PRX Life Pub Date : 2024-07-25 DOI: 10.1103/prxlife.2.033004

Ameya G. Prabhune, A. S. García-Gordillo, Igor S. Aranson, Thomas R. Powers, Nuris Figueroa-Morales

{"title":"Bacteria Navigate Anisotropic Media using a Flagellar Tug-of-Oars","authors":"Ameya G. Prabhune, A. S. García-Gordillo, Igor S. Aranson, Thomas R. Powers, Nuris Figueroa-Morales","doi":"10.1103/prxlife.2.033004","DOIUrl":"https://doi.org/10.1103/prxlife.2.033004","url":null,"abstract":"Bacteria thrive in anisotropic media such as biofilms, biopolymer solutions, and soil pores. In strongly mechanically anisotropic media, physical interactions force bacteria to swim along a preferred direction rather than to execute the three-dimensional random walk due to their run-and-tumble behavior. Despite their ubiquity in nature and importance for human health, there is little understanding of bacterial mechanisms to navigate these media while constrained to one-dimensional motion. Using a biocompatible liquid crystal, we discovered two mechanisms used by bacteria to switch directions in anisotropic media. First, the flagella assemble in bundles that work against each other from opposite ends of the cell body, and the dominating side in this flagellar “Tug-of-Oars” propels the bacterium along the nematic direction. Bacteria frequently revert their swimming direction 180∘ by a mechanism of flagellar buckling and reorganization on the opposite side of the cell. The Frank elastic energies of the liquid crystal dictate the minimum compression for the Euler buckling of a flagellum. Beyond a critical elasticity of the medium, flagellar motors cannot generate the necessary torque for flagellar buckling, and bacteria are stuck in their configuration. However, we found that bacteria can still switch swimming directions using a second mechanism where individual bundles alternate their rotation. Our results shed light on bacterial strategies to navigate anisotropic media and give rise to questions about sensing environmental cues and adapting at the level of flagellar bundles. The two adaptation mechanisms found here support the use of biocompatible liquid crystals as a synthetic model for bacterial natural environments.\u0000 \u0000 \u0000 \u0000 \u0000 Published by the American Physical Society\u0000 2024\u0000 \u0000 \u0000","PeriodicalId":500583,"journal":{"name":"PRX Life","volume":"58 47","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141804732","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Editorial: PRX Life Celebrates Its First Anniversary 社论：PRX Life 庆祝成立一周年

PRX Life Pub Date : 2024-07-25 DOI: 10.1103/prxlife.2.030001

S. Bradde, Margaret Gardel

引用次数: 0

Molecular Drivers of Aging in Biomolecular Condensates: Desolvation, Rigidification, and Sticker Lifetimes 生物分子凝聚态老化的分子驱动因素：脱溶、僵化和贴纸寿命

PRX Life Pub Date : 2024-06-06 DOI: 10.1103/prxlife.2.023011

Subhadip Biswas, D. Potoyan

{"title":"Molecular Drivers of Aging in Biomolecular Condensates: Desolvation, Rigidification, and Sticker Lifetimes","authors":"Subhadip Biswas, D. Potoyan","doi":"10.1103/prxlife.2.023011","DOIUrl":"https://doi.org/10.1103/prxlife.2.023011","url":null,"abstract":"Biomolecular condensates are dynamic intracellular entities defined by their sequence- and composition-encoded material properties. During aging, these properties can change dramatically, potentially leading to pathological solidlike states, the mechanisms of which remain poorly understood. Recent experiments reveal that the aging of condensates involves a complex interplay of solvent depletion, strengthening of sticker links, and the formation of rigid structural segments such as beta fibrils. In this study, we use various coarse-grained models to investigate how solvent expulsion, biopolymer chain rigidity, and the lifetimes of sticker contacts influence the viscoelastic properties and aging dynamics of condensates. We find that the rigidity of the biopolymer backbone is essential for replicating the predominant elastic behavior observed in experiments. In contrast, models using fully flexible chains—an assumption common in simulations of intrinsically disordered proteins—fail to exhibit a dominant elastic regime. We also demonstrate that altering the solvent content within condensates affects the crossover between storage and loss moduli. This suggests that desolvation plays a significant role in condensate aging by promoting the transition from a viscous to an elastic state. Furthermore, the lifetime of sticker pairs profoundly influences the mature state of the condensates; short-lived stickers lead to a Maxwell fluid behavior, while longer-lived, irreversibly cross-linked stickers result in solidlike properties, consistent with the Kelvin-Voigt model. Finally, by incorporating the chain rigidification, desolvation, and sticker pair formation into a nonequilibrium dynamic aging simulation, we show the molecular mechanism of forming solid shells around the condensate surfaces observed in a recent experimental report.\u0000 \u0000 \u0000 \u0000 \u0000 Published by the American Physical Society\u0000 2024\u0000 \u0000 \u0000","PeriodicalId":500583,"journal":{"name":"PRX Life","volume":"22 42","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141380178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Effect of Synaptic Heterogeneity on Neuronal Coordination 突触异质性对神经元协调性的影响

PRX Life Pub Date : 2024-03-14 DOI: 10.1103/prxlife.2.013013

Moritz Layer, M. Helias, David Dahmen

引用次数: 0

Geometrical Structure of Bifurcations during Spatial Decision-Making 空间决策过程中分岔的几何结构

PRX Life Pub Date : 2024-02-13 DOI: 10.1103/prxlife.2.013008

Dan Gorbonos, N. Gov, I. Couzin

引用次数: 0

Geometrical Structure of Bifurcations during Spatial Decision-Making 空间决策过程中分岔的几何结构

PRX Life Pub Date : 2024-02-13 DOI: 10.1103/prxlife.2.013008

Dan Gorbonos, N. Gov, I. Couzin