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+杆菌鞭毛马达,可以同时使用na +和k +离子作为一个耦合转换由单个突变只使用na +.pdfVIP

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+ Naoya Terahara1., Motohiko Sano2., Masahiro Ito2,3* 1 Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan, 2 Graduate School of Life Sciences, Toyo University, Oura-gun, Japan, 3 Bio-Nano Electronics Research Centre, Toyo University, Kawagoe Saitama, Japan 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