Open AccessIn vitro discrimination of replicases acting on carcinogen-modified polynucleotide templates
Author(s) -
Singer B,
Jarosław T. Kuśmierek,
H. FraenkelConrat
Publication year - 1983
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.80.4.969
Subject(s) - polynucleotide , polymerase , rna polymerase , rna , transcription (linguistics) , dna , chemistry , enzyme , in vitro , template , dna polymerase , biochemistry , rna dependent rna polymerase , biology , microbiology and biotechnology , stereochemistry , gene , nanotechnology , materials science , linguistics , philosophy
Three different poly(dC)s with modifications that block the N-3 of deoxycytidine were used as templates for polymer synthesis byEscherichia coli DNA polymerase I (EC 2.7.7.7). In contrast to previously reported results with transcriptases, the hydrated form of 3,N 4 -ethenodeoxycytidine (εdC·H2 O) did not mispair. Both 3,N 4 -ethenodeoxycytidine (εdC) and 3-methyldeoxycytidine (m3 dC) led to dTMP misincorporation: 1/20 εdC and 1/80 m3 dC. No other misincorporations appeared to be significant in amount. Thus, both qualitatively and quantitatively, replication errors resulting from carcinogen-modified bases are less frequent than errors in transcription of the same deoxypolynucleotides. Replication of comparable ribopolynucleotide templates by cucumber RNA-dependent RNA polymerase (EC 2.7.7.48) was strongly inhibited by εrC·H2 O and εrC, so that the fidelity of this enzyme could not be assessed. However, both poly(dC) and poly(rC) containing dU or rU led to incorporation of rA. The presence of even small amounts of purines in poly(rC) greatly depressed synthesis, but the complementary base was incorporated. The finding that an RNA replicase can utilize a deoxypolynucleotide template is a further indication that, at leastin vitro , the specificity of the relationship of enzymes and their natural templates is not absolute.