Interaction between Na+ ion and carboxylates of the PomA-PomB stator unit studied by ATR-FTIR spectroscopy

Yuki Sudo, Yuya Kitade, Yuji Furutani, Masaru Kojima, Seiji Kojima, Michio Homma, Hideki Kandori

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

Bacterial flagellar motors are molecular machines powered by the electrochemical potential gradient of specific ions across the membrane. The PomA-PomB stator complex of Vibrio alginolyticus couples Na+ influx to torque generation in this supramolecular motor, but little is known about how Na+ associates with the PomA-PomB complex in the energy conversion process. Here, by means of attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy, we directly observed binding of Na+ to carboxylates in the PomA-PomB complex, including the functionally essential residue Asp24. The Na+ affinity of Asp24 is estimated to be ∼85 mM, close to the apparent Km value from the swimming motility of the cells (78 mM). At least two other carboxylates are shown to be capable of interacting with Na+, but with somewhat lower affinities. We conclude that Asp24 and at least two other carboxylates constitute Na+ interaction sites in the PomA-PomB complex. This work reveals features of the Na+ pathway in the PomA-PomB Na+ channel by using vibrational spectroscopy.

Original languageEnglish
Pages (from-to)11699-11705
Number of pages7
JournalBiochemistry
Volume48
Issue number49
DOIs
Publication statusPublished - Dec 15 2009
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry

Fingerprint Dive into the research topics of 'Interaction between Na<sup>+</sup> ion and carboxylates of the PomA-PomB stator unit studied by ATR-FTIR spectroscopy'. Together they form a unique fingerprint.

  • Cite this

    Sudo, Y., Kitade, Y., Furutani, Y., Kojima, M., Kojima, S., Homma, M., & Kandori, H. (2009). Interaction between Na+ ion and carboxylates of the PomA-PomB stator unit studied by ATR-FTIR spectroscopy. Biochemistry, 48(49), 11699-11705. https://doi.org/10.1021/bi901517n