Role of the yeast DNA repair protein Nej1 in end processing during the repair of DNA double strand breaks by non-homologous end joining.
DNA double strand breaks (DSB)s often require end processing prior to joining during their repair by non-homologous end joining (NHEJ). Although the yeast proteins, Pol4, a Pol X family DNA polymerase, and Rad27, a nuclease, participate in the end processing reactions of NHEJ, the mechanisms underlying the recruitment of these factors to DSBs are not known. Here we demonstrate that Nej1, a NHEJ factor that interacts with and modulates the activity of the NHEJ DNA ligase complex (Dnl4/Lif1), physically and functionally interacts with both Pol4 and Rad27. Notably, Nej1 and Dnl4/Lif1, which also interacts with both Pol4 and Rad27, independently recruit the end processing factors to in vivo DSBs via mechanisms that are additive rather than redundant. As was observed with Dnl4/Lif1, the activities of both Pol4 and Rad27 were enhanced by the interaction with Nej1. Furthermore, Nej1 increased the joining of incompatible DNA ends in reconstituted reactions containing Pol4, Rad27 and Dnl4/Lif1, indicating that the stimulatory activities of Nej1 and Dnl4/Lif1 are also additive. Together our results reveal novel roles for Nej1 in the recruitment of Pol4 and Rad27 to in vivo DSBs and the coordination of the end processing and ligation reactions of NHEJ.
Department of Internal Medicine, University of New Mexico Cancer Center, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA.
Hui
H
Yang
Department of Internal Medicine, University of New Mexico Cancer Center, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA.
Yoshihiro
Y
Matsumoto
Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA.
Kelly M
KM
Trujillo
Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 14N, Canada.
Susan P
SP
Lees-Miller
Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA.
Mary Ann
MA
Osley
Department of Internal Medicine, University of New Mexico Cancer Center, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA. Electronic address: atomkinson@salud.unm.edu.
Alan E
AE
Tomkinson
D053903:DNA Breaks, Double-Stranded; D059766:DNA End-Joining Repair; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000235:genetics / Q000378:metabolism; D019951:DNA Polymerase beta; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D045585:Flap Endonucleases / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism
D004268:DNA-Binding Proteins; C114091:LIF1 protein, S cerevisiae; C441270:NEJ1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D019951:DNA Polymerase beta; C084892:POL4 protein, S cerevisiae; D045585:Flap Endonucleases; C468323:RAD27 protein, S cerevisiae; D011088:DNA Ligases; D000072481:DNA Ligase ATP
DNA damage; DNA double-strand break; DNA ligase; DNA nuclease; DNA polymerase; Genomic instability; Protein–protein interaction