scholarly journals Cell Shape Can Mediate the Spatial Organization of the Bacterial Cytoskeleton

2013 ◽  
Vol 104 (2) ◽  
pp. 642a
Author(s):  
Siyuan Wang ◽  
Ned S. Wingreen
Keyword(s):  
Cell Shape ◽  
Spatial Organization ◽  
Bacterial Cytoskeleton

scholarly journals Localization and Interactions of Teichoic Acid Synthetic Enzymes in Bacillus subtilis

2007 ◽  
Vol 190 (5) ◽  
pp. 1812-1821 ◽  
Author(s):  
Alex Formstone ◽  
Rut Carballido-López ◽  
Philippe Noirot ◽  
Jeffery Errington ◽  
Dirk-Jan Scheffers
Keyword(s):  
Bacillus Subtilis ◽  
Cell Shape ◽  
Spatial Organization ◽  
Structural Integrity ◽  
Fluorescent Protein ◽  
Teichoic Acid ◽  
Cytoskeletal Proteins ◽  
Thick Wall ◽  
Wall Teichoic Acid ◽  
Critical Function

ABSTRACT The thick wall of gram-positive bacteria is a polymer meshwork composed predominantly of peptidoglycan (PG) and teichoic acids, both of which have a critical function in maintenance of the structural integrity and the shape of the cell. In Bacillus subtilis 168 the major teichoic acid is covalently coupled to PG and is known as wall teichoic acid (WTA). Recently, PG insertion/degradation over the lateral wall has been shown to occur in a helical pattern. However, the spatial organization of WTA assembly and its relationship with cell shape and PG assembly are largely unknown. We have characterized the localization of green fluorescent protein fusions to proteins involved in several steps of WTA synthesis in B. subtilis: TagB, -F, -G, -H, and -O. All of these localized similarly to the inner side of the cytoplasmic membrane, in a pattern strikingly similar to that displayed by probes of nascent PG. Helix-like localization patterns are often attributable to the morphogenic cytoskeletal proteins of the MreB family. However, localization of the Tag proteins did not appear to be substantially affected by single disruption of any of the three MreB homologues of B. subtilis. Bacterial and yeast two-hybrid experiments revealed a complex network of interactions involving TagA, -B, -E, -F, -G, -H, and -O and the cell shape determinants MreC and MreD (encoded by the mreBCD operon and presumably involved in the spatial organization of PG synthesis). Taken together, our results suggest that, in B. subtilis at least, the synthesis and export of WTA precursors are mediated by a large multienzyme complex that may be associated with the PG-synthesizing machinery.

scholarly journals Contact guidance requires spatial control of leading-edge protrusion

2017 ◽  
Vol 28 (8) ◽  
pp. 1043-1053 ◽  
Author(s):  
G. R. Ramirez-San Juan ◽  
P. W. Oakes ◽  
M. L. Gardel
Keyword(s):  
Cell Shape ◽  
Spatial Organization ◽  
Leading Edge ◽  
Contact Guidance ◽  
Spatial Constraints ◽  
Migration Direction ◽  
Line Spacing ◽  
Geometric Cues ◽  
And Migration

In vivo, geometric cues from the extracellular matrix (ECM) are critical for the regulation of cell shape, adhesion, and migration. During contact guidance, the fibrillar architecture of the ECM promotes an elongated cell shape and migration along the fibrils. The subcellular mechanisms by which cells sense ECM geometry and translate it into changes in shape and migration direction are not understood. Here we pattern linear fibronectin features to mimic fibrillar ECM and elucidate the mechanisms of contact guidance. By systematically varying patterned line spacing, we show that a 2-μm spacing is sufficient to promote cell shape elongation and migration parallel to the ECM, or contact guidance. As line spacing is increased, contact guidance increases without affecting migration speed. To elucidate the subcellular mechanisms of contact guidance, we analyze quantitatively protrusion dynamics and find that the structured ECM orients cellular protrusions parallel to the ECM. This spatial organization of protrusion relies on myosin II contractility, and feedback between adhesion and Rac-mediated protrusive activity, such that we find Arp2/3 inhibition can promote contact guidance. Together our data support a model for contact guidance in which the ECM enforces spatial constraints on the lamellipodia that result in cell shape elongation and enforce migration direction.

scholarly journals RodZ modulates geometric localization of the bacterial actin MreB to regulate cell shape

2017 ◽  
Author(s):  
Alexandre Colavin ◽  
Handuo Shi ◽  
Kerwyn Casey Huang
Keyword(s):  
Cell Wall ◽  
Cell Shape ◽  
Spatial Organization ◽  
Dependent Manner ◽  
Cell Width ◽  
E Coli ◽  
Wall Growth ◽  
The Rich ◽  
Dynamics Simulations ◽  
Geometric Localization

AbstractIn the rod-shaped bacteriumEscherichia coli, the actin-like protein MreB localizes in a curvature-dependent manner and spatially coordinates cell-wall insertion to maintain cell shape across changing environments, although the molecular mechanism by which cell width is regulated remains unknown. Here, we demonstrate that the bitopic membrane protein RodZ regulates the biophysical properties of MreB and alters the spatial organization ofE. colicell-wall growth. The relative expression levels of MreB and RodZ changed in a manner commensurate with variations in growth rate and cell width. We carried out single-cell analyses to determine that RodZ systematically alters the curvature-based localization of MreB and cell width in a manner dependent on the concentration of RodZ. Finally, we identified MreB mutants that we predict using molecular dynamics simulations to alter the bending properties of MreB filaments at the molecular scale similar to RodZ binding, and showed that these mutants rescued rod-like shape in the absence of RodZ alone or in combination with wild-type MreB. Together, our results show thatE. colicontrols its shape and dimensions by differentially regulating RodZ and MreB to alter the patterning of cell-wall insertion, highlighting the rich regulatory landscape of cytoskeletal molecular biophysics.

scholarly journals Masters of asymmetry – lessons and perspectives from 50 years of septins

2020 ◽  
Vol 31 (21) ◽  
pp. 2289-2297
Author(s):  
Elias T. Spiliotis ◽  
Michael A. McMurray
Keyword(s):  
Symmetry Breaking ◽  
Cell Polarity ◽  
Actin Filaments ◽  
Cell Shape ◽  
Spatial Organization ◽  
Protein Localization ◽  
50Th Anniversary ◽  
Small Gtpases ◽  
Molecular Asymmetry ◽  
Distinct Membrane

Septins are a unique family of GTPases, which were discovered 50 years ago as essential genes for the asymmetric cell shape and division of budding yeast. Septins assemble into filamentous nonpolar polymers, which associate with distinct membrane macrodomains and subpopulations of actin filaments and microtubules. While structurally a cytoskeleton-like element, septins function predominantly as spatial regulators of protein localization and interactions. Septin scaffolds and barriers have provided a long-standing paradigm for the generation and maintenance of asymmetry in cell membranes. Septins also promote asymmetry by regulating the spatial organization of the actin and microtubule cytoskeleton, and biasing the directionality of membrane traffic. In this 50th anniversary perspective, we highlight how septins have conserved and adapted their roles as effectors of membrane and cytoplasmic asymmetry across fungi and animals. We conclude by outlining principles of septin function as a module of symmetry breaking, which alongside the monomeric small GTPases provides a core mechanism for the biogenesis of molecular asymmetry and cell polarity.

scholarly journals Ninein is essential for apico-basal microtubule formation and CLIP-170 facilitates its redeployment to non-centrosomal microtubule organizing centres

Open Biology ◽  
2017 ◽  
Vol 7 (2) ◽  
pp. 160274 ◽  
Author(s):  
Deborah A. Goldspink ◽  
Chris Rookyard ◽  
Benjamin J. Tyrrell ◽  
Jonathan Gadsby ◽  
James Perkins ◽  
...  
Keyword(s):  
Cell Shape ◽  
Spatial Organization ◽  
Dependent Manner ◽  
Microtubule Organizing Centres ◽  
Functional Inhibition ◽  
Genes Encoding ◽  
Anchoring Protein ◽  
Microtubule Formation ◽  
And Function

Differentiation of columnar epithelial cells involves a dramatic reorganization of the microtubules (MTs) and centrosomal components into an apico-basal array no longer anchored at the centrosome. Instead, the minus-ends of the MTs become anchored at apical non-centrosomal microtubule organizing centres (n-MTOCs). Formation of n-MTOCs is critical as they determine the spatial organization of MTs, which in turn influences cell shape and function. However, how they are formed is poorly understood. We have previously shown that the centrosomal anchoring protein ninein is released from the centrosome, moves in a microtubule-dependent manner and accumulates at n-MTOCs during epithelial differentiation. Here, we report using depletion and knockout (KO) approaches that ninein expression is essential for apico-basal array formation and epithelial elongation and that CLIP-170 is required for its redeployment to n-MTOCs. Functional inhibition also revealed that IQGAP1 and active Rac1 coordinate with CLIP-170 to facilitate microtubule plus-end cortical targeting and ninein redeployment. Intestinal tissue and in vitro organoids from the Clip1/Clip2 double KO mouse with deletions in the genes encoding CLIP-170 and CLIP-115, respectively, confirmed requirement of CLIP-170 for ninein recruitment to n-MTOCs, with possible compensation by other anchoring factors such as p150 Glued and CAMSAP2 ensuring apico-basal microtubule formation despite loss of ninein at n-MTOCs.

Modulated polarization microscopy displays the dynamics of cytoskeletal structures in living, motile cells

1995 ◽  
Vol 53 ◽  
pp. 902-903
Author(s):  
J. R. Kuhn ◽  
M. Poenie
Keyword(s):  
Mitotic Spindle ◽  
Actin Filaments ◽  
Cell Shape ◽  
Dynamic Structure ◽  
Living Cells ◽  
Cytoskeletal Proteins ◽  
Polarization Microscopy ◽  
Video Enhancement ◽  
Ultrastructural Studies ◽  
Motile Cells

Cell shape and movement are controlled by elements of the cytoskeleton including actin filaments an microtubules. Unfortunately, it is difficult to visualize the cytoskeleton in living cells and hence follow it dynamics. Immunofluorescence and ultrastructural studies of fixed cells while providing clear images of the cytoskeleton, give only a static picture of this dynamic structure. Microinjection of fluorescently Is beled cytoskeletal proteins has proved useful as a way to follow some cytoskeletal events, but long terry studies are generally limited by the bleaching of fluorophores and presence of unassembled monomers.Polarization microscopy has the potential for visualizing the cytoskeleton. Although at present, it ha mainly been used for visualizing the mitotic spindle. Polarization microscopy is attractive in that it pro vides a way to selectively image structures such as cytoskeletal filaments that are birefringent. By combing ing standard polarization microscopy with video enhancement techniques it has been possible to image single filaments. In this case, however, filament intensity depends on the orientation of the polarizer and analyzer with respect to the specimen.

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