RelA_SpoT

Region found in RelA / SpoT proteins
RelA_SpoT
SMART accession number:SM00954
Description: The functions of Escherichia coli RelA and SpoT differ somewhat. RelA produces pppGpp (or ppGpp) from ATP and GTP (or GDP). SpoT degrades ppGpp, but may also act as a secondary ppGpp synthetase. The two proteins are strongly similar. In many species, a single homolog to SpoT and RelA appears reponsible for both ppGpp synthesis and ppGpp degradation. (p)ppGpp is a regulatory metabolite of the stringent response, but appears also to be involved in antibiotic biosynthesis in some species.
Interpro abstract (IPR007685):

This entry includes the catalytic domains of Escherichia coli ppGpp synthetase (RelA), ppGpp synthetase/hydrolase (SpoT), and related proteins. The functions of Escherichia coli RelA and SpoT differ somewhat. RelA ( EC 2.7.6.5 ) produces pppGpp (or ppGpp) from ATP and GTP (or GDP) in response to amino-acid starvation and in association with ribosomes [ (PUBMED:2844820) ]. SpoT ( EC 3.1.7.2 ) degrades ppGpp, but may also act as a secondary ppGpp synthetase under carbon limitation in a ribosome-independent manner [ (PUBMED:8730877) (PUBMED:8648647) ]. Gram-negative bacteria have two enzymes involved in (p)ppGpp metabolism while most Gram-positive organisms have a single Rel-Spo enzyme (Rel), which both synthesizes and degrades (p)ppGpp [ (PUBMED:12003927) (PUBMED:8631718) ]. The Arabidopsis thaliana Rel-Spo proteins, At-RSH1, At-RSH2, and At-RSH3 appear to regulate a rapid (p)ppGpp-mediated response to pathogens and other stresses [ (PUBMED:10725385) ]. This catalytic domain is found in association with an N-terminal HD domain and a C-terminal metal dependent phosphohydrolase domain (TGS). Some Rel-Spo proteins also have a C-terminal regulatory ACT domain. This subgroup belongs to the Pol beta-like NT superfamily [ (PUBMED:10075991) (PUBMED:7482698) ].

(p)ppGpp is a regulatory metabolite of the stringent response [ (PUBMED:16554711) ], but appears also to be involved in antibiotic biosynthesis in some species [ (PUBMED:9531539) ].

In the Pol beta-like NT superfamily [ (PUBMED:10075991) (PUBMED:7482698) ], the majority of enzymes have two carboxylates, Dx[D/E], together with a third more distal carboxylate, which coordinate two divalent metal cations involved in a two-metal ion mechanism of nucleotide addition. These carboxylate residues are fairly well conserved in this family.

GO process:guanosine tetraphosphate metabolic process (GO:0015969)
Family alignment:
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There are 35291 RelA_SpoT domains in 35288 proteins in SMART's nrdb database.

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