Proteomics Reveals Scope of Mycolactone-mediated Sec61 Blockade and Distinctive Stress Signature.
Jean-David MorelAnja O PaateroJiajie WeiJonathan W YewdellLaure Guenin-MacéDelphi Van HaverFrancis ImpensNatalia PietrosemoliVille O PaavilainenCaroline DemangelPublished in: Molecular & cellular proteomics : MCP (2018)
Mycolactone is a bacteria-derived macrolide that blocks the biogenesis of a large array of secretory and integral transmembrane proteins (TMP) through potent inhibition of the Sec61 translocon. Here, we used quantitative proteomics to delineate the direct and indirect effects of mycolactone-mediated Sec61 blockade in living cells. In T lymphocytes, dendritic cells and sensory neurons, Sec61 substrates downregulated by mycolactone were in order of incidence: secretory proteins (with a signal peptide but no transmembrane domain), TMPs with a signal peptide (Type I) and TMPs without signal peptide and a cytosolic N terminus (Type II). TMPs without a signal peptide and the opposite N terminus topology (Type III) were refractory to mycolactone inhibition. This rule applied comparably to single- and multi-pass TMPs, and extended to exogenous viral proteins. Parallel to its broad-spectrum inhibition of Sec61-mediated protein translocation, mycolactone rapidly induced cytosolic chaperones Hsp70/Hsp90. Moreover, it activated an atypical endoplasmic reticulum stress response, differing from conventional unfolded protein response by the down-regulation of Bip. In addition to refining our mechanistic understanding of Sec61 inhibition by mycolactone, our findings thus reveal that Sec61 blockade induces proteostatic stress in the cytosol and the endoplasmic reticulum.
Keyphrases
- endoplasmic reticulum
- dendritic cells
- living cells
- heat shock
- type iii
- mass spectrometry
- heat stress
- heat shock protein
- fluorescent probe
- immune response
- high resolution
- binding protein
- single molecule
- risk factors
- spinal cord injury
- amino acid
- oxidative stress
- regulatory t cells
- high throughput
- label free
- high glucose
- anti inflammatory
- protein protein