Solution structure of ASPP2 N-terminal domain (N-ASPP2) reveals a ubiquitin-like fold

Proteins of the ASPP family bind to p53 and regulate p53-mediated apoptosis. Two family members, ASPP1 and ASPP2, have pro-apoptotic functions while iASPP shows anti-apoptotic responses. However, both the mechanism of enhancement/repression of apoptosis and the molecular basis for their different responses remain unknown. To address the role of the N-termini of pro-apoptotic ASPP proteins, we solved the solution structure of N-ASPP2 (1-83) by NMR spectroscopy. The structure of this domain reveals a beta-Grasp ubiquitin-like fold. Our findings suggest a possible role for the N-termini of ASPP proteins in binding to other proteins in the apoptotic response network and thus mediating their selective pro-apoptotic function.