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 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 Tuning the flagellar motor

Microbiology ◽  
2010 ◽  
Vol 156 (5) ◽  
pp. 1275-1283 ◽  
Author(s):  
Kai M. Thormann ◽  
Anja Paulick
Keyword(s):  
Cell Wall ◽  
Environmental Conditions ◽  
Survival Advantage ◽  
Sodium Ion ◽  
Flagellar Motor ◽  
Numerous Species ◽  
Flagellar Motors ◽  
Wide Range ◽  
Flagellar Rotation

Many bacteria are motile by means of flagella, semi-rigid helical filaments rotated at the filament's base and energized by proton or sodium-ion gradients. Torque is created between the two major components of the flagellar motor: the rotating switch complex and the cell-wall-associated stators, which are arranged in a dynamic ring-like structure. Being motile provides a survival advantage to many bacteria, and thus the flagellar motor should work optimally under a wide range of environmental conditions. Recent studies have demonstrated that numerous species possess a single flagellar system but have two or more individual stator systems that contribute differentially to flagellar rotation. This review describes recent findings on rotor–stator interactions, on the role of different stators, and on how stator selection could be regulated. An emerging model suggests that bacterial flagellar motors are dynamic and can be tuned by stator swapping in response to different environmental conditions.

Flagellar motors of marine bacteria Halomonas are driven by both protons and sodium ions

2004 ◽  
Vol 50 (5) ◽  
pp. 369-374 ◽  
Author(s):  
K Kita-Tsukamoto ◽  
M Wada ◽  
K Yao ◽  
T Nishino ◽  
K Kogure
Keyword(s):  
Marine Bacteria ◽  
Specific Inhibitor ◽  
Proton Conductor ◽  
Bacterial Cells ◽  
Flagellar Motor ◽  
Sodium Ions ◽  
Ion Specificity ◽  
Nutrient Patches ◽  
Flagellar Motors ◽  
Wide Range

Bacterial cells in aquatic environments are able to reach or stay near nutrient patches by using motility. Motility is usually attained by rotating flagellar motors that are energized by electrochemical potential of H+ or Na+. In this paper, the ion specificity for flagellar rotation of two marine isolates Halomonas spp. strains US172 and US201 was investigated. Both isolates require sodium for growth and possess a respiratory-driven primary sodium pump. They are motile because of lateral flagella regardless of the presence of sodium ions. Their swimming speed under various concentrations of sodium ions with and without carbonylcyanide m-chlorophenylhydrazone, a proton conductor, and with and without phenamil, a specific inhibitor for the sodium-driven flagellar motors, was examined. The effect of carbonylcyanide m-chlorophenylhydrazone on the transmembrane proton gradient was also determined. Our results showed that the flagellar motors of the Halomonas strains were energized by both H+ and Na+ in one cell. The bimodal nature of Halomonas spp. motility with respect to the driving energy source may reflect ecophysiological versatility to adapt to a wide range of salt conditions of the marine environment.Key words: marine bacteria, Halomonas, flagellar motor, sodium, proton.

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 In vivo structure of the Legionella type II secretion system by electron cryotomography

2019 ◽  
Author(s):  
Debnath Ghosal ◽  
Ki Woo Kim ◽  
Huaixin Zheng ◽  
Mohammed Kaplan ◽  
Joseph P. Vogel ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Cell Envelope ◽  
Secretion System ◽  
Type Ii Secretion ◽  
Type Ii ◽  
Type Iv ◽  
Type Ii Secretion System ◽  
Wide Range ◽  
Electron Cryotomography

AbstractThe type II secretion system (T2SS) is a multi-protein envelope-spanning assembly that translocates a wide range of virulence factors, enzymes and effectors through the outer membrane (OM) of many Gram-negative bacteria. Here, using electron cryotomography and subtomogram averaging methods, we present the first in situ structure of an intact T2SS, imaged within the human pathogen Legionella pneumophila. Although the T2SS has only limited sequence and component homology with the evolutionarily-related Type IV pilus (T4P) system, we show that their overall architectures are remarkably similar. Despite similarities, there are also differences, including for instance that the T2SS-ATPase complex is usually present but disengaged from the inner membrane, the T2SS has a much longer periplasmic vestibule, and it has a short-lived flexible pseudopilus. Placing atomic models of the components into our ECT map produced a complete architectural model of the intact T2SS that provides new insights into the structure and function of its components, its position within the cell envelope, and the interactions between its different subcomplexes. Overall, these structural results strongly support the piston model for substrate extrusion.

scholarly journals PIKfyve/Fab1 is required for efficient V-ATPase and hydrolase delivery to phagosomes, phagosomal killing, and restriction ofLegionellainfection

2018 ◽  
Author(s):  
Catherine M. Buckley ◽  
Victoria L. Heath ◽  
Aurélie Guého ◽  
Cristina Bosmani ◽  
Paulina Knobloch ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Pathogenic Bacteria ◽  
Host Cells ◽  
Central Component ◽  
Phagosome Maturation ◽  
General Role ◽  
Phagosomal Maturation ◽  
General Importance ◽  
Wide Range ◽  
Opportunistic Human Pathogen

AbstractBy engulfing potentially harmful microbes, professional phagocytes are continually at risk from intracellular pathogens. To avoid becoming infected, the host must kill pathogens in the phagosome before they can escape or establish a survival niche. Here, we analyse the role of the phosphoinositide (PI) 5-kinase PIKfyve in phagosome maturation and killing, using the amoeba and model phagocyteDictyostelium discoideum.PIKfyve plays important but poorly understood roles in vesicular trafficking by catalysing formation of the lipids phosphatidylinositol (3,5)-bisphosphate (PI(3,5)2) and phosphatidylinositol-5-phosphate (PI(5)P). Here we show that its activity is essential during early phagosome maturation inDictyostelium. Disruption ofPIKfyveinhibited delivery of both the vacuolar V-ATPase and proteases, dramatically reducing the ability of cells to acidify newly formed phagosomes and digest their contents. Consequently,PIKfyve-cells were unable to generate an effective antimicrobial environment and efficiently kill captured bacteria. Moreover, we demonstrate that cells lackingPIKfyveare more susceptible to infection by the intracellular pathogenLegionella pneumophila. We conclude that PIKfyve-catalysed phosphoinositide production plays a crucial and general role in ensuring early phagosomal maturation, protecting host cells from diverse pathogenic microbes.ImportanceCells that capture or eat bacteria must swiftly kill them to prevent pathogens from surviving long enough to escape the bactericidal pathway and establish an infection. This is achieved by the rapid delivery of components that produce an antimicrobial environment in the phagosome, the compartment containing the captured microbe. This is essential both for the function of immune cells and for amoebae that feed on bacteria in their environment. Here we identify a central component of the pathway used by cells to deliver antimicrobial components to the phagosome and show that bacteria survive over three times as long within the host if this pathway is disabled. We show that this is of general importance for killing a wide range of pathogenic and non-pathogenic bacteria, and that it is physiologically important if cells are to avoid infection by the opportunistic human pathogenLegionella.

scholarly journals Stator Dynamics Depending on Sodium Concentration in Sodium-Driven Bacterial Flagellar Motors

2021 ◽  
Vol 12 ◽  
Author(s):  
Tsai-Shun Lin ◽  
Seiji Kojima ◽  
Hajime Fukuoka ◽  
Akihiko Ishijima ◽  
Michio Homma ◽  
...  
Keyword(s):  
Exchange Process ◽  
Sodium Concentration ◽  
Motive Force ◽  
Flagellar Motor ◽  
Rotary Machine ◽  
Low Sodium ◽  
Flagellar Motors ◽  
Wide Range ◽  
Membrane Spanning ◽  
Fast Perfusion

Bacterial flagellar motor (BFM) is a large membrane-spanning molecular rotary machine for swimming motility. Torque is generated by the interaction between the rotor and multiple stator units powered by ion-motive force (IMF). The number of bound stator units is dynamically changed in response to the external load and the IMF. However, the detailed dynamics of stator unit exchange process remains unclear. Here, we directly measured the speed changes of sodium-driven chimeric BFMs under fast perfusion of different sodium concentration conditions using computer-controlled, high-throughput microfluidic devices. We found the sodium-driven chimeric BFMs maintained constant speed over a wide range of sodium concentrations by adjusting stator units in compensation to the sodium-motive force (SMF) changes. The BFM has the maximum number of stator units and is most stable at 5 mM sodium concentration rather than higher sodium concentration. Upon rapid exchange from high to low sodium concentration, the number of functional stator units shows a rapidly excessive reduction and then resurrection that is different from predictions of simple absorption model. This may imply the existence of a metastable hidden state of the stator unit during the sudden loss of sodium ions.

Colloidal Plasmonic Nanostar Antennas with Wide Range Resonance Tunability

2019 ◽  
Author(s):  
Theodoros Tsoulos ◽  
Supriya Atta ◽  
Maureen Lagos ◽  
Michael Beetz ◽  
Philip Batson ◽  
...  
Keyword(s):  
Single Particle ◽  
Structural Complexity ◽  
Field Enhancement ◽  
Hot Electron ◽  
Structure Property ◽  
Plasmon Band ◽  
Gold Nanostars ◽  
Wide Range ◽  
Particle Level ◽  
Spectrally Resolved

<div>Gold nanostars display exceptional field enhancement properties and tunable resonant modes that can be leveraged to create effective imaging tags or phototherapeutic agents, or to design novel hot-electron based photocatalysts. From a fundamental standpoint, they represent important tunable platforms to study the dependence of hot carrier energy and dynamics on plasmon band intensity and position. Toward the realization of these platforms, holistic approaches taking into account both theory and experiments to study the fundamental behavior of these</div><div>particles are needed. Arguably, the intrinsic difficulties underlying this goal stem from the inability to rationally design and effectively synthesize nanoparticles that are sufficiently monodispersed to be employed for corroborations of the theoretical results without the need of single particle experiments. Herein, we report on our concerted computational and experimental effort to design, synthesize, and explain the origin and morphology-dependence of the plasmon modes of a novel gold nanostar system, with an approach that builds upon the well-known plasmon hybridization model. We have synthesized monodispersed samples of gold nanostars with finely tunable morphology employing seed-mediated colloidal protocols, and experimentally observed narrow and spectrally resolved harmonics of the primary surface plasmon resonance mode both at the single particle level (via electron energy loss spectroscopy) and in ensemble (by UV-Vis and ATR-FTIR spectroscopies). Computational results on complex anisotropic gold nanostructures are validated experimentally on samples prepared colloidally, underscoring their importance as ideal testbeds for the study of structure-property relationships in colloidal nanostructures of high structural complexity.</div>

scholarly journals Frequency of myelin oligodendrocyte glycoprotein antibodies in a large cohort of neurological patients

2021 ◽  
Vol 7 (2) ◽  
pp. 205521732110227
Author(s):  
Friederike Held ◽  
Sudhakar Reddy Kalluri ◽  
Achim Berthele ◽  
Ana-Katharina Klein ◽  
Markus Reindl ◽  
...  
Keyword(s):  
Time Course ◽  
Neurological Diseases ◽  
External Validation ◽  
Diagnostic Value ◽  
Myelin Oligodendrocyte Glycoprotein ◽  
Large Cohort ◽  
Wide Range ◽  
Neurological Patients ◽  
A Cell ◽  
Nosological Entity

Background Myelin oligodendrocyte glycoprotein (MOG) antibody disease (MOG-AD) is recognized as a distinct nosological entity. IgG antibodies against MOG (MOG-Ab) overlap with neuromyelitis optica spectrum disorders (NMOSD) phenotype in adults. However, an increasing number of clinical phenotypes have been reported to be associated with MOG-Ab. Objective To investigate the seroprevalence of MOG-Ab under consideration of demographics, disease entities and time course in a large cohort of unselected neurological patients. Methods Blood samples of 2.107 consecutive adult neurologic patients admitted to our department between 2016-2017 were tested for MOG-Ab using a cell-based assay. MOG-Ab persistence was analyzed in follow-up samples. External validation was performed in two independent laboratories. Results We found MOG-Ab in 25 of 2.107 (1.2%) patients. High antibody ratios were mostly associated with NMOSD and MOG-AD phenotype (5/25). Low ratios occurred in a wide range of neurological diseases, predominantly in other demyelinating CNS diseases (5/25) and stroke (6/25). MOG-Ab persistence over time was not confined to NMOSD and MOG-AD phenotype. Conclusion The present study demonstrates the occurrence of MOG-Ab in a wide range of neurological diseases. Only high MOG-Ab ratios were associated with a defined clinical phenotype, but low MOG-Ab ratios were not. The diagnostic value of low MOG-Ab is thus highly limited.

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