Aphidicolin-resistant and -sensitive base excision repair in wild-type and DNA polymerase beta-defective mouse cells.
Several DNA polymerases (Pols) can add complementary bases at the gap created during the base excision repair (BER). To characterize the BER resynthesis step, the repair of a single abasic site by wild-type and Pol beta-defective mouse cell extracts was analysed in the presence of aphidicolin, a specific inhibitor of replicative Pols. We show that there is a competition between distributive and processive Pols for the nucleotide addition at the primer terminus. In wild-type cell extracts, the initial nucleotide insertion involves mainly Pol beta but the elongation step is carried out by a replicative Pol. Conversely, in Pol beta-null cell extracts the synthesis step is carried out by a replicative Pol without any switching to an auxiliary polymerase. We present evidence that short-patch repair synthesis occurs even in the absence of both Pol beta and replicative Pols. Exogeneously added purified human Pol lambda was unable to stimulate this back-up synthesis.
Parlanti
Eleonora
E
Department of Environment and Primary Prevention, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Roma, Italy.
Pascucci
Barbara
B
Terrados
Gloria
G
Blanco
Luis
L
Dogliotti
Eugenia
E
D000818:Animals; D016590:Aphidicolin / Q000494:pharmacology*; D001483:Base Sequence; D002457:Cell Extracts; D019951:DNA Polymerase beta / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D004260:DNA Repair / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D007700:Kinetics; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D009841:Oligonucleotides / Q000235:genetics / Q000378:metabolism; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism
D002457:Cell Extracts; D004791:Enzyme Inhibitors; D009841:Oligonucleotides; D018809:Proliferating Cell Nuclear Antigen; D016590:Aphidicolin; D019951:DNA Polymerase beta