Site-Specific Inhibition of Transcription Factor Binding to DNA by a Metallointercalator

Abstract

The metallointercalator Lambda-1-Rh(MGP)2phi5+ binds tightly and specifically to the site 5'-CATATG-3' in the major groove of double helical DNA by a combination of direct readout and shape selection. To examine competitive interactions between this small metal complex and a DNA-binding transcription factor, the preferred binding site for Lambda-1-Rh(MGP)2phi5+ was engineered into the AP-1 recognition element (ARE) of the major-groove binding bZIP transcription factor yAP-1, the yeast analogue of mammalian AP-1. Binding experiments confirmed that the modified ARE retained normal yAP-1 binding affinity. Photocleavage experiments demonstrated that the modified ARE contained a high-affinity binding site for Lambda-1-Rh(MGP)2phi5+, whereas the native ARE showed no interaction. Competition experiments using gel shift mobility assays demonstrated that Lambda-1-Rh(MGP)2phi5+ at 120 nM competes 50% of yAP-1 binding to the 5'-CATATG-3' containing oligonucleotide. In contrast, competitive disruption of protein binding to the native ARE requires 3 microM Lambda-1-Rh(MGP)2phi5+. Metallointercalator derivatives, including geometric isomers of Lambda-1-Rh(MGP)2phi5+, show no specific binding to the target site and show no inhibition of yAP-1/DNA complexes at concentrations as high as 20 microM. Thus, metallointercalators can be tuned to show selectivity for major groove sites on DNA comparable to transcription factors and indeed can inhibit transcription factor binding site selectively.

MnTE-2-PyP reduces prostate cancer growth and metastasis by suppressing p300 activity and p300/HIF-1/CREB binding to the promoter region of the PAI-1 gene

“…In agreement with this rationale, it has previously been demonstrated that MnTE-2-PyP oxidizes the p50 [40] and p65 subunits [18] of NF-κB, which results in reduced DNA binding. Alternatively, other metalloporphyrins have been reported to bind directly to specific DNA sequences and potentially mask the transcription factor binding site [41]. Another manganese porphyrin, MnTM-4-PyP, has been shown to bind to RNA and DNA [42].…”

Metal complexes for DNA-mediated charge transport

“…Additionally, modification of a ruthenium complex with octaarginine allows for the facile uptake of complexes into the nuclei of cancer cells [34,35]. Functionalization of the ancillary ligands may also lead to sequence-selective recognition and cleavage by metallointercalators via hydrogen bonding or van der Waals interactions with modified ethylenediamine ligands [36–40], peptide sequences [41–43], or modified phen ligands [44–47], or nuclease activity [48]. …”

Spectroscopic properties of N1,N5-bis[pyridine-2-methylene]-thiocarbohydrazone and its corresponding zinc (II) and nickel (II) metal complexes: A DFT and TD-DFT study

“…Great concerns have been focused on developing metal complexes as diagnostic or therapeutic agents. The non-covalent binding of metal complexes with DNA has been used as synthetic restriction enzymes [11], DNA repair agents [12], selective probes of DNA structure [13], and artificial regulators of gene expression [14]. N 1 ,N 5 -bis[pyridine-2-methylene]-thiocarbohydrazone ligand and zinc (II) and nickel (II) schiff-base complexes were synthesized by Mishra and co-workers [15].…”