Triplex DNA structure
Structure
Function
Purpose
Sharmilla W56M P13 Structural Biology Individual Assignment
The triplex DNA structure is formed when pyrimidine and purine bases take up he space in the major groove of the DNA double helix
Hoogsteen pairs formed with purines of the Watson-Crick base pairs
Purines refer to adenine and guanine Pyrimidines refer to cytosine and thymine
Intermolecular triplexes forms between triplex that forms oligonucleotides (TFO) and target sequences on the duplex DNA
Intramolecular triplexes are the major elements of H-DNAs which is an unusual DNA structure formed in homopurine-homopyrimidine regions of supercoiled DNAs
TFO binding has shown the inhibition of transcription, replication and protein binding to DNA
Since this structure involves bindings that inhibit transcription, replication and protein binding to DNA
If this structure occurs it could play a part in controlling protein expression
Drug design
Use of TFOs for sequence specific recognition of double helix DNA is the basis of anti-gene strategy
In this idea, it is thought that the binding of TFO to a gene of interest could prevent its normal function (due to its ability to inhibit transcription).
The TFO's targets on the DNA would be the homopurine-homopyrimidine stretches in the promoter of eukaryotes.
This strategy could lead to great rational drug designs
Many chemical modifications of TFO are known one of which is the the replacement of sugar phosphate backbone in peptide nucleic acid (PNA) with a protein-like backbone
These form P-loops while interacting with duplex DNA fonning triplex with a DNA strand
this interaction displaces the other DNA strand
very weird recombinants have been assumes to form under RecA protein during homologous recombination