PT - JOURNAL ARTICLE AU - Dominique V. Lessard AU - Oraya J. Zinder AU - Takashi Hotta AU - Kristen J. Verhey AU - Ryoma Ohi AU - Christopher L. Berger TI - Regulation of KIF1A motility via polyglutamylation of tubulin C-terminal tails AID - 10.1101/410860 DP - 2018 Jan 01 TA - bioRxiv PG - 410860 4099 - http://biorxiv.org/content/early/2018/09/08/410860.short 4100 - http://biorxiv.org/content/early/2018/09/08/410860.full AB - Axonal transport is a highly regulated cellular process responsible for site-specific neuronal cargo delivery. This process is mediated in part by KIF1A, a member of the kinesin-3 family of molecular motors. It is imperative that KIF1A’s highly efficient, superprocessive motility along microtubules is tightly regulated as misregulation of KIF1A cargo delivery is observed in many neurodegenerative diseases. However, the regulatory mechanisms responsible for KIF1A’s motility, and subsequent proper spatiotemporal cargo delivery, are largely unknown. One potential regulatory mechanism of KIF1A motility is through the posttranslational modifications (PTMs) of axonal microtubules. These PTMs, often occurring on the C-terminal tails of the microtubule tracks, act as molecular “traffic signals” helping to direct kinesin motor cargo delivery. Occurring on neuronal microtubules, C-terminal tail polygutamylation is known to be important for KIF1A cargo transport. KIF1A’s initial interaction with microtubule C-terminal tails is facilitated by the K-loop, a positively charged surface loop of the KIF1A motor domain. However, the K-loop’s role in KIF1A motility and response to perturbations in C-terminal tail polyglutamylation is underexplored. Using single-molecule imaging, we present evidence of KIF1A’s previously unreported pausing behavior on multiple microtubule structures. Further analysis revealed that these pauses link multiple processive segments together, contributing to KIF1A’s characteristic superprocessive run length. We further demonstrate that KIF1A pausing is mediated by a K-loop/polyglutamylated C-terminal tail interaction and is a regulatory mechanism of KIF1A motility. In summary, we introduce a new mechanism of KIF1A motility regulation, providing further insight into KIF1A’s role in axonal transport.