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Binding of actinomycin D to mRNA in vivo and in vitro
Abstract:
1. When rats received an intraperitoneal injection of [3H]actinomycin D, it bound to the RNA moiety of free and bound polysomes of rat liver. The labeling increased gradually up to 6 h or 6 + 6 h. The poly(A)-containing mRNA showed definite radioactivity and its specific activity was higher than that of rRNA, although the total radioactivity of rRNA was markedly higher than that of poly(A)-containing mRNAs. 2. An equilibrium dialysis method using rabbit globin mRNA showed that the binding constant of actinomycin D to globin mRNA was 0.056 x 10(6) M-1, and globin mRNA had 2 binding sites per mol for actinomycin D. 3. From the results of the present experiments and those described in the preceding paper, it is suggested that one of the mechanisms by which actinomycin D treatment in vivo and in vitro stimulates the template activity of mRNA may be binding to mRNA, which alters the conformation of mRNA.
Insights
Actinomycin D binds to messenger RNA (mRNA) in rat liver, increasing its template activity. This binding may alter mRNA conformation, enhancing its function in protein synthesis.
Area of Science:
- Molecular Biology
- Biochemistry
- Pharmacology
Background:
- Actinomycin D is known to interact with nucleic acids.
- The effect of Actinomycin D on messenger RNA (mRNA) template activity is not fully understood.
Purpose of the Study:
- To investigate the binding of Actinomycin D to mRNA in rat liver.
- To elucidate the mechanism by which Actinomycin D influences mRNA template activity.
Main Methods:
- Intraperitoneal injection of radiolabeled Actinomycin D in rats.
- Analysis of radioactivity in free and bound polysomes, including poly(A)-containing mRNA and ribosomal RNA (rRNA).
- Equilibrium dialysis using rabbit globin mRNA to determine binding constants and sites for Actinomycin D.
Main Results:
- Actinomycin D preferentially bound to the RNA moiety of polysomes in rat liver, with increased labeling over time.
- Poly(A)-containing mRNA exhibited significant radioactivity, with higher specific activity compared to rRNA.
- Equilibrium dialysis revealed a binding constant of 0.056 x 10(6) M-1 and two binding sites per mole for Actinomycin D on globin mRNA.
Conclusions:
- Actinomycin D binds to mRNA in vivo and in vitro.
- mRNA binding by Actinomycin D likely alters mRNA conformation, potentially stimulating its template activity.