title: In vitro studies on ppGpp synthetase I from polyamine-starved and unstarved Escherichia coli.
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.
authors.affiliation: Instituto de Investigaciones Bioquímicas Fundación Campomar, Buenos Aires, Argentina.
authors.forename: S H
authors.initials: SH
authors.lastname: Goldemberg
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D005672:Fusidic Acid / Q000494:pharmacology; D006159:Guanosine Tetraphosphate / Q000096:biosynthesis; D008025:Ligases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D008274:Magnesium / Q000494:pharmacology; D011073:Polyamines / Q000494:pharmacology*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011691:Puromycin / Q000494:pharmacology; D012270:Ribosomes / Q000378:metabolism; D013095:Spermidine / Q000494:pharmacology; D013307:Streptomycin / Q000494:pharmacology; D013347:Subcellular Fractions / Q000201:enzymology; D013752:Tetracycline / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D004791:Enzyme Inhibitors; D011073:Polyamines; D011500:Protein Synthesis Inhibitors; D006159:Guanosine Tetraphosphate; D011691:Puromycin; D005672:Fusidic Acid; D008025:Ligases; C028812:guanosine 3',5'-polyphosphate synthetases; D013752:Tetracycline; D008274:Magnesium; D013095:Spermidine; D013307:Streptomycin