title: A method for the specific inhibition of poly[d(A-T)] synthesis using the A-T specific quinoxaline antibiotic TANDEM.
abstract: A serious problem in the replication of repeating-sequence DNa polymers using Escherichia coli DNA polymerase I arises from the fact that this polymerase has a very strong preference for the replication of poly[d(A-T)]. Thus reactions primed with DNA containing small amounts of contaminating poly[d(A-T)] will eventually result in complete domination of the synthesis by poly[d(A-T)]. This problem can be overcome by the addition to the reaction mixture of the synthetic quinoxaline antibiotic TANDEM which binds specifically to poly[d(A-T)] completely inhibiting its replication. Using thermal denaturation experiments it can be shown that TANDEM does not bind to most other synthetic DNA polymers (e.g., poly(dA) . poly(dT) and poly[d(A-T-C)] . poly[d(G-A-T)] and therefore their replication is not inhibited. The only exception we have encountered is poly[d(T-A-C)] . poly[d(G-T-A)] which does bind TANDEM and therefore the drug cannot be used during the synthesis of this polymer. The fact that poly[d(T-A-C)] . poly[d(G-T-A)] does bind TANDEM while poly[d(A-T-C)] . poly[d(G-A-T)] does not, suggests that the drug recognizes T-A rather than A-T sequences.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004256:DNA Polymerase I / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology; D011067:Poly dA-dT / Q000096:biosynthesis*; D011089:Polydeoxyribonucleotides / Q000096:biosynthesis* / Q000378:metabolism; D011810:Quinoxalines / Q000494:pharmacology; D013379:Substrate Specificity; D014158:Transcription, Genetic / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents; D011089:Polydeoxyribonucleotides; D011810:Quinoxalines; D011067:Poly dA-dT; C017738:TANDEM (quinoxaline); D004256:DNA Polymerase I