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Assembly and Architecture of Gram-Positive and -Negative Cell Walls

Gumbart, James C. and Beeby, Morgan and Jensen, Grant J. and Roux, Benoit (2013) Assembly and Architecture of Gram-Positive and -Negative Cell Walls. Biophysical Journal, 104 (2). 642A. ISSN 0006-3495. doi:10.1016/j.bpj.2012.11.3544.

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The cell wall, a porous mesh-like structure, provides shape and physical protection for bacteria. At the atomic level, it is composed of peptidoglycan (PG), a polymer of stiff glycan strands cross-linked by short, flexible peptides. However, at the mesoscale, multiple models for the organization of PG have been put forth, distinguished by glycan strands parallel to the cell surface (the so-called "layered'' model) or perpendicular (the “scaffold” model). To test these models, and to resolve the mechanical properties of PG, we have built and simulated at an atomic scale patches of both Gram-positive and negative cell walls in different organizations up to 50 nanometers in size. In the case of Gram-positive PG, molecular dynamics simulations of the layered model are found to elucidate the mechanisms behind a distinct curling effect observed in three-dimensional electron cryo-tomography images of fragmented cell walls. For Gram-negative PG, simulations of patches with different average-glycan-strand lengths reveal an anisotropic elasticity, in good agreement with atomic-force microscopy experiments. Insights from the simulations reveal how mesoscopic and macroscopic properties of a ubiquitous bacterial ultrastructure arise from its atomic-scale interactions and organization.

Item Type:Article
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Beeby, Morgan0000-0001-6413-9835
Jensen, Grant J.0000-0003-1556-4864
Additional Information:© 2013 Biophysical Society. Published by Elsevier Inc.
Issue or Number:2
Record Number:CaltechAUTHORS:20130425-135202813
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Official Citation:James C. Gumbart, Morgan Beeby, Grant Jensen, Benoit Roux, Assembly and Architecture of Gram-Positive and -Negative Cell Walls, Biophysical Journal, Volume 104, Issue 2, Supplement 1, 29 January 2013, Page 642a, ISSN 0006-3495, 10.1016/j.bpj.2012.11.3544.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:38121
Deposited By: Tony Diaz
Deposited On:03 May 2013 21:47
Last Modified:09 Nov 2021 23:33

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