Dual stator dynamics in the Shewanella oneidensis MR-1 flagellar motor.
The bacterial flagellar motor is an intricate nanomachine which converts ion gradients into rotational movement. Torque is created by ion-dependent stator complexes which surround the rotor in a ring. Shewanella oneidensis MR-1 expresses two distinct types of stator units: the Na(+)-dependent PomA4 B2 and the H(+)-dependent MotA4 B2. Here, we have explored the stator unit dynamics in the MR-1 flagellar system by using mCherry-labeled PomAB and MotAB units. We observed a total of between 7 and 11 stator units in each flagellar motor. Both types of stator units exchanged between motors and a pool of stator complexes in the membrane, and the exchange rate of MotAB, but not of PomAB, units was dependent on the environmental Na(+)-levels. In 200 mM Na(+), the numbers of PomAB and MotAB units in wild-type motors was determined to be about 7:2 (PomAB:MotAB), shifting to about 6:5 without Na(+). Significantly, the average swimming speed of MR-1 cells at low Na(+) conditions was increased in the presence of MotAB. These data strongly indicate that the S. oneidensis flagellar motors simultaneously use H(+) and Na(+) driven stators in a configuration governed by MotAB incorporation efficiency in response to environmental Na(+) levels.
Max-Planck-Institute für terrestrische Mikrobiologie, Department of Ecophysiology, 35043, Marburg, Germany.
Anja
A
Paulick
Biochemistry Department, University of Oxford, Oxford, OX1 3QU, UK.
Nicolas J
NJ
Delalez
Max-Planck-Institute für terrestrische Mikrobiologie, Department of Ecophysiology, 35043, Marburg, Germany.|Justus-Liebig-Universität Gießen, Department of Microbiology and Molecular Biology at the IFZ, Gießen, 35392, Germany.
Susanne
S
Brenzinger
Physics Department, University of Oxford, Oxford, OX1 3QU, UK.
Bradley C
BC
Steel
Physics Department, University of Oxford, Oxford, OX1 3QU, UK.
Richard M
RM
Berry
Biochemistry Department, University of Oxford, Oxford, OX1 3QU, UK.
Judith P
JP
Armitage
Max-Planck-Institute für terrestrische Mikrobiologie, Department of Ecophysiology, 35043, Marburg, Germany.|Justus-Liebig-Universität Gießen, Department of Microbiology and Molecular Biology at the IFZ, Gießen, 35392, Germany.
Kai M
KM
Thormann
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D005407:Flagella / Q000235:genetics* / Q000502:physiology*; D036681:Fluorescence Recovery After Photobleaching; D020409:Molecular Motor Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D020592:Shewanella / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D012964:Sodium / Q000378:metabolism
D001426:Bacterial Proteins; D020409:Molecular Motor Proteins; D012964:Sodium