The inhibition of ribonucleic acid polymerase by acridines

Abstract

1. The aminoacridines, proflavine (3,6-diaminoacridine) and 9-aminoacridine, and a hydrogenated derivative, 9-amino-1,2,3,4-tetrahydroacridine, were shown to inhibit in vitro the DNA-primed RNA polymerase of Escherichia coli. The inhibition is strong with both proflavine and 9-aminoacridine, but weak with 9-amino-1,2,3,4-tetrahydroacridine. 2. The extent to which the three acridines bind to calf-thymus DNA in the enzyme medium was studied spectrophotometrically. The extent of binding decreases in the order: proflavine, 9-aminoacridine, 9-amino-1,2,3,4-tetrahydroacridine. Some evidence was also obtained for interaction between the nucleoside triphosphate substrates and proflavine or 9-aminoacridine; no such interaction was detectable with 9-amino-1,2,3,4-tetrahydroacridine. 3. Although the amount of acridine bound to DNA increases with increasing inhibition, a stage is reached where an increase in acridine concentration still causes an increase in inhibition, with practically no increase in the amount bound to DNA. 4. Plots of reciprocal rates against the reciprocal of DNA concentration were linear and had a common intercept when proflavine or 9-aminoacridine was present. Similar relations were obtained when the reciprocal concentration of nucleoside triphosphates was plotted. The observations are interpreted kinetically in terms of a competitive inhibition of the enzyme by proflavine or 9-aminoacridine and of a kinetic role for the DNA analogous to ;activation'. 5. This suggests that inhibitory acridine molecules can occupy the sites on the RNA polymerase that are specific for binding the nucleoside triphosphate substrate or the bases of the DNA, when these become accessible during the copying process.

Deciphering the Function of New Gonococcal Vaccine Antigens Using Phenotypic Microarrays

“…WT, knockout mutants, and all complemented strains were spotted on gonococcal base (GCB) solid medium plates supplemented with isopropyl-␤-D-1-thiogalactopyranoside (IPTG) and 9-aminoacridine, bile salts, azathioprine, or polymyxin B. Exposure to 9-aminoacridine, a DNA binding dye that inhibits the activity of E. coli RNA polymerase (112), affected the Δngo2054, Δngo2111, Δngo1205, and ΔbamE GC mutants. Resistance to this compound was restored to the WT level upon expression of the genes (Fig.…”

Some effects of testosterone on the rat ventral prostate

“…The purification was carried out as far as the fraction 3 stage. This fraction (15mg of protein/ml) was stored at -70°C in the storage medium recommended by Nicholson & Peacocke (1966). Assays of RNA polymerase activity were carried out by using the assay medium described by Chamberlin & Berg (1962).…”

Chance and Necessity in Arthur Peacocke's Scientific Work

“…He continued to study the structure of "naked" DNA but also started to work on DNA isolated from cells still wrapped in proteins that normally accompany it inside cells. Among the studies on "naked" DNA was the work that resulted in a long series of highly noted publications on the binding of various dyes to RNA and DNA, and the effects of such molecules on the structure, and in later works the function, of nucleic acids (Drummond, Simpson, et al 1965;Blake and Peacocke 1966;Drummond, Pritchard, et al 1966;Nicholson and Peacocke 1966;Pritchard, Blake, et al 1966;Blake and Peacocke 1967a, b;Blake and Peacocke 1968;Lloyd, Prutton, et al 1968;. Most of the dyes that Peacocke studied fit into the category known as DNA intercalating agents; such molecules bind specifically to DNA by fitting into the inner structure of the DNA double helix and find their way to fit into a space between DNA bases.…”