The four-step process of enzyme loading underlying DNA replication
DNA replication is crucial for life; without it we wouldn’t grow. A key step in replication is the formation of a fork. A replication fork can be compared to the zip on your jeans – the DNA helix is unwound by an enzyme, helicase, allowing other enzymes access to copy the DNA. However, how helicase binds to DNA was a mystery. Researchers at MRC LMS and Imperial College London discovered in yeast that helicase, made of six proteins called Mcm2–7, is loaded onto the DNA in four steps and undergoes structural changes throughout the process. Seen here in cryo-EM images are the first three steps (rows top to bottom) with helicase highlighted in green and the loading complex in blue around the DNA coloured red. DNA replication in yeast and humans is extremely similar so this research has the potential to be applied in healthcare, such as inhibiting DNA replication in cancer.
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