Requirements for Conversion of the Na+-Driven Flagellar Motor of Vibrio cholerae to the H+-Driven Motor of Escherichia coli
AUTOR(ES)
Gosink, Khoosheh K.
FONTE
American Society for Microbiology
RESUMO
Bacterial flagella are powered by a motor that converts a transmembrane electrochemical potential of either H+ or Na+ into mechanical work. In Escherichia coli, the MotA and MotB proteins form the stator and function in proton translocation, whereas the FliG protein is located on the rotor and is involved in flagellar assembly and torque generation. The sodium-driven polar flagella of Vibrio species contain homologs of MotA and MotB, called PomA and PomB, and also contain two other membrane proteins called MotX and MotY, which are essential for motor rotation and that might also function in ion conduction. Deletions in pomA, pomB, motX, or motY in Vibrio cholerae resulted in a nonmotile phenotype, whereas deletion of fliG gave a nonflagellate phenotype. fliG genes on plasmids complemented fliG-null strains of the parent species but not fliG-null strains of the other species. FliG-null strains were complemented by chimeric FliG proteins in which the C-terminal domain came from the other species, however, implying that the C-terminal part of FliG can function in conjunction with the ion-translocating components of either species. A V. cholerae strain deleted of pomA, pomB, motX, and motY became weakly motile when the E. coli motA and motB genes were introduced on a plasmid. Like E. coli, but unlike wild-type V. cholerae, motility of some V. cholerae strains containing the hybrid motor was inhibited by the protonophore carbonyl cyanide m-chlorophenylhydrazone under neutral as well as alkaline conditions but not by the sodium motor-specific inhibitor phenamil. We conclude that the E. coli proton motor components MotA and MotB can function in place of the motor proteins of V. cholerae and that the hybrid motors are driven by the proton motive force.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=101923Documentos Relacionados
- Functional Interaction between PomA and PomB, the Na+-Driven Flagellar Motor Components of Vibrio alginolyticus
- Hybrid Motor with H+- and Na+-Driven Components Can Rotate Vibrio Polar Flagella by Using Sodium Ions
- Coupling ion specificity of chimeras between H+- and Na+-driven motor proteins, MotB and PomB, in Vibrio polar flagella
- NorM of Vibrio parahaemolyticus Is an Na+-Driven Multidrug Efflux Pump
- Cystinosin, the protein defective in cystinosis, is a H+-driven lysosomal cystine transporter