PMID: 24369353

Authors:

Ren J, Wang J, Wang Z, Wu J

Title:

Structural and biochemical insights into the homotypic PB1-PB1 complex between PKCzeta and p62.

Journal:

Sci China Life Sci. 2014 Jan;57(1):69-80. doi: 10.1007/s11427-013-4592-z. Epub, 2013 Dec 26.

Abstract:

The atypical PKC isoforms (zeta and i) play essential roles in regulating various cellular processes. Both the hetero-interaction between PKCzeta and p62 through their N-terminal PB1 domains and the homo-oligomerization of p62 via its PB1 domain are critical for the activation of NF-kappaB signaling; however, the molecular mechanisms concerning the formation and regulation of these homotypic complexes remain unclear. Here we determined the crystal structure of PKCzeta-PB1 in complex with a monomeric p62-PB1 mutant, where the massive electrostatic interactions between the acidic OPCA motif of PKCzeta-PB1 and the basic surface of p62-PB1, as well as additional hydrogen bonds, ensure the formation of a stable and specific complex. The PKCzeta-p62 interaction is interfered with the modification of a specific Cys of PKCzeta by the antiarthritis drug aurothiomalate, though all four cysteine residues in the PKCzeta-PB1 domain can be modified in in vitro assay. In addition, detailed structural and biochemical analyses demonstrate that the PB1 domains of aPKCs belong to the type I group, which can depolymerize the high-molecular-weight p62 aggregates into homo-oligomers of lower order. These data together unravel the molecular mechanisms of the homo-or hetero-interactions between p62 and PKCzeta and provide the basis for designing inhibitors of NF-kappaB signaling.