on April 3, 2020
When DNA breaks, cells need to join the broken DNA pieces in an accurate way to prevent mutations. Cells utilize the so-called homologous recombination pathway to achieve this goal. In the first step of this repair process, several nucleases remove one strand of double-stranded DNA near the break. This activity reveals a single-stranded DNA overhang, which is used by the recombination machinery to search for a matching template DNA to guarantee an accurate repair. While the use of nucleases is necessary for the mechanism of the recombination process, it is also potentially dangerous, because unscheduled DNA degradation may also be dangerous. Therefore, cells need to control this process in a tight manner to allow these nucleases to act only when needed.
A new study from the Cejka laboratory, just published in the Proceedings of the National Academy of Sciences, describes a new function of a factor termed CtIP, which controls the function of nucleases in the first step of the recombination pathway.
The study was carried out in collaboration with the Seidel laboratory (University of Leipzig). Ilaria Ceppi, a PhD student in the Cejka lab, carried out most of the biochemical experiments. The Cejka laboratory is located at the IRB, affiliated with the Faculty of Biomedical Sciences at USI.
Ilaria Ceppi, Sean M. Howard, Kristina Kasaciunaite, Cosimo Pinto, Roopesh Anand, Ralf Seidel, and Petr Cejka
PNAS ; DOI : 10.1073/pnas.2001165117