Ultraviolet radiation causes damage to DNA in skin cells, blocking DNA replication and causing mutations that can lead to cancer. One way in which the cell deals with such damage involves specialized DNA polymerases, such as Polη, that can bypass lesions. Here the crystal structure of Polη is presented at four consecutive steps during DNA synthesis through thymine dimers. Polη acts like a 'molecular splint' to stabilize damaged DNA, and accommodates the thymine dimer in an atypically large active site.
- Christian Biertümpfel
- Ye Zhao
- Wei Yang
