Damaged DNA Spotter Protein Purified

A protein called ATR that preferentially binds to damaged DNA has been purified, and it appears to function as an initial sensor for injury to genetic material. The ATR protein is a member of the phosphatidylinositol kinase-related family. Details of purification of the protein and subsequent biochemical and electron microscope analysis have been published in the May 14, 2002, edition of the Proceedings of the National Academy of Sciences.

Researchers at the University of North Carolina (UNC, Chapel Hill, USA) have found that ATR binds to UV-damaged DNA with higher affinity than to undamaged DNA. Furthermore, damaged DNA stimulates the kinase activity of ATR to a significantly higher degree than does undamaged DNA. Damage to DNA may be caused by such agents as pollution, ultraviolet radiation, and chemotherapy.

The downstream effects of the ATR alarm protein were already known, but it was not clear whether ATR sensed damaged DNA directly or was simply part of the cascade of repair activated by another protein upstream. The results of the current study suggest that ATR senses damaged DNA and also helps start the cascade.

"This is a very important phenomenon in both normal and cancerous cells, and there has been a great deal of research about it,” said Dr. Aziz Sancar, professor of microbiology and immunology at UNC. "ATR appears to act as a switch that starts the repair process and also stops cells from proliferating while they are being repaired. This new work is not going to cure cancer by itself, but it is a significant step forward.”



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