Motor Properties of PilT-Independent Type 4 Pilus Retraction in Gonococci

Zöllner, Robert; Cronenberg, Tom; Maier, Berenike

doi:10.1128/jb.00778-18

Cited by 28 publications

(9 citation statements)

References 47 publications

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“…In contrast, the Δ pilU and Δ pilT strains exhibited a similar reduction in the retraction force (~2-fold for both) compared to the parent strain ( Fig 1G ). As other groups have also reported, data collected on pilus retraction forces tend to be highly variable [18, 32, 34], which we also observed here ( Fig 1G and 1H ). Despite this variability, a histogram reveals that PilT and PilU promote retraction forces >12 pN because retraction events exceeding this force are relatively rare in the Δ pilT and Δ pilU strains ( Fig 1H ).…”

Section: Resultssupporting

confidence: 89%

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PilT and PilU are homohexameric ATPases that coordinate to retract type IVa pili

et al. 2019

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Bacterial type IV pili are critical for diverse biological processes including horizontal gene transfer, surface sensing, biofilm formation, adherence, motility, and virulence. These dynamic appendages extend and retract from the cell surface. In many type IVa pilus systems, extension occurs through the action of an extension ATPase, often called PilB, while optimal retraction requires the action of a retraction ATPase, PilT. Many type IVa systems also encode a homolog of PilT called PilU. However, the function of this protein has remained unclear because pilU mutants exhibit inconsistent phenotypes among type IV pilus systems and because it is relatively understudied compared to PilT. Here, we study the type IVa competence pilus of Vibrio cholerae as a model system to define the role of PilU. We show that the ATPase activity of PilU is critical for pilus retraction in PilT Walker A and/or Walker B mutants. PilU does not, however, contribute to pilus retraction in ΔpilT strains. Thus, these data suggest that PilU is a bona fide retraction ATPase that supports pilus retraction in a PilT-dependent manner. We also found that a ΔpilU mutant exhibited a reduction in the force of retraction suggesting that PilU is important for generating maximal retraction forces. Additional in vitro and in vivo data show that PilT and PilU act as independent homo-hexamers that may form a complex to facilitate pilus retraction. Finally, we demonstrate that the role of PilU as a PilT-dependent retraction ATPase is conserved in Acinetobacter baylyi, suggesting that the role of PilU described here may be broadly applicable to other type IVa pilus systems.

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Section: Resultssupporting

confidence: 89%

“…Recent work in Neisseria indicates that PilTU-independent retraction is not unique to the V . cholerae type IVa competence pilus [34]. The mechanism underlying PilTU-independent retraction remains unclear.…”

Section: Discussionmentioning

confidence: 99%

PilT and PilU are homohexameric ATPases that coordinate to retract type IVa pili

et al. 2019

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“…These strains, however, did display rare pilus retraction, which occurred at rates that were markedly slower than the parent (>40-fold), which is independent of PilT and PilU. Recent work in Neisseria indicates that PilTU-independent retraction is not unique to the V. cholerae competence pilus [38]. The mechanism underlying PilTU-independent retraction is still unclear [5] and will be the focus of future work.…”

Section: Discussionmentioning

confidence: 99%

PilT and PilU are homohexameric ATPases that coordinate to retract type IVa pili

Chlebek

Hughes

Ratkiewicz

et al. 2019

Preprint

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19Bacterial type IV pili are critical for diverse biological processes including horizontal gene 20 transfer, surface sensing, biofilm formation, adherence, motility, and virulence. These dynamic 21 appendages extend and retract from the cell surface. In many type IVa pilus systems, extension 22 occurs through the action of an extension ATPase, often called PilB, while optimal retraction 23 requires the action of a retraction ATPase, PilT. Many type IVa systems also encode a homolog 24 of PilT called PilU. However, the function of this protein has remained unclear because pilU 25 mutants exhibit inconsistent phenotypes among type IV pilus systems and because it is 26 relatively understudied compared to PilT. Here, we study the type IVa competence pilus of 27Vibrio cholerae as a model system to define the role of PilU. We show that the ATPase activity 28 of PilU is critical for pilus retraction in PilT Walker A and/or Walker B mutants. PilU does not, 29 however, contribute to pilus retraction in ΔpilT strains. Thus, these data suggest that PilU is a 30 bona fide retraction ATPase that supports pilus retraction in a PilT-dependent manner. We also 31 found that a ΔpilU mutant exhibited a reduction in the force of retraction suggesting that PilU is 32 important for generating maximal retraction forces. Additional in vitro and in vivo data show that 33PilT and PilU act as independent homo-hexamers that may form a complex to facilitate pilus 34 retraction. Finally, we demonstrate that the role of PilU as a PilT-dependent retraction ATPase 35 is conserved in Acinetobacter baylyi, suggesting that the role of PilU described here may be 36 broadly applicable to other type IVa pilus systems. 37 38Author Summary 39 Almost all bacterial species use thin surface appendages called pili to interact with their 40 environments. These structures are critical for the virulence of many pathogens and represent 41 one major way that bacteria share DNA with one another, which contributes to the spread of 42 antibiotic resistance. To carry out their function, pili dynamically extend and retract from the 43 bacterial surface. Here, we show that retraction of pili in some systems is determined by the 44 combined activity of two motor ATPase proteins. 45 46Type IV pili are ubiquitous surface appendages in Gram-negative bacteria that promote diverse 48 activities including attachment, virulence, biofilm formation, horizontal gene transfer, and 49 twitching motility [1][2][3][4][5]. These structures can dynamically extend and retract from the cell 50 surface, which is often critical for their function. A detailed mechanistic understanding of pilus 51 dynamic activity, however, remains lacking. 52Type IV pili are composed almost exclusively of a single protein called the major pilin, which 53 forms a helical fiber that extends from the cell surface [6]. Extension and retraction of the pilus is 54 hypothesized to occur through the interaction of cytoplasmic hexameric ATPases with the inner 55 membrane platform of the pilus machine, whereby ATP ...

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“…This model puts the T2SS in a category with related nanomachines like the T4P, which can serve as a natural competence pilus ( 57 ) that depends on ATPase-energized transenvelope assemblies to import DNA. While these systems generally include an active retraction ATPase, which is lacking in the T2SS, recent work has uncovered pilus retraction and DNA uptake models that are independent of this second ATPase ( 58 , 59 ). Our work highlights the importance of studies on phage–host interactions to support the renaissance of phages as biocontrol agents.…”

Section: Discussionmentioning

confidence: 99%

In through the Out Door: A Functional Virulence Factor Secretion System Is Necessary for Phage Infection in Ralstonia solanacearum

Xavier

Melo

Hendrich

et al. 2022

mBio

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Motor Properties of PilT-Independent Type 4 Pilus Retraction in Gonococci

Cited by 28 publications

References 47 publications

PilT and PilU are homohexameric ATPases that coordinate to retract type IVa pili

PilT and PilU are homohexameric ATPases that coordinate to retract type IVa pili

PilT and PilU are homohexameric ATPases that coordinate to retract type IVa pili

In through the Out Door: A Functional Virulence Factor Secretion System Is Necessary for Phage Infection in Ralstonia solanacearum

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