Motor properties of PilT-independent type 4 pilus retraction in gonococci

Mapping Intimacies ◽

10.1101/497933 ◽

2018 ◽

Author(s):

Robert Zöllner ◽

Tom Cronenberg ◽

Berenike Maier

Keyword(s):

Host Cell ◽

Cell Response ◽

Molecular Machines ◽

Proton Motive Force ◽

Motive Force ◽

Maximum Force ◽

Twitching Motility ◽

Host Cell Response ◽

Bacterial Type

Bacterial type 4 pili (T4P) belong to the strongest molecular machines. The gonococcal T4P retraction ATPase PilT supports forces exceeding 100 pN during T4P retraction. Here, we address the question whether gonococcal T4P retract in the absence of PilT. We show that pilT deletion strains indeed retract their T4P but the maximum force is reduced to 5 pN. Similarly, the speed of T4P retraction is lower by orders of magnitude compared to T4P retraction driven by PilT. Deleting the pilT paralogues pilU and pilT2 in the DpilT background did not inhibit T4P retraction, indicating that the PilT-like proteins do not compensate for PilT. Furthermore, we show that depletion of proton motive force did not inhibit pilT-independent T4P retraction. We conclude that the retraction ATPase is not essential for gonococcal T4P retraction. However, the force generated in the absence of PilT is too low to support important functions of T4P including twitching motility, fluidization of colonies, or induction of host cell response.

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

Journal of Bacteriology ◽

10.1128/jb.00778-18 ◽

2019 ◽

Vol 201 (18) ◽

Cited By ~ 6

Author(s):

Robert Zöllner ◽

Tom Cronenberg ◽

Berenike Maier

Keyword(s):

Host Cell ◽

Cell Response ◽

Cell Interaction ◽

Dna Uptake ◽

Twitching Motility ◽

Biophysical Characterization ◽

Host Cell Response ◽

Surface Sensing ◽

Bacterial Type ◽

Host Cell Interaction

ABSTRACT Bacterial type 4 pili (T4P) belong to the strongest molecular machines. The gonococcal T4P retraction ATPase PilT supports forces exceeding 100 pN during T4P retraction. Here, we address the question of whether gonococcal T4P retract in the absence of PilT. We show that pilT deletion strains indeed retract their T4P, but the maximum force is reduced to 5 pN. Similarly, the speed of T4P retraction is lower by orders of magnitude compared to that of T4P retraction driven by PilT. Deleting the pilT paralogue pilT2 further reduces the speed of T4P retraction, yet T4P retraction is detectable in the absence of all three pilT paralogues. Furthermore, we show that depletion of proton motive force (PMF) slows but does not inhibit pilT-independent T4P retraction. We conclude that the retraction ATPase is not essential for gonococcal T4P retraction. However, the force generated in the absence of PilT is too low to support important functions of T4P, including twitching motility, fluidization of colonies, and induction of host cell response. IMPORTANCE Bacterial type 4 pili (T4P) have been termed the “Swiss Army knives” of bacteria because they perform numerous functions, including host cell interaction, twitching motility, colony formation, DNA uptake, protein secretion, and surface sensing. The pilus fiber continuously elongates or retracts, and these dynamics are functionally important. Curiously, only a subset of T4P systems employ T4P retraction ATPases to power T4P retraction. Here, we show that one of the strongest T4P machines, the gonococcal T4P, retracts without a retraction ATPase. Biophysical characterization reveals strongly reduced force and speed compared to retraction with ATPase. We propose that bacteria encode retraction ATPases when T4P have to generate high-force-supporting functions like twitching motility, triggering host cell response, or fluidizing colonies.

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The Hypervariable Region of Meningococcal Major Pilin PilE Controls the Host Cell Response via Antigenic Variation

mBio ◽

10.1128/mbio.01024-13 ◽

2014 ◽

Vol 5 (1) ◽

Cited By ~ 13

Author(s):

Florence Miller ◽

Gilles Phan ◽

Terry Brissac ◽

Coralie Bouchiat ◽

Ghislaine Lioux ◽

...

Keyword(s):

Endothelial Cells ◽

Neisseria Meningitidis ◽

Host Cell ◽

Cell Response ◽

Gram Negative Bacteria ◽

Twitching Motility ◽

Content Type ◽

Host Cell Response ◽

Pilin Subunit ◽

D Region

ABSTRACTType IV pili (Tfp) are expressed by many Gram-negative bacteria to promote aggregation, adhesion, internalization, twitching motility, or natural transformation. Tfp ofNeisseria meningitidis, the causative agent of cerebrospinal meningitis, are involved in the colonization of human nasopharynx. After invasion of the bloodstream, Tfp allow adhesion ofN. meningitidisto human endothelial cells, which leads to the opening of the blood-brain barrier and meningitis. To achieve firm adhesion,N. meningitidisinduces a host cell response that results in elongation of microvilli surrounding the meningococcal colony. Here we study the role of the major pilin subunit PilE during host cell response using human dermal microvascular endothelial cells and the pharynx carcinoma-derived FaDu epithelial cell line. We first show that some PilE variants are unable to induce a host cell response. By engineering PilE mutants, we observed that the PilE C-terminus domain, which contains a disulfide bonded region (D-region), is critical for the host cell response and that hypervariable regions confer different host cell specificities. Moreover, the study of point mutants of the pilin D-region combined with structural modeling of PilE revealed that the D-region contains two independent regions involved in signaling to human dermal microvascular endothelial cells (HDMECs) or FaDu cells. Our results indicate that the diversity of the PilE D-region sequence allows the induction of the host cell response via several receptors. This suggests thatNeisseria meningitidishas evolved a powerful tool to adapt easily to many niches by modifying its ability to interact with host cells.IMPORTANCEType IV pili (Tfp) are long appendages expressed by many Gram-negative bacteria, includingNeisseria meningitidis, the causative agent of cerebrospinal meningitis. These pili are involved in many aspects of pathogenesis: natural competence, aggregation, adhesion, and twitching motility. More specifically,Neisseria meningitidis, which is devoid of a secretion system to manipulate its host, has evolved its Tfp to signal to brain endothelial cells and open the blood-brain barrier. In this report, we investigate, at the molecular level, the involvement of the major pilin subunit PilE in host cell response. Our results indicate that the PilE C-terminal domain, which contains a disulfide bonded region (D-region), is critical for the host cell response and contains two independent regions involved in host cell signaling.

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Faculty Opinions recommendation of Bartonella adhesin a mediates a proangiogenic host cell response.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1023274.268641 ◽

2005 ◽

Author(s):

Rino Rappuoli

Keyword(s):

Host Cell ◽

Cell Response ◽

Host Cell Response

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Defective Interfering RNA Viruses and the Host-Cell Response

Comprehensive Virology ◽

10.1007/978-1-4613-3129-2_3 ◽

1980 ◽

pp. 137-192 ◽

Cited By ~ 48

Author(s):

John J. Holland ◽

S. Ian T. Kennedy ◽

Bert L. Semler ◽

Charlotte L. Jones ◽

Laurent Roux ◽

...

Keyword(s):

Host Cell ◽

Cell Response ◽

Rna Viruses ◽

Host Cell Response ◽

Defective Interfering Rna ◽

Interfering Rna

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Interspecies communication in the gut, from bacterial delivery to host-cell response

The Journal of Physiology ◽

10.1113/jphysiol.2011.220822 ◽

2012 ◽

Vol 590 (3) ◽

pp. 433-440 ◽

Cited By ~ 10

Author(s):

Kim Hodges ◽

Gail Hecht

Keyword(s):

Host Cell ◽

Cell Response ◽

Interspecies Communication ◽

Host Cell Response

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Pore Formation Triggered by Legionella spp. Is an Nlrc4 Inflammasome-Dependent Host Cell Response That Precedes Pyroptosis

Infection and Immunity ◽

10.1128/iai.00905-09 ◽

2010 ◽

Vol 78 (3) ◽

pp. 1403-1413 ◽

Cited By ~ 63

Author(s):

Tatiana N. Silveira ◽

Dario S. Zamboni

Keyword(s):

Host Cell ◽

Legionella Pneumophila ◽

Cell Response ◽

Pore Formation ◽

De Novo ◽

Membrane Damage ◽

Secretion System ◽

Cell Permeabilization ◽

Host Cell Response ◽

Caspase 1

ABSTRACT Legionella pneumophila, the etiological agent of Legionnaires disease, is known to trigger pore formation in bone marrow-derived macrophages (BMMs) by mechanisms dependent on the type IVB secretion system known as Dot/Icm. Here, we used several mutants of L. pneumophila in combination with knockout mice to assess the host and bacterial factors involved in pore formation in BMMs. We found that regardless of Dot/Icm activity, pore formation does not occur in BMMs deficient in caspase-1 and Nlrc4/Ipaf. Pore formation was temporally associated with interleukin-1β secretion and preceded host cell lysis and pyroptosis. Pore-forming ability was dependent on bacterial Dot/Icm but independent of several effector proteins, multiplication, and de novo protein synthesis. Flagellin, which is known to trigger the Nlrc4 inflammasome, was required for pore formation as flaA mutant bacteria failed to induce cell permeabilization. Accordingly, transfection of purified flagellin was sufficient to trigger pore formation independent of infection. By using 11 different Legionella species, we found robust pore formation in response to L. micdadei, L. bozemanii, L. gratiana, L. jordanis, and L. rubrilucens, and this trait correlated with flagellin expression by these species. Together, the results suggest that pore formation is neither L. pneumophila specific nor the result of membrane damage induced by Dot/Icm activity; instead, it is a highly coordinated host cell response dependent on host Nlrc4 and caspase-1 and on bacterial flagellin and type IV secretion system.

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