Mechanical properties of inner-arm dynein-f (dynein I1) studied with in vitro motility assays.
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.
Kotani
Norito
N
Graduate School of Life Science, University of Hyogo, Harima Science Park City, Hyogo 6781297, Japan.
Sakakibara
Hitoshi
H
Burgess
Stan A
SA
Kojima
Hiroaki
H
Oiwa
Kazuhiro
K
D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism; D002465:Cell Movement; D016825:Chlamydomonas reinhardtii / Q000737:chemistry / Q000201:enzymology* / Q000502:physiology; D004398:Dyneins / Q000737:chemistry* / Q000648:ultrastructure; D005407:Flagella / Q000737:chemistry* / Q000502:physiology; D008854:Microscopy, Electron; D008958:Models, Molecular; D010446:Peptide Fragments / Q000737:chemistry
D001426:Bacterial Proteins; D010446:Peptide Fragments; D017301:Ca(2+) Mg(2+)-ATPase; D004398:Dyneins