Notes on the E. coli (p)ppGpp synthase, RelA:
Tedin and Bremer 1993: Toxic Effects of High Levels of ppGpp in Escherichia coli Are Relieved by RpoB mutations.
"The E coli gene RelA is required for the inhibition of stable ribosomal and transfer RNA (rRNA and tRNA) synthesis during amino acid starvation , an effect known as the "stringent response". (Stent and Brenner 1961, Alfoldi et al. 1962.)"
Isolation of RelA mutants:
From Xiao et al. 1991: In general, relAs ingle null strains show growth properties similar to relAl strains in that they fail to grow on the serine + methionine + glycine plates devised by Uzan and Danchin (34, 35) for detecting relaxed (relAl) mutants as well as on 17 amino acids lacking isoleucine, leucine, and valine (data not shown"
The cited references are:
34: Uzan, M., and Danchin, A. (1976) Biochem. Biophys. Res. Commun. 69,751-758
35: Uzan, M., and Danchin, A. (1978) Mol. Gen. Genet. 165, 21-30