Single-molecule investigation of the interference between kinesin, tau and MAP2c.
Motor proteins and microtubule-associated proteins (MAPs) play important roles in cellular transport, regulation of shape and polarity of cells. While motor proteins generate motility, MAPs are thought to stabilize the microtubule tracks. However, the proteins also interfere with each other, such that MAPs are able to inhibit transport of vesicles and organelles in cells. In order to investigate the mechanism of MAP-motor interference in molecular detail, we have studied single kinesin molecules by total internal reflection fluorescence microscopy in the presence of different neuronal MAPs (tau, MAP2c). The parameters observed included run-length (a measure of processivity), velocity and frequency of attachment. The main effect of MAPs was to reduce the attachment frequency of motors. This effect was dependent on the concentration, the affinity to microtubules and the domain composition of MAPs. In contrast, once attached, the motors did not show a change in speed, nor in their run-length. The results suggest that MAPs can regulate motor activity on the level of initial attachment, but not during motion.
Seitz
Arne
A
Max-Planck-Unit for Structural Molecular Biology, Notkestrasse 85, D-22607 Hamburg, Germany. seitz@mpasmb.desy.de
Kojima
Hiroaki
H
Oiwa
Kazuhiro
K
Mandelkow
Eva-Maria
EM
Song
Young-Hwa
YH
Mandelkow
Eckhard
E
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001692:Biological Transport / Q000502:physiology*; D017930:Genes, Reporter; D006801:Humans; D007526:Isoelectric Point; D016547:Kinesins / Q000235:genetics / Q000378:metabolism*; D008856:Microscopy, Fluorescence / Q000379:methods*; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D008954:Models, Biological; D020409:Molecular Motor Proteins / Q000378:metabolism; D011485:Protein Binding; D020033:Protein Isoforms; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D016875:tau Proteins / Q000378:metabolism*
C489788:MAP2 protein, human; C489787:MAP2 protein, rat; D008869:Microtubule-Associated Proteins; D020409:Molecular Motor Proteins; D020033:Protein Isoforms; D011994:Recombinant Proteins; D016875:tau Proteins; D000251:Adenosine Triphosphatases; D016547:Kinesins