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Gene Review

relA  -  (p)ppGpp synthetase I/GTP pyrophosphokinase

Escherichia coli str. K-12 substr. MG1655

Synonyms: ECK2778, JW2755, RC
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Disease relevance of relA


High impact information on relA

  • We find that rRNA synthesized from plasmids does exhibit a relA-dependent, stringent response [2].
  • A promoter has been identified that directs relA gene transcription towards the pyrG gene, in a counterclockwise direction on the E. coli chromosome [1].
  • The relA gene product of Escherichia coli is known to be responsible for the synthesis of guanosine 3',5'-bispyrophosphate (ppGpp) during the stringent response to amino acid starvation [1].
  • The activation was dependent on relA and spoT, which encode enzymes for the synthesis and degradation of ppGpp, and on dksA, which encodes an RNA polymerase accessory protein required for the stringent response [3].
  • The genome of Borrelia burgdorferi encodes a single chromosomal rel gene (BB0198) (B. burgdorferi rel [rel(Bbu)]) homologous to relA and spoT of E. coli [4].

Chemical compound and disease context of relA


Biological context of relA


Anatomical context of relA

  • Subsequent in vitro assays using ribosomes isolated from wild-type and relA and relC mutant strains confirmed that (p)ppGpp is synthesized by ribosomes and that mutation of RelA or L11 blocks that activity [8].

Associations of relA with chemical compounds

  • In contrast, derepression of the tryptophan biosynthetic enzyme, but not of the arginine biosynthetic enzyme, was inhibited during the relaxed response produced in an isogenic relA strain by the partial deprivation of valyl transfer ribonucleic acid [9].

Other interactions of relA

  • In the absence of rpoZ, the promoter for the relA gene was severely impaired, but the promoters from the ribosomal protein genes were not affected as much [10].

Analytical, diagnostic and therapeutic context of relA

  • The apparent molecular mass of the cloned relA gene product is calculated to be 83,856 daltons and as visualized by immunoblotting is identical to that of the previously characterized protein [1].


  1. The nucleotide sequence and characterization of the relA gene of Escherichia coli. Metzger, S., Dror, I.B., Aizenman, E., Schreiber, G., Toone, M., Friesen, J.D., Cashel, M., Glaser, G. J. Biol. Chem. (1988) [Pubmed]
  2. Regions of DNA involved in the stringent control of plasmid-encoded rRNA in vivo. Gourse, R.L., Stark, M.J., Dahlberg, A.E. Cell (1983) [Pubmed]
  3. ppGpp with DksA controls gene expression in the locus of enterocyte effacement (LEE) pathogenicity island of enterohaemorrhagic Escherichia coli through activation of two virulence regulatory genes. Nakanishi, N., Abe, H., Ogura, Y., Hayashi, T., Tashiro, K., Kuhara, S., Sugimoto, N., Tobe, T. Mol. Microbiol. (2006) [Pubmed]
  4. Borrelia burgdorferi rel is responsible for generation of guanosine-3'-diphosphate-5'-triphosphate and growth control. Bugrysheva, J.V., Bryksin, A.V., Godfrey, H.P., Cabello, F.C. Infect. Immun. (2005) [Pubmed]
  5. The effect of intracellular ppGpp levels on glutamate and lysine overproduction in Escherichia coli. Imaizumi, A., Kojima, H., Matsui, K. J. Biotechnol. (2006) [Pubmed]
  6. Amplification of pBR322 plasmid DNA in Escherichia coli relA strains during batch and fed-batch fermentation. Hofmann, K.H., Neubauer, P., Riethdorf, S., Hecker, M. J. Basic Microbiol. (1990) [Pubmed]
  7. Effect of amino acid deprivation and chloramphenicol treatment on cell sizes of rel+ and relA- strains of Escherichia coli. Ishiguro, E.E., Ramey, W.D. Can. J. Microbiol. (1978) [Pubmed]
  8. Physiological Analysis of the Stringent Response Elicited in an Extreme Thermophilic Bacterium, Thermus thermophilus. Kasai, K., Nishizawa, T., Takahashi, K., Hosaka, T., Aoki, H., Ochi, K. J. Bacteriol. (2006) [Pubmed]
  9. Effect of the relA gene on derepression of amino acid biosynthetic enzymes in growing Escherichia coli depends on the pathway being derepressed. Furano, A.V., Wittel, F.P. J. Bacteriol. (1977) [Pubmed]
  10. The role of the omega subunit of RNA polymerase in expression of the relA gene in Escherichia coli. Chatterji, D., Ogawa, Y., Shimada, T., Ishihama, A. FEMS Microbiol. Lett. (2007) [Pubmed]
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