Nishino Yuuki, Onoue Yasuhiro, Kojima Seiji, Homma Michio
Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan.
Microbiologyopen. 2015 Apr;4(2):323-331. doi: 10.1002/mbo3.240. Epub 2015 Jan 29.
The bacterial flagellar motor has a stator and a rotor. The stator is composed of two membrane proteins, MotA and MotB in Escherichia coli and PomA and PomB in Vibrio alginolyticus. The Vibrio motor has a unique structure, the T ring, which is composed of MotX and MotY. Based on the structural information of PomB and MotB, we constructed three chimeric proteins between PomB and MotB, named PotB , PotB and PotB , with various chimeric junctions. When those chimeric proteins were produced with PomA in a ΔmotAB strain of E. coli or in ΔpomAB and ΔpomAB ΔmotX strains of Vibrio, all chimeras were functional in E. coli or Vibrio, either with or without the T ring, although the motilities were very weak in E. coli. Furthermore, we could isolate some suppressors in E. coli and identified the mutation sites on PomA or the chimeric B subunit. The weak function of chimeric PotBs in E. coli is derived mainly from the defect in the rotational switching of the flagellar motor. In addition, comparing the motilities of chimera strains in ΔpomAB, PotB had the highest motility. The difference between the origin of the α1 and α2 helices, E. coli MotB or Vibro PomB, seems to be important for motility in E. coli and especially in Vibrio.
细菌鞭毛马达有一个定子和一个转子。定子由两种膜蛋白组成，在大肠杆菌中是MotA和MotB，在溶藻弧菌中是PomA和PomB。弧菌马达有一种独特的结构，即T环，它由MotX和MotY组成。基于PomB和MotB的结构信息，我们构建了三种PomB和MotB之间的嵌合蛋白，分别命名为PotB₁、PotB₂和PotB₃，它们具有不同的嵌合连接点。当这些嵌合蛋白与PomA在大肠杆菌的ΔmotAB菌株中或在弧菌的ΔpomAB和ΔpomAB ΔmotX菌株中表达时，所有嵌合体在大肠杆菌或弧菌中都具有功能，无论有无T环，尽管在大肠杆菌中的运动性非常弱。此外，我们在大肠杆菌中分离出了一些抑制子，并确定了PomA或嵌合B亚基上的突变位点。嵌合PotBs在大肠杆菌中的弱功能主要源于鞭毛马达旋转切换的缺陷。此外，比较ΔpomAB中嵌合体菌株的运动性，PotB₁具有最高的运动性。α1和α2螺旋的起源差异，即大肠杆菌MotB或弧菌PomB，似乎对大肠杆菌尤其是弧菌的运动性很重要。
