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 The structural complexity of the Gammaproteobacteria flagellar motor is related to the type of its torque-generating stators

2018 ◽  
Author(s):  
Mohammed Kaplan ◽  
Debnath Ghosal ◽  
Poorna Subramanian ◽  
Catherine M. Oikonomou ◽  
Andreas Kjær ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Pathogenic Bacteria ◽  
Cell Envelope ◽  
Shewanella Oneidensis ◽  
Structural Complexity ◽  
High Viscosity ◽  
Flagellar Motor ◽  
Flagellar Motors ◽  
Wide Range ◽  
A Cell

AbstractThe bacterial flagellar motor is a cell-envelope-embedded macromolecular machine that functions as a propeller to move the cell. Rather than being an invariant machine, the flagellar motor exhibits significant variability between species, allowing bacteria to adapt to, and thrive in, a wide range of environments. For instance, different torque-generating stator modules allow motors to operate in conditions with different pH and sodium concentrations and some motors are adapted to drive motility in high-viscosity environments. How such diversity evolved is unknown. Here we use electron cryo-tomography to determine thein situmacromolecular structures of the flagellar motors of three Gammaproteobacteria species:Legionella pneumophila,Pseudomonas aeruginosa, andShewanella oneidensisMR-1, providing the first views of intact motors with dual stator systems. Complementing our imaging with bioinformatics analysis, we find a correlation between the stator system of the motor and its structural complexity. Motors with a single H+-driven stator system have only the core P- and L-rings in their periplasm; those with dual H+-driven stator systems have an extra component elaborating their P-ring; and motors with Na+- (or dual Na+-H+)- driven stator systems have additional rings surrounding both their P- and L-rings. Our results suggest an evolution of structural complexity that may have enabled pathogenic bacteria likeL. pneumophilaandP. aeruginosato colonize higher-viscosity environments in animal hosts.

scholarly journals Intact Flagellar Motor of Borrelia burgdorferi Revealed by Cryo-Electron Tomography: Evidence for Stator Ring Curvature and Rotor/C-Ring Assembly Flexion

2009 ◽  
Vol 191 (16) ◽  
pp. 5026-5036 ◽  
Author(s):  
Jun Liu ◽  
Tao Lin ◽  
Douglas J. Botkin ◽  
Erin McCrum ◽  
Hanspeter Winkler ◽  
...  
Keyword(s):  
Borrelia Burgdorferi ◽  
Electron Tomography ◽  
Rotational Symmetry ◽  
Flagellar Motor ◽  
Cell Axis ◽  
Ring Assembly ◽  
Flagellar Motors ◽  
Cryo Electron Tomography ◽  
Flagellar Rotation

ABSTRACT The bacterial flagellar motor is a remarkable nanomachine that provides motility through flagellar rotation. Prior structural studies have revealed the stunning complexity of the purified rotor and C-ring assemblies from flagellar motors. In this study, we used high-throughput cryo-electron tomography and image analysis of intact Borrelia burgdorferi to produce a three-dimensional (3-D) model of the in situ flagellar motor without imposing rotational symmetry. Structural details of B. burgdorferi, including a layer of outer surface proteins, were clearly visible in the resulting 3-D reconstructions. By averaging the 3-D images of ∼1,280 flagellar motors, a ∼3.5-nm-resolution model of the stator and rotor structures was obtained. flgI transposon mutants lacked a torus-shaped structure attached to the flagellar rod, establishing the structural location of the spirochetal P ring. Treatment of intact organisms with the nonionic detergent NP-40 resulted in dissolution of the outermost portion of the motor structure and the C ring, providing insight into the in situ arrangement of the stator and rotor structures. Structural elements associated with the stator followed the curvature of the cytoplasmic membrane. The rotor and the C ring also exhibited angular flexion, resulting in a slight narrowing of both structures in the direction perpendicular to the cell axis. These results indicate an inherent flexibility in the rotor-stator interaction. The FliG switching and energizing component likely provides much of the flexibility needed to maintain the interaction between the curved stator and the relatively symmetrical rotor/C-ring assembly during flagellar rotation.

scholarly journals Stable sub-complexes observedin situsuggest a modular assembly pathway of the bacterial flagellar motor

2018 ◽  
Author(s):  
Mohammed Kaplan ◽  
Poorna Subramanian ◽  
Debnath Ghosal ◽  
Catherine M. Oikonomou ◽  
Sahand Pirbadian ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Self Assembly ◽  
Protein Localization ◽  
Shewanella Oneidensis ◽  
Flagellar Motor ◽  
Inner Membrane ◽  
Assembly Mechanism ◽  
Alternate Model ◽  
Bacterial Flagellar Motor ◽  
Spatio Temporal

AbstractThe self-assembly of cellular macromolecular machines such as the bacterial flagellar motor requires the spatio-temporal synchronization of gene expression, protein localization and association of a dozen or more unique components. InSalmonellaandEscherichia coli, a sequential, outward assembly mechanism has been proposed for the flagellar motor starting from the inner membrane, with each subsequent component stabilizing the last. Here, using electron cryo-tomography of intactLegionella pneumophila,Pseudomonas aeruginosaandShewanella oneidensiscells, we observe stable outer-membrane-embedded sub-complexes of the flagellar motor. These sub-complexes consist of the periplasmic embellished P- and L-rings, in the absence of other flagellar components, and bend the membrane inward dramatically. Additionally, we also observe independent inner-membrane sub-complexes consisting of the C- and MS-rings and export apparatus. These results suggest an alternate model for flagellar motor assembly in which outer- and inner-membrane-associated sub-complexes form independently and subsequently join, enabling later steps of flagellar production to proceed.

scholarly journals MotP Subunit is Critical for Ion Selectivity and Evolution of a K+-Coupled Flagellar Motor

Biomolecules ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 691 ◽  
Author(s):  
Shun Naganawa ◽  
Masahiro Ito
Keyword(s):  
Molecular Mechanisms ◽  
Cell Envelope ◽  
Ion Selectivity ◽  
Flagellar Motor ◽  
Transmembrane Segment ◽  
Electrochemical Gradient ◽  
Genus Bacillus ◽  
Interaction Forces ◽  
Flagellar Motors ◽  
Selection Of

The bacterial flagellar motor is a sophisticated nanomachine embedded in the cell envelope. The flagellar motor is driven by an electrochemical gradient of cations such as H+, Na+, and K+ through ion channels in stator complexes embedded in the cell membrane. The flagellum is believed to rotate as a result of electrostatic interaction forces between the stator and the rotor. In bacteria of the genus Bacillus and related species, the single transmembrane segment of MotB-type subunit protein (MotB and MotS) is critical for the selection of the H+ and Na+ coupling ions. Here, we constructed and characterized several hybrid stators combined with single Na+-coupled and dual Na+- and K+-coupled stator subunits, and we report that the MotP subunit is critical for the selection of K+. This result suggested that the K+ selectivity of the MotP/MotS complexes evolved from the single Na+-coupled stator MotP/MotS complexes. This finding will promote the understanding of the evolution of flagellar motors and the molecular mechanisms of coupling ion selectivity.

scholarly journals Lifestyle of sponge symbiont phages by host prediction and correlative microscopy

2021 ◽  
Author(s):  
M. T. Jahn ◽  
T. Lachnit ◽  
S. M. Markert ◽  
C. Stigloher ◽  
L. Pita ◽  
...  
Keyword(s):  
Distinct Pattern ◽  
Microbial Consortia ◽  
Bacterial Symbionts ◽  
Correlative Microscopy ◽  
Phage Ecology ◽  
Infection Dynamics ◽  
Imaging Approach ◽  
Animal Hosts ◽  
Viral Distribution

AbstractBacteriophages (phages) are ubiquitous elements in nature, but their ecology and role in animals remains little understood. Sponges represent the oldest known extant animal-microbe symbiosis and are associated with dense and diverse microbial consortia. Here we investigate the tripartite interaction between phages, bacterial symbionts, and the sponge host. We combined imaging and bioinformatics to tackle important questions on who the phage hosts are and what the replication mode and spatial distribution within the animal is. This approach led to the discovery of distinct phage-microbe infection networks in sponge versus seawater microbiomes. A new correlative in situ imaging approach (‘PhageFISH-CLEM‘) localised phages within bacterial symbiont cells, but also within phagocytotically active sponge cells. We postulate that the phagocytosis of free virions by sponge cells modulates phage-bacteria ratios and ultimately controls infection dynamics. Prediction of phage replication strategies indicated a distinct pattern, where lysogeny dominates the sponge microbiome, likely fostered by sponge host-mediated virion clearance, while lysis dominates in seawater. Collectively, this work provides new insights into phage ecology within sponges, highlighting the importance of tripartite animal-phage-bacterium interplay in holobiont functioning. We anticipate that our imaging approach will be instrumental to further understanding of viral distribution and cellular association in animal hosts.

Fate and transport of faecal contamination microbial indicators, pathogenic protozoa and Campylobacter in the artificially recharged fractured aquifer of Salento, Italy

2008 ◽  
Vol 57 (6) ◽  
pp. 849-856 ◽  
Author(s):  
R. La Mantia ◽  
C. Masciopinto ◽  
C. Levantesi ◽  
V. Tandoi
Keyword(s):  
Pathogenic Bacteria ◽  
Fate And Transport ◽  
Fractured Aquifer ◽  
Specific Detection ◽  
Microbial Indicators ◽  
Faecal Contamination ◽  
Time Required ◽  
Indicators Of Faecal Contamination ◽  
Campylobacter Spp

The study investigates the fate and transport of microorganisms introduced by artificial groundwater recharge at the Nardò fractured aquifer in Salento, Italy. Microbial indicators of faecal contamination, parasitic protozoa (Giardia and Cryptosporidium) and pathogenic bacteria (Campylobacter spp.), were monitored into injected water and groundwater to test the efficiency of the “natural disinfection” into the fractured aquifer. A remarkable decrease of microbial indicators and pathogens was observed suggesting that pathogens removal or inactivation may be possible during water flow in fractured aquifer. The recently described PNA probe CJE195 (Lehtola et al. 2005) was utilised for the rapid and specific detection of Campylobacter spp. by fluorescence in situ hybridization (FISH) after enrichment. FISH results were consistent with those of traditional cultural method (ISO 17995) applied in parallel: time required for Campylobacter identification was reduced of 4 days.

scholarly journals An in situ near-ambient pressure X-ray Photoelectron Spectroscopy study of Mn polarised anodically in a cell with solid oxide electrolyte

2015 ◽  
Vol 174 ◽  
pp. 532-541 ◽  
Author(s):  
Benedetto Bozzini ◽  
Matteo Amati ◽  
Patrizia Bocchetta ◽  
Simone Dal Zilio ◽  
Axel Knop-Gericke ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
Solid Oxide ◽  
Spectroscopy Study ◽  
Solid Oxide Electrolyte ◽  
X Ray ◽  
A Cell ◽  
Oxide Electrolyte

scholarly journals Order and stochasticity in the folding of individual Drosophila genomes

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sergey V. Ulianov ◽  
Vlada V. Zakharova ◽  
Aleksandra A. Galitsyna ◽  
Pavel I. Kos ◽  
Kirill E. Polovnikov ◽  
...  
Keyword(s):  
Random Walk ◽  
High Resolution ◽  
3D Genome ◽  
Topologically Associating Domains ◽  
Chromatin Folding ◽  
A Cell ◽  
Single Nucleus ◽  
High Level ◽  
Cell To Cell Variability

AbstractMammalian and Drosophila genomes are partitioned into topologically associating domains (TADs). Although this partitioning has been reported to be functionally relevant, it is unclear whether TADs represent true physical units located at the same genomic positions in each cell nucleus or emerge as an average of numerous alternative chromatin folding patterns in a cell population. Here, we use a single-nucleus Hi-C technique to construct high-resolution Hi-C maps in individual Drosophila genomes. These maps demonstrate chromatin compartmentalization at the megabase scale and partitioning of the genome into non-hierarchical TADs at the scale of 100 kb, which closely resembles the TAD profile in the bulk in situ Hi-C data. Over 40% of TAD boundaries are conserved between individual nuclei and possess a high level of active epigenetic marks. Polymer simulations demonstrate that chromatin folding is best described by the random walk model within TADs and is most suitably approximated by a crumpled globule build of Gaussian blobs at longer distances. We observe prominent cell-to-cell variability in the long-range contacts between either active genome loci or between Polycomb-bound regions, suggesting an important contribution of stochastic processes to the formation of the Drosophila 3D genome.

How the parasitic bacterium Legionella pneumophila modifies its phagosome and transforms it into rough ER: implications for conversion of plasma membrane to the ER membrane

2001 ◽  
Vol 114 (24) ◽  
pp. 4637-4650 ◽  
Author(s):  
Lewis G. Tilney ◽  
Omar S. Harb ◽  
Patricia S. Connelly ◽  
Camenzind G. Robinson ◽  
Craig R. Roy
Keyword(s):  
Legionella Pneumophila ◽  
Mitochondrial Membranes ◽  
Macrophage Infection ◽  
Thin Sections ◽  
Stage Process ◽  
Legionnaires Disease ◽  
Rough Er ◽  
Membrane Changes ◽  
Phagosomal Membrane

Within five minutes of macrophage infection by Legionella pneumophila, the bacterium responsible for Legionnaires’ disease, elements of the rough endoplasmic reticulum (RER) and mitochondria attach to the surface of the bacteria-enclosed phagosome. Connecting these abutting membranes are tiny hairs, which are frequently periodic like the rungs of a ladder. These connections are stable and of high affinity - phagosomes from infected macrophages remain connected to the ER and mitochondria (as they were in situ) even after infected macrophages are homogenized. Thin sections through the plasma and phagosomal membranes show that the phagosomal membrane is thicker (72±2 Å) than the ER and mitochondrial membranes (60±2 Å), presumably owing to the lack of cholesterol, sphingolipids and glycolipids in the ER. Interestingly, within 15 minutes of infection, the phagosomal membrane changes thickness to resemble that of the attached ER vesicles. Only later (e.g. after six hours) does the ER-phagosome association become less frequent. Instead ribosomes stud the former phagosomal membrane and L. pneumophila reside directly in the rough ER. Examination of phagosomes of various L. pneumophila mutants suggests that this membrane conversion is a four-stage process used by L. pneumophila to establish itself in the RER and to survive intracellularly. But what is particularly interesting is that L. pneumophila is exploiting a poorly characterized naturally occuring cellular process.

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