Components and dynamics of fiber formation define a ubiquitous biogenesis pathway for bacterial pili

Wolfgang, Matthew C.; Putten, Jos P. M. van; Hayes, Stanley F.; Dorward, David W.; Koomey, Michael

doi:10.1093/emboj/19.23.6408

Cited by 231 publications

(288 citation statements)

References 59 publications

(86 reference statements)

Supporting

Mentioning

272

Contrasting

Order By: Relevance

“…1 A. These results imply that fluorescent subunits are recycled, consistent with current models of pilus assembly that use a membrane pool of pilin subunits (23)(24)(25). However, the cell bodies were so highly fluorescent that we were not able to tell where this pool might be located.…”

Section: Resultssupporting

confidence: 74%

Direct observation of extension and retraction of type IV pili

Skerker

Berg

2001

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

570

525

View full text Add to dashboard Cite

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...

show abstract

Section: Resultssupporting

confidence: 74%

Direct observation of extension and retraction of type IV pili

Skerker

Berg

2001

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

570

525

View full text Add to dashboard Cite

show abstract

“…3. nected to the envelope. Phenotypic observations of the properties of pilus biogenesis mutants in diverse bacterial species have provided evidence that pilus formation occurs within the periplasm, rather than in the outer membrane (43,44). It is difficult, however, to reconcile the structure of the PilQ complex presented here with a role as a passive portal or pore within the outer membrane.…”

Section: Figmentioning

confidence: 86%

Structure of the Neisseria meningitidis Outer Membrane PilQ Secretin Complex at 12 Å Resolution

Collins

Frye

Kitmitto

et al. 2004

Journal of Biological Chemistry

118

123

View full text Add to dashboard Cite

The bacterial pathogen Neisseria meningitidis expresses long, thin, retractile fibers (called type IV pili) from its cell surface and uses these adhesive structures to mediate primary attachment to epithelial cells during host colonization and invasion. PilQ is an outer membrane protein complex that is essential for the translocation of these pili across the outer membrane. Here, we present the structure of the PilQ complex determined by cryoelectron microscopy to 12 Å resolution. The dominant feature of the structure is a large central cavity, formed by four arm features that spiral upwards from a squared ring base and meet to form a prominent cap region. The cavity, running through the center of the complex, is continuous and is effectively sealed at both the top and bottom. Analysis of the complex using selforientation and by examination of two-dimensional crystals indicates a strong C4 rotational symmetry, with a much weaker C12 rotational symmetry, consistent with PilQ possessing true C4 symmetry with C12 quasisymmetry. We therefore suggest that the complex is a homododecamer, formed by association of 12 PilQ polypeptide chains into a tetramer of trimers. The structure of the PilQ complex, with its large and well defined central chamber, suggests that it may not function solely as a passive portal in the outer membrane, but could be actively involved in mediating pilus assembly or modification.

show abstract

Section: Introductionmentioning

confidence: 99%

“…Tfp participate in important biological processes such as DNA uptake/genetic exchange, twitching motility, attachment, and host cell signalling (Mattick, 2002;. These activities require, or are enhanced by, the retraction of Tfp fibres (Wolfgang et al, 2000).Gonococcal Tfp retraction is an activity that requires PilT, the Tfp retraction motor subunit (Wolfgang et al, 1998). Retracting Tfp generate strong 'pull' forces, ranging from 50 picoNewtons (pN) to 1 nanoNewton (nN) (Biais et al, 2008;Opitz et al, 2009).…”

mentioning

confidence: 99%

Influence of type IV pilus retraction on the architecture of the Neisseria gonorrhoeae-infected cell cortex

et al. 2009

View full text Add to dashboard Cite

Early in infection, Neisseria gonorrhoeae can be observed to attach to the epithelial cell surface as microcolonies and induce dramatic changes to the host cell cortex. We tested the hypothesis that type IV pili (Tfp) retraction plays a role in the ultrastructure of both the host cell cortex and the bacterial microcolony. Using serial ultrathin sectioning, transmission electron microscopy and 3D reconstruction of serial 2D images, we have obtained what we believe to be the first 3D reconstructions of the N. gonorrhoeae-host cell interface, and determined the architecture of infected cell microvilli as well as the attached microcolony. Tfp connect both wild-type (wt) and Tfp retraction-deficient bacteria with each other, and with the host cell membrane. Tfp fibres and microvilli form a lattice in the wt microcolony and at its periphery. Wt microcolonies induce microvilli formation and increases of surface area, leading to an approximately ninefold increase in the surface area of the host cell membrane at the site of attachment. In contrast, Tfp retractiondeficient microcolonies do not affect these parameters. Wt microcolonies had a symmetrical, dome-shaped structure with a circular 'footprint', while Tfp retraction-deficient microcolonies were notably less symmetrical. These findings support a major role for Tfp retraction in microvilli and microcolony architecture. They are consistent with the biophysical attributes of Tfp and the effects of Tfp retraction on epithelial cell signalling. INTRODUCTIONNeisseria gonorrhoeae (the gonococcus, or GC) remains a significant public health concern. The Gram-negative diplococcus causes a million cases of gonorrhoea annually in Western Europe and North America, and over 62 million cases worldwide (World Health Organization). Humans are the only known reservoir for GC. The exquisite tropism of GC for man and the ability of GC to establish a carrier state (Turner et al., 2002) reflect a highly evolved relationship between pathogen and host.Gonococcal attachment is promoted by type IV pili (Tfp), peritrichous fibres that are 6 nm in width and up to several micrometres in length. The Tfp filament is composed of helical polymers of pilin subunits (Craig et al., 2006;Parge et al., 1995) and minor proteins (Carbonnelle et al., 2005;Winther-Larsen et al., 2005). Tfp participate in important biological processes such as DNA uptake/genetic exchange, twitching motility, attachment, and host cell signalling (Mattick, 2002;. These activities require, or are enhanced by, the retraction of Tfp fibres (Wolfgang et al., 2000).Gonococcal Tfp retraction is an activity that requires PilT, the Tfp retraction motor subunit (Wolfgang et al., 1998). Retracting Tfp generate strong 'pull' forces, ranging from 50 picoNewtons (pN) to 1 nanoNewton (nN) (Biais et al., 2008;Opitz et al., 2009). Repeated cycles of Tfp extension, substrate attachment and Tfp retraction allow GC to crawl over surfaces and aggregate into microcolonies. Tfp retraction from bacteria in a microcolony allows the community to craw...

show abstract

Components and dynamics of fiber formation define a ubiquitous biogenesis pathway for bacterial pili

Cited by 231 publications

References 59 publications

Direct observation of extension and retraction of type IV pili

Direct observation of extension and retraction of type IV pili

Structure of the Neisseria meningitidis Outer Membrane PilQ Secretin Complex at 12 Å Resolution

Influence of type IV pilus retraction on the architecture of the Neisseria gonorrhoeae-infected cell cortex

Contact Info

Product

Resources

About