DNA polymerase beta and flap endonuclease 1 enzymatic specificities sustain DNA synthesis for long patch base excision repair. Article

Liu, Yuan, Beard, William A, Shock, David D et al. (2005). DNA polymerase beta and flap endonuclease 1 enzymatic specificities sustain DNA synthesis for long patch base excision repair. . JOURNAL OF BIOLOGICAL CHEMISTRY, 280(5), 3665-3674. 10.1074/jbc.m412922200

cited authors

  • Liu, Yuan; Beard, William A; Shock, David D; Prasad, Rajendra; Hou, Esther W; Wilson, Samuel H

authors

abstract

  • DNA polymerase beta (pol beta) and flap endonuclease 1 (FEN1) are key players in pol beta-mediated long-patch base excision repair (LP-BER). It was proposed that this type of LP-BER is accomplished through FEN1 removal of a 2- to 11-nucleotide flap created by pol beta strand displacement DNA synthesis. To understand how these enzymes might cooperate during LP-BER, we characterized purified human pol beta DNA synthesis by utilizing various BER intermediates, including single-nucleotide-gapped DNA, nicked DNA, and nicked DNA with various lengths of flaps all with a 5'-terminal tetrahydrofuran (THF) residue. We observed that nicked DNA and nicked-THF flap DNA were poor substrates for pol beta-mediated DNA synthesis; yet, DNA synthesis was strongly stimulated by purified human FEN1. FEN1 did not improve pol beta substrate binding. FEN1 cleavage activity was required for the stimulation, suggesting that FEN1 removed a barrier to pol beta DNA synthesis. In addition, FEN1 cleavage on both nicked and nicked-THF flap DNA resulted in a one-nucleotide gapped DNA molecule that was an ideal substrate for pol beta. This study demonstrates that pol beta cooperates with FEN1 to remove DNA damage via a "Hit and Run" mechanism, involving alternating short gap production by FEN1 and gap filling by pol beta, rather than through coordinated formation and removal of a strand-displaced flap.

publication date

  • February 1, 2005

published in

keywords

  • DNA
  • DNA Polymerase beta
  • DNA Repair
  • Electrophoretic Mobility Shift Assay
  • Flap Endonucleases
  • Humans
  • Substrate Specificity

Digital Object Identifier (DOI)

Medium

  • Print-Electronic

start page

  • 3665

end page

  • 3674

volume

  • 280

issue

  • 5