I am super excited to share our latest work on the native in-cell organization of the mitochondrial respiratory chain 🥳 Using cryo-electron tomography 🔬, we show how the respiratory complexes (and other complexes) are organized inside native mitochondria! www.biorxiv.org/content/10.1... - ThreadSky

florentwaltz.bsky.social • 174 days ago

I am super excited to share our latest work on the native in-cell organization of the mitochondrial respiratory chain 🥳
Using cryo-electron tomography 🔬, we show how the respiratory complexes (and other complexes) are organized inside native mitochondria!
https://www.biorxiv.org/content/10.1101/2024.09.03.610704v1

Comments

saladcookies.bsky.social•174 days ago

This is so cool!! Idk if this is a stupid question given that I know literally nothing about sample prep methods for cryo-EM, but how difficult would it be to do this kind of imaging on mitos isolated from mammalian tissues?

florentwaltz.bsky.social•174 days ago

If you want to do it on isolated mito from mammalian tissues (which is not what we've done here, no isolation in our case!) it was already done ! You can check here
https://www.nature.com/articles/s41586-024-07488-9
But it's still very challenging!

saladcookies.bsky.social•174 days ago

Oh awesome!

peiferlabunc.bsky.social•174 days ago

Incredible images--tomography has the power to bridge the gap between protein structure and super-resolution light microscopy

florentwaltz.bsky.social•174 days ago

First, using subtomogram averaging, we determined a 5 Å structure of the respiratoty chain. We show that the majority of respiratory complexes I, III and IV are organized into a single type of supercomplex, the respirasome, with a distinct arrangement described from other organisms

florentwaltz.bsky.social•174 days ago

This was super exciting to be able to resolve all this directly from subtomo averaging, seeing bulky chains and large ligands. But, in Chlamydomonas 🦠 no structures of these complexes were available, and we were just at the limit for protein identification from the density

florentwaltz.bsky.social•174 days ago

Combining subtomo with single particle (2.4 Å resolution), we built a complete model of this 5.4 MDa (214 proteins 😬) respirasome. This allowed us to see how each complex interacts with each others. They actually do so with few protein-protein contacts. Lipids play a crucial role here!

florentwaltz.bsky.social•174 days ago

From the subtome average we also resolved cyt. c densities bound to the respirasame. Interestingly, the distances from complex III te complex IV binding sites range from ~90 Å to ~230 Å with an average distance of ~175 Å, which is quite far!

florentwaltz.bsky.social•174 days ago

Previously, complex III and complex IV have been shown to be close to each other, but here, out of the 6 complex IV, only 2 contact the complex III dimers. In Chlamy, the average IMS distance is actually less than the distance cyt. c would have to travel within a respirasome

florentwaltz.bsky.social•174 days ago

This suggests that cyt. c are probably freely diffusing in the IMS between respirasomes, supporting the "free diffusion model" rather than the "substrate channeling model" where a specific pool of cyt. c and ubiquinone would only shuttle within respirasomes and not between them