Zaburdaev Vasily, Biais Nicolas, Schmiedeberg Michael, Eriksson Jens, Jonsson Ann-Beth, Sheetz Michael P, Weitz David A
School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts.
Department of Biological Sciences, Columbia University, New York, New York; Department of Biology, Brooklyn College, New York, New York.
Biophys J. 2014 Oct 7;107(7):1523-31. doi: 10.1016/j.bpj.2014.07.061.
Neisseria gonorrheae bacteria are the causative agent of the second most common sexually transmitted infection in the world. The bacteria move on a surface by means of twitching motility. Their movement is mediated by multiple long and flexible filaments, called type IV pili, that extend from the cell body, attach to the surface, and retract, thus generating a pulling force. Moving cells also use pili to aggregate and form microcolonies. However, the mechanism by which the pili surrounding the cell body work together to propel bacteria remains unclear. Understanding this process will help describe the motility of N. gonorrheae bacteria, and thus the dissemination of the disease which they cause. In this article we track individual twitching cells and observe that their trajectories consist of alternating moving and pausing intervals, while the cell body is preferably oriented with its wide side toward the direction of motion. Based on these data, we propose a model for the collective pili operation of N. gonorrheae bacteria that explains the experimentally observed behavior. Individual pili function independently but can lead to coordinated motion or pausing via the force balance. The geometry of the cell defines its orientation during motion. We show that by changing pili substrate interactions, the motility pattern can be altered in a predictable way. Although the model proposed is tangibly simple, it still has sufficient robustness to incorporate further advanced pili features and various cell geometries to describe other bacteria that employ pili to move on surfaces.
淋病奈瑟菌是世界上第二常见的性传播感染的病原体。该细菌通过颤动运动在表面移动。它们的运动由多条长而灵活的细丝介导，这些细丝称为IV型菌毛，从细胞体延伸出来，附着在表面并缩回，从而产生拉力。移动的细胞还利用菌毛聚集并形成微菌落。然而，围绕细胞体的菌毛共同推动细菌的机制仍不清楚。了解这一过程将有助于描述淋病奈瑟菌的运动，进而了解它们所引发疾病的传播。在本文中，我们追踪单个颤动细胞，观察到它们的轨迹由交替的移动和暂停间隔组成，而细胞体的宽边更倾向于朝向运动方向。基于这些数据，我们提出了一个淋病奈瑟菌细菌菌毛集体运作的模型，该模型解释了实验观察到的行为。单个菌毛独立发挥作用，但可通过力的平衡导致协调运动或暂停。细胞的几何形状决定了其运动过程中的方向。我们表明，通过改变菌毛与底物的相互作用，可以以可预测的方式改变运动模式。虽然所提出的模型明显简单，但它仍具有足够的稳健性，能够纳入进一步的先进菌毛特征和各种细胞几何形状，以描述其他利用菌毛在表面移动的细菌。
