DNA repair proteins action revealed

2010-03-12
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Tiny errors in the DNA code are repaired swiftly by proteins that jump between molecules like fleas, slide over them or pause at suspicious-looking sections, according to scientists who studied the movements using nanotechnology.

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Tiny errors in the DNA code are repaired swiftly by proteins that jump between molecules like fleas, slide over them or pause at suspicious-looking sections, according to scientists who studied the movements using nanotechnology.

Researchers from the Universities of Pittsburgh and Vermont in the US and the University of Essex labelled these repair proteins using tiny quantum dots to make them glow in imaging devices.

Quantum dots are semiconductors composed of nanocrystals that emit light of different colours.

For their experiments, the researchers tagged two repair proteins - UvrA and UvrB - and observed their action on DNA molecules that were straightened out into "tightropes" for better visibility.

They discovered that UvrA proteins randomly hop around from one DNA molecule to the next scanning for errors - staying one spot for about seven seconds before moving on to another site.

But an even more efficient mechanism emerges when UvrA forms a complex with two UvrB molecules. The UvrAB complex slides along the DNA tightrope for as long as 40 seconds before detaching itself and hopping off to another molecule.

According to the senior author Bennett Van Houten, from the University of Pittsburgh, repair proteins perform a vital function by fixing minor errors in the DNA code due to environmental toxins that people are constantly exposed to.

Findings from the study are published in the latest edition of Molecular Cell.

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