Role of peptide chain elongation factor G in guanosine 5'-diphosphate 3'-diphosphate synthesis.
In a wild-type strain (relA+) of Escherichia coli, starvation of amino acid led to an immediate cessation of the synthesis of stable ribonucleic acids, together with the accumulation of an unusual nucleotide, guanosine 5'-diphosphate 3'-diphosphate, commonly known as ppGpp. This compound also accumulated during heat shock. When temperature-sensitive protein synthesis elongation factor G (EF-G) was introduced into E. coli NF859, a relA+ strain, the synthesis of ppGpp was reduced to approximately one-half that of wild-type EF-G+ cells at a nonpermissive temperature of 40 degrees C. Furthermore, fusidic acid, an inhibitor of protein synthesis which specifically inactivates EF-G, prevented any accumulation of ppGpp during the heat shock. We suggest that a functional EF-G protein is necessary for ppGpp accumulation under temperature shift conditions, possibly by mediating changes in the function of another protein, the relA gene product. However, EF-G is probably not required for the synthesis of ppGpp during the stringent response, since its inactivation did not prevent ppGpp accumulation during amino acid starvation.
D000596:Amino Acids / Q000378:metabolism; D001426:Bacterial Proteins / Q000096:biosynthesis; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D006150:Guanine Nucleotides / Q000096:biosynthesis*; D006159:Guanosine Tetraphosphate / Q000096:biosynthesis*; D006358:Hot Temperature; D009154:Mutation; D010445:Peptide Elongation Factors / Q000502:physiology*
D000596:Amino Acids; D001426:Bacterial Proteins; D006150:Guanine Nucleotides; D010445:Peptide Elongation Factors; D006159:Guanosine Tetraphosphate