dorsal/arxiv
View SchemaFluctuations in type IV pilus retraction
| Authors | Martin Linden, Emil Johansson, Ann-Beth Jonsson, Mats Wallin |
|---|---|
| Categories | |
| ArXiv ID | physics/0504084 |
| URL | https://arxiv.org/abs/physics/0504084 |
Abstract
The type IV pilus retraction motor is found in many important bacterial pathogens. It is the strongest known linear motor protein and is required for bacterial infectivity. We characterize the dynamics of type IV pilus retraction in terms of a stochastic chemical reaction model. We find that a two state model can describe the experimental force velocity relation and qualitative dependence of ATP concentration. The results indicate that the dynamics is limited by an ATP-dependent step at low load and a force-dependent step at high load, and that at least one step is effectively irreversible in the measured range of forces. The irreversible nature of the sub-step(s) lead to interesting predictions for future experiments: We find different parameterizations with mathematically identical force velocity relations but different fluctuations (diffusion constant). We also find a longer elementary step compared to an earlier analysis, which agrees better with known facts about the structure of the pilus filament and energetic considerations. We conclude that more experimental data is needed, and that further retraction experiments are likely to resolve interesting details and give valuable insights into the PilT machinery. In light of our findings, the fluctuations of the retraction dynamics emerge as a key property to be studied in future experiments.
{
"annotation_id": "af6e05f0-bc65-4f34-8e14-d834aedb0354",
"date_created": "2026-03-02T18:00:57.004000Z",
"date_modified": "2026-03-02T18:00:57.004000Z",
"file_hash": "882832960b6cd2e0894804cc54f7d70f7fd029ccd820bfdf1d6b3781f2c76cec",
"private": false,
"record": {
"abstract": "The type IV pilus retraction motor is found in many important bacterial\npathogens. It is the strongest known linear motor protein and is required for\nbacterial infectivity. We characterize the dynamics of type IV pilus retraction\nin terms of a stochastic chemical reaction model. We find that a two state\nmodel can describe the experimental force velocity relation and qualitative\ndependence of ATP concentration. The results indicate that the dynamics is\nlimited by an ATP-dependent step at low load and a force-dependent step at high\nload, and that at least one step is effectively irreversible in the measured\nrange of forces. The irreversible nature of the sub-step(s) lead to interesting\npredictions for future experiments: We find different parameterizations with\nmathematically identical force velocity relations but different fluctuations\n(diffusion constant). We also find a longer elementary step compared to an\nearlier analysis, which agrees better with known facts about the structure of\nthe pilus filament and energetic considerations. We conclude that more\nexperimental data is needed, and that further retraction experiments are likely\nto resolve interesting details and give valuable insights into the PilT\nmachinery. In light of our findings, the fluctuations of the retraction\ndynamics emerge as a key property to be studied in future experiments.",
"arxiv_id": "physics/0504084",
"authors": [
"Martin Linden",
"Emil Johansson",
"Ann-Beth Jonsson",
"Mats Wallin"
],
"categories": [
"physics.bio-ph",
"cond-mat.other",
"q-bio.OT",
"q-bio.SC"
],
"title": "Fluctuations in type IV pilus retraction",
"url": "https://arxiv.org/abs/physics/0504084"
},
"schema_id": "dorsal/arxiv",
"source": {
"execution_id": "4e30fb01-cfe3-43ce-ae0c-ab871695d664",
"id": "arXiv Dataset IDs",
"type": "Model",
"variant": "snapshot-2026-03-01",
"version": "0.1.0"
},
"user_id": 1000002
}