An Elastic Model of Spirochete Morphology and Motility

螺旋体形态和运动的弹性模型

• 批准号: 7229013
• 负责人: CHARLES W WOLGEMUTH
• 金额: $ 22.45万
• 依托单位: UNIVERSITY OF CONNECTICUT SCH OF MED/DNT
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-05-01 至 2010-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7229013
• 关键词: Affect; Bacteria; Biological Models; Borrelia burgdorferi; Cell Wall; Cell membrane; Cells; Cellular Morphology; Coupled; Coupling; Decompression Sickness; Elasticity; Environment; Filament; Flagella; Grant; Lead; Length; Liquid substance; Measurement; Modeling; Molecular Conformation; Morphology; Motor; Numbers; Order Spirochaetales; Play; Polymers; Role; Rotation; Shapes; Swimming; System; Systems Analysis; Testing; Torque; Work; cell motility; periplasm

DESCRIPTION (provided by applicant): Polymer filaments play a major role in bacterial motility and morphology. Spirochetes, bacteria that swim by rotating helical flagella that are encased within a periplasmic space (the space between the inner and outer cell membranes where the cell wall material is located), are excellent model systems to study how elastic polymer filaments coupled to a bacterial cell wall can affect motility and morphology. Rotation of the flagella induces rotation and deformations in the cell wall. Because the flagella remain within the periplasm, the elasticity of the helical flagella competes with the preferred morphology of the cell wall. How this interplay between flagella and wall elasticity leads to total cell morphology and how forces developed by the flagellar motor drive motility is poorly understood. This grant will support the broadening of elastohydrodynamics to handle systems in which two or more elastic filaments are coupled together. This new mathematical framework will then be employed to model the morphology and motility of spirochete bacteria. Through study of the static shapes predicted by this model, this work will test the experimentally justified hypothesis that the flagella and cell wall are the dominant morphological determinants in spirochete bacteria and explore how the number and length of the periplasmic flagella affect these shapes. A detailed analysis of how this system responds to external forces and torques, as would be produced by the flagellar motor, will lead to an understanding of the dynamic shape changes that spirochetes undergo while swimming. Finally, the coupling of the resulting cell conformations to the viscous fluid environment surrounding them will be investigated to quantify the propulsive force generated by the rotation of the flagellar motor for many spirochetes and also explain the precession of the flat wave morphology in Borrelia burgdorferi. This grant will also support the experimental measurement of the bending moduli of the cell wall and the periplasmic flagella.

描述(申请人提供)：聚合物纤维在细菌的运动和形态中起着重要的作用。螺旋体是一种通过包裹在周质空间(细胞壁材料所在的内外细胞膜之间的空间)中旋转的螺旋鞭毛游泳的细菌，是研究弹性聚合物细丝与细菌细胞壁耦合如何影响运动和形态的优秀模式系统。鞭毛的旋转会导致细胞壁的旋转和变形。由于鞭毛留在周质内，螺旋鞭毛的弹性与细胞壁的首选形态竞争。鞭毛和壁弹性之间的这种相互作用如何导致总的细胞形态，以及鞭毛马达如何驱动运动所产生的力，目前还知之甚少。 这笔赠款将支持扩大弹性流体动力学的范围，以处理两个或更多弹性细丝耦合在一起的系统。然后，这个新的数学框架将被用来模拟螺旋体细菌的形态和运动性。通过对该模型预测的静态形状的研究，本工作将检验实验证明的假设，即鞭毛和细胞壁是螺旋体细菌的主要形态决定因素，并探索周质鞭毛的数量和长度如何影响这些形状。对这一系统如何对鞭毛马达产生的外力和扭矩做出反应的详细分析，将有助于理解螺旋体在游泳时经历的动态形状变化。最后，将研究产生的细胞构象与其周围粘性流体环境的耦合，以量化许多螺旋体鞭毛马达旋转所产生的推动力，并解释伯氏疏螺旋体扁平波形态的进动。这笔赠款还将支持对细胞壁和周质鞭毛弯曲模数的实验测量。