Figure 5: Conformational changes of ABCE1 during ribosome recycling.

During the cyclic process of translation, post-termination/pre-recycling complexes occur, which need to be recycled into their components to be available for the subsequent re-initiation. After e/aRF3 dissociation, ABCE1 binds to the GTPase binding site of these complexes, establishing contacts to the r-proteins of the large and small subunit (P0, L9, S24, S6)⁸. ATP occlusion of ABCE1 leads to major conformational changes, especially a large rotational and translational repositioning of the FeS cluster domain, which splits the ribosomal subunits apart—either directly or via the bound e/aRF1. ABCE1 itself remains bound to the small subunit until ATP is hydrolysed (PRC). Consequently, the contacts to proteins of the large subunit are released and major contacts to the proteins of the small subunit like S24e are preserved. Additionally, a new contact to the S12 protein is established, caused by the large rotational and translational movement of the FeS cluster domain, anchoring ABCE1 on the 30S.