A novel mechanism for activation of Aurora-A kinase by Ajuba

• PreLIM of Ajuba interacts with Cd of Aurora A, not with the full length.
• PreLIM domain can activate Cd of Aurora A, but not the full length.
• LIM can competitively bind with Aurora-A Nt, preventing its binding with Cd.
• PreLIM domain is phosphorylated by C-terminal kinase domain of Aurora-A.
• Suggest a novel model for Aurora-A regulation by Ajuba

Aurora-A is a centrosome-localized serine/threonine kinase, which plays a critical role in mitotic and meiotic cell division processes. However, the regulation of Aurora-A is still not fully understood. Previously, we have found an intramolecular inhibitory regulation mechanism of Aurora-A: the N-terminal regulatory domain (aa 1–128, Nt) can interact with the C-terminal catalytic domain (aa 129–403, Cd) and inhibit the kinase activity of Aurora-A. In this study, we found that the PreLIM domain of Ajuba, another important activator of Aurora-A, induces the autophosphorylation of the C-terminal kinase domain of Aurora-A, and is phosphorylated by the C-terminal. Moreover, the LIM domain of Ajuba can competitively bind to the N-terminal of Aurora-A, and inhibited the interaction between N-terminal and C-terminal of Aurora A. Taken together, these results suggest a novel mechanism for regulation of Aurora-A by Ajuba.