When it comes to DNA replication, humans and baker’s yeast are more alike than different, scientists discover. They found that a molecular complex called CTF18-RFC in humans and Ctf18-RFC in yeast loads a “clamp” onto DNA to keep the replication machinery from falling off the DNA strand.
This mechanism is crucial for accurate DNA copying. The discovery sheds light on how genetic information passes from one generation of cells to the next, which can fail in diseases like cancer. This process can lead to uncontrolled or faulty replication with devastating consequences.
DNA replication is a tightly controlled process that copies the genetic code. It begins by unzipping DNA’s structure, resulting in two strands called the leading and lagging strands. A molecular construction crew then assembles the missing halves of the strands, turning a single DNA helix into two.
Polymerases are enzymes that assemble the building blocks of DNA. However, they aren’t good at staying on the DNA strand. They require CTF18-RFC in humans and Ctf18-RFC in yeast to thread a ring-shaped clamp onto the DNA leading strand. This clamp then closes and signals to the polymerases that they can begin replicating DNA.
Using high-powered cryo-electron microscopes, scientists revealed previously unknown facets of the leading strand clamp loaders’ structures, including a “hook” that forces the leading strand polymerase to let go of the new DNA strand so it can be recognized by the clamp loader.
Source: https://phys.org/news/2024-08-dna-replication-humans-baker-yeast.html