Motility and chemotaxis in alkaliphilic Bacillus species.
Alkaliphilic Bacillus species grow at pH values up to approximately 11. Motile alkaliphilic Bacillus use electrochemical gradients of Na(+) (sodium-motive force) to power ion-coupled, flagella-mediated motility as opposed to the electrochemical gradients of H(+) (proton-motive force) used by most neutralophilic bacteria. Membrane-embedded stators of bacterial flagella contain ion channels through which either H(+) or Na(+) flow to energize flagellar rotation. Stators of the major H(+)-coupled type, MotAB, are distinguishable from Na(+)-coupled stators, PomAB of marine bacteria and MotPS of alkaliphilic Bacillus. Dual ion-coupling capacity is found in neutralophilic Bacillus strains with both MotAB and MotPS. There is also a MotAB variant that uses both coupling ions, switching as a function of pH. Chemotaxis of alkaliphilic Bacillus depends upon flagellar motility but also requires a distinct voltage-gated NaChBac-type channel. The two alkaliphile Na(+) channels provide new vistas on the diverse adaptations of sensory responses in bacteria.
Fujinami
Shun
S
NITE Bioresource Information Center, Department of Biotechnology, National Institute of Technology and Evaluation, Nishihara, Shibuya-ku, Tokyo, Japan. fujinami-shun@nite.go.jp
Terahara
Naoya
N
Krulwich
Terry Ann
TA
Ito
Masahiro
M
D001407:Bacillus / Q000502:physiology*; D027682:Cation Transport Proteins / Q000378:metabolism; D002633:Chemotaxis; D005407:Flagella / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D020409:Molecular Motor Proteins / Q000378:metabolism; D012964:Sodium / Q000378:metabolism
D027682:Cation Transport Proteins; D020409:Molecular Motor Proteins; D012964:Sodium