2005/04/13 by Martin Linden, Martin Lindén, Linden, Martin +7 · 1 citation
Biochemistry, Genetics and Molecular Biology · Physics and Astronomy · #Advanced X-ray Imaging Techniques #Biological Physics (physics.bio-ph) #FOS: Biological sciences #FOS: Physical sciences #Other Condensed Matter (cond-mat.other) #Other Quantitative Biology (q-bio.OT) #Subcellular Processes (q-bio.SC) #cond-mat.other #physics.bio-ph #q-bio.OT #q-bio.SC
paper · pdf · doi:10.48550/arxiv.physics/0504084
10 pages, 2 figures, 1 table
arxiv created 2005/04/13 · openalex publication_date 2005/04/13 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
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.