Shelter in a Swarm

Harshey, Rasika M.; Partridge, Jonathan D.

doi:10.1016/j.jmb.2015.07.025

Cited by 70 publications

(58 citation statements)

References 111 publications

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“…Some bacteria also use flagellum-associated proteins such as FliL and signaling molecules, including c-di-GMP, to facilitate stator remodeling and function. Because stator rearrangement is a common output to extracellular stimuli, we and others speculate that the level of stator engagement within the motor may be actively recognized by cells (26) and could thereby serve as an input for subsequent signal transduction events. Alternatively, modulation of stator occupancy or exchange offers a way for the bacterium to indirectly sense and/or respond to environmental perturbations, such as surface contact and ion availability, by surveying its motor status.…”

Section: Discussionmentioning

confidence: 91%

“…These data indicate that V. parahaemolyticus may be sensing decreased flagellar rotation or decreased Na ϩ flux through the stators (25). Interestingly, Harshey and Partridge proposed that changes in flagellar rotation speed and/or ion flux might be a direct response to an altered conformation at the rotorstator interface (26). Such a model would posit that an external change in load is propagated to an intracellular change in the motor shape and thereby serve as a means to initiate a signal transduction event.…”

Section: Environmental Factors Driving Stator Exchangementioning

confidence: 99%

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Bacteria, Rev Your Engines: Stator Dynamics Regulate Flagellar Motility

Baker

O’Toole

2017

J Bacteriol

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Many bacteria move through liquids and across surfaces by using flagella-filaments propelled by a membrane-embedded rotary motor. Much is known about the flagellum: its basic structure, the function of its individual motor components, and the regulation of its synthesis. However, we are only beginning to identify the dynamics of flagellar proteins and to understand how the motor structurally adapts to environmental stimuli. In this review, we discuss the external and cellular factors that influence the dynamics of stator complexes (the ion-conducting channels of the flagellar motor). We focus on recent discoveries suggesting that stator dynamics are a means for controlling flagellar function in response to different environments.KEYWORDS flagella, stators, MotAB, swarming, swimming, c-di-GMP T he flagellar motor is an intricate machine that drives the rotation of the flagellum by converting ion motive force to mechanical energy (1). Torque is generated via association between two main motor components: membrane-embedded stator complexes and the cytoplasmic rotor ( Fig. 1). On the basis of work with the model organism Escherichia coli, each stator complex is composed of protein subunits, MotA and MotB, assembled in a 4MotA-2MotB stoichiometry (2). MotB has been shown to interact with the P-ring protein FlgI (3) and is also thought to associate with peptidoglycan through its peptidoglycan-binding motif. The interactions made by the periplasmic domain of MotB likely serve to anchor stator complexes around the rotor, where the stators act as ion channels. It is thought that the ions passing through these channels are bound by a conserved aspartic acid residue in the transmembrane segment of MotB, causing conformational changes in MotA (4). These conformational changes are coupled to rotation by specific electrostatic interactions between MotA and the rotor protein FliG (5, 6). Work with Vibrio alginolyticus suggests that FliG contributes to both rotation and stator assembly (7).While stators are named for their "stationary" role as the nonrotating motor component, the composition of stators surrounding the motor is highly dynamic (Fig. 2). Stator dynamics were first demonstrated in "resurrection experiments." These experiments showed that stators could incorporate themselves into and restore rotation to paralyzed flagellar motors, with each successive stator incorporation resulting in a stepwise increase in motor speed (8, 9). Importantly, stochastic fluctuations in torque were also observed in these experiments, in which torque would periodically decrease in steps (8). Specifically, 11 distinct rotational speeds were observed in E. coli, indicating that a maximum of at least 11 stator complexes can engage in the motor at any one time in this species (10). Stator turnover was directly observed and measured by total internal reflection fluorescence microscopy combined with fluorescence recovery after photobleaching (FRAP) and fluorescence loss in photobleaching. These experiments demonstrated that green fluo...

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Section: Discussionmentioning

confidence: 91%

Section: Environmental Factors Driving Stator Exchangementioning

confidence: 99%

Bacteria, Rev Your Engines: Stator Dynamics Regulate Flagellar Motility

Baker

O’Toole

2017

J Bacteriol

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“…45 Flagella mediate both swimming and swarming motility. 46 All strains of P. aeruginosa and S. marcescens showed (flagella-mediated) swimming motility, and S. marcescens strains ATCC 13880, 27, and 35 showed swarming motility. As only two of the S. marcescens strains and only the ocular isolates of P. aeruginosa (i.e., three strains) showed coaggregation, this demonstrates that possession of flagella per se was not associated with coaggregation.…”

Section: Discussionmentioning

confidence: 95%

Bacterial Coaggregation Among the Most Commonly Isolated Bacteria From Contact Lens Cases

Datta

Stapleton

Willcox

2017

Invest. Ophthalmol. Vis. Sci.

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PURPOSE. To examine the coaggregation and cohesion between the commonly isolated bacteria from contact lens cases.METHODS. Four or five strains each of commonly isolated bacteria from contact lens cases, Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Serratia marcescens, were grown, washed, mixed in equal proportions, and allowed to coaggregate for 24 hours. Lactose (0.06 M), sucrose (0.06 M), and pronase (2 mg/mL; 2 hours, 378C) were used to inhibit coaggregation. Oral bacterial isolates of Actinomyces naeslundii and Streptococcus sanguinis were used as a positive control for coaggregation. Cohesion was performed with the ocular bacteria that demonstrated the highest level of coaggregation. Production of growth-inhibitory substances was measured by growing strains together on agar plates. RESULTS.The oral bacterial pair showed >80% coaggregation. Coaggregation occurred between ocular strains of S. aureus (2/5) or S. epidermidis (2/5) with P. aeruginosa strains (3/5); 42% to 62%. There was only slight coaggregation between staphylococci and S. marcescens. Staphylococcus aureus coaggregated with S. epidermidis. Lactose or sucrose treatment of S. aureus but pronase treatment of P. aeruginosa reversed the coaggregation. There was no cohesion between the ocular isolates. P. aeruginosa was able to stop growth of S. aureus but not vice versa.CONCLUSIONS. This study demonstrated for the first time that ocular isolates of P. aeruginosa and S. aureus could coaggregate, probably through lectin-carbohydrate interactions. However, this may not be related to biofilm formation in contact lens cases, as there was no evidence that the coaggregation was associated with cohesion between the strains.

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“…The vegetative swimmer cells exhibit normal chemotactic behavior in liquid medium, being attracted by nutrients and repelled by toxic substances or unfavorable conditions (310), while swarm cells allow for migration across solid surfaces, forming a characteristic bull’s eye pattern through sequential rounds of the differentiation process (95). Swarm cell differentiation and the mechanics and regulation of swimming and swarming motility in P. mirabilis have been extensively reviewed elsewhere (3, 18, 19, 311). We will therefore sharply focus on the direct contribution of flagella and motility to pathogenesis.…”

Section: Virulence Factorsmentioning

confidence: 99%

Pathogenesis of Proteus mirabilis Infection

2018

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Proteus mirabilis, a Gram-negative rod-shaped bacterium most noted for its swarming motility and urease activity, frequently causes catheter-associated urinary tract infections (CAUTI) that are often polymicrobial. These infections may be accompanied by urolithiasis, development of bladder or kidney stones due to alkalinization of urine from urease-catalyzed urea hydrolysis. Adherence of the bacterium to epithelial and catheter surfaces is mediated by 17 different fimbriae, most notably MR/P fimbriae. Repressors of motility are often encoded by these fimbrial operons. Motility is mediated by flagella encoded on a single contiguous 54 kb chromosomal sequence. On agar plates, P. mirabilis undergoes a morphological conversion to a filamentous swarmer cell expressing hundreds of flagella. When swarms from different strains meet, a line of demarcation, a “Dienes line”, develops due to the killing action of each strain’s type VI secretion system. During infection, histological damage is caused by cytotoxins including hemolysin and a variety of proteases, some autotransported. The pathogenesis of infection, including assessment of individual genes or global screens for virulence or fitness factors has been assessed in murine models of ascending UTI or CAUTI using both single-species and polymicrobial models. Global gene expression studies carried out in culture and in the murine model have revealed the unique metabolism of this bacterium. Vaccines, using MR/P fimbria and its adhesin, MrpH, have been shown to be efficacious in the murine model. A comprehensive review of factors associated with urinary tract infection is presented, encompassing both historical perspectives and current advances.

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Shelter in a Swarm

Cited by 70 publications

References 111 publications

Bacteria, Rev Your Engines: Stator Dynamics Regulate Flagellar Motility

Bacteria, Rev Your Engines: Stator Dynamics Regulate Flagellar Motility

Bacterial Coaggregation Among the Most Commonly Isolated Bacteria From Contact Lens Cases

Pathogenesis of Proteus mirabilis Infection

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