New insights into DNA repair

Brandeis University News

New insights into DNA repairThe lab of biologist James Haber advances our understanding of these processes in a paper in the journal Nature. Photo/Mike LovettBiologist James HaberApril 18, 2017A new paper in the prestigious journal Nature from Brandeis researchers in the laboratory of James Haber provides a detailed description of the processes of DNA repair.Chromosomes undergo DNA repair to correct insults to our genetic code, caused either by errors in copying the DNA or by external factors such as exposure to radiation or toxins. Most damage gets accurately repaired, so the cell is unaffected, but some result in permanent errors (mutations or chromosome rearrangements) that may lead to diseases, including cancer. Especially dangerous are double-strand DNA breaks (DSB’s) that sever the chromosome.The work was principally carried out by postdoctoral fellow Ranjith Anand with contributions by technician Annette Beach and physics Phd student Kevin Li. They examined repair of a double-strand break in yeast cells.When a DSB occurs, the cell needs to patch up the break by matching up the ends of the broken chromosome with similar DNA sequences located on an intact chromosome; the intact sequences can be used as a template to repair the break by DNA copying. To accomplish repair, the cell must be able to locate another chromosome with similar sequences to use as a template.Finding such a template is no easy task. Chromosomes are made up of base pairs — pairings of the molecules guanine and cytosine or adenine and thymine. (As you may remember from biology class, G goes with C and A with T). The end of the broken chromosome must be compared with millions of possible short DNA regions in order to find a chromosome with the same arrangement of base pairs. This search is mediated by the RAD51 protein, which promotes the matching up of the broken end ...

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