Bacteria use type-IV pili to slingshot on surfaces
Bacteria use type-IV pili to slingshot on surfaces
复制标题
DOI：
10.1073/pnas.1105073108
复制
发表时间：
2011-08-02
影响因子：
11.1
通讯作者：
Wong, Gerard C. L.
中科院分区：
文献类型：
--
作者：
Jin, Fan;Conrad, Jacinta C.;Wong, Gerard C. L.
在形成多细胞细菌生物膜之前，细菌优化其运动性附属物的使用以在广泛的表面上有效地移动。许多细菌物种用于表面探索的“抽搐”运动模式使用IV型皮利（TFP）作为线性致动器以实现定向爬行。然而，除了直线运动之外，能动性还需要转向和方向的改变。此外，运动机制必须适应生物膜形成过程中遇到的不断变化的表面条件。在这里，我们开发了一种新的两点跟踪算法，在这种情况下解剖抽搐运动。我们发现，在铜绿假单胞菌中，TFP介导的爬行始终在两个不同的动作之间交替：恒定速度的平移和瞬时速度快约20倍的组合的平移-旋转。这些行动的方向分布表明，前者是由于多个TFP拉动，而后者是由于单一的TFP释放。释放动作导致快速的“弹弓”运动，可以通过过度转向有效地转动细胞体。此外，弹弓运动的大速度使细菌能够有效地移动通过含有剪切稀化粘弹性流体的环境，例如细菌在生物膜形成期间在表面上分泌的细胞外聚合物（EPS）。
Bacteria optimize the use of their motility appendages to move efficiently on a wide range of surfaces prior to forming multicellular bacterial biofilms. The "twitching" motility mode employed by many bacterial species for surface exploration uses type-IV pili (TFP) as linear actuators to enable directional crawling. In addition to linear motion, however, motility requires turns and changes of direction. Moreover, the motility mechanism must be adaptable to the continually changing surface conditions encountered during biofilm formation. Here, we develop a novel two-point tracking algorithm to dissect twitching motility in this context. We show that TFP-mediated crawling in Pseudomonas aeruginosa consistently alternates between two distinct actions: a translation of constant velocity and a combined translation-rotation that is approximately 20x faster in instantaneous velocity. Orientational distributions of these actions suggest that the former is due to pulling by multiple TFP, whereas the latter is due to release by single TFP. The release action leads to a fast "slingshot" motion that can turn the cell body efficiently by oversteering. Furthermore, the large velocity of the slingshot motion enables bacteria to move efficiently through environments that contain shear-thinning viscoelastic fluids, such as the extracellular polymeric substances (EPS) that bacteria secrete on surfaces during biofilm formation.