Cas12a Sensor Detects DNA Damage in One Step

The new sensor uses a single CRISPR enzyme, Cas12a, to spot damaged DNA without extra steps. A specially designed double‑stranded DNA keeps Cas12a quiet until the enzyme uracil‑DNA glycosylase (UDG) removes a uracil base. When UDG cuts the uracil out, the balance of the DNA changes and Cas12a can bind its guide RNA. This triggers Cas12a to cut nearby reporter molecules, creating a bright signal that shows how much UDG is active. The system can tell the difference between normal and damaged DNA more than 1, 800 times better than before. It can detect tiny amounts of UDG—only five hundred nanomoles per milliliter. Scientists also made a version that works inside cell nuclei.

When introduced into living cells, the sensor shows UDG activity during different stages of the cell cycle. This lets researchers see where and when DNA repair happens in real time, like a map of the cell’s own maintenance crew. The approach is simple because it needs only one enzyme and a balanced DNA gate, avoiding extra reactions that can confuse the readout. Because it works directly from the damage event, the method could help diagnose diseases linked to DNA repair problems or monitor how cells respond to stress. The technique illustrates a new way to activate CRISPR tools with minimal parts and could inspire similar sensors for other biological signals.

Actions