Mechanical properties of inner-arm dynein-f (dynein I1) studied with in vitro motility assays

Biophys J. 2007 Aug 1;93(3):886-94. doi: 10.1529/biophysj.106.101964. Epub 2007 May 11.


Inner-arm dynein-f of Chlamydomonas flagella is a heterodimeric dynein. We performed conventional in vitro motility assays showing that dynein-f translocates microtubules at the comparatively low velocity of approximately 1.2 microm/s. From the dependence of velocity upon the surface density of dynein-f, we estimate its duty ratio to be 0.6-0.7. The relation between microtubule landing rate and surface density of dynein-f are well fitted by the first-power dependence, as expected for a processive motor. At low dynein densities, progressing microtubules rotate erratically about a fixed point on the surface, at which a single dynein-f molecule is presumably located. We conclude that dynein-f has high processivity. In an axoneme, however, slow and processive dynein-f could impede microtubule sliding driven by other fast dyneins (e.g., dynein-c). To obtain insight into the in vivo roles of dynein-f, we measured the sliding velocity of microtubules driven by a mixture of dyneins -c and -f at various mixing ratios. The velocity is modulated as a function of the ratio of dynein-f in the mixture. This modulation suggests that dynein-f acts as a load in the axoneme, but force pushing dynein-f molecules forward seems to accelerate their dissociation from microtubules.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism
  • Ca(2+) Mg(2+)-ATPase / metabolism
  • Cell Movement
  • Chlamydomonas reinhardtii / chemistry
  • Chlamydomonas reinhardtii / enzymology*
  • Chlamydomonas reinhardtii / physiology
  • Dyneins / chemistry*
  • Dyneins / ultrastructure
  • Flagella / chemistry*
  • Flagella / physiology
  • Microscopy, Electron
  • Models, Molecular
  • Peptide Fragments / chemistry


  • Bacterial Proteins
  • Peptide Fragments
  • Ca(2+) Mg(2+)-ATPase
  • Dyneins