Structure of archaeal proteasomal ATPase PAN by single particle cryoEM

ATP dependent protein degradation in eukaryotes by 26S proteasome are essential for many cellular processes including apoptosis, cell cycles and signal transduction. 26S proteasome is composed of a barrel shaped 20S protease core and two regulatory particles capped on each end. The ATPases in the 19S regulatory particles unfold and translocate substrates into 20S for degradation. Archaea has a homologous yet simpler 20S proteasome and a regulatory ATPase, proteasome activating nucleotidase (PAN.) In this study we used single particle cryoEM to study the three dimensional structure of PAN. We obtained a 3D reconstruction of PAN at a resolution of 18 Angstroms. By docking the atomic structure of PAN's N-terminal domain and ATPase domain to the atomic structure determined x-ray crystallography, we generated an atomic model of full length PAN ATPase.