Biogenesis of <scp><i>P</i></scp><i>seudomonas aeruginosa</i> type <scp>IV</scp> pili and regulation of their function

Leighton, Tiffany L.; Buensuceso, Ryan N. C.; Howell, P. Lynne; Burrows, Lori L.

doi:10.1111/1462-2920.12849

Cited by 98 publications

(82 citation statements)

References 144 publications

(256 reference statements)

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“…The T4P biogenesis machinery is composed of several sub-complexes, which are all required to form a functional system 64 (FIG. 2a).…”

Section: T4p Biogenesismentioning

confidence: 99%

“…Figure 2b shows a hypothetical architectural model built by fitting existing structures into the densities observed by the cryo-ET studies of the M. xanthus system 84 . The ring-forming components of the T4P machinery were modeled in a 12-fold stoichiometry as this provided the best fit with cryo-ET density observed 84 , although other stoichiometries have also been proposed 64,75 . Changes that were observed in the piliated state of both systems include the pilus traversing the periplasm and extending into the extracellular space, the opening of the PilQ gate (there is an additional gate present in the longer T. thermophilus PilQ protein), and the presence of additional cytoplasmic density attributed to the elongating ATPase in both studies 83,84 (FIG.…”

Section: Structure Of T4p Machinerymentioning

confidence: 99%

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A comprehensive guide to pilus biogenesis in Gram-negative bacteria

2017

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Pili are critical virulence factors of many Gram-negative pathogens. These surface structures provide bacteria with a link to their outside environments, allowing bacteria to interact with their hosts, other surfaces or with each other. They can even provide a conduit for the exchange of information. The surface chemistries and other biophysical properties of pili are uniquely adapted to the environmental challenges faced by bacteria. The assembly of these surface structures presents a molecular engineering challenge, which bacteria have solved in a variety of unique ways. In this review, we examine recent advances in our structural understanding of various Gram-negative pilus systems and discuss their functional implications.

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“…The T4P biogenesis machinery is composed of several sub-complexes, which are all required to form a functional system 64 (FIG. 2a).…”

Section: T4p Biogenesismentioning

confidence: 99%

Section: Structure Of T4p Machinerymentioning

confidence: 99%

A comprehensive guide to pilus biogenesis in Gram-negative bacteria

2017

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“…The pilus polymer is anchored within the cell envelope by a membranespanning complex (6). Importantly, the length of the T4P is dynamic; elongation of T4P requires a cytoplasmic ATPase formed by PilB, and retraction requires its antagonist PilT (7). For Neisseria gonorrhoeae and Myxococcus xanthus, retraction of T4P generates a high mechanical force exceeding 100 pN (8,9).…”

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confidence: 99%

Role of Cyclic Di-GMP and Exopolysaccharide in Type IV Pilus Dynamics

et al. 2017

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For Pseudomonas aeruginosa, levels of cyclic di-GMP (c-di-GMP) govern the transition from the planktonic state to biofilm formation. Type IV pili (T4P) are crucial determinants of biofilm structure and dynamics, but it is unknown how levels of c-di-GMP affect pilus dynamics. Here, we scrutinized how c-di-GMP affects molecular motor properties and adhesive behavior of T4P. By means of retraction, T4P generated forces of ϳ30 pN. Deletion mutants in the proteins with known roles in biofilm formation, swarming motility, and exopolysaccharide (EPS) production (specifically, the diguanylate cyclases sadC and roeA or the c-di-GMP phosphodiesterase bifA) showed only modest effects on velocity or force of T4P retraction. At high levels of c-di-GMP, the production of exopolysaccharides, particularly of Pel, is upregulated. We found that Pel production strongly enhances T4P-mediated surface adhesion of P. aeruginosa, suggesting that T4P-matrix interactions may be involved in biofilm formation by P. aeruginosa. Finally, our data support the previously proposed model of slingshot-like "twitching" motility of P. aeruginosa. IMPORTANCE Type IV pili (T4P) play various important roles in the transition of bacteria from the planktonic state to the biofilm state, including surface attachment and surface sensing. Here, we investigate adhesion, dynamics, and force generation of T4P after bacteria engage a surface. Our studies showed that two critical components of biofilm formation by Pseudomonas aeruginosa, T4P and exopolysaccharides, contribute to enhanced T4P-mediated force generation by attached bacteria. These data indicate a crucial role for the coordinated impact of multiple biofilm-promoting factors during the early stages of attachment to a surface. Our data are also consistent with a previous model explaining why pilus-mediated motility in P. aeruginosa results in characteristic "twitching" behavior.

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“…6, B and C), suggesting that the PilNO interface no longer adopts an orientation permissive for disulfide bond formation. New crystal structures of a P. aeruginosa PilM homodimer and of monomeric PilM fused to part of its binding partner, PilN (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12), revealed that in the absence of PilN, the seven N-terminal residues of PilM (PilM (1-7)) bind in the PilN binding cleft of a second PilM monomer (41). Thus, PilM dimerizes in the absence of PilN.…”

Section: Piln and Pilo Homodimers May Represent A Functional Rather Tmentioning

confidence: 99%

“…Many bacteria, including Pseudomonas aeruginosa, use type IV pili (T4P) 3 for surface attachment/adhesion, biofilm formation, and twitching motility (1)(2)(3)(4)(5)(6). T4P are divided into T4aP and T4bP subgroups, based on differences in pilin size and organization of the assembly machinery (6, 7).…”

mentioning

confidence: 99%

Type IV Pilus Alignment Subcomplex Proteins PilN and PilO Form Homo- and Heterodimers in Vivo

Leighton

Yong

Howell

et al. 2016

Journal of Biological Chemistry

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Pseudomonas aeruginosa is a leading cause of hospital-acquired infections and is resistant to many antibiotics. Type IV pili (T4P) are among the key virulence factors used by P. aeruginosa for host cell attachment, biofilm formation, and twitching motility, making this system a promising target for novel therapeutics. Point mutations in the conserved PilMNOP alignment subcomplex were previously shown to have distinct effects on assembly and disassembly of T4P, suggesting that it may function in a dynamic manner. We introduced mutations encoding Cys substitutions into pilN and/or pilO on the chromosome to maintain normal stoichiometry and expression levels and captured covalent PilNO heterodimers, as well as PilN and PilO homodimers, in vivo. Most covalent PilN or PilO homodimers had minimal functional impact in P. aeruginosa, suggesting that homodimers are a physiologically relevant state. However, certain covalent homo-or heterodimers eliminated twitching motility, suggesting that specific PilNO configurations are essential for T4P function. These data were verified using soluble N-terminal truncated fragments of PilN and PilO Cys mutants, which purified as a mixture of homo-and heterodimers at volumes consistent with a tetramer. Deletion of genes encoding alignment subcomplex components, PilM or PilP, but not other T4P components, including the motor ATPases PilB or PilT, blocked in vivo formation of disulfide-bonded PilNO heterodimers, suggesting that both PilM and PilP influence the heterodimer interface. Combined, our data suggest that T4P function depends on rearrangements at PilN and PilO interfaces.Many bacteria, including Pseudomonas aeruginosa, use type IV pili (T4P) 3 for surface attachment/adhesion, biofilm formation, and twitching motility (1-6). T4P are divided into T4aP and T4bP subgroups, based on differences in pilin size and organization of the assembly machinery (6, 7). Here we focus on T4aP, henceforth referred to as T4P. T4P are long, thin, fibrous appendages, which extend from the bacteria, attach to a surface, and are retracted back into the cell, winching the cell forward. This flagellum-independent form of locomotion is called twitching motility. Four subcomplexes make up a T4P machine in P. aeruginosa as follows: the outer membrane (OM) secretin (PilQ) and its pilotin (PilF) (8 -12); the inner membrane (IM) platform protein (PilC) and cytoplasmic motor proteins (ATPases PilBTU) (13,14); the helical pilus fiber, composed mainly of the major pilin subunit (PilA) plus minor pilins (PilVWXE and FimU) and adhesin PilY1 (5, 15, 16); and the alignment subcomplex proteins (PilMNOP) that span from the cytoplasm to the OM secretin (17-20). PilN and PilO are bitopic IM proteins with similar predicted secondary structures. These proteins are essential for T4P function and connect the cytoplasmic alignment subcomplex component, PilM, with the IM-associated lipoprotein PilP that interacts with the N0 domain of the secretin monomer PilQ (19,21). Proposed functions of the PilMNOP subcomplex include ali...

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Biogenesis of Pseudomonas aeruginosa type IV pili and regulation of their function

Cited by 98 publications

References 144 publications

A comprehensive guide to pilus biogenesis in Gram-negative bacteria

A comprehensive guide to pilus biogenesis in Gram-negative bacteria

Role of Cyclic Di-GMP and Exopolysaccharide in Type IV Pilus Dynamics

Type IV Pilus Alignment Subcomplex Proteins PilN and PilO Form Homo- and Heterodimers in Vivo

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