Molecular Basis for Specific Regulation of Neuronal Kinesin-3 Motors by Doublecortin Family Proteins

Abstract

SummaryDoublecortin (Dcx) defines a growing family of microtubule (MT)-associated proteins (MAPs) involved in neuronal migration and process outgrowth. We show that Dcx is essential for the function of Kif1a, a kinesin-3 motor protein that traffics synaptic vesicles. Neurons lacking Dcx and/or its structurally conserved paralogue, doublecortin-like kinase 1 (Dclk1), show impaired Kif1a-mediated transport of Vamp2, a cargo of Kif1a, with decreased run length. Human disease-associated mutations in Dcx's linker sequence (e.g., W146C, K174E) alter Kif1a/Vamp2 transport by disrupting Dcx/Kif1a interactions without affecting Dcx MT binding. Dcx specifically enhances binding of the ADP-bound Kif1a motor domain to MTs. Cryo-electron microscopy and subnanometer-resolution image reconstruction reveal the kinesin-dependent conformational variability of MT-bound Dcx and suggest a model for MAP-motor crosstalk on MTs. Alteration of kinesin run length by MAPs represents a previously undiscovered mode of control of kinesin transport and provides a mechanism for regulation of MT-based transport by local signals.

Podosome-regulating kinesin KIF1C translocates to the cell periphery in a CLASP-dependent manner

“…Also, CLASP is essential for the transport or positioning of mitochondria in Schizosaccharomyces pombe (Chiron et al, 2008), which could be interpreted as a result of CLASP-dependent kinesin regulation in that system. Because CLASP2 can recruit KIF1C to mitochondria, we propose that MT-bound CLASPs directly stabilize the association of KIF1C with MTs, similar to the recently discovered function of doublecortin-KIF1A cooperation in neurons (Liu et al, 2012) or EB1-KIF17 cooperation in polarizing epithelia (Jaulin and Kreitzer, 2010). A less likely possibility is that CLASPs activate KIF1C in an MT-independent manner, similar to kinesin-1 activation by the MT-associated protein ensconsin (Barlan et al, 2013).…”

Building the Neuronal Microtubule Cytoskeleton

“…These observations suggest that both MT modifications and MAPs can determine protofilament number. In contrast, the precise neuronal function of the variation in protofilament numbers remains unclear, with models ranging from MT stabilization and MT bundling to regulating specific transport routes (Cueva et al, 2012;Liu et al, 2012;Topalidou et al, 2012).…”

Crystal Structures of the Human Doublecortin C- and N-terminal Domains in Complex with Specific Antibodies

“…2). A closed conformation derived from the NMR structure of N-DCX was also used to fit the doublecortin density at the vertex of four tubulin dimers in microtubules observed in cryo-EM (8,10). In PDB entry 5IOI chains A and E, the C-terminal sequence regions are observed in an extended open conformation (Fig.…”