Comparison of the envelope architecture of E. coli using two methods: CEMOVIS and 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.

Download Full-text

Alternative Architecture of the E. coli Chemosensory Array

Biomolecules ◽

10.3390/biom11040495 ◽

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.

Download Full-text

Alternative Architecture of the E. Coli Chemosensory Array

10.21203/rs.3.rs-124318/v1 ◽

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.

Download Full-text

Alternative architecture of the E. coli chemosensory array

10.1101/2021.02.05.429929 ◽

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.

Download Full-text