title: Clustering of a kinesin-14 motor enables processive retrograde microtubule-based transport in plants.
abstract: The molecular motors kinesin and dynein drive bidirectional motility along microtubules (MTs) in most eukaryotic cells. Land plants, however, are a notable exception, because they contain a large number of kinesins but lack cytoplasmic dynein, the foremost processive retrograde transporter. It remains unclear how plants achieve retrograde cargo transport without dynein. Here, we have analysed the motility of the six members of minus-end-directed kinesin-14 motors in the mossPhyscomitrella patensand found that none are processive as native dimers. However, when artificially clustered into as little as dimer of dimers, the type-VI kinesin-14 (a homologue ofArabidopsisKCBP (kinesin-like calmodulin binding protein)) exhibited highly processive and fast motility (up to 0.6 μm s-1). Multiple kin14-VI dimers attached to liposomes also induced transport of this membrane cargo over several microns. Consistent with these results,in vivoobservations of green fluorescent protein-tagged kin14-VI in moss cells revealed fluorescent punctae that moved processively towards the minus-ends of the cytoplasmic MTs. These data suggest that clustering of a kinesin-14 motor serves as a dynein-independent mechanism for retrograde transport in plants.
authors: Marine Biological Laboratory (MBL), Woods Hole, Massachusetts 02543, USA ; Howard Hughes Medical Institute and Department of Cellular and Molecular Pharmacology, UCSF, 600 16th St., San Francisco, California 94158, USA.
authors: Erik
authors: E
authors: Jonsson
authors: Marine Biological Laboratory (MBL), Woods Hole, Massachusetts 02543, USA ; Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.
authors: Moé
authors: M
authors: Yamada
authors: Marine Biological Laboratory (MBL), Woods Hole, Massachusetts 02543, USA ; Howard Hughes Medical Institute and Department of Cellular and Molecular Pharmacology, UCSF, 600 16th St., San Francisco, California 94158, USA.
authors: Ronald D
authors: RD
authors: Vale
authors: Marine Biological Laboratory (MBL), Woods Hole, Massachusetts 02543, USA ; Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.
authors: Gohta
authors: G
authors: Goshima