Polymerases in nonhomologous end joining: building a bridge over broken chromosomes.
Repair of double-strand breaks in chromosomal DNA is essential. Unfortunately, a paradigm central to most DNA repair pathways--damaged DNA is replaced by polymerases, by using an intact, undamaged complementary strand as a template--no longer works. The nonhomologous end joining (NHEJ) pathway nevertheless still uses DNA polymerases to help repair double-strand breaks. Bacteria use a member of the archaeo-eukaryal primase superfamily, whereas eukaryotes use multiple members of the polymerase X family. These polymerases can, depending on the biologic context, accurately replace break-associated damage, mitigate loss of flanking DNA, or diversify products of repair. Polymerases specifically implicated in NHEJ are uniquely effective in these roles: relative to canonic polymerases, NHEJ polymerases have been engineered to do more with less.
Ramsden
Dale A
DA
Department of Biochemistry and Biophysics, Lineberger Comprehensive Cancer Center, and Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, NC 27599, USA. dale_ramsden@med.unc.edu
D000818:Animals; D004247:DNA / Q000235:genetics / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism*; D011995:Recombination, Genetic
D004247:DNA; D004259:DNA-Directed DNA Polymerase