National Institutes of Health/National Cancer Institute (NIH/NCI)
米国
引用
ジャーナル: Sci Adv / 年: 2024 タイトル: Molecular basis of TMED9 oligomerization and entrapment of misfolded protein cargo in the early secretory pathway. 著者: Le Xiao / Xiong Pi / Alissa C Goss / Tarick El-Baba / Julian F Ehrmann / Elizabeth Grinkevich / Silvana Bazua-Valenti / Valeria Padovano / Seth L Alper / Dominique Carey / Namrata D Udeshi / ...著者: Le Xiao / Xiong Pi / Alissa C Goss / Tarick El-Baba / Julian F Ehrmann / Elizabeth Grinkevich / Silvana Bazua-Valenti / Valeria Padovano / Seth L Alper / Dominique Carey / Namrata D Udeshi / Steven A Carr / Juan Lorenzo Pablo / Carol V Robinson / Anna Greka / Hao Wu / 要旨: Intracellular accumulation of misfolded proteins causes serious human proteinopathies. The transmembrane emp24 domain 9 (TMED9) cargo receptor promotes a general mechanism of cytotoxicity by ...Intracellular accumulation of misfolded proteins causes serious human proteinopathies. The transmembrane emp24 domain 9 (TMED9) cargo receptor promotes a general mechanism of cytotoxicity by entrapping misfolded protein cargos in the early secretory pathway. However, the molecular basis for this TMED9-mediated cargo retention remains elusive. Here, we report cryo-electron microscopy structures of TMED9, which reveal its unexpected self-oligomerization into octamers, dodecamers, and, by extension, even higher-order oligomers. The TMED9 oligomerization is driven by an intrinsic symmetry mismatch between the trimeric coiled coil domain and the tetrameric transmembrane domain. Using frameshifted Mucin 1 as an example of aggregated disease-related protein cargo, we implicate a mode of direct interaction with the TMED9 luminal Golgi-dynamics domain. The structures suggest and we confirm that TMED9 oligomerization favors the recruitment of coat protein I (COPI), but not COPII coatomers, facilitating retrograde transport and explaining the observed cargo entrapment. Our work thus reveals a molecular basis for TMED9-mediated misfolded protein retention in the early secretory pathway.