Skip to Content
Merck
  • Recruitment of two dyneins to an mRNA-dependent Bicaudal D transport complex.

Recruitment of two dyneins to an mRNA-dependent Bicaudal D transport complex.

eLife (2018-06-27)
Thomas E Sladewski, Neil Billington, M Yusuf Ali, Carol S Bookwalter, Hailong Lu, Elena B Krementsova, Trina A Schroer, Kathleen M Trybus
ABSTRACT

We investigated the role of full-length Drosophila Bicaudal D (BicD) binding partners in dynein-dynactin activation for mRNA transport on microtubules. Full-length BicD robustly activated dynein-dynactin motility only when both the mRNA binding protein Egalitarian (Egl) and K10 mRNA cargo were present, and electron microscopy showed that both Egl and mRNA were needed to disrupt a looped, auto-inhibited BicD conformation. BicD can recruit two dimeric dyneins, resulting in faster speeds and longer runs than with one dynein. Moving complexes predominantly contained two Egl molecules and one K10 mRNA. This mRNA-bound configuration makes Egl bivalent, likely enhancing its avidity for BicD and thus its ability to disrupt BicD auto-inhibition. Consistent with this idea, artificially dimerized Egl activates dynein-dynactin-BicD in the absence of mRNA. The ability of mRNA cargo to orchestrate the activation of the mRNP (messenger ribonucleotide protein) complex is an elegant way to ensure that only cargo-bound motors are motile.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Benzamidine, ≥95.0%
Sigma-Aldrich
Ribonucleic acid, transfer from Escherichia coli, Type XX, Strain W, lyophilized powder
Millipore
ANTI-FLAG® M2 Affinity Gel, purified immunoglobulin, buffered aqueous glycerol solution
Sigma-Aldrich
S-Nitroso-N-acetyl-DL-penicillamine, ≥97%, powder
Millipore
HIS-Select® Nickel Affinity Gel, (1:1 suspension in a 20% ethanol solution)