title: Transient binding of dynein controls bidirectional long-range motility of early endosomes.
abstract: In many cell types, bidirectional long-range endosome transport is mediated by the opposing motor proteins dynein and kinesin-3. Here we use a fungal model system to investigate how both motors cooperate in early endosome (EE) motility. It was previously reported that Kin3, a member of the kinesin-3 family, and cytoplasmic dynein mediate bidirectional motility of EEs in the fungus Ustilago maydis. We fused the green fluorescent protein to the endogenous dynein heavy chain and the kin3 gene and visualized both motors and their cargo in the living cells. Whereas kinesin-3 was found on anterograde and retrograde EEs, dynein motors localize only to retrograde organelles. Live cell imaging shows that binding of retrograde moving dynein to anterograde moving endosomes changes the transport direction of the organelles. When dynein is leaving the EEs, the organelles switch back to anterograde kinesin-3-based motility. Quantitative photobleaching and comparison with nuclear pores as an internal calibration standard show that single dynein motors and four to five kinesin-3 motors bind to the organelles. These data suggest that dynein controls kinesin-3 activity on the EEs and thereby determines the long-range motility behavior of the organelles.
authors.affiliation: Department of Biosciences, University of Exeter, Exeter EX4 4PE, United Kingdom.
authors.forename: Martin
authors.initials: M
authors.lastname: Schuster
authors.forename: Reinhard
authors.initials: R
authors.lastname: Lipowsky
authors.forename: Marcus-Alexander
authors.initials: MA
authors.lastname: Assmann
authors.forename: Peter
authors.initials: P
authors.lastname: Lenz
authors.forename: Gero
authors.initials: G
authors.lastname: Steinberg
mesh_terms: D001692:Biological Transport; D004398:Dyneins / Q000378:metabolism*; D011992:Endosomes / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D016547:Kinesins / Q000378:metabolism; D007734:Kymography; D008954:Models, Biological; D011485:Protein Binding; D014588:Ustilago / Q000166:cytology / Q000378:metabolism*
chemical_list: D049452:Green Fluorescent Proteins; D004398:Dyneins; D016547:Kinesins