The crystal structure of a partial mouse Notch-1 ankyrin domain: Repeats 4 through 7 preserve an ankyrin fold

摘要

Folding and stability of proteins containing ankyrin repeats (ARs) is of great interest because they mediate numerous protein–protein interactions involved in a wide range of regulatory cellular processes. Notch, an ankyrin domain containing protein, signals by converting a transcriptional repression complex into an activation complex. The Notch ANK domain is essential for Notch function and contains seven ARs. Here, we present the 2.2 Å crystal structure of ARs 4–7 from mouse Notch 1 (m1ANK). These C-terminal repeats were resistant to degradation during crystallization, and their secondary and tertiary structures are maintained in the absence of repeats 1–3. The crystallized fragment adopts a typical ankyrin fold including the poorly conserved seventh AR, as seen in the Drosophila Notch ANK domain (dANK). The structural preservation and stability of the C-terminal repeats shed a new light onto the mechanism of hetero-oligomeric assembly during Notch-mediated transcriptional activation.