title: 2-Aminopurine-induced mutagenesis in T4 bacteriophage: a model relating mutation frequency to 2-aminopurine incorporation in DNA.
abstract: We measured the in vivo incorporation of 2-aminopurine into DNA of T4 bacteriophage allelic for gene 43 (DNA polymerase), mutator (L56), 43+, and antimutator (L141). The magnitude of incorporation (mol/mol of Thy) was 1/1500 in L56, 1/1600 in 43+, and 1/8900 in L141. The incorporation ratio L56:43+:L141 in vivo was equal to that mediated by the purified DNA polymerases of these allelic phages in vitro. A model for 2-aminopurine-induced A-T in equilibrium G-C transitions is discussed. The model is used to predict the magnitudes of replication errors (C mispairing with a template 2-aminopurine) and incorporation errors (2-aminopurine mispairing with a template C) per round of replication and to investigate the asymmetry in 2-aminopurine-induced transitions favoring the A-T leads to G-C pathway over G-C leads to A-T. We suggest that the fidelity of L56 and L141 DNA polymerases exemplifies one-step and two-step editing, respectively.
mesh_terms: D015075:2-Aminopurine / Q000494:pharmacology*; D000225:Adenine / Q000031:analogs & derivatives*; D000632:Aminopyrine / Q000378:metabolism; D003090:Coliphages / Q000187:drug effects / Q000235:genetics*; D004279:DNA, Viral / Q000096:biosynthesis*; D008954:Models, Biological; D009153:Mutagens
chemical_list: D004279:DNA, Viral; D009153:Mutagens; D000632:Aminopyrine; D015075:2-Aminopurine; D000225:Adenine
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