High-resolution crystal structure of the leucine-rich repeat domain of the human tumour suppressor PP32A (ANP32A).

Acidic leucine-rich nuclear phosphoprotein 32A (PP32A) is a tumour suppressor whose expression is altered in many cancers. It is an apoptotic enhancer that stimulates apoptosome-mediated caspase activation and also forms part of a complex involved in caspase-independent apoptosis (the SET complex). Crystals of a fragment of human PP32A corresponding to the leucine-rich repeat domain, a widespread motif suitable for protein-protein interactions, have been obtained. The structure has been refined to 1.56 Šresolution. This domain was previously solved at 2.4 and 2.69 Šresolution (PDB entries 2je0 and 2je1, respectively). The new high-resolution structure shows some differences from previous models: there is a small displacement in the turn connecting the first α-helix (α1) to the first ß-strand (ß1), which slightly changes the position of α1 in the structure. The shift in the turn is observed in the context of a new crystal packing unrelated to those of previous structures.