Inosine-5'-monophosphate dehydrogenase, (guaB); Catalyzes the conversion of inosine 5'-phosphate (IMP) to xanthosine 5'-phosphate (XMP), the first committed and rate-limiting step in the de novo synthesis of guanine nucleotides, and therefore plays an important role in the regulation of cell growth. Belongs to the IMPDH/GMPR family.

Adenine phosphoribosyltransferase (apt); Catalyzes a salvage reaction resulting in the formation of IMP that is energically less costly than de novo synthesis. Belongs to the purine/pyrimidine phosphoribosyltransferase family. Archaeal HPRT subfamily.

surE stationary-phase survival protein SurE; Nucleotidase that shows phosphatase activity on nucleoside 5'-monophosphates; Belongs to the SurE nucleotidase family.

Conserved hypothetical protein; Pyrophosphatase that catalyzes the hydrolysis of nucleoside triphosphates to their monophosphate derivatives, with a high preference for the non-canonical purine nucleotides xanthosine triphosphate (XTP), deoxyinosine triphosphate (dITP) and ITP. Probably functions as a house- cleaning enzyme that removes non-canonical purine nucleotides from the nucleotide pool, thus preventing their incorporation into DNA/RNA and avoiding chromosomal lesions. Shows very low activity on GTP or dGTP, both of which are hydrolyzed more than 100-fold less efficiently than X [...]

Anthranilate synthase component I (trpE); Part of a heterotetrameric complex that catalyzes the two- step biosynthesis of anthranilate, an intermediate in the biosynthesis of L-tryptophan. In the first step, the glutamine-binding beta subunit (TrpG) of anthranilate synthase (AS) provides the glutamine amidotransferase activity which generates ammonia as a substrate that, along with chorismate, is used in the second step, catalyzed by the large alpha subunit of AS (TrpE) to produce anthranilate. In the absence of TrpG, TrpE can synthesize anthranilate directly from chorismate and high c [...]

Methionyl aminopeptidase (map); Removes the N-terminal methionine from nascent proteins. The N-terminal methionine is often cleaved when the second residue in the primary sequence is small and uncharged (Met-Ala-, Cys, Gly, Pro, Ser, Thr, or Val); Belongs to the peptidase M24A family. Methionine aminopeptidase archaeal type 2 subfamily.

Anthranilate synthase component II (trpD); Catalyzes the transfer of the phosphoribosyl group of 5- phosphorylribose-1-pyrophosphate (PRPP) to anthranilate to yield N-(5'- phosphoribosyl)-anthranilate (PRA).

Ribokinase (rbsK); Catalyzes the phosphorylation of a wide range of nucleosides to yield nucleoside monophosphates. Shows the highest activity for inosine, guanosine and cytidine, but very poor kinase activity with adenosine, thymidine, uridine and xanthosine. ATP is the best phosphate donor, but can also use ITP and GTP. Shows extremely low activity with fructose-6-phosphate; Belongs to the carbohydrate kinase PfkB family.

Adenylosuccinate synthetase (purA); Plays an important role in the de novo pathway of purine nucleotide biosynthesis. Catalyzes the first committed step in the biosynthesis of AMP from IMP; Belongs to the adenylosuccinate synthetase family.