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PubMed · 8262040

Suicidal nucleotide sequences for DNA polymerization.

G M Samadashwily·A Dayn·S M Mirkin
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Abstract

Studying the activity of T7 DNA polymerase (Sequenase) on open circular DNAs, we observed virtually complete termination within potential triplex-forming sequences. Mutations destroying the triplex potential of the sequences prevented termination, while compensatory mutations restoring triplex potential restored it. We hypothesize that strand displacement during DNA polymerization of double-helical templates brings three DNA strands (duplex DNA downstream of the polymerase plus a displaced overhang) into close proximity, provoking triplex formation, which in turn prevents further DNA synthesis. Supporting this idea, we found that Sequenase is unable to propagate through short triple-helical stretches within single-stranded DNA templates. Thus, DNA polymerase, by inducing triplex formation at specific sequences in front of the replication fork, causes self-termination. Possible biological implications of such 'conformational suicide' are discussed. Our data also provide a novel way to target DNA polymerases at specific sequences using triplex-forming oligonucleotides.

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Base SequenceDNADNA, Single-StrandedDNA-Directed DNA PolymeraseMolecular Sequence DataNucleic Acid ConformationStructure-Activity RelationshipSubstrate SpecificityTemplates, GeneticJournal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.

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G M Samadashwily, A Dayn, S M Mirkin. 1993-12-15. Suicidal nucleotide sequences for DNA polymerization.. https://doi.org/10.1002/j.1460-2075.1993.tb06191.x

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