scholarly journals The Flagellar Motor of Caulobacter Crescentus Generates More Torque When a Cell Swims Backward

2016 ◽  
Vol 110 (3) ◽  
pp. 198a
Author(s):  
Pushkar Lele ◽  
Howard Berg
Keyword(s):  
Caulobacter Crescentus ◽  
Flagellar Motor ◽  
A Cell

scholarly journals The flagellar motor of Caulobacter crescentus generates more torque when a cell swims backwards

2015 ◽  
Vol 12 (2) ◽  
pp. 175-178 ◽  
Author(s):  
Pushkar P. Lele ◽  
Thibault Roland ◽  
Abhishek Shrivastava ◽  
Yihao Chen ◽  
Howard C. Berg
Keyword(s):  
Caulobacter Crescentus ◽  
Flagellar Motor ◽  
A Cell

scholarly journals The presence and absence of periplasmic rings in bacterial flagellar motors correlates with stator type

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Mohammed Kaplan ◽  
Debnath Ghosal ◽  
Poorna Subramanian ◽  
Catherine M Oikonomou ◽  
Andreas Kjaer ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Pathogenic Bacteria ◽  
Bioinformatics Analysis ◽  
Cell Envelope ◽  
Shewanella Oneidensis ◽  
Flagellar Motor ◽  
Flagellar Motors ◽  
A Cell ◽  
Animal Hosts

The bacterial flagellar motor, a cell-envelope-embedded macromolecular machine that functions as a cellular propeller, exhibits significant structural variability between species. Different torque-generating stator modules allow motors to operate in different pH, salt or viscosity levels. How such diversity evolved is unknown. Here, we use electron cryo-tomography to determine the in situ macromolecular structures of three Gammaproteobacteria motors: Legionella pneumophila, Pseudomonas aeruginosa, and Shewanella oneidensis, providing the first views of intact motors with dual stator systems. Complementing our imaging with bioinformatics analysis, we find a correlation between the motor’s stator system and its structural elaboration. Motors with a single H+-driven stator have only the core periplasmic P- and L-rings; those with dual H+-driven stators have an elaborated P-ring; and motors with Na+ or Na+/H+-driven stators have both their P- and L-rings embellished. Our results suggest an evolution of structural elaboration that may have enabled pathogenic bacteria to colonize higher-viscosity environments in animal hosts.

scholarly journals Mutations in the Lipopolysaccharide Biosynthesis Pathway Interfere with Crescentin-Mediated Cell Curvature in Caulobacter crescentus

2010 ◽  
Vol 192 (13) ◽  
pp. 3368-3378 ◽  
Author(s):  
Matthew T. Cabeen ◽  
Michelle A. Murolo ◽  
Ariane Briegel ◽  
N. Khai Bui ◽  
Waldemar Vollmer ◽  
...  
Keyword(s):  
Cell Wall ◽  
Caulobacter Crescentus ◽  
Cell Envelope ◽  
Cellular Systems ◽  
Biosynthesis Pathway ◽  
Cell Morphogenesis ◽  
Division Site ◽  
Growth Properties ◽  
A Cell ◽  
Cellular Components

ABSTRACT Bacterial cell morphogenesis requires coordination among multiple cellular systems, including the bacterial cytoskeleton and the cell wall. In the vibrioid bacterium Caulobacter crescentus, the intermediate filament-like protein crescentin forms a cell envelope-associated cytoskeletal structure that controls cell wall growth to generate cell curvature. We undertook a genetic screen to find other cellular components important for cell curvature. Here we report that deletion of a gene (wbqL) involved in the lipopolysaccharide (LPS) biosynthesis pathway abolishes cell curvature. Loss of WbqL function leads to the accumulation of an aberrant O-polysaccharide species and to the release of the S layer in the culture medium. Epistasis and microscopy experiments show that neither S-layer nor O-polysaccharide production is required for curved cell morphology per se but that production of the altered O-polysaccharide species abolishes cell curvature by apparently interfering with the ability of the crescentin structure to associate with the cell envelope. Our data suggest that perturbations in a cellular pathway that is itself fully dispensable for cell curvature can cause a disruption of cell morphogenesis, highlighting the delicate harmony among unrelated cellular systems. Using the wbqL mutant, we also show that the normal assembly and growth properties of the crescentin structure are independent of its association with the cell envelope. However, this envelope association is important for facilitating the local disruption of the stable crescentin structure at the division site during cytokinesis.

Inroads through the bacterial cell envelope: seeing is believing

2018 ◽  
Vol 64 (9) ◽  
pp. 601-617 ◽  
Author(s):  
Cezar M. Khursigara ◽  
Susan F. Koval ◽  
Dianne M. Moyles ◽  
Robert J. Harris
Keyword(s):  
Electron Microscopy ◽  
Bacterial Cell ◽  
Caulobacter Crescentus ◽  
Cell Envelope ◽  
Cell Fractionation ◽  
Doctoral Studies ◽  
Cryo Electron Microscopy ◽  
A Cell ◽  
Cell Envelopes ◽  
Microscopy Techniques

A singular feature of all prokaryotic cells is the presence of a cell envelope composed of a cytoplasmic membrane and a cell wall. The introduction of bacterial cell fractionation techniques in the 1950s and 1960s along with developments in procedures for electron microscopy opened the window towards an understanding of the chemical composition and architecture of the cell envelope. This review traces the contribution of Terry Beveridge in these endeavours, beginning with his doctoral studies in the 1970s on the structure of paracrystalline surface arrays (S-layers), followed by an exploration of cryogenic methods for preserving bacteria for ultrastructural analyses. His insights are reflected in a current example of the contribution of cryo-electron microscopy to S-layer studies — the structure and assembly of the surface array of Caulobacter crescentus. The review then focuses on Terry’s contributions to imaging the ultrastructure of bacterial cell envelopes and to the development of cryo-electron microscopy techniques, including the use of CEMOVIS (Cryo-electron Microscopy of Vitreous Sections) to “see” the ultrastructure of the Gram-positive cell envelope — his last scientific endeavour.

scholarly journals HdaB: a novel and conserved DnaA-related protein that targets the RIDA process to stimulate replication initiation

2019 ◽  
Vol 48 (5) ◽  
pp. 2412-2423 ◽  
Author(s):  
Antonio Frandi ◽  
Justine Collier
Keyword(s):  
Stationary Phase ◽  
Caulobacter Crescentus ◽  
Replication Initiation ◽  
Lag Phase ◽  
Related Protein ◽  
Free Living ◽  
Changing Environments ◽  
A Cell ◽  
The Impact

Abstract Exquisite control of the DnaA initiator is critical to ensure that bacteria initiate chromosome replication in a cell cycle-coordinated manner. In many bacteria, the DnaA-related and replisome-associated Hda/HdaA protein interacts with DnaA to trigger the Regulatory Inactivation of DnaA (RIDA) and prevent over-initiation events. In the Caulobacter crescentus Alphaproteobacterium, the RIDA process also targets DnaA for its rapid proteolysis by Lon. The impact of the RIDA process on adaptation of bacteria to changing environments remains unexplored. Here, we identify a novel and conserved DnaA-related protein, named HdaB, and show that homologs from three different Alphaproteobacteria can inhibit the RIDA process, leading to over-initiation and cell death when expressed in actively growing C. crescentus cells. We further show that HdaB interacts with HdaA in vivo, most likely titrating HdaA away from DnaA. Strikingly, we find that HdaB accumulates mainly during stationary phase and that it shortens the lag phase upon exit from stationary phase. Altogether, these findings suggest that expression of hdaB during stationary phase prepares cells to restart the replication of their chromosome as soon as conditions improve, a situation often met by free-living or facultative intracellular Alphaproteobacteria.

scholarly journals Conserved Promoter Motif Is Required for Cell Cycle Timing of dnaX Transcription inCaulobacter

2001 ◽  
Vol 183 (16) ◽  
pp. 4860-4865 ◽  
Author(s):  
Kenneth C. Keiler ◽  
Lucy Shapiro
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Caulobacter Crescentus ◽  
Transcriptional Networks ◽  
Cellular Processes ◽  
Genes Encoding ◽  
Constitutive Gene Expression ◽  
A Cell ◽  
Replication Factors

ABSTRACT Cells use highly regulated transcriptional networks to control temporally regulated events. In the bacterium Caulobacter crescentus, many cellular processes are temporally regulated with respect to the cell cycle, and the genes required for these processes are expressed immediately before the products are needed. Genes encoding factors required for DNA replication, includingdnaX, dnaA, dnaN,gyrB, and dnaK, are induced at the G1/S-phase transition. By analyzing mutations in thednaX promoter, we identified a motif between the −10 and −35 regions that is required for proper timing of gene expression. This motif, named RRF (for repression of replication factors), is conserved in the promoters of other coordinately induced replication factors. Because mutations in the RRF motif result in constitutive gene expression throughout the cell cycle, this sequence is likely to be the binding site for a cell cycle-regulated transcriptional repressor. Consistent with this hypothesis, Caulobacter extracts contain an activity that binds specifically to the RRF in vitro.

scholarly journals Bactofilins, a ubiquitous class of cytoskeletal proteins mediating polar localization of a cell wall synthase in Caulobacter crescentus

2009 ◽  
Vol 29 (2) ◽  
pp. 327-339 ◽  
Author(s):  
Juliane Kühn ◽  
Ariane Briegel ◽  
Erhard Mörschel ◽  
Jörg Kahnt ◽  
Katja Leser ◽  
...  
Keyword(s):  
Cell Wall ◽  
Caulobacter Crescentus ◽  
Cytoskeletal Proteins ◽  
Polar Localization ◽  
A Cell

scholarly journals A cell cycle-regulated adenine DNA methyltransferase from Caulobacter crescentus processively methylates GANTC sites on hemimethylated DNA

1998 ◽  
Vol 95 (6) ◽  
pp. 2874-2879 ◽  
Author(s):  
A. J. Berdis ◽  
I. Lee ◽  
J. K. Coward ◽  
C. Stephens ◽  
R. Wright ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Methyltransferase ◽  
Caulobacter Crescentus ◽  
A Cell

Locomotion of a single-flagellated bacterium

2018 ◽  
Vol 859 ◽  
pp. 586-612 ◽  
Author(s):  
Yunyoung Park ◽  
Yongsam Kim ◽  
Sookkyung Lim
Keyword(s):  
Rotational Frequency ◽  
Geometrical Parameters ◽  
Flagellar Motor ◽  
Bending Rigidity ◽  
Elastic Rod ◽  
Critical Thresholds ◽  
Kirchhoff Rod ◽  
Bending Modulus ◽  
Swimming Pattern ◽  
A Cell

Single-flagellated bacteria propel themselves by rotating a flagellar motor, translating rotation to the filament through a compliant hook and subsequently driving the rotation of the flagellum. The flagellar motor alternates the direction of rotation between counterclockwise and clockwise, and this leads to the forward and backward directed swimming. Such bacteria can change the course of swimming as the hook experiences its buckling caused by the change of bending rigidity. In this paper, we present a comprehensive model of a monotrichous bacterium as a free swimmer in a viscous fluid. We describe a cell body as a rigid body using the penalty method and a flagellum as an elastic rod using Kirchhoff rod theory. The hydrodynamic interaction of the bacterium is described by the regularized Stokes formulation. Our model of a single-flagellated micro-organism is able to mimic a swimming pattern that is well matched with the experimental observation. Furthermore, we find the critical thresholds of the rotational frequency of the motor and the bending modulus of the hook for the buckling instability, and investigate the dependence of the buckling angle and the reorientation of the swimming cell after buckling on the physical and geometrical parameters of the model.

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