scholarly journals Alternative Architecture of the E. coli Chemosensory Array

Biomolecules ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 495
Author(s):  
Alister Burt ◽  
C. Keith Cassidy ◽  
Phillip J. Stansfeld ◽  
Irina Gutsche
Keyword(s):  
Electron Tomography ◽  
Structural Basis ◽  
Published Data ◽  
Molecular Models ◽  
E Coli ◽  
Array Architecture ◽  
Tremendous Progress ◽  
Cryo Electron Tomography ◽  
Functional Implications ◽  
And Function

Chemotactic responses in motile bacteria are the result of sophisticated signal transduction by large, highly organized arrays of sensory proteins. Despite tremendous progress in the understanding of chemosensory array structure and function, a structural basis for the heightened sensitivity of networked chemoreceptors is not yet complete. Here, we present cryo-electron tomography visualisations of native-state chemosensory arrays in E. coli minicells. Strikingly, these arrays appear to exhibit a p2-symmetric array architecture that differs markedly from the p6-symmetric architecture previously described in E. coli. Based on this data, we propose molecular models of this alternative architecture and the canonical p6-symmetric assembly. We evaluate our observations and each model in the context of previously published data, assessing the functional implications of an alternative architecture and effects for future studies.

scholarly journals Alternative Architecture of the E. Coli Chemosensory Array

2020 ◽  
Author(s):  
Alister Burt ◽  
C Cassidy ◽  
Phillip Stansfeld ◽  
Irina Gutsche
Keyword(s):  
Electron Tomography ◽  
Structural Basis ◽  
Published Data ◽  
Molecular Models ◽  
E Coli ◽  
Array Architecture ◽  
Tremendous Progress ◽  
Cryo Electron Tomography ◽  
Functional Implications ◽  
And Function

Abstract Chemotactic responses in motile bacteria are the result of sophisticated signal transduction by large, highly organized arrays of sensory proteins. Despite tremendous progress in the understanding of chemosensory array structure and function, a structural basis for the heightened sensitivity of networked chemoreceptors is not yet complete. Here we present cryo-electron tomography visualisations of native-state chemosensory arrays in E. coli minicells. Strikingly, these arrays exhibit a p2-symmetric array architecture that differs markedly from the p6-symmetric architecture previously described in E. coli. Based on this data, we propose molecular models of this alternative architecture and the canonical p6-symmetric assembly. We evaluate our observations and each model in the context of previously published data, assessing the functional implications of an alternative architecture and effects for future studies.

scholarly journals Alternative architecture of the E. coli chemosensory array

2021 ◽  
Author(s):  
Alister Burt ◽  
C. Keith Cassidy ◽  
Phillip J. Stansfeld ◽  
Irina Gutsche
Keyword(s):  
Electron Tomography ◽  
Structural Basis ◽  
Published Data ◽  
Molecular Models ◽  
E Coli ◽  
Array Architecture ◽  
Tremendous Progress ◽  
Cryo Electron Tomography ◽  
Functional Implications ◽  
And Function

AbstractChemotactic responses in motile bacteria are the result of sophisticated signal transduction by large, highly organized arrays of sensory proteins. Despite tremendous progress in the understanding of chemosensory array structure and function, a structural basis for the heightened sensitivity of networked chemoreceptors is not yet complete. Here we present cryo-electron tomography visualisations of native-state chemosensory arrays in E. coli minicells. Strikingly, these arrays exhibit a p2-symmetric array architecture that differs markedly from the p6-symmetric architecture previously described in E. coli. Based on this data, we propose molecular models of this alternative architecture and the canonical p6-symmetric assembly. We evaluate our observations and each model in the context of previously published data, assessing the functional implications of an alternative architecture and effects for future studies.

scholarly journals Tubulin glycylation controls axonemal dynein activity, flagellar beat, and male fertility

Science ◽  
2021 ◽  
Vol 371 (6525) ◽  
pp. eabd4914
Author(s):  
Sudarshan Gadadhar ◽  
Gonzalo Alvarez Viar ◽  
Jan Niklas Hansen ◽  
An Gong ◽  
Aleksandr Kostarev ◽  
...  
Keyword(s):  
Posttranslational Modifications ◽  
Male Fertility ◽  
Electron Tomography ◽  
Structural Basis ◽  
Cellular Functions ◽  
Flagellar Beat ◽  
Cryo Electron Tomography ◽  
Axonemal Dynein ◽  
Dynein Arms ◽  
Cilia And Flagella

Posttranslational modifications of the microtubule cytoskeleton have emerged as key regulators of cellular functions, and their perturbations have been linked to a growing number of human pathologies. Tubulin glycylation modifies microtubules specifically in cilia and flagella, but its functional and mechanistic roles remain unclear. In this study, we generated a mouse model entirely lacking tubulin glycylation. Male mice were subfertile owing to aberrant beat patterns of their sperm flagella, which impeded the straight swimming of sperm cells. Using cryo–electron tomography, we showed that lack of glycylation caused abnormal conformations of the dynein arms within sperm axonemes, providing the structural basis for the observed dysfunction. Our findings reveal the importance of microtubule glycylation for controlled flagellar beating, directional sperm swimming, and male fertility.

scholarly journals Structure and dynamics of the E. coli chemotaxis core signaling complex by cryo-electron tomography and molecular simulations

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
C. Keith Cassidy ◽  
Benjamin A. Himes ◽  
Dapeng Sun ◽  
Jun Ma ◽  
Gongpu Zhao ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Electron Tomography ◽  
Conformational Dynamics ◽  
Molecular Simulations ◽  
Adaptor Protein ◽  
Signaling Mechanism ◽  
E Coli ◽  
Signaling Complex ◽  
Chemical Gradients ◽  
Cryo Electron Tomography

AbstractTo enable the processing of chemical gradients, chemotactic bacteria possess large arrays of transmembrane chemoreceptors, the histidine kinase CheA, and the adaptor protein CheW, organized as coupled core-signaling units (CSU). Despite decades of study, important questions surrounding the molecular mechanisms of sensory signal transduction remain unresolved, owing especially to the lack of a high-resolution CSU structure. Here, we use cryo-electron tomography and sub-tomogram averaging to determine a structure of the Escherichia coli CSU at sub-nanometer resolution. Based on our experimental data, we use molecular simulations to construct an atomistic model of the CSU, enabling a detailed characterization of CheA conformational dynamics in its native structural context. We identify multiple, distinct conformations of the critical P4 domain as well as asymmetries in the localization of the P3 bundle, offering several novel insights into the CheA signaling mechanism.

scholarly journals Cryo-electron tomography of cells: connecting structure and function

2008 ◽  
Vol 130 (2) ◽  
pp. 185-196 ◽  
Author(s):  
Vladan Lučić ◽  
Andrew Leis ◽  
Wolfgang Baumeister
Keyword(s):  
Electron Tomography ◽  
Structure And Function ◽  
Cryo Electron Tomography ◽  
And Function

scholarly journals Detailed structural and biochemical characterization of the nexin-dynein regulatory complex

2015 ◽  
Vol 26 (2) ◽  
pp. 294-304 ◽  
Author(s):  
Toshiyuki Oda ◽  
Haruaki Yanagisawa ◽  
Masahide Kikkawa
Keyword(s):  
Biochemical Characterization ◽  
Electron Tomography ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Dynein Motor ◽  
Cryo Electron Tomography ◽  
Regulatory Complex ◽  
And Function

The nexin-dynein regulatory complex (N-DRC) forms a cross-bridge between the outer doublet microtubules of the axoneme and regulates dynein motor activity in cilia/flagella. Although the molecular composition and the three-dimensional structure of N-DRC have been studied using mutant strains lacking N-DRC subunits, more accurate approaches are necessary to characterize the structure and function of N-DRC. In this study, we precisely localized DRC1, DRC2, and DRC4 using cryo–electron tomography and structural labeling. All three N-DRC subunits had elongated conformations and spanned the length of N-DRC. Furthermore, we purified N-DRC and characterized its microtubule-binding properties. Purified N-DRC bound to the microtubule and partially inhibited microtubule sliding driven by the outer dynein arms (ODAs). Of interest, microtubule sliding was observed even in the presence of fourfold molar excess of N-DRC relative to ODA. These results provide insights into the role of N-DRC in generating the beating motions of cilia/flagella.

scholarly journals Architecture and mechanism of metazoan retromer:SNX3 tubular coat assembly

2021 ◽  
Vol 7 (13) ◽  
pp. eabf8598 ◽  
Author(s):  
Natalya Leneva ◽  
Oleksiy Kovtun ◽  
Dustin R. Morado ◽  
John A. G. Briggs ◽  
David J. Owen
Keyword(s):  
Electron Tomography ◽  
Structural Basis ◽  
Cellular Transport ◽  
Sorting Nexins ◽  
Membrane Recruitment ◽  
Sorting Nexin ◽  
Cellular Processes ◽  
Cryo Electron Tomography ◽  
Membrane Tubulation ◽  
Membrane Bending

Retromer is a master regulator of cargo retrieval from endosomes, which is critical for many cellular processes including signaling, immunity, neuroprotection, and virus infection. The retromer core (VPS26/VPS29/VPS35) is present on cargo-transporting, tubular carriers along with a range of sorting nexins. Here, we elucidate the structural basis of membrane tubulation and coupled cargo recognition by metazoan and fungal retromer coats assembled with the non–Bin1/Amphiphysin/Rvs (BAR) sorting nexin SNX3 using cryo–electron tomography. The retromer core retains its arched, scaffolding structure but changes its mode of membrane recruitment when assembled with different SNX adaptors, allowing cargo recognition at subunit interfaces. Thus, membrane bending and cargo incorporation can be modulated to allow retromer to traffic cargoes along different cellular transport routes.

Assembly of COPI and COPII Vesicular Coat Proteins on Membranes

2018 ◽  
Vol 47 (1) ◽  
pp. 63-83 ◽  
Author(s):  
Julien Béthune ◽  
Felix T. Wieland
Keyword(s):  
Electron Tomography ◽  
Coat Proteins ◽  
Structural Elements ◽  
X Ray Crystallography ◽  
Transport Vesicles ◽  
Cryo Electron Tomography ◽  
Functional Implications ◽  
Cargo Proteins ◽  
Intracellular Compartments ◽  
Proteins And Peptides

In eukaryotes, distinct transport vesicles functionally connect various intracellular compartments. These carriers mediate transport of membranes for the biogenesis and maintenance of organelles, secretion of cargo proteins and peptides, and uptake of cargo into the cell. Transport vesicles have distinct protein coats that assemble on a donor membrane where they can select cargo and curve the membrane to form a bud. A multitude of structural elements of coat proteins have been solved by X-ray crystallography. More recently, the architectures of the COPI and COPII coats were elucidated in context with their membrane by cryo-electron tomography. Here, we describe insights gained from the structures of these two coat lattices and discuss the resulting functional implications.

scholarly journals Structural Conservation and Adaptation of the Bacterial Flagella Motor

Biomolecules ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1492
Author(s):  
Brittany L. Carroll ◽  
Jun Liu
Keyword(s):  
Electron Tomography ◽  
X Ray ◽  
Bacterial Flagella ◽  
X Ray Crystallography ◽  
Cryo Electron Microscopy ◽  
Cryo Electron Tomography ◽  
Flagellar Assembly ◽  
Structural Conservation ◽  
And Function ◽  
Structural Insights

Many bacteria require flagella for the ability to move, survive, and cause infection. The flagellum is a complex nanomachine that has evolved to increase the fitness of each bacterium to diverse environments. Over several decades, molecular, biochemical, and structural insights into the flagella have led to a comprehensive understanding of the structure and function of this fascinating nanomachine. Notably, X-ray crystallography, cryo-electron microscopy (cryo-EM), and cryo-electron tomography (cryo-ET) have elucidated the flagella and their components to unprecedented resolution, gleaning insights into their structural conservation and adaptation. In this review, we focus on recent structural studies that have led to a mechanistic understanding of flagellar assembly, function, and evolution.

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