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  • Title: In vitro studies on ppGpp synthetase I from polyamine-starved and unstarved Escherichia coli.
    Author: Goldemberg SH.
    Journal: Cell Mol Biol (Noisy-le-grand); 1996 Jul; 42(5):719-27. PubMed ID: 8832104.
    Abstract:
    We have studied the in vitro formation of guanosine 5'-diphosphate 3'-diphosphate (ppGpp) using a partially purified ppGpp synthetase I (PSI) from Escherichia coli BGA8, a polyamine auxotrophic strain. A comparison of the enzyme obtained from polyamine-supplemented or deprived bacteria showed similar requirements for the reaction, Mg+2 optimum levels and sparing effect of spermidine. No differences in the inhibitory effects of tetracycline, puromycin and fusidic acid were detected either. However, a modified subcellular distribution, as well as a larger specific activity and a larger stimulation by streptomycin was observed when PSI was prepared from polyamine-depleted bacteria. The role of ribosome assembly and subunit distribution on the altered properties of the enzyme are discussed.
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