Melanie McDowell

@melaniemcdowell.bsky.social

Group Leader at MPI of Biophysics exploring ER membrane protein biogenesis

The last chapter from my postdoc days is finally online! We solve structures of the ER membrane O-mannosyltransferase Pmt4 and uncover a functionally important cytosolic binding site for the Dol-P-Man substrate lipid - allosteric regulation or a long sought after Dol-P-Man flippase?? 🔄 rdcu.be/eUJfb

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Our first lab paper is out! We identify and solve the first structure of the SND3 translocon involved in fungal membrane protein insertion. Congratulations @tzujingyang.bsky.social, and our colleagues @saumyakm.bsky.social, @hummerlab.bsky.social and Julian Langer. Read more ⬇️ and ➡️ rdcu.be/eNgIO

Max Planck Institute of Biophysics@mpibp.bsky.social · 9mo ago

SNDing proteins into the membrane! Our new publication from @melaniemcdowell.bsky.social ’s group identifies the SND3 protein as a new route for membrane protein insertion! 🍄 📘 Read more here: www.mpg.de/25599408/102... Image: Louise Duever.

Structure of the ribosome-bound SND3 translocon complex from the heat-tolerant fungus Chaetomium thermophilum. The SND3 translocon inserts proteins into the endoplasmic reticulum membrane as they are produced by the ribosome.

Very special feelings to announce this one... A project that started like 10 years ago is reaching the finish line, ready to shine. In a dream-team with @beckmannlab.bsky.social we solved the long-chased structure of the active membrane protein insertase SecYEG-YidC www.biorxiv.org/content/10.1...

Substrate-induced assembly and functional mechanism of the bacterial membrane protein insertase SecYEG-YidC

The universally conserved Sec translocon and the YidC/Oxa1-type insertases mediate biogenesis of alpha-helical membrane proteins, but the molecular basis of their cooperation has remained disputed over decades. A recent discovery of a multi-subunit insertase in eukaryotes has raised the question about the architecture of the putative bacterial ortholog SecYEG-YidC and its functional mechanism. Here, we combine cryogenic electron microscopy with cell-free protein synthesis in nanodiscs to visualize biogenesis of the polytopic membrane protein NuoK, the subunit K of NADH-quinone oxidoreductase, that requires both SecYEG and YidC for insertion. We demonstrate that YidC is recruited to the back of the translocon at the late stage of the substrate insertion, in resemblance to the eukaryotic system, and in vivo experiments indicate that the complex assembly is vital for the cells. The nascent chain does not utilize the lateral gate of SecYEG, but enters the lipid membrane at the SecYE-YidC interface, with YidC being the primary insertase. SecYEG-YidC complex promotes folding of the nascent helices at the interface prior their insertion, so the examined cellular pathway follows the fundamental thermodynamic principles of membrane protein folding. Our data provide the first detailed insight on the elusive insertase machinery in the physiologically relevant environment, highlight the importance of the nascent chain for its assembly, and prove the evolutionary conservation of the gate-independent insertion route. ### Competing Interest Statement The authors have declared no competing interest. Deutsche Forschungsgemeinschaft, https://ror.org/018mejw64, Ke1879/3, 267205415 (CRC 1208) European Research Council, https://ror.org/0472cxd90, CRYOTRANSLATION

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Thank you so much for guiding me on this amazing journey, @poulnissen.bsky.social, @charlottstock.bsky.social, and @tdieudonne.bsky.social. So great and thorough discussion with @melaniemcdowell.bsky.social, @henrietteautzen.bsky.social and Daan van Aalten. I highly appreciate your involvement.

Thibaud Dieudonné@tdieudonne.bsky.social · 2y ago

🎉Congrats @tomasheger.bsky.social for this excellent PhD defense. You were the expert in the room. Very very proud supervisors with @charlottstock.bsky.social and @poulnissen.bsky.social ! Many thanks to the jury members Daan van Aalten, @henrietteautzen.bsky.social and @melaniemcdowell.bsky.social

Congratulations on an excellent PhD defense Dr. @tomasheger.bsky.social! It was a fun day and great discussion.

Charlott Stock@charlottstock.bsky.social · 2y ago

Huge congrats to @tomasheger.bsky.social who succesfully defended his PhD yesterday. Such a joy to supervise with @tdieudonne.bsky.social and @poulnissen.bsky.social. Big thank you to @melaniemcdowell.bsky.social, @henrietteautzen.bsky.social and Daan van Aalten for a great discussion. P-type ❤️💙💛