4BL6 image
Deposition Date 2013-05-02
Release Date 2013-06-12
Last Version Date 2024-11-13
Entry Detail
PDB ID:
4BL6
Title:
Bicaudal-D uses a parallel, homodimeric coiled coil with heterotypic registry to co-ordinate recruitment of cargos to dynein
Biological Source:
Source Organism:
Host Organism:
Method Details:
Experimental Method:
Resolution:
2.18 Å
R-Value Free:
0.23
R-Value Work:
0.20
R-Value Observed:
0.20
Space Group:
P 61
Macromolecular Entities
Polymer Type:polypeptide(L)
Molecule:PROTEIN BICAUDAL D
Gene (Uniprot):BicD
Chain IDs:A, B, C, D
Chain Length:94
Number of Molecules:4
Biological Source:DROSOPHILA MELANOGASTER
Primary Citation
Bicaudal-D Uses a Parallel, Homodimeric Coiled Coil with Heterotypic Registry to Coordinate Recruitment of Cargos to Dynein
Genes Dev. 27 1233 ? (2013)
PMID: 23723415 DOI: 10.1101/GAD.212381.112

Abstact

Cytoplasmic dynein is the major minus end-directed microtubule motor in eukaryotes. However, there is little structural insight into how different cargos are recognized and linked to the motor complex. Here we describe the 2.2 Å resolution crystal structure of a cargo-binding region of the dynein adaptor Bicaudal-D (BicD), which reveals a parallel coiled-coil homodimer. We identify a shared binding site for two cargo-associated proteins-Rab6 and the RNA-binding protein Egalitarian (Egl)-within a region of the BicD structure with classical, homotypic core packing. Structure-based mutagenesis in Drosophila provides evidence that occupancy of this site drives association of BicD with dynein, thereby coupling motor recruitment to cargo availability. The structure also contains a region in which, remarkably, the same residues in the polypeptide sequence have different heptad registry in each chain. In vitro and in vivo analysis of a classical Drosophila dominant mutation reveals that this heterotypic region regulates the recruitment of dynein to BicD. Our results support a model in which the heterotypic segment is part of a molecular switch that promotes release of BicD autoinhibition following cargo binding to the neighboring, homotypic coiled-coil region. Overall, our data reveal a pivotal role of a highly asymmetric coiled-coil domain in coordinating the assembly of cargo-motor complexes.

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