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Guanosine tetraphosphate inhibits protein synthesis in vivo. A possible protective mechanism for starvation stress in Escherichia coli
Ist Teil von
The Journal of biological chemistry, 1993-02, Vol.268 (4), p.2307-2311
Ort / Verlag
Bethesda, MD: American Society for Biochemistry and Molecular Biology
Erscheinungsjahr
1993
Quelle
MEDLINE
Beschreibungen/Notizen
Guanosine 3',5'-bispyrophosphate (ppGpp) accumulates in bacteria in response to either amino acid or energy source starvation.
Here we demonstrate that levels of ppGpp similar to those induced by amino acid starvation inhibit the rate of protein synthesis
by 84-91%. The intracellular concentration of ppGpp is manipulated in our studies by increasing the expression of a truncated
relA gene encoding a smaller but catalytically active peptide with ppGpp synthetase activity. We find that the intracellular
activity of the truncated RelA peptide is insensitive to chloramphenicol, unlike the product of the wild-type relA gene, ppGpp
synthetase I. Previously, this same ppGpp expression system was used (Schreiber, G., Metzger, S., Aizenman, E., Roza, S.,
Cashel, M., and Glaser, G. (1991) J. Biol. Chem. 226, 3760-3767) to demonstrate that increasing the ppGpp concentration inhibits
growth and ribosomal RNA transcription, and they found suggestive evidence for ppGpp inhibition of protein synthesis. We further
investigated the effect of ppGpp on protein synthesis and find that ppGpp is a potent inhibitor of protein synthesis as well
as glycerol accumulation but has no effect on transport of methionine, the amino acid used in measuring protein synthesis
rates, or on uptake of alpha-methylglucoside, a non-metabolizable analogue of glucose.