ATP-driven subunit turnover powers the processive mechanical work of a meiotic-clade AAA+ dislocase

AAA+ ATPases convert the chemical energy of ATP hydrolysis into mechanical work to remodel diverse cellular assemblies, driving essential biological processes. Canonically, these molecular motors are understood to function as stable oligomeric rings in which nucleotide turnover orchestrates coordinated conformational changes among subunits to act on pore-threaded substrates. However, how the meiotic-clade AAA+ ATPases, with their transient and compositionally fluid assemblies, generate sustained mechanical output remains unclear. Here we elucidate the structural and mechanistic basis of Msp1, a membrane-anchored meiotic-clade AAA+ dislocase that removes mistargeted tail-anchored proteins from organellar membranes. Using cryo-EM, we determined high-resolution structures of substrate-engaged, full-length Msp1 across distinct oligomeric states, revealing that ATP hydrolysis powers a continuous protomer flux along a membrane-anchored spiral. This dynamic assembly encodes intrinsic directionality, coupling tight substrate grip with rapid catalytic turnover to drive stepwise extraction. Collectively, our findings define a dynamic relay mechanism, demonstrating that AAA+ motors can drive processive work through architectural self-renewal rather than cyclic movements within a fixed ring.