2003•PubMedRequires access
Requirement for XRCC4 and DNA ligase IV in alignment-based gap filling for nonhomologous DNA end joining in vitro.
Jae Wan Lee, Steven M. Yannone, David J. Chen, Lawrence F. Povirk
Open publisher page 48 citations
Abstract
In the nonhomologous end joining pathway of DNA double-strand break repair, the ligation step is catalyzed by a complex of XRCC4 and DNA ligase IV. Extracts of CHO-K1 cells are able to accurately rejoin a site-specific free radical-mediated double-strand break with partially complementary overhangs, by a mechanism involving alignment-based gap filling followed by ligation. Extracts of XR-1 cells, which lack XRCC4 and DNA ligase IV, carried out neither gap filling nor ligation. Supplementation of the extracts with recombinant XRCC4/ligase IV, but not with XRCC4 alone, restored gap filling and accurate end joining. The results imply that XRCC4 and ligase IV are essential for alignment-based gap filling, as well as for final ligation of the breaks.