摘要翻译：
在许多重要的细菌病原体中都发现了IV型菌毛回缩运动。它是已知最强的直线运动蛋白，是细菌传染性所需的。我们用一个随机化学反应模型描述了IV型针头回缩的动力学。我们发现一个两态模型可以描述ATP浓度的实验力、速度关系和定性依赖关系。结果表明，在低载荷下，动力学受ATP相关阶跃的限制，在高载荷下受力相关阶跃的限制，在测力范围内，至少有一个阶跃是有效不可逆的。子步骤的不可逆性质为将来的实验带来了有趣的预测：我们发现不同的参数具有数学上相同的力速度关系，但不同的涨落（扩散常数）。我们还发现，与先前的分析相比，一个较长的基本步骤，这更符合关于毛芯细丝结构和能量考虑的已知事实。我们的结论是，需要更多的实验数据，进一步的回缩实验可能会解决有趣的细节，并对PilT机械提供有价值的见解。根据我们的发现，回缩动力学的涨落成为未来实验研究的一个关键性质。
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英文标题：
《Fluctuations in type IV pilus retraction》
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作者：
Martin Linden, Emil Johansson, Ann-Beth Jonsson, Mats Wallin
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最新提交年份：
2005
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分类信息：

一级分类：Physics        物理学
二级分类：Biological Physics        生物物理学
分类描述：Molecular biophysics, cellular biophysics, neurological biophysics, membrane biophysics, single-molecule biophysics, ecological biophysics, quantum phenomena in biological systems (quantum biophysics), theoretical biophysics, molecular dynamics/modeling and simulation, game theory, biomechanics, bioinformatics, microorganisms, virology, evolution, biophysical methods.
分子生物物理、细胞生物物理、神经生物物理、膜生物物理、单分子生物物理、生态生物物理、生物系统中的量子现象（量子生物物理）、理论生物物理、分子动力学/建模与模拟、博弈论、生物力学、生物信息学、微生物、病毒学、进化论、生物物理方法。
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一级分类：Physics        物理学
二级分类：Other Condensed Matter        其他凝聚态物质
分类描述：Work in condensed matter that does not fit into the other cond-mat classifications
在不适合其他cond-mat分类的凝聚态物质中工作
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一级分类：Quantitative Biology        数量生物学
二级分类：Other Quantitative Biology        其他定量生物学
分类描述：Work in quantitative biology that does not fit into the other q-bio classifications
不适合其他q-bio分类的定量生物学工作
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一级分类：Quantitative Biology        数量生物学
二级分类：Subcellular Processes        亚细胞过程
分类描述：Assembly and control of subcellular structures (channels, organelles, cytoskeletons, capsules, etc.); molecular motors, transport, subcellular localization; mitosis and meiosis
亚细胞结构（通道、细胞器、细胞骨架、囊膜等）的组装和控制；分子马达；转运；亚细胞定位；有丝分裂和减数分裂
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英文摘要：
  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.
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PDF链接：
https://arxiv.org/pdf/physics/0504084