Cryo-EM structure of dodecamer human p97 in complex with NMS-873 reveals S-G peptide plays critical role for D2 ring oligomerization.

The AAA + ATPase p97 is a well-known hexametric enzyme that is evolutionary conserved in eukaryotes. p97 contains an amino-terminal N domain, two tandem ATPase domains (D1 and D2 domain) and a C-terminal unstructured extensive tail, involved in many cellular processes and plays important biological functions, but the structural basis of p97 for its biological roles still remain unclear. Here we report the Cryo-EM structure of full-length human p97 dodecamer in 3.0 Å resolution, the structure was captured in ADP-bound form but only D1 ATPase sites were well occupied by nucleotide and D2 sites are empty, furthermore, 12 non-ATP-competitive inhibitors of NMS-873 bound in the interface between each p97 monomer. We also found that the C-terminal S-G (765-'SRGFGSFRFPSGNQG'-779) peptide plays critical roles for the D2 ring oligomerization, biochemical and electron microscopy studies confirm that the S-G peptide could induce the D2 ring itself to form the heptamer, this give new insights how p97 protomers assemble to the biological functional multimers.