Nonconventional cation-coupled flagellar motors derived from the alkaliphilic Bacillus and Paenibacillus species
- 397 Downloads
Prior to 2008, all previously studied conventional bacterial flagellar motors appeared to utilize either H+ or Na+ as coupling ions. Membrane-embedded stator complexes support conversion of energy using transmembrane electrochemical ion gradients. The main H+-coupled stators, known as MotAB, differ from Na+-coupled stators, PomAB of marine bacteria, and MotPS of alkaliphilic Bacillus. However, in 2008, a MotAB-type flagellar motor of alkaliphilic Bacillus clausii KSM-K16 was revealed as an exception with the first dual-function motor. This bacterium was identified as the first bacterium with a single stator–rotor that can utilize both H+ and Na+ for ion-coupling at different pH ranges. Subsequently, another exception, a MotPS-type flagellar motor of alkaliphilic Bacillus alcalophilus AV1934, was reported to utilize Na+ plus K+ and Rb+ as coupling ions for flagellar rotation. In addition, the alkaline-tolerant bacterium Paenibacillus sp. TCA20, which can utilize divalent cations such as Ca2+, Mg2+, and Sr2+, was recently isolated from a hot spring in Japan, which contains a high Ca2+ concentration. These findings show that bacterial flagellar motors isolated from unique environments utilize unexpected coupling ions. This suggests that bacteria that grow in different extreme environments adapt to local conditions and evolve their motility machinery.
KeywordsAlkaliphiles MotPS Stator Flagellar motor Divalent cation
Carbonyl cyanide m-chlorophenyl hydrazone
Proton motive force
Sodium motive force
We thank Dr. Arthur A. Guffanti for critical discussions and reading of the manuscript. This work was supported by a Grant-in-Aid for Scientific Research on Innovative Areas No. 24117005 of the Ministry of Education, Culture, Sports, Science and Technology of Japan (MI).
Compliance with ethical standards
This work was supported by a Grant-in-Aid for Scientific Research on Innovative Areas No. 24117005 of the Ministry of Education, Culture, Sports, Science and Technology of Japan (MI).
Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
- Dow JA (1984) Extremely high pH in biological systems: a model for carbonate transport. Am J Physiol Regul Integr Comp Physiol 246:R633–R635Google Scholar
- Fujinami S, Terahara N, Lee S, Ito M (2007b) Na+ and flagella-dependent swimming of alkaliphilic Bacillus pseudofirmus OF4: a basis for poor motility at low pH and enhancement in viscous media in an “up-motile” variant. Arch Microbiol 187:239–247. doi: 10.1007/s00203-006-0192-7 CrossRefPubMedGoogle Scholar
- Horikoshi K, Akiba T (1982) Alkalophilic microorganisms: a new microbial world. Springer-Verlag, Heidelberg, TokyoGoogle Scholar
- Horikoshi K (1991) Microorganisms in alkaline environments. VCH Publishers Inc., New YorkGoogle Scholar
- Ito M (2002) Aerobic alkaliphiles. In: Bitton G (ed) Encyclopedia of environmental microbiology. Wiley, New York, pp 133–140Google Scholar
- Krulwich TA, Hicks DB, Swartz TH, Ito M (2006) Bioenergetic adaptations that support alkaliphily. In: Gerday C, Glansdorff N (eds) Physiology and biochemistry of extremophiles. ASM Press, Washington, DC, pp 295–329Google Scholar
- Terahara N, Fujisawa M, Powers B, Henkin TM, Krulwich TA, Ito M (2006) An intergenic stem-loop mutation in the Bacillus subtilis ccpA-motPS operon increases motPS transcription and the MotPS contribution to motility. J Bacteriol 188:2701–2705. doi: 10.1128/JB.188.7.2701-2705.2006 CrossRefPubMedPubMedCentralGoogle Scholar