Credit: ELSEVIER

Cell 139, 87–99 (2009); Cell 139, 100–111 (2009)

Work by two independent groups has deduced the structure and role of a key component of a protein complex that repairs dangerous double-stranded breaks in DNA.

The teams — one led by John Tainer and Paul Russell of the Scripps Research Institute in La Jolla, California, the other by Steve Smerdon of the National Institute for Medical Research in London and Stephen Jackson of the University of Cambridge, UK — crystallized and characterized one of three subunits that make up the MRN protein complex, which responds to DNA damage.

The researchers found that the subunit, Nbs1 (pictured), extends from the complex like a flexible arm and tethers the protein Ctp1, which is essential for the repair of double-stranded breaks. Nbs1 helps Ctp1 to home in on the site of the break.