Selective repression of transcription by base sequence specific synthetic polymers

Area of Science:

• Biochemistry
• Polymer Chemistry
• Molecular Biology

Background:

• Synthetic polymers can interact with deoxyribonucleic acid (DNA).
• Controlling polymer-DNA interactions is key for applications like targeted drug delivery.
• Existing methods for specific DNA binding lack sufficient selectivity.

Purpose of the Study:

• To investigate the effect of novel synthetic polymers on DNA-directed RNA synthesis in vitro.
• To determine if polymers synthesized using a DNA template can exhibit preferential binding and inhibition.
• To explore a new approach for enhancing the specificity of DNA-binding drugs.

Main Methods:

• Radical chain polymerization of base-selective monomers (GC-specific and AT-specific) using template DNA (lambda or T7 bacteriophage).
• Isolation and reannealing of synthesized polymers with competitive DNA mixtures.
• Measurement of transcription inhibition using Escherichia coli RNA polymerase and hybridization assays to determine relative inhibition.

Main Results:

• Micromolar concentrations of incorporated dyes in polymers significantly inhibit transcription.
• Polymers synthesized using a specific DNA template showed stronger inhibition of transcription from that original template compared to competitor DNA.
• The relative affinity of polymers for competing DNAs could be altered by an order of magnitude based on the synthesis template.

Conclusions:

• Template-directed synthesis of DNA-binding polymers leads to preferential inhibition of the original template's function.
• This approach offers a novel strategy for developing highly specific DNA-binding drugs.
• The specificity of polymer-DNA interactions can be tuned by controlling the synthesis template.