Three-dimensional structure of a complex between the death domains of Pelle and Tube

The interaction of the serine/threonine kinase Pelle and adaptor protein Tu be through their N-terminal death domains leads to the nuclear translocatio n of the transcription factor Dorsal and activation of zygotic patterning g enes during Drosophila embryogenesis. Crystal structure of the Pelle and Tu be death domain heterodimer reveals that the two death domains adopt a six- helix bundle fold and are arranged in an open-ended linear array with plast ic interfaces mediating their interactions. The Tube death domain has an in sertion between helices 2 and 3, and a C-terminal tail making significant a nd indispensable contacts in the heterodimer. In vivo assays of Pelle and T ube mutants confirmed that the integrity of the major heterodimer interface is critical to the activity of these molecules.