Using the now famous optical tweezers from Nynke Dekker’s group, it was recently shown that certain sequences on the genome bring the mobile start proteins of DNA replication to a halt, which is crucial for the start of DNA duplication and cell division.

DNA replication is one of the first steps in the complex process of cell division. In the process, genetic material is doubled, pulled apart, and each copy ends up neatly in its own cell during cell division. It is broadly clear how this process proceeds and we know dozens of proteins that are involved, but many details are still unknown.

The group of Nynke Dekker at TU Delft, in collaboration with researchers at the Francis Crick Institute in London, has now shown in Nature Communications that the protein with which DNA replication starts, called ORC, moves quickly across the chromosome and stops at DNA sequences with which ORC was known to have a high affinity. The fact that ORC stops at these specific sequences ensures that, among others, the proteins Cdt1 and Cdc6 are recruited, after which so-called MCM-helicases in the S-phase of cell division (the phase in which the actual DNA duplication takes place) make the DNA accessible to the replication machinery.