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Updated: Aug 3, 2026

Inducing a Site Specific Replication Blockage in E. coli Using a Fluorescent Repressor Operator System
Published on: August 21, 2016
Rec-A protein-mediated irreversible fixation of an oligodeoxyribonucleotide to specific site in DNA
E I Golub1, P M Glazer, D C Ward
1Yale University School of Medicine, Department of Genetics, New Haven, CT 06510, USA.
Abstract:
RecA protein can polymerize on an oligodeoxyribonucleotide to form a filament that finds its homologous sequence in double-stranded DNA. When such an oligonucleotide is linked to psoralen, a photoactivatable DNA intercalator, it irreversibly binds to the homologous site in double stranded DNA as a result of psoralen photoadduct formation at thymidines. The relative efficiency of specific vs. nonspecific binding of an oligonucleotide depended upon the ratio of psoralenated oligonucleotide to total DNA. Na+ ions at concentrations greater than 50 mM eliminated specific binding. Under optimal conditions. the probability of binding of an 80-mer oligonucleotide to a specific site was > 10(5) times greater than that of binding to any single nonspecific site. Under the conditions described, RecA-mediated photoadduction was equally efficient with superhelical and linear double-stranded DNA.
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