Structural Basis for Dodecameric Assembly States and Conformational Plasticity of the Full-Length AAA plus ATPases Rvb1.Rvb2

As building blocks of diverse macromolecular complexes, the AAA+ ATPases Rvb1 and Rvb2 are crucial for many cellular activities including cancer-related processes. Their oligomeric structure and function remain unclear. We report the crystal structures of full-length heteromeric Rvb1.Rvb2 complexes in distinct nucleotide binding states. Chaetomium thermophilum Rvb1.Rvb2 assemble into hexameric rings of alternating molecules and into stable do-decamers. Intriguingly, the characteristic oligonucleotide-binding (OB) fold domains (DIIs) of Rvb1 and Rvb2 occupy unequal places relative to the compact AAA+ core ring. While Rvb1's DII forms contacts between hexamers, Rvb2's DII is rotated 100 degrees outward, occupying lateral positions. ATP was retained bound to Rvb1 but not Rvb2 throughout purification, suggesting nonconcerted ATPase activities and nucleotide binding. Significant conformational differences between nucleotide-free and ATP-/ADP-bound states in the crystal structures and in solution suggest that the functional role of Rvb1.Rvb2 is mediated by highly interconnected structural switches. Our structures provide an atomic framework for do-decameric states and Rvb1.Rvb2's conformational plasticity.