The adsorption of Pseudomonas aeruginosa pilus-dependent bacteriophages to a host mutant with nonretractile pili

Bradley, D. E.

doi:10.1016/0042-6822(74)90150-0

Cited by 127 publications

(90 citation statements)

References 17 publications

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“…According to their model, adsorption of phage to the side or tip of a pilus, or binding of an F Ϫ cell to the tip, triggers retraction. Subsequent studies in Escherichia coli (30,31), P. aeruginosa (32)(33)(34), and Caulobacter crescentus (35,36) strengthened the hypothesis that pilus retraction plays a role in the translocation of pili-specific phage to the cell surface. The role of pilus retraction in cell motility was first proposed by Bradley (3).…”

Section: Discussionmentioning

confidence: 97%

Direct observation of extension and retraction of type IV pili

Skerker

Berg

2001

Proc. Natl. Acad. Sci. U.S.A.

557

525

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Type IV pili are thin filaments that extend from the poles of a diverse group of bacteria, enabling them to move at speeds of a few tenths of a micrometer per second. They are required for twitching motility, e.g., in Pseudomonas aeruginosa and Neisseria gonorrhoeae, and for social gliding motility in Myxococcus xanthus. Here we report direct observation of extension and retraction of type IV pili in P. aeruginosa. Cells without flagellar filaments were labeled with an amino-specific Cy3 fluorescent dye and were visualized on a quartz slide by total internal reflection microscopy. When pili were attached to a cell and their distal ends were free, they extended or retracted at rates of about 0.5 m s ؊1 (29°C). They also flexed by Brownian motion, exhibiting a persistence length of about 5 m. Frequently, the distal tip of a filament adsorbed to the substratum and the filament was pulled taut. From the absence of lateral deflections of such filaments, we estimate tensions of at least 10 pN. Occasionally, cell bodies came free and were pulled forward by pilus retraction. Thus, type IV pili are linear actuators that extend, attach at their distal tips, exert substantial force, and retract.Pseudomonas aeruginosa ͉ twitching motility ͉ fluorescence M otile bacteria swim, swarm, or glide. Gliding refers to movement on a solid surface, such as glass or hard agar, without flagella, usually in the direction of the long axis of a cell (1). One form of gliding, known either as twitching motility or as social gliding, depends on 6-nm diameter filaments called type IV pili that extend from the pole of a cell (2-6). Twitching cells can exhibit chemotaxis (7) and͞or phototaxis (8). Twitching motility is required for formation of biofilms (9), and social gliding is important for formation of fruiting bodies (10).We studied twitching motility in Pseudomonas aeruginosa, a common Gram-negative bacterium that acts as an opportunistic human pathogen. It causes bacteremia in burn victims, infections of the urinary tract in catheterized patients, chronic lung infections in patients with cystic fibrosis, and acute ulcerative keratitis in users of extended-wear soft-contact lenses (11,12). P. aeruginosa has a single flagellum and multiple type IV pili; thus, it can move by swimming or twitching motility. Pili-mediated adhesion is a known virulence factor (13) and the molecular genetics of pilus assembly has been studied extensively (14). It is thought that twitching motility allows cells to spread on body surfaces during infection (6).Type IV pili have been seen with an electron microscope (15, 16) but have not been visualized in vivo. Recently, the motion of bacterial flagella was analyzed by labeling intact cells with amino-specific fluorescent dyes (17). By labeling cells of P. aeruginosa with an amino-specific Cy3, we have observed directly pilus extension, pilus retraction, and retraction-mediated cell movement. Our work confirms and extends that of Mertz et al. (18), who used an optical trap to measure the force of retraction of pi...

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Section: Discussionmentioning

confidence: 97%

Direct observation of extension and retraction of type IV pili

Skerker

Berg

2001

Proc. Natl. Acad. Sci. U.S.A.

557

525

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“…Using an anti-pilus antiserum, Bradley was able to stop not only this shortening effect, but also twitching motility in P. aeruginosa, suggesting that antibodies attached along the pilus fibre block retraction, and retraction plays an essential role in twitching motility (Bradley, 1974(Bradley, , 1980. In M. xanthus, retraction of pili was first reported by Sun et al (2000), when the tethered cells (standing vertically on one cell pole) were found to move along the vertical axis over time.…”

Section: Discussionmentioning

confidence: 97%

Analysis of type IV pilus and its associated motility in Myxococcus xanthus using an antibody reactive with native pilin and pili

Lux

Pelling

et al. 2005

Microbiology

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Myxococcus xanthus possesses a social gliding motility that requires type IV pili (TFP). According to the current model, M. xanthus pili attach to an external substrate and retract, pulling the cell body forward along their long axis. By analogy with the situation in other bacteria employing TFP-dependent motility, M. xanthus pili have been assumed to be composed of pilin (PilA) subunits, but this has not previously been confirmed. The first 28 amino acids of the M. xanthus PilA protein share extensive homology with the N-terminal oligomerization domain of pilins in other bacterial species. To facilitate purification, the authors engineered a truncated form of M. xanthus PilA lacking the first 28 amino acids and purified this protein in soluble form. Polyclonal antibody generated against this protein was reactive with native pilin and pili. Using this antibody, it was confirmed that TFP of M. xanthus are indeed composed of PilA, and that TFP are located unipolarly and required for social gliding motility via retraction. Using tethering as well as motility assays, details of pili function in M. xanthus social motility were further examined.

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“…aeruginosa strain PAK is susceptible to killing by the pilus-specific bacteriophage PO4, which attaches to the pili and is brought into contact with the cell surface upon pilus retraction (Bradley, 1974). Complementation of the phageresistant pilB and pilT mutants with modified proteins that Using the published structures of EpsE (PDB 1P9W) and PilT Aa (PDB 2EWW) as models, the orientation of the seven highly conserved motif residues targeted for mutagenesis in the P. aeruginosa ATPases relative to the bound ligand (in yellow) is shown.…”

Section: Effect Of Atpase Mutations On Surface Piliationmentioning

confidence: 99%