# DNA repair in darkness: evolutionary conservation of photolyase function beyond light

## TL;DR

A study shows that a DNA repair enzyme in cavefish works in the dark, challenging the belief that it only functions in light.

## Contribution

CPD photolyase was found to repair oxidative DNA damage in darkness, revealing a new dual function.

## Key findings

- CPD photolyase protects against oxidative DNA lesions in the absence of light.
- The enzyme's dual function explains its evolutionary conservation in cavefish.
- Comparative models showed functional differences between surface and cave-dwelling fish.

## Abstract

DNA repair by photolyases has classically been viewed as a light-dependent process, restricted to the reversal of UV-induced pyrimidine dimers. A recent study published in Nature Communications overturns this paradigm by showing that CPD photolyase in the blind cavefish Phreatichthys andruzzii is still involved in DNA repair function in complete darkness. Using comparative models of surface-dwelling and cave-dwelling fish, the authors demonstrate that CPD photolyase not only mediates photoreactivation under light but also protects against oxidative DNA lesions in the absence of light, explaining its remarkable evolutionary conservation.

A recent cavefish study overturns the classic view of photolyases as light-dependent enzymes. Research shows CPD photolyase repairs oxidative DNA damage in darkness, revealing a dual function that explains its conservation in cave species