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UniProt functional annotation for Q54089 | ||
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| UniProt code: Q54089. |
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| Organism: | |
Streptococcus dysgalactiae subsp. equisimilis (Streptococcus equisimilis). |
| Taxonomy: | |
Bacteria; Firmicutes; Bacilli; Lactobacillales; Streptococcaceae; Streptococcus. |
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| Function: | |
In eubacteria ppGpp (guanosine 3'-diphosphate 5'-diphosphate) is a mediator of the stringent response that coordinates a variety of cellular activities in response to changes in nutritional abundance. This enzyme catalyzes both the formation of pppGpp which is then hydrolyzed to form ppGpp, and the hydrolysis of ppGpp. The enzyme does not simultaneously display both synthase and hydrolase activities. In the structure of residues 1-385 there are 2 conformations seen, the hydrolase-OFF/synthase-ON and hydrolase-ON/synthase-OFF, suggesting there is ligand-induced signal transmission between the 2 active sites. |
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| Catalytic activity: | |
Reaction=ATP + GTP = AMP + guanosine 3'-diphosphate 5'-triphosphate; Xref=Rhea:RHEA:22088, ChEBI:CHEBI:30616, ChEBI:CHEBI:37565, ChEBI:CHEBI:142410, ChEBI:CHEBI:456215; EC=2.7.6.5; |
| Catalytic activity: | |
Reaction=guanosine 3',5'-bis(diphosphate) + H2O = diphosphate + GDP + H(+); Xref=Rhea:RHEA:14253, ChEBI:CHEBI:15377, ChEBI:CHEBI:15378, ChEBI:CHEBI:33019, ChEBI:CHEBI:58189, ChEBI:CHEBI:77828; EC=3.1.7.2; |
| Cofactor: | |
Name=Mg(2+); Xref=ChEBI:CHEBI:18420; Evidence={ECO:0000305}; Note=Binds 1 Mg(2+) ion per subunit. {ECO:0000305}; |
| Cofactor: | |
Name=Mn(2+); Xref=ChEBI:CHEBI:29035; Evidence={ECO:0000269|PubMed:15066282}; Note=Binds 1 Mn(2+) ion per subunit. {ECO:0000269|PubMed:15066282}; |
| Activity regulation: | |
Alpha-beta methylenyl ATP, an ATP-analog inhibitor of the synthase activity also reduces the hydrolase activity about 4- fold. {ECO:0000269|PubMed:12003927, ECO:0000269|PubMed:15066282}. |
| Biophysicochemical properties: | |
Kinetic parameters: KM=2 mM for GTP {ECO:0000269|PubMed:12003927}; KM=5 mM for ATP {ECO:0000269|PubMed:12003927}; |
| Pathway: | |
Purine metabolism; ppGpp biosynthesis; ppGpp from GDP: step 1/1. |
| Pathway: | |
Purine metabolism; ppGpp biosynthesis; ppGpp from GTP: step 1/2. |
| Domain: | |
Based on a random mutagenesis study of the catalytic fragment (residues 1-385), the (p)ppGpp phosphohydrolase domain seems to encompass approximately the first 225 residues, while the (p)ppGpp synthase domain seems to be found between residues 226 and 385. |
| Similarity: | |
Belongs to the RelA/SpoT family. {ECO:0000305}. |
Annotations taken from UniProtKB at the EBI.