Endotoxicosis induced by Coxiella burnetii lipopolysaccharide stimulates a ribosomal protein S6 kinase: some properties of the partially purified enzyme.
Guinea pig endotoxicosis induced by lipopolysaccharide from Coxiella burnetii Nine Mile phase I stimulates phosphorylation of liver ribosomal protein S6, with a 50% increase at 12 h postinoculation. The responsible protein kinase (S6PK) has been partially purified from liver; its activity is independent of cyclic AMP and of Ca2+ plus phosphatidyl serine or diacylglycerol. The preparation has an apparent optimum concentration of 20 mM Mg2+, while Ca2+ and Mn2+ are each inhibitory at 2 mM. The apparent Km for ATP is 30 microM with intact ribosomes. Because of the central role of phosphorylation in metabolic regulation and a purported role of phosphorylated S6 in protein synthesis, the lipopolysaccharide-induced stimulation of S6PK suggests a significant regulatory role of such enzymes in the pathobiochemistry of Q fever infection and endotoxicosis.
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Department of Microbiology, University of Kansas, Lawrence 66045.
Hackstadt
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Paretsky
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D000818:Animals; D003381:Coxiella / Q000472:pathogenicity*; D015180:Electrophoresis, Gel, Two-Dimensional; D004731:Endotoxins / Q000494:pharmacology*; D006168:Guinea Pigs; D007700:Kinetics; D008070:Lipopolysaccharides / Q000494:pharmacology*; D010750:Phosphoproteins / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism*; D011778:Q Fever / Q000201:enzymology; D038601:Ribosomal Protein S6; D019893:Ribosomal Protein S6 Kinases; D012269:Ribosomal Proteins / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism; D013379:Substrate Specificity
D004731:Endotoxins; D008070:Lipopolysaccharides; D010750:Phosphoproteins; D038601:Ribosomal Protein S6; D012269:Ribosomal Proteins; D011494:Protein Kinases; D019893:Ribosomal Protein S6 Kinases