Structural Basis for Mitotic Centrosome Assembly in Flies

July 28, 2017

Title

Structural Basis for Mitotic Centrosome Assembly in Flies

Author

Zhe Feng, Anna Caballe, Alan Wainman, Steven Johnson, Andreas F.M. Haensele, Matthew A. Cottee, Paul T. Conduit, Susan M. Lea, Jordan W. Raff

Year

2017

Journal

Cell

Abstract

In flies, Centrosomin (Cnn) forms a phosphorylation-dependent scaffold that recruits proteins to the mitotic centrosome, but how Cnn assembles into a scaffold is unclear. We show that scaffold assembly requires conserved leucine zipper (LZ) and Cnn-motif 2 (CM2) domains that co-assemble into a 2:2 complex in vitro. We solve the crystal structure of the LZ:CM2 complex, revealing that both proteins form helical dimers that assemble into an unusual tetramer. A slightly longer version of the LZ can form micron-scale structures with CM2, whose assembly is stimulated by Plk1 phosphorylation in vitro. Mutating individual residues that perturb LZ:CM2 tetramer assembly perturbs the formation of these micron-scale assemblies in vitro and Cnn-scaffold assembly in vivo. Thus, Cnn molecules have an intrinsic ability to form large, LZ:CM2-interaction-dependent assemblies that are critical for mitotic centrosome assembly. These studies provide the first atomic insight into a molecular interaction required for mitotic centrosome assembly.

Instrument

J-815

Keywords

Circular dichroism, Secondary structure, Biochemistry