Direct observation of stepped proteolipid ring rotation in E. coli F o F 1-ATP synthase

Robert Ishmukhametov, Tassilo Hornung, David Spetzler, Wayne Frasch

Research output: Contribution to journalArticlepeer-review

84 Scopus citations


Although single-molecule experiments have provided mechanistic insight for several molecular motors, these approaches have proved difficult for membrane bound molecular motors like the Fo F1-ATP synthase, in which proton transport across a membrane is used to synthesize ATP. Resolution of smaller steps in Fo has been particularly hampered by signal-to-noise and time resolution. Here, we show the presence of a transient dwell between Fo subunits a and c by improving the time resolution to 10 μ at unprecedented S/N, and by using Escherichia coli Fo F 1 embedded in lipid bilayer nanodiscs. The transient dwell interaction requires 163 μ to form and 175 μ to dissociate, is independent of proton transport residues aR210 and cD61, and behaves as a leash that allows rotary motion of the c-ring to a limit of ∼36 ° while engaged. This leash behaviour satisfies a requirement of a Brownian ratchet mechanism for the Fo motor where c-ring rotational diffusion is limited to 36 °.

Original languageEnglish (US)
Pages (from-to)3911-3923
Number of pages13
JournalEMBO Journal
Issue number23
StatePublished - Dec 1 2010


  • Brownian ratchet mechanism
  • FoF1-ATP synthase
  • gold nanorods
  • nanodiscs
  • single-molecule measurements

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)


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