TY - JOUR
T1 - Sodium-dependent dynamic assembly of membrane complexes in sodium-driven flagellar motors
AU - Fukuoka, Hajime
AU - Wada, Tomoyuki
AU - Kojima, Seiji
AU - Ishijima, Akihiko
AU - Homma, Michio
PY - 2009/2/1
Y1 - 2009/2/1
N2 - The bacterial flagellar motor is driven by the electrochemical potential of specific ions, H+ or Na+. The motor consists of a rotor and stator, and their interaction generates rotation. The stator, which is composed of PomA and PomB in the Na+ motor of Vibrio alginolyticus, is thought to be a torque generator converting the energy of ion flux into mechanical power. We found that specific mutations in PomB, including D24N, F33C and S248F, which caused motility defects, affected the assembly of stator complexes into the polar flagellar motor using green fluorescent protein-fused stator proteins. D24 of PomB is the predicted Na+-binding site. Furthermore, we demonstrated that the coupling ion, Na+, is required for stator assembly and that phenamil (an inhibitor of the Na+-driven motor) inhibited the assembly. Carbonyl cyanide m-chlorophenylhydrazone, which is a proton ionophore that collapses the sodium motive force in this organism at neutral pH, also inhibited the assembly. Thus we conclude that the process of Na+ influx through the channel, including Na+ binding, is essential for the assembly of the stator complex to the flagellar motor as well as for torque generation.
AB - The bacterial flagellar motor is driven by the electrochemical potential of specific ions, H+ or Na+. The motor consists of a rotor and stator, and their interaction generates rotation. The stator, which is composed of PomA and PomB in the Na+ motor of Vibrio alginolyticus, is thought to be a torque generator converting the energy of ion flux into mechanical power. We found that specific mutations in PomB, including D24N, F33C and S248F, which caused motility defects, affected the assembly of stator complexes into the polar flagellar motor using green fluorescent protein-fused stator proteins. D24 of PomB is the predicted Na+-binding site. Furthermore, we demonstrated that the coupling ion, Na+, is required for stator assembly and that phenamil (an inhibitor of the Na+-driven motor) inhibited the assembly. Carbonyl cyanide m-chlorophenylhydrazone, which is a proton ionophore that collapses the sodium motive force in this organism at neutral pH, also inhibited the assembly. Thus we conclude that the process of Na+ influx through the channel, including Na+ binding, is essential for the assembly of the stator complex to the flagellar motor as well as for torque generation.
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U2 - 10.1111/j.1365-2958.2008.06569.x
DO - 10.1111/j.1365-2958.2008.06569.x
M3 - Article
C2 - 19183284
AN - SCOPUS:60349120504
VL - 71
SP - 825
EP - 835
JO - Molecular Microbiology
JF - Molecular Microbiology
SN - 0950-382X
IS - 4
ER -