Phosphoribosylanthranilate isomerase
| phosphoribosylanthranilate isomerase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| EC no. | 5.3.1.24 | ||||||||
| CAS no. | 37259-82-8 | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / QuickGO | ||||||||
| |||||||||
| PRAI | |||||||||
|---|---|---|---|---|---|---|---|---|---|
 crystal structure of mutually generated monomers of dimeric phosphoribosylantranilate isomerase from thermotoga maritima | |||||||||
| Identifiers | |||||||||
| Symbol | PRAI | ||||||||
| Pfam | PF00697 | ||||||||
| Pfam clan | CL0036 | ||||||||
| InterPro | IPR001240 | ||||||||
| SCOP2 | 1pii / SCOPe / SUPFAM | ||||||||
| |||||||||
In enzymology, a phosphoribosylanthranilate isomerase (EC 5.3.1.24) is an enzyme that catalyzes the third step of tryptophan biosynthesis.[1]
- N-(5-phospho-beta-D-ribosyl)anthranilate 1-(2-carboxyphenylamino)-1-deoxy-D-ribulose 5-phosphate
Hence, this enzyme has one substrate, N-(5-phospho-beta-D-ribosyl)anthranilate, and one product, 1-(2-carboxyphenylamino)-1-deoxy-D-ribulose 5-phosphate.
This enzyme belongs to the family of isomerases, specifically those intramolecular oxidoreductases interconverting aldoses and ketoses. The systematic name of this enzyme class is N-(5-phospho-beta-D-ribosyl)anthranilate aldose-ketose-isomerase. Other names in common use include PRA isomerase, PRAI, IGPS:PRAI (indole-3-glycerol-phosphate, synthetase/N-5'-phosphoribosylanthranilate isomerase complex), and N-(5-phospho-beta-D-ribosyl)anthranilate ketol-isomerase. In yeast it is expressed from the TRP1 gene.[2] This enzyme participates in the phenylalanine, tyrosine and tryptophan biosynthesis pathway.
Structural studies
Phosphoribosylanthranilate isomerase (PRAI) is monomeric and labile in most mesophilic microorganisms, but dimeric and stable in the hyperthermophile Thermotoga maritima (tPRAI).[3] The comparison to the known 2.0 A structure of PRAI from Escherichia coli (ePRAI) shows that tPRAI has a TIM-barrel fold, whereas helix alpha5 in ePRAI is replaced by a loop. The subunits of tPRAI associate via the N-terminal faces of their central beta-barrels. Two long, symmetry-related loops that protrude reciprocally into cavities of the other subunit provide for multiple hydrophobic interactions. Moreover, the side chains of the N-terminal methionines and the C-terminal leucines of both subunits are immobilized in a hydrophobic cluster, and the number of salt bridges is increased in tPRAI. These features appear to be mainly responsible for the high thermostability of tPRAI.[4]
As of late 2007, 5 structures have been solved for this class of enzymes, with PDB accession codes 1DL3, 1LBM, 1NSJ, 1V5X, and 1VZW.
References
- ^ Creighton TE and Yanofsky C (1970). "Chorismate to tryptophan (Escherichia coli) - Anthranilate synthetase, PR transferase, PRA isomerase, InGP synthetase, tryptophan synthetase". Methods Enzymol. 17A: 365–380.
- ^ "TRP1/YDR007W Summary". Saccharomyces genome database. Stanford University.
- ^ Thoma R, Hennig M, Sterner R, Kirschner K (2000). "Structure and function of mutationally generated monomers of dimeric phosphoribosylanthranilate isomerase from Thermotoga maritima". Structure. 8 (3): 265–76. PMID 10745009.
{{cite journal}}: Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ Hennig M, Sterner R, Kirschner K, Jansonius JN (1997). "Crystal structure at 2.0 A resolution of phosphoribosyl anthranilate isomerase from the hyperthermophile Thermotoga maritima: possible determinants of protein stability". Biochemistry. 36 (20): 6009–16. doi:10.1021/bi962718q. PMID 9166771.
{{cite journal}}: Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link)