Evaluation Summary:
Xing and colleagues present a cryoEM structure of the protein phosphatase 2A (PP2A)-B56 holoenzyme in complex with protein phosphatase methyltransferase-1 (PME-1). The structure reveals that PME-1 blocks the substrate binding site of PP2A by inserting an unstructured loop. This unexpected inhibitory mechanism is also coupled to a large conformation change in the PP2A-B56 holoenzyme and PME-1. Combined with biochemical and cellular assays, the authors suggest how PME-1 can regulate p53-mediated DNA damage responses via inhibiting PP2A. This manuscript will be of importance for structural biologists as well as colleagues in the p53 field.
(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #2 agreed to share their name with the authors.)