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Stimulation of RNA polymerases from mouse spleen by polyamines and its modification by ammonium sulfate

D G Blair

    The International Journal of Biochemistry
    |January 1, 1984
    PubMed

    Insights

    Polyamines like spermine and spermidine significantly stimulate mouse spleen nuclear RNA polymerases in vitro. Their optimal concentrations and effects, particularly on RNA polymerase II, depend on the presence of sulfate ions.

    Area of Science:

    • Biochemistry
    • Molecular Biology
    • Cellular Biology

    Background:

    • Nuclear RNA polymerases are crucial enzymes responsible for transcribing genetic information.
    • Polyamines are essential cations involved in various cellular processes, including nucleic acid metabolism.
    • Understanding the regulation of RNA polymerases by polyamines is vital for comprehending gene expression.

    Purpose of the Study:

    • To investigate the in vitro effects of polyamines, spermine and spermidine, on mouse spleen nuclear RNA polymerases (Ia, Ib, II, and III).
    • To determine the influence of ammonium sulfate and sulfate ions on polyamine-mediated stimulation or inhibition of RNA polymerases.
    • To elucidate the specific mechanisms by which spermine affects RNA polymerase II activity, distinguishing between initiation and elongation phases.

    Main Methods:

    • Purification of nuclear RNA polymerases Ia, Ib, II, and III from Swiss albino mouse spleen.
    • In vitro enzymatic assays to measure RNA polymerase activity in the presence and absence of polyamines (spermine, spermidine) and ammonium sulfate.
    • Analysis of polyamine concentrations required for optimal enzyme stimulation.
    • Assessment of the impact of sulfate ions on polyamine-enzyme interactions.
    • Characterization of spermine's effect on RNA chain elongation versus initiation for RNA polymerase II.

    Main Results:

    • Spermine and spermidine significantly stimulated mouse spleen nuclear RNA polymerases in the presence of ammonium sulfate.
    • In the absence of ammonium sulfate, lower, more physiological concentrations of polyamines were optimal for stimulation.
    • A specific concentration (8 mM) of spermine stimulated RNA polymerases Ia and II with sulfate ions but inhibited them without sulfate ions.
    • Spermine's stimulation of RNA polymerase II was linked to enhanced RNA chain elongation, while its inhibition affected RNA synthesis initiation.

    Conclusions:

    • Polyamines, spermine and spermidine, are potent modulators of nuclear RNA polymerase activity in mouse spleen.
    • The presence of sulfate ions significantly influences the concentration-dependent effects of polyamines on RNA polymerases.
    • Spermine differentially regulates RNA polymerase II activity by affecting both RNA chain initiation and elongation, depending on ionic conditions.

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