Early Steps in the DNA Base Excision Repair Pathway of a Fission Yeast Schizosaccharomyces pombe
Figure 1
A schematic illustration of the BER pathway in S. pombe. In the Nth1p-dependent (or short patch) pathway, repair of the AP site is initiated by incision of Nth1p leaving the -block. Apn2p functions primarily in the removal of the -block, and poorly in the incision of AP sites. Apn1p is a back-up enzyme for -phosphodiesterase activity of Apn2p. Finally, a DNA polymerase (Pol.) fills the gap, and a DNA ligase seals the nick. NER and HR could repair a part of the AP sites and single-strand breaks with blocks. AP endonuclease incises the AP site leaving -dRP end, which will be removed by -dRP lyase activity of Pol4p to feed into short-patch BER. In the long patch pathway, Rad2p incises the flap DNA containing the lesion after DNA synthesis. Uve1p and Apn1p are possibly involved in the NIR pathway. Details are discussed in the text.
