Biology subjects

Gicking, A. M.

Publications and source records attributed to Gicking, A. M..

2 recordsLinked to original sources

bioRxiv2018

The Orphan Kinesin PAKRP2 Achieves Processive Motility Via Noncanonical Stepping

PAKRP2 is an orphan kinesin in Arabidopsis thaliana that is thought to transport vesicles along phragmoplast microtubules for cell plate formation. Here, using single-molecule fluorescence microscopy, we show that PAKRP2 exhibits processive plus-end-directed motility on single microtubules as individual homodimers despite having an exceptionally long (32 residues) neck linker. Furthermore, using high-resolution nanoparticle tracking to visualize motor stepping dynamics, we find that PAKRP2 achieves processivity via a noncanonical stepping mechanism that includes small step sizes and frequent lateral steps to adjacent protofilaments. We propose that the small steps sizes are due to a transient intermediate step that involves a prolonged diffusional search of the tethered head due to its long neck linker. Despite this different stepping behavior, ATP is tightly coupled to each 8-nm step. Collectively, this study reveals PAKRP2 as the first orphan kinesin to demonstrate processive motility and broadens our understanding of the diverse kinesin stepping mechanisms.

biophysics↗

bioRxiv2017

The preprophase band-associated kinesin-14 OsKCH2 is a processive minus-end-directed microtubule motor

In animals and fungi, cytoplasmic dynein is a processive motor that plays dominant roles in various intracellular processes. In contrast, land plants lack cytoplasmic dynein but contain many minus-end-directed kinesin-14s. No plant kinesin-14 is known to produce processive motility as a homodimer. OsKCH2 is a plant-specific kinesin-14 with an N-terminal actin-binding domain and a central motor domain flanked by two predicted coiled-coils (CC1 and CC2). Here, we show that OsKCH2 specifically decorates preprophase band microtubules in vivo and transports actin filaments along microtubules in vitro. Importantly, OsKCH2 exhibits processive minus-end-directed motility on single microtubules as individual homodimers. We find that CC1 but not CC2 forms the coiled-coil for OsKCH2 dimerization. Instead, CC2 functions to enable OsKCH2 processivity by enhancing its binding to microtubules. Collectively, these results show that land plants have evolved unconventional kinesin-14 homodimers with inherent minus-end-directed processivity that may function to compensate for the loss of cytoplasmic dynein.

biophysics↗