A Direct Interaction with NEDD1 Regulates γ-Tubulin Recruitment to the Centrosome

The centrosome is the primary microtubule organizing centre of the cell. gamma-tubulin is a core component of the centrosome and is required for microtubule nucleation and centrosome function. The recruitment of gamma-tubulin to centrosomes is mediated by its interaction with NEDD1, a WD40-repeat containing protein. Here we demonstrate that NEDD1 is likely to be oligomeric in vivo and binds directly to gamma-tubulin through a small region of just 62 residues at the carboxyl-terminus of the protein. This carboxyl-terminal domain that binds gamma-tubulin has a helical structure and is a stable tetramer in solution. Mutation of residues in NEDD1 that disrupt binding to gamma-tubulin result in a mis-localization of gamma-tubulin away from the centrosome. Hence, this study defines the binding site on NEDD1 that is required for its interaction with gamma-tubulin, and shows that this interaction is required for the correct localization of gamma-tubulin.