Cryo-EM structures of RAD51 assembled on nucleosomes containing a DSB site. (https://pubmed.ncbi.nlm.nih.gov/38509361/)

These scientists wanted to understand how a protein called RAD51 helps to fix breaks in our DNA. They used a special technique called cryo-electron microscopy to take pictures of RAD51 when it is attached to a structure called a nucleosome in our cells.

They found that RAD51 can form different shapes - either a ring or a filament - when it is near the nucleosome. In the ring shape, parts of RAD51 called N-terminal lobe domains stick out and grab onto the DNA in the nucleosome. The parts of RAD51 that face the middle of the ring can recognize where the DNA is broken.

In the filament shape, RAD51 stretches out and pulls the DNA away from the nucleosome. Other parts of RAD51 then attach to the DNA and the histones in the nucleosome.

The scientists also discovered that if they changed certain parts of RAD51 that grab onto the nucleosome, it made RAD51 less effective at binding to the nucleosome. This also made RAD51 not work as well at repairing DNA breaks in living cells.

Overall, this study helped the scientists learn more about how RAD51 interacts with the nucleosome and DNA to help fix breaks in our genetic code.

Shioi T., Hatazawa S., Oya E., Hosoya N., Kobayashi W., Ogasawara M., Kobayashi T., Takizawa Y., Kurumizaka H. Cryo-EM structures of RAD51 assembled on nucleosomes containing a DSB site. Nature. 2024 Mar 20. doi: 10.1038/s41586-024-07196-4.