Mycolactone subverts immunity by selectively blocking the Sec61 translocon

Baron, Ludivine; Paatero, Anja O.; Morel, Jean-David; Impens, Francis; Guenin-Macé, Laure; Saint-Auret, Sarah; Blanchard, Nicolas; Dillmann, Rabea; Niang, Fatoumata; Pellegrini, Sandra; Taunton, Jack; Paavilainen, Ville O.; Demangel, Caroline

doi:10.1084/jem.20160662

Cited by 114 publications

(295 citation statements)

References 34 publications

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“…In contrast to previously described Sec61 inhibitors, such as cotransin (18), mycolactone prevents the biogenesis of secretory and transmembrane proteins with minor selectivity toward Sec61 substrates, as well as uniformly high efficacy (13,16). Single-amino acid mutagenesis localized its binding site on the luminal side of the translocon, near the plug domain that occludes Sec61 in its inactive state (13). Mycolactone allows acute blockade of Sec61, and we used it in the present study to examine the direct contribution of this channel to antigen cross-presentation, endosome-to-cytosol export, and ER-tocytosol export.…”

Section: Significancecontrasting

confidence: 61%

“…β-Galactosidase levels were quantified using a colorimetric substrate, chlorophenol red-β-D-galactopyranoside (CPRG). To ensure that B3Z activation itself was not affected by mycolactone, we used a B3Z line expressing the R66G mycolactone-resistant mutant of Sec61 (Sec61-R66G), generated as described (13). We observed no difference in the efficiency of OVA cross-presentation or in the capacity of DCs to activate T cells when incubated directly with the OVA 257-264 peptide (Fig.…”

Section: Resultsmentioning

confidence: 98%

Section: Significancementioning

confidence: 99%

“…Mycolactone is a polyketidederived macrolide produced by the human pathogen Mycobacterium ulcerans, which was recently identified as a potent Sec61 inhibitor (13)(14)(15)(16). Mycolactone diffuses passively across the plasma membrane to target the pore-forming subunit of the translocon (Sec61α) (13), leading to the proteasomal degradation of newly synthesized Sec61 clients blocked in translocation (17). In contrast to previously described Sec61 inhibitors, such as cotransin (18), mycolactone prevents the biogenesis of secretory and transmembrane proteins with minor selectivity toward Sec61 substrates, as well as uniformly high efficacy (13,16).…”

Section: Significancementioning

confidence: 99%

“…Mycolactone diffuses passively across the plasma membrane to target the pore-forming subunit of the translocon (Sec61α) (13), leading to the proteasomal degradation of newly synthesized Sec61 clients blocked in translocation (17). In contrast to previously described Sec61 inhibitors, such as cotransin (18), mycolactone prevents the biogenesis of secretory and transmembrane proteins with minor selectivity toward Sec61 substrates, as well as uniformly high efficacy (13,16). Single-amino acid mutagenesis localized its binding site on the luminal side of the translocon, near the plug domain that occludes Sec61 in its inactive state (13).…”

Section: Significancementioning

confidence: 99%

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Sec61 blockade by mycolactone inhibits antigen cross-presentation independently of endosome-to-cytosol export

Grotzke

Kozik

Morel

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Although antigen cross-presentation in dendritic cells (DCs) is critical to the initiation of most cytotoxic immune responses, the intracellular mechanisms and traffic pathways involved are still unclear. One of the most critical steps in this process, the export of internalized antigen to the cytosol, has been suggested to be mediated by Sec61. Sec61 is the channel that translocates signal peptide-bearing nascent polypeptides into the endoplasmic reticulum (ER), and it was also proposed to mediate protein retrotranslocation during ER-associated degradation (a process called ERAD). Here, we used a newly identified Sec61 blocker, mycolactone, to analyze Sec61's contribution to antigen cross-presentation, ERAD, and transport of internalized antigens into the cytosol. As shown previously in other cell types, mycolactone prevented protein import into the ER of DCs. Mycolactone-mediated Sec61 blockade also potently suppressed both antigen cross-presentation and direct presentation of synthetic peptides to CD8 + T cells. In contrast, it did not affect protein export from the ER lumen or from endosomes into the cytosol, suggesting that the inhibition of cross-presentation was not related to either of these trafficking pathways. Proteomic profiling of mycolactoneexposed DCs showed that expression of mediators of antigen presentation, including MHC class I and β2 microglobulin, were highly susceptible to mycolactone treatment, indicating that Sec61 blockade affects antigen cross-presentation indirectly. Together, our data suggest that the defective translocation and subsequent degradation of Sec61 substrates is the cause of altered antigen cross-presentation in Sec61-blocked DCs.Sec61 | cross-presentation | ERAD | mycolactone

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Section: Significancecontrasting

confidence: 61%

Section: Resultsmentioning

confidence: 98%

Section: Significancementioning

confidence: 99%

Section: Significancementioning

confidence: 99%

Section: Significancementioning

confidence: 99%

See 3 more Smart Citations

Sec61 blockade by mycolactone inhibits antigen cross-presentation independently of endosome-to-cytosol export

Grotzke

Kozik

Morel

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Toward Understanding the Mechanism of Client‐Selective Small Molecule Inhibitors of the Sec61 Translocon

Sorout,

Helms

2024

J of Molecular Recognition

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The Sec61 translocon mediates the translocation of numerous, newly synthesized precursor proteins into the lumen of the endoplasmic reticulum or their integration into its membrane. Recently, structural biology revealed conformations of idle or substrate‐engaged Sec61, and likewise its interactions with the accessory membrane proteins Sec62, Sec63, and TRAP, respectively. Several natural and synthetic small molecules have been shown to block Sec61‐mediated protein translocation. Since this is a key step in protein biogenesis, broad inhibition is generally cytotoxic, which may be problematic for a putative drug target. Interestingly, several compounds exhibit client‐selective modes of action, such that only translocation of certain precursor proteins was affected. Here, we discuss recent advances of structural biology, molecular modelling, and molecular screening that aim to use Sec61 as feasible drug target.

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Characterization of the interaction between the Sec61 translocon complex and ppαF using optical tweezers

Robeson,

Casanova‐Morales,

Burgos‐Bravo

et al. 2024

Protein Science

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The Sec61 translocon allows the translocation of secretory preproteins from the cytosol to the endoplasmic reticulum lumen during polypeptide biosynthesis. These proteins possess an N‐terminal signal peptide (SP) which docks at the translocon. SP mutations can abolish translocation and cause diseases, suggesting an essential role for this SP/Sec61 interaction. However, a detailed biophysical characterization of this binding is still missing. Here, optical tweezers force spectroscopy was used to characterize the kinetic parameters of the dissociation process between Sec61 and the SP of prepro‐alpha‐factor. The unbinding parameters including off‐rate constant and distance to the transition state were obtained by fitting rupture force data to Dudko–Hummer–Szabo models. Interestingly, the translocation inhibitor mycolactone increases the off‐rate and accelerates the SP/Sec61 dissociation, while also weakening the interaction. Whereas the translocation deficient mutant containing a single point mutation in the SP abolished the specificity of the SP/Sec61 binding, resulting in an unstable interaction. In conclusion, we characterize quantitatively the dissociation process between the signal peptide and the translocon, and how the unbinding parameters are modified by a translocation inhibitor.

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Mycolactone subverts immunity by selectively blocking the Sec61 translocon

Abstract: Baron et al. show that mycolactone, an immunosuppressive macrolide produced by the pathogen Mycobacterium ulcerans, operates by targeting the Sec61 translocon. This identifies the most potent Sec61 inhibitor reported to date and the potential of inhibiting Sec61 for immune modulation.

Cited by 114 publications

References 34 publications

Sec61 blockade by mycolactone inhibits antigen cross-presentation independently of endosome-to-cytosol export

Sec61 blockade by mycolactone inhibits antigen cross-presentation independently of endosome-to-cytosol export

Toward Understanding the Mechanism of Client‐Selective Small Molecule Inhibitors of the Sec61 Translocon

Characterization of the interaction between the Sec61 translocon complex and ppαF using optical tweezers

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