an ultimately simplified FG phase assembled solely from a tandemly repeated 12mer GLFG peptide.

    • Sheung Chun Ng
    • , Thomas Güttler
    •  & Dirk Görlich
  • Article
    | Open Access

    CNNM/CorB proteins are a conserved family of membrane proteins associated with Mg2+ transport. Here, structures of an archaeal CorB protein in apo state and with Mg2+-ATP bound and accompanying biophysical experiments suggest direct Mg2+ transport by CorB proteins.

    • Yu Seby Chen
    • , Guennadi Kozlov
    •  & Kalle Gehring
  • 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

    Here, cryo-EM structures of human retinal ABCA4 transporter, either in apo state, in complex with ATP or with the physiological lipid substrate N-retinylidene-phosphatidylethanolamine (NRPE), reveal lateral opening, substrate recognition and suggest ‘lateral access and extrusion’ mechanism for ABCA-mediated lipid transport.

    • Tian Xie
    • , Zike Zhang
    •  & Xin Gong
  • Article
    | Open Access

    The glucagon-like peptide-1 (GLP-1) receptor is a key regulator of glucose homeostasis and a drug target for type 2 diabetes but available GLP-1R agonists are suboptimal due to several side-effects. Here authors report the cryo-EM structure of GLP-1R bound to an ago-allosteric modulator in complex with heterotrimeric Gs which offers insights into the molecular details of ago-allosterism.

    • Zhaotong Cong
    • , Li-Nan Chen
    •  & Ming-Wei Wang
  • Article
    | Open Access

    The tasks of the cytoskeleton depend on the fine-tuned interplay between the three filamentous components: actin filaments, microtubules, and intermediate filaments. Here, the authors show in a reconstituted in vitro system that vimentin intermediate filaments stabilize microtubules against depolymerization and support microtubule rescue by direct interactions.

    • Laura Schaedel
    • , Charlotta Lorenz
    •  & Sarah Köster
  • 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

    Gangliosides such as GM1 present in the outer leaflet of the plasma membrane of eukaryotic cells are essential for many cellular functions and pathogenic interactions. Here the authors show that the acyl chain structure of GM1 determines the establishment of nanodomains when actively clustered by actin, which depended on membrane cholesterol and phosphatidylserine or superimposed by the GM1-binding bacterial cholera toxin.

    • Senthil Arumugam
    • , Stefanie Schmieder
    •  & Ludger Johannes
  • Article
    | Open Access

    Here, Geoghegan, Evelyn et al. provide a lattice light-sheet microscopy based 4D imaging pipeline to quantitatively investigate Plasmodium spp. invasion and show that the nascent parasitophorous vacuole is predominantly formed from host’s erythrocyte membrane and undergoes continuous remodeling throughout invasion.

    • Niall D. Geoghegan
    • , Cindy Evelyn
    •  & Kelly L. Rogers
  • Article
    | Open Access

    Proteins need to overcome energy barriers to induce intermediate steps in membrane fusion. Using lipid vesicles in which progression to hemifusion is arrested, the authors show that the metastable intermediate is enhanced by divalent cations and is characterized by the absence of proteins and local membrane thickening. Simulations reveal that thickening is induced by dehydration of the membrane surface.

    • Agata Witkowska
    • , Leonard P. Heinz
    •  & Reinhard Jahn
  • Article
    | Open Access

    Molecular scale force application in physiological environments is important for studying mechanotransduction. Here, the authors use a molecular machine to apply forces at cell-matrix and cell-cell junctions using light to trigger twisting actuation which then pulls on cell membrane receptors.

    • Yijun Zheng
    • , Mitchell K. L. Han
    •  & Aránzazu del Campo
  • Article
    | Open Access

    miRNA profiling from patient blood can be used for cancer diagnosis. Here the authors present an electro-optical nanopore sensing platform which allows sensitive and specific miRNA detection directly in human serum and apply to monitoring of miR-141-3p and miR-375-3p in different stage of prostate cancer.

    • Shenglin Cai
    • , Thomas Pataillot-Meakin
    •  & Joshua B. Edel
  • Article
    | Open Access

    Cyanobacterial thylakoid membranes host the molecular machinery for the light-dependent reactions of photosynthesis and respiratory electron flow. Here, the authors show that newly synthesized thylakoids emerge between the plasma membrane and pre-existing thylakoids and describe the time-dependent assembly process of photosynthetic complexes.

    • Tuomas Huokko
    • , Tao Ni
    •  & Lu-Ning Liu
  • Article
    | Open Access

    Sodium/proton exchanger 1 (NHE1) and its obligate binding partner Calcineurin B-homologous protein 1 (CHP1) regulate intracellular pH and volume homeostasis. Structures of the human NHE1-CHP1 complex offer insight into the regulation of NHE1 pH-sensitivity by CHP1 and into the interactions with NHE1 inhibitors.

    • Yanli Dong
    • , Yiwei Gao
    •  & Yan Zhao
  • Article
    | Open Access

    Ring ATPase translocases that operate on disordered substrates adopt lockwasher architectures and use a hand-over-hand mechanism. By challenging the dsDNA packaging motor of bacteriophage ϕ29 with hybrid and dsRNA, the authors propose that the motor cycles between planar and lock-washer structures.

    • Juan P. Castillo
    • , Alexander B. Tong
    •  & Carlos Bustamante
  • Article
    | Open Access

    The effect of fallopian tube’s curvature on sperm motion has not been studied in detail. Here, the authors use droplet microfluidics to create soft curved interfaces, revealing a dynamic switch in sperm motility from a progressive surface-aligned mode at low curvatures, to an aggressive surface-attacking mode at high curvatures.

    • Mohammad Reza Raveshi
    • , Melati S. Abdul Halim
    •  & Reza Nosrati
  • Article
    | Open Access

    Nanopores have been used for direct observation of RNA structure in native environments but have limited RNA differentiation capabilities. Here, the authors report on the use of Mycobacterium smegmatis porin A nanopores for the trapping and translocation identification of microRNA, siRNA, tRNA and ribosomal RNA.

    • Yuqin Wang
    • , Xiaoyu Guan
    •  & Shuo Huang
  • Article
    | Open Access

    Self-organisation of Min protein patterns observed in vivo and in vitro differ qualitatively and quantitatively. Here the authors reconstituted Min proteins in laterally wide microchambers with a well-controlled height and show that the Min protein dynamics on the membrane crucially depend on the micro chamber height.

    • Fridtjof Brauns
    • , Grzegorz Pawlik
    •  & Cees Dekker
  • Article
    | Open Access

    During bacterial cell division, the protein FtsZ is the main component of the contractile ring, though how precisely FtsZ treadmilling and its ability to deform membranes cooperate are unclear. Here, the authors show that dynamic FtsZ may deform lipid membranes via torsional stress that may provide sufficient force to constrict membranes in vivo and in vitro.

    • Diego A. Ramirez-Diaz
    • , Adrián Merino-Salomón
    •  & Petra Schwille
  • Article
    | Open Access

    Vibrational energy transfer (VET) is essential for protein function as it is responsible for efficient energy dissipation in reaction sites and is linked to pathways of allosteric communication. Here authors equipped a tryptophan zipper with a VET injector and a VET sensor for femtosecond pump probe experiments to map the VET.

    • Erhan Deniz
    • , Luis Valiño-Borau
    •  & Jens Bredenbeck
  • Article
    | Open Access

    Ito and co-workers unravel how bacteria such as Salmonella switch gears with their flagellar driving machinery. External load triggers the dynamic remodeling of the molecular complex sustaining the torque, and the number of stator units is adapted in a non-trivial, cooperative manner.

    • Kenta I. Ito
    • , Shuichi Nakamura
    •  & Shoichi Toyabe
  • Article
    | Open Access

    During transcription, RNA polymerase II (RNAP2) is recruited to promoters and phosphorylated stepwise; so far, these steps have not been visualized in a single-copy gene in live cells. Here the authors use single-molecule microscopy to visualize endogenous phosphorylated RNAP2 and nascent mRNA synthesis at a single locus in living cells.

    • Linda S. Forero-Quintero
    • , William Raymond
    •  & Timothy J. Stasevich
  • Article
    | Open Access

    Focal adhesions (FAs) initiate chemical and mechanical signals involved in cell polarity, migration, proliferation and differentiation. Here, authors combine single protein tracking, super-resolution microscopy and functional assays, which allow correlating the molecular behaviour and 3D nanoscale localization of kindlin with its function in integrin activation inside FAs.

    • Thomas Orré
    • , Adrien Joly
    •  & Grégory Giannone
  • Article
    | Open Access

    Most insights on DNA-mediated allostery upon transcription factor (TF) binding were either based on artificial promoters or found to be short-ranged. Here authors use single-molecule FRET and cryo-EM to show that Bacillus subtilis bacteria utilize long-range allostery in a stochastic and reversible phenotype switch.

    • Gabriel Rosenblum
    • , Nadav Elad
    •  & Hagen Hofmann
  • Article
    | Open Access

    Artificial molecular systems can show complex kinetics of reproduction, however their integration into larger ensembles remains a challenge towards evolving higher order functionality. Here authors use show that self-reproducing lipids can initiate and accelerate octanol droplet movement and that reciprocally chemotactic movement of these droplets increases the rate of lipid reproduction substantially.

    • Dhanya Babu
    • , Robert J. H. Scanes
    •  & Nathalie Katsonis
  • Article
    | Open Access

    While rheology studies have contributed to the understanding of the viscoelastic properties of living cells, the use of higher frequencies promises elucidate the link between cellular and molecular properties. Here authors introduce a rheological assay that measures the cell mechanical response across a continuous frequency range ≈ 1 – 40 kHz.

    • Gotthold Fläschner
    • , Cosmin I. Roman
    •  & Daniel J. Müller