RRC ID 35454
Author Terahara N, Sano M, Ito M.
Title A Bacillus flagellar motor that can use both Na+ and K+ as a coupling ion is converted by a single mutation to use only Na+.
Journal PLoS ONE
Abstract In bacteria, the sodium ion (Na(+)) cycle plays a critical role in negotiating the challenges of an extremely alkaline and sodium-rich environment. Alkaliphilic bacteria that grow optimally at high pH values use Na(+) for solute uptake and flagellar rotation because the proton (H(+)) motive force is insufficient for use at extremely alkaline pH. Only three types of electrically driven rotary motors exist in nature: the F-type ATPase, the V-type ATPase, and the bacterial flagellar motor. Until now, only H(+) and Na(+) have been reported as coupling ions for these motors. Here, we report that the alkaliphilic bacterium Bacillus alcalophilus Vedder 1934 can grow not only under a Na(+)-rich and potassium ion (K(+))-poor condition but also under the opposite condition in an extremely alkaline environment. In this organism, swimming performance depends on concentrations of Na(+), K(+) or Rb(+). In the absence of Na(+), swimming behavior is clearly K(+)- dependent. This pattern was confirmed in swimming assays of stator-less Bacillus subtilis and Escherichia coli mutants expressing MotPS from B. alcalophilus (BA-MotPS). Furthermore, a single mutation in BA-MotS was identified that converted the naturally bi-functional BA-MotPS to stators that cannot use K(+) or Rb(+). This is the first report that describes a flagellar motor that can use K(+) and Rb(+) as coupling ions. The finding will affect the understanding of the operating principles of flagellar motors and the molecular mechanisms of ion selectivity, the field of the evolution of environmental changes and stresses, and areas of nanotechnology.
Volume 7(9)
Pages e46248
Published 2012
DOI 10.1371/journal.pone.0046248
PII PONE-D-12-14435
PMID 23049994
PMC PMC3457975
MeSH Amino Acid Sequence Bacillus / drug effects Bacillus / genetics Bacillus / metabolism* Bacillus / physiology* Bacterial Proteins / chemistry Bacterial Proteins / genetics Bacterial Proteins / metabolism* Blotting, Western Hydrogen-Ion Concentration Molecular Motor Proteins / chemistry Molecular Motor Proteins / genetics Molecular Motor Proteins / metabolism* Molecular Sequence Data Mutation Point Mutation Potassium / metabolism* Potassium Chloride / pharmacology Promoter Regions, Genetic / genetics Sequence Homology, Amino Acid Sodium Sodium Chloride / pharmacology
IF 2.766
Times Cited 17
Prokaryotes E. coli ?