title: DNA repair in Escherichia coli mutants deficient in DNA polymerases I, II and-or 3.
abstract: E. coli mutants deficient in DNA polymerase I, in DNA polymerases I and II, or in DNA polymerase III, can efficiently and completely execute excision repair and post-replication repair of UV-damaged DNA at 43 degrees when assayed by alkaline sucrose gradients. Repair by cells deficient in polymerase I and in polymerases I and II is inhibited by 1-beta-D-arabinofuranosylcytosine at 43 degrees , whereas that by cells deficient in polymerase III is insensitive to the inhibitor. When both DNA polymerases I and III are deficient, both excision repair and post-replication repair are greatly reduced at 43 degrees , and the residual repair capability is inhibited by 1-beta-D-arabinofuranosylcytosine. Very little dark repair is observed in cells deficient in DNA polymerases I, II, and III, and the DNA is extensively degraded. These results suggest that either DNA polymerase I or DNA polymerase III is required for complete and efficient repair, and that when both DNA polymerases I and III are deficient, DNA polymerase II mediates a limited, incomplete dark repair of UV-damaged DNA. DNA polymerases I and III thus appear to be important enzymes in both DNA replication and DNA dark repair.
mesh_terms: D002250:Carbon Radioisotopes; D002499:Centrifugation, Density Gradient; D003561:Cytarabine / Q000494:pharmacology; D004254:DNA Nucleotidyltransferases / Q000096:biosynthesis / Q000378:metabolism*; D004260:DNA Repair / Q000187:drug effects*; D004269:DNA, Bacterial / Q000032:analysis / Q000528:radiation effects; D003864:Depression, Chemical; D004926:Escherichia coli / Q000201:enzymology / Q000378:metabolism*; D009154:Mutation; D011830:Radiation Effects; D013696:Temperature; D013936:Thymidine / Q000378:metabolism; D013941:Thymine / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: D002250:Carbon Radioisotopes; D004269:DNA, Bacterial; D003561:Cytarabine; D004254:DNA Nucleotidyltransferases; D013941:Thymine; D013936:Thymidine