Glutathione-dependent depalmitoylation of phospholemman by peroxiredoxin 6

Phospholemman (PLM) regulates the cardiac sodium pump: PLM phosphorylation activates the pump whereas PLM palmitoylation inhibits its activity. Here, we show that the anti-oxidant protein peroxiredoxin 6 (Prdx6) interacts with and depalmitoylates PLM in a glutathione-dependent manner. Glutathione loading cells acutely reduce PLM palmitoylation; glutathione depletion significantly increases PLM palmitoylation. Prdx6 silencing abolishes these effects, suggesting that PLM can be depalmitoylated by reduced Prdx6. In vitro, only recombinant Prdx6, among several peroxiredoxin isoforms tested, removes palmitic acid from recombinant palmitoylated PLM. The broad-spectrum depalmitoylase inhibitor palmostatin B prevents Prdx6-dependent PLM depalmitoylation in cells and in vitro. Our data suggest that Prdx6 is a thioesterase that can depalmitoylate proteins by nucleophilic attack via its reactive thiol, linking PLM palmitoylation and hence sodium pump activity to cellular glutathione status. We show that protein depalmitoylation can occur via a catalytic cysteine in which substrate specificity is determined by a protein-protein interaction. [Display omitted] •Identify peroxiredoxin 6 (Prdx6) as a thioesterase•Protein depalmitoylation by Prdx6 occurs via its catalytic cysteine•Phospholemman depalmitoylation by Prdx6 is glutathione dependent•Prdx6 thioesterase activity confers redox sensitivity on the Na pump The activities and cellular localizations of membrane proteins are frequently controlled by palmitoylation, a reversible covalent post-translational modification. Here, Howie et al. have shown that peroxiredoxin 6 is a novel thioesterase that removes palmitate from the acylated protein phospholemman in a glutathione-dependent mechanism, conferring redox sensitivity on Na pump activity.