TY - JOUR
T1 - Distinct roles of highly conserved charged residues at the MotA-FliG interface in bacterial flagellar motor rotation
AU - Morimoto, Yusuke V.
AU - Nakamura, Shuichi
AU - Hiraoka, Koichi D.
AU - Namba, Keiichi
AU - Minamino, Tohru
PY - 2013/2
Y1 - 2013/2
N2 - Electrostatic interactions between the stator protein MotA and the rotor protein FliG are important for bacterial flagellar motor rotation. Arg90 and Glu98 of MotA are required not only for torque generation but also for stator assembly around the rotor, but their actual roles remain unknown. Here we analyzed the roles of functionally important charged residues at the MotA-FliG interface in motor performance. About 75% of the motA(R90E) cells and 45% of the motA(E98K) cells showed no fluorescent spots of green fluorescent protein (GFP)-MotB, indicating reduced efficiency of stator assembly around the rotor. The FliG(D289K) and FliG(R281V) mutations, which restore the motility of the motA(R90E) and motA(E98K) mutants, respectively, showed reduced numbers and intensity of GFP-MotB spots as well. The FliG(D289K) mutation significantly recovered the localization of GFP-MotB to the motor in the motA(R90E) mutant, whereas the FliG(R281V) mutation did not recover the GFP-MotB localization in the motA(E98K) mutant. These results suggest that the MotA-Arg90-FliG-Asp289 interaction is critical for the proper positioning of the stators around the rotor, whereas the MotA-Glu98-FliG-Arg281 interaction is more important for torque generation.
AB - Electrostatic interactions between the stator protein MotA and the rotor protein FliG are important for bacterial flagellar motor rotation. Arg90 and Glu98 of MotA are required not only for torque generation but also for stator assembly around the rotor, but their actual roles remain unknown. Here we analyzed the roles of functionally important charged residues at the MotA-FliG interface in motor performance. About 75% of the motA(R90E) cells and 45% of the motA(E98K) cells showed no fluorescent spots of green fluorescent protein (GFP)-MotB, indicating reduced efficiency of stator assembly around the rotor. The FliG(D289K) and FliG(R281V) mutations, which restore the motility of the motA(R90E) and motA(E98K) mutants, respectively, showed reduced numbers and intensity of GFP-MotB spots as well. The FliG(D289K) mutation significantly recovered the localization of GFP-MotB to the motor in the motA(R90E) mutant, whereas the FliG(R281V) mutation did not recover the GFP-MotB localization in the motA(E98K) mutant. These results suggest that the MotA-Arg90-FliG-Asp289 interaction is critical for the proper positioning of the stators around the rotor, whereas the MotA-Glu98-FliG-Arg281 interaction is more important for torque generation.
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U2 - 10.1128/JB.01971-12
DO - 10.1128/JB.01971-12
M3 - Article
C2 - 23161029
AN - SCOPUS:84873045159
VL - 195
SP - 474
EP - 481
JO - Journal of Bacteriology
JF - Journal of Bacteriology
SN - 0021-9193
IS - 3
ER -