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bioRxiv · 10.1101/2025.03.21.644525

The Hitchdock domain in Kinesin-2 Tail Enables Adaptor Assembly and Cargo Binding

Jiang, X.·Danev, R.·Niu, B.·Ohtsuki, S.·Yanagisawa, H.·Hirokawa, N.·Kikkawa, M.
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Abstract

Intracellular transport relies on motor proteins like kinesins to deliver essential cargoes along microtubules, yet the mechanisms of cargo recognition remain unclear. Here, we present high-resolution cryo-electron microscopy structures of the heterotrimeric kinesin-2 complex (KIF3A/KIF3B/KAP3) bound to the adenomatous polyposis coli (APC) cargo. Our findings reveal a previously uncharacterized KIF3 tail motif, termed the "Hitchdock domain," which plays a pivotal role in mediating interactions with both the KAP3 adaptor and the APC cargo. In this domain, the KIF3A helical regions facilitate specific cargo binding, while the {beta}-hairpin region and KIF3B provide structural support. Mutagenesis and molecular dynamics simulations confirm the domains functional importance. Interestingly, the Hitchdock/KAP3 structure suggests a conserved structural basis for cargo recognition across molecular motors, including kinesin-1 and dynein, which utilize similar hook-like architectures, highlighting the potential universality of this mechanism. Furthermore, our findings provide insights into kinesin-2 cargo specificity and offer a molecular framework for understanding related diseases.

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Jiang, X., Danev, R., Niu, B., Ohtsuki, S., Yanagisawa, H., Hirokawa, N., Kikkawa, M.. 2025-03-25. The Hitchdock domain in Kinesin-2 Tail Enables Adaptor Assembly and Cargo Binding. https://doi.org/10.1101/2025.03.21.644525

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