PMID: 28263418

Authors:

Kurimoto E, Satoh T, Ito Y, Ishihara E, Okamoto K, Yagi-Utsumi M, Tanaka K, Kato K

Title:

Crystal structure of human proteasome assembly chaperone PAC4 involved in proteasome formation.

Journal:

Protein Sci. 2017 May;26(5):1080-1085. doi: 10.1002/pro.3153. Epub 2017 Mar 16.

Abstract:

The 26S proteasome is a large protein complex, responsible for degradation of ubiquinated proteins in eukaryotic cells. Eukaryotic proteasome formation is a highly ordered process that is assisted by several assembly chaperones. The assembly of its catalytic 20S core particle depends on at least five proteasome-specific chaperones, i.e., proteasome-assembling chaperons 1-4 (PAC1-4) and proteasome maturation protein (POMP). The orthologues of yeast assembly chaperones have been structurally characterized, whereas most mammalian assembly chaperones are not. In the present study, we determined a crystal structure of human PAC4 at 1.90-A resolution. Our crystallographic data identify a hydrophobic surface that is surrounded by charged residues. The hydrophobic surface is complementary to that of its binding partner, PAC3. The surface also exhibits charge complementarity with the proteasomal alpha4-5 subunits. This will provide insights into human proteasome-assembling chaperones as potential anticancer drug targets.