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bioRxiv · 10.1101/2025.05.18.654709

Cargo recognition of Nesprin-2 by the dynein adapter Bicaudal D2 for a nuclear positioning pathway that is important for neuronal migration

Putta, S.·Rodriguez Castro, E. D.·Ali, M. Y.·Garcia Martin, J. M.·Zhao, X.·Sylvain, S.·Trybus, K. M.·Solmaz, S. R.
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Abstract

Nesprin-2 and its paralog Nesprin-1 are subunits of LINC complexes that are essential for brain development. To position the nucleus for neuronal migration, Nesprin-2 interacts with the motors kinesin-1 and dynein, which are recruited by the adapter Bicaudal D2 (BicD2), but the molecular details of these interactions are elusive. Here, structural models of minimal Nesprin-2/BicD2 complexes with 1:2 and 2:2 stoichiometry were predicted using AlphaFold and experimentally validated by mutagenesis, binding assays and single-molecule biophysical studies. The core of the binding site is formed by spectrin repeats of Nesprin-2, which form an alpha-helical bundle with BicD2 that is structurally distinct from the Rab6/BicD2 and Nup358/BicD2 complexes. Such structural differences could fine tune motility of associated dynein and kinesin-1 motors for these transport pathways. Furthermore, the Nesprin-2 fragment interacts with full-length BicD2 and activates dynein/dynactin/BicD2 complexes for processive motility, suggesting that no additional components are required to reconstitute this transport pathway. Interestingly, either one or two Nesprin-2 molecules can bind to a BicD2 dimer and activate BicD2/dynein/dynactin complexes for processive motion, resulting in similar speed and run lengths. The BicD2/dynein-binding site is spatially close but does not overlap with the kinesin-1 recruitment site, thus both motors may interact with Nesprin-2 simultaneously. Several mutations of Nesprin-1 and 2 that cause Emery-Dreifuss muscular dystrophy are found in the motor-recruiting domain and may alter interactions with kinesin-1 and BicD2/dynein, consistent with the abnormally positioned nuclei found in patients with this disease.

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Putta, S., Rodriguez Castro, E. D., Ali, M. Y., Garcia Martin, J. M., Zhao, X., Sylvain, S., Trybus, K. M., Solmaz, S. R.. 2025-05-23. Cargo recognition of Nesprin-2 by the dynein adapter Bicaudal D2 for a nuclear positioning pathway that is important for neuronal migration. https://doi.org/10.1101/2025.05.18.654709

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