Solution Structure and Interaction Surface of the C-terminal Domain from P47: a Major P97-cofactor Involved in SNARE Disassembly

p47 is the major protein identified in complex with the cytosolic AAA ATPase p97. It functions as an essential cofactor of p97-regulated membrane fusion, which has been suggested to disassemble t-t-SNARE complexes and prepare them for further rounds of membrane fusion. Here, we report the high-resolution NMR structure of the C-terminal domain from p47. It comprises a UBX domain and a 13 residue long structured N-terminal extension. The UBX domain adopts a characteristic ubiquitin fold with a betabetaalphabetabetaalphabeta secondary structure arrangement. Three hydrophobic residues from the N-terminal extension pack closely against a cleft in the UBX domain. We also identify, for the first time, the p97 interaction surface using NMR chemical shift perturbation studies.