Parkin inhibits BAK and BAX apoptotic function by distinct mechanisms during mitophagy

We report that following mitochondrial damage-induced mitophagy, Parkin directly ubiquitinates the apoptotic effector protein BAK at a conserved lysine in its hydrophobic groove, a region that is crucial for BAK activation by BH3-only proteins and its homo-dimerisation during apoptosis. Ubiquitination inhibited BAK activity by impairing its activation and the formation of lethal BAK oligomers. Parkin also suppresses BAX-mediated apoptosis, but in the absence of BAX ubiquitination suggesting an indirect mechanism. In addition, we find that BAK-dependent mitochondrial outer membrane permeabilisation during apoptosis promotes PINK1-dependent Parkin activation. Hence, we propose that Parkin directly inhibits BAK to suppress errant apoptosis, thereby allowing the effective clearance of damaged mitochondria, but also promotes clearance of apoptotic mitochondria to limit their potential pro-inflammatory effect.

Source: EMBO Journal - January 15, 2019 Category: Molecular Biology Authors: Bernardini, J. P., Brouwer, J. M., Tan, I. K., Sandow, J. J., Huang, S., Stafford, C. A., Bankovacki, A., Riffkin, C. D., Wardak, A. Z., Czabotar, P. E., Lazarou, M., Dewson, G. Tags: Autophagy & Cell Death, Post-translational Modifications, Proteolysis & Proteomics Articles Source Type: research