The complex flagellar torque generator of Pseudomonas aeruginosa
The complex flagellar torque generator of Pseudomonas aeruginosa
复制标题
DOI：
10.1128/jb.186.19.6341-6350.2004
复制
发表时间：
2004-10-01
影响因子：
3.2
通讯作者：
McCarter, LL
中科院分区：
文献类型：
--
作者：
Doyle, TB;Hawkins, AC;McCarter, LL
鞭毛充当半刚性螺旋桨，由可逆旋转电机提供动力。 MotA 和 MotB 两种膜蛋白作为复合物发挥作用，充当定子并产生驱动旋转的扭矩。铜绿假单胞菌 PAO1 的基因组序列包含双组 motA 和 motB 基因，PA1460-PA1461 (motAB) 和 PA4954-PA4953 (motCD)，以及另一个基因 motY (PA3526)，已知该基因是某些细菌运动功能所必需的。在这里，我们证明这五个基因有助于运动。对于水环境中的易位来说，任一 motAB 样基因座的功能丧失都是不必要的。然而，通过在两个 motAB 编码区域引入突变组合可以完全消除游泳。编码 MotA 同源物或 MotB 同源物的两个基因的突变足以消除运动性。在非等价基因（即 motA motD 或 motB motC）中携带双突变的突变体保留了运动性，表明非同源成分可以一起发挥作用。 motY 似乎是 motAB 功能所必需的。 motY 和 motCD 突变的组合使细胞不能运动。 motAB、motY 或 motAB motY 功能丧失产生相似的表型；尽管游动速度仅降低到野生型速度的85%左右，但在半固体运动琼脂中的易位和在凝固琼脂表面的群聚受到严重阻碍。因此，铜绿假单胞菌的鞭毛运动代表了比其他细菌研究的结构更复杂的结构，并且它能够在不同的情况下进行有效的运动。
Flagella act as semirigid helical propellers that are powered by reversible rotary motors. Two membrane proteins, MotA and MotB, function as a complex that acts as the stator and generates the torque that drives rotation. The genome sequence of Pseudomonas aeruginosa PAO1 contains dual sets of motA and motB genes, PA1460-PA1461 (motAB) and PA4954-PA4953 (motCD), as well as another gene, motY (PA3526), which is known to be required for motor function in some bacteria. Here, we show that these five genes contribute to motility. Loss of function of either motAB-like locus was dispensable for translocation in aqueous environments. However, swimming could be entirely eliminated by introduction of combinations of mutations in the two motAB-encoding regions. Mutation of both genes encoding the MotA homologs or MotB homologs was sufficient to abolish motility. Mutants carrying double mutations in nonequivalent genes (i.e., motA motD or motB motC) retained motility, indicating that noncognate components can function together. motY appears to be required for motAB function. The combination of motY and motCD mutations rendered the cells nonmotile. Loss of function of motAB, motY, or motAB motY produced similar phenotypes; although the swimming speed was only reduced to similar to85% of the wild-type speed, translocation in semisolid motility agar and swarming on the surface of solidified agar were severely impeded. Thus, the flagellar motor of P. aeruginosa represents a more complex configuration than the configuration that has been studied in other bacteria, and it enables efficient movement under different circumstances.