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| Open AccessSorting at embryonic boundaries requires high heterotypic interfacial tension
The mechanisms that cause different cells to segregate into distinct tissues are unclear. Here the authors show in Xenopus that formation of a boundary between two tissues is driven by local tension along the interface rather than by global differences in adhesion or cortical contractility.
- Laura Canty
- , Eleyine Zarour
- & François Fagotto
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| Open AccessSlow conformational exchange and overall rocking motion in ubiquitin protein crystals
X-ray crystallography is the main method for protein structure determination. Here the authors combine solid-state NMR measurements and molecular dynamics simulations and show that crystal packing alters the thermodynamics and kinetics of local conformational exchange as well as overall rocking motion of protein molecules in the crystal lattice.
- Vilius Kurauskas
- , Sergei A. Izmailov
- & Paul Schanda
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| Open AccessPhysical limits to biomechanical sensing in disordered fibre networks
Cells in the connective tissue are surrounded by a heterogeneous network of biopolymers. Here, the authors investigate how such heterogeneity affects cellular mechanosensing by simulating the deformation response of experimental and modelled biopolymer networks to locally applied forces.
- Farzan Beroz
- , Louise M. Jawerth
- & Ned S. Wingreen
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| Open AccessDe novo active sites for resurrected Precambrian enzymes
The emergence of novel catalytic functions in ancient proteins likely played a role in the evolution of modern enzymes. Here, the authors use protein sequences from Precambrian beta-lactamases and demonstrate that a single hydrophobic-to-ionizable amino acid mutation can lead to substantial Kemp eliminase activity.
- Valeria A. Risso
- , Sergio Martinez-Rodriguez
- & Jose M. Sanchez-Ruiz
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| Open AccessFronts and waves of actin polymerization in a bistability-based mechanism of circular dorsal ruffles
Circular dorsal ruffles (CDRs) are important for the vesicular uptake of extracellular matter, but the basis of their wave dynamics is not understood. Here, the authors propose and experimentally test a bistable reaction-diffusion system, which they show accounts for the typical CDR expansion and shrinkage and for aberrant formation of pinned waves and spirals.
- Erik Bernitt
- , Hans-Günther Döbereiner
- & Arik Yochelis
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Article
| Open AccessFinding multiple reaction pathways via global optimization of action
Identifying pathways and transition states is critical to understanding chemical and biological reactions. Here, the authors introduce a capable computational approach using conformational space annealing to find multiple reaction pathways via global optimization of the Onsager-Machlup action.
- Juyong Lee
- , In-Ho Lee
- & Bernard R. Brooks
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Article
| Open AccessShifting the optimal stiffness for cell migration
Cell migration is sensitive to environmental stiffness, but how cells sense optimal stiffness is not known. Here the authors develop a model that predicts that the optimum can be shifted by altering the number of active molecular motors and clutches, and verify their model in two cell types.
- Benjamin L. Bangasser
- , Ghaidan A. Shamsan
- & David J. Odde
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Article
| Open AccessKinesin-5-independent mitotic spindle assembly requires the antiparallel microtubule crosslinker Ase1 in fission yeast
Bipolar spindle assembly requires a balance of kinesin 14 pulling and kinesin 5 pushing forces. Here, the authors show that in fission yeast, spindle formation can occur in the absence of kinesin 5 (Cut7) and 14 (Pkl1) but requires the microtubule-associated protein Ase1 for spindle bipolarity.
- Sergio A. Rincon
- , Adam Lamson
- & Phong T. Tran
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Article
| Open AccessExchange pathways of plastoquinone and plastoquinol in the photosystem II complex
Plastoquinone (PLQ) shuttles electrons between photosystem II (PSII) and cytochrome b6f. Here the authors perform molecular dynamics simulations and propose that PLQ enters the exchange cavity of PSII by a promiscuous diffusion mechanism whereby three different channels each act as entry and exit points.
- Floris J. Van Eerden
- , Manuel N. Melo
- & Siewert J. Marrink
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Article
| Open AccessPressure modulates the self-cleavage step of the hairpin ribozyme
Studying the reactivity of ribozymes under extreme pressure could provide insights to optimize biocatalytic RNA design. Here, the authors show that at high pressure the transesterification step of the hairpin ribozyme self-cleavage reaction accelerates, while the overall process is slower.
- Caroline Schuabb
- , Narendra Kumar
- & Roland Winter
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Article
| Open AccessMolecular dynamics simulations reveal ligand-controlled positioning of a peripheral protein complex in membranes
Natural supplies of bryostatin, a compound in clinical trials for Alzheimer’s disease, cancer, and HIV, are scarce. Here, the authors perform molecular dynamics simulations to understand how bryostatin interacts with membrane-bound protein kinase C, offering insights for the design of bryostatin analogs.
- Steven M. Ryckbosch
- , Paul A. Wender
- & Vijay S. Pande
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Article
| Open AccessC-edge loops of arrestin function as a membrane anchor
The activity of G-protein-coupled receptors is regulated by their interaction with arrestins. Here the authors show that loops located on C-edge of arrestin-1 serve as a membrane anchor during the multi-step binding process that leads to a stable receptor–arrestin complex.
- Ciara C M. Lally
- , Brian Bauer
- & Martha E Sommer
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Article
| Open AccessAn elastic element in the protocadherin-15 tip link of the inner ear
Tip-link filaments convey force to activate hair cells, important sensory receptors. Here the authors solve a partial structure of human protocadherin-15, a tip-link component with an unusual Ca2+–free linker that bends and is predicted to confer flexibility to this filament during inner-ear mechanotransduction.
- Raul Araya-Secchi
- , Brandon L. Neel
- & Marcos Sotomayor
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| Open AccessHow EF-Tu can contribute to efficient proofreading of aa-tRNA by the ribosome
The translation of mRNA by the ribosome is governed by a series of large-scale conformational transitions. Here the authors use MD simulations to demonstrate how the rate of dissociation of elongation factor Tu affects the dynamics of tRNA accommodation and proofreading.
- Jeffrey K. Noel
- & Paul C. Whitford
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| Open AccessMechanism of pH-dependent activation of the sodium-proton antiporter NhaA
The pH dependence of the activity of Escherichia colimain sodium-proton antiporter NhaA is still not fully understood. Here, the authors use continuous constant pH molecular dynamics simulations to identify NhaA proton carrier residues and elucidate its gating and ion transport processes.
- Yandong Huang
- , Wei Chen
- & Jana Shen
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| Open AccessSizing nanomaterials in bio-fluids by cFRAP enables protein aggregation measurements and diagnosis of bio-barrier permeability
Measuring the size distribution of nanomaterials in biological fluids is crucial to understand their properties in vivo. Here, the authors apply fluorescence recovery after photobleaching to measure protein aggregation in serum and to study permeability of biological membranes in mouse models.
- Ranhua Xiong
- , Roosmarijn E. Vandenbroucke
- & Kevin Braeckmans
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Article
| Open AccessPrediction and validation of protein intermediate states from structurally rich ensembles and coarse-grained simulations
Protein conformational changes are key to a wide range of cellular functions but remain difficult to access experimentally. Here the authors describe eBDIMS, a novel approach to predict intermediates observed in structural transition pathways from experimental ensembles.
- Laura Orellana
- , Ozge Yoluk
- & Erik Lindahl
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Article
| Open AccessEl Niño and coral larval dispersal across the eastern Pacific marine barrier
Over 5,000 km of open ocean separate central and eastern Pacific coral reefs. Here, the authors combine a biophysical dispersal model with genetic data to show that eastern Pacific coral populations have been isolated from western sources of larval recruitment since the 1997-98 El Niño-induced bleaching event.
- S. Wood
- , I. B. Baums
- & E. J. Hendy
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Article
| Open AccessUnbiased measurements of reconstruction fidelity of sparsely sampled magnetic resonance spectra
The use of sparse-sampling techniques in NMR data acquisition requires quality assessment criteria for the reconstructed spectra. Here, the authors propose a pair of measurements that might serve as these quality measurements.
- Qinglin Wu
- , Brian E. Coggins
- & Pei Zhou
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| Open AccessSuperstatistical analysis and modelling of heterogeneous random walks
Conventional methods to quantify the migratory behaviour of cells assume that underlying parameters are constant. Mark et al.apply a superstatistical approach to extract time-dependent parameters of motile cells, and demonstrate an enhanced ability to distinguish between different migration strategies.
- Claus Metzner
- , Christoph Mark
- & Ben Fabry
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| Open AccessIntracellular signalling and intercellular coupling coordinate heterogeneous contractile events to facilitate tissue folding
Epithelial sheet migration proceeds via a series of actomyosin contractions, called pulses, that are stabilized, or ratcheted. Here, Xie and Martin develop a computational framework to determine how pulses are coordinated, and show that ratcheting of pulses allows collective migration by preventing competition with neighbouring pulses.
- Shicong Xie
- & Adam C. Martin
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A fully atomistic computer simulation study of cold denaturation of a β-hairpin
Cold denaturation is the process by which globular proteins lose their structural integrity at sufficiently low temperatures. Here, the authors present an all-atom MD simulation of cold denaturation of the 16-mer hairpin peptide MrH1 using an explicit water model.
- Changwon Yang
- , Soonmin Jang
- & Youngshang Pak
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| Open AccessA CLASP-modulated cell edge barrier mechanism drives cell-wide cortical microtubule organization in Arabidopsis
How microtubules are organized correctly in plant cells is not well understood. Ambroseet al. use 4D imaging and computer modelling to show that sharp cell edges induce microtubule depolymerization and that the microtubule-associated protein CLASP mitigates this process to modulate array organization.
- Chris Ambrose
- , Jun F. Allard
- & Geoffrey O. Wasteneys
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Article |
An adaptive explanation for the horse-like shape of seahorses
Seahorses evolved from pipefish, which have a remarkably different body shape. Here, by examining seahorse feeding behaviour and using a mathematical model, Van Wassenberghet al. demonstrate that the head, neck and trunk posture of the seahorse allows for the effective capture of their prey.
- Sam Van Wassenbergh
- , Gert Roos
- & Lara Ferry