RT Journal Article
SR Electronic
T1 Recruitment of Two Dyneins to an mRNA-Dependent Bicaudal D Transport Complex
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 273755
DO 10.1101/273755
A1 Thomas E. Sladewski
A1 Neil Billington
A1 M. Yusuf Ali
A1 Carol S. Bookwalter
A1 Hailong Lu
A1 Elena B. Krementsova
A1 Trina A. Schroer
A1 Kathleen M. Trybus
YR 2018
UL http://biorxiv.org/content/early/2018/02/28/273755.abstract
AB We investigated the role of binding partners of full-length Drosophila Bicaudal D (BicD) in the activation of dynein-dynactin motility for mRNA transport on microtubules. In single-molecule assays, full-length BicD robustly activated dynein-dynactin only when both the mRNA binding protein Egalitarian (Egl), and K10 mRNA cargo were present. Electron microscopy showed that both Egl and mRNA were needed to disrupt an auto-inhibited, looped BicD conformation that sterically prevents dynein-dynactin binding. In vitro reconstituted messenger ribonucleoprotein (mRNP) complexes with two Egl molecules showed faster speeds and longer run lengths than mRNPs with one Egl, suggesting that cargo binding enhances dynein recruitment. Labeled dynein showed that BicD can recruit two dimeric dyneins to the mRNP, resulting in faster speeds and longer run lengths than with one dynein. The fully reconstituted mRNP provides a model for understanding how adaptor proteins and cargo cooperate to confer optimal transport properties to a dynein-driven transport complex.