| indole-3-glycerol-phosphate synthase | |
| Ec Number: | 4.1.1.48 |
| Cas Number: | 9031-60-1 |
| Go Code: | 0004425 |
| Width: | 270 |
| Symbol: | IGPS |
| Indole-3-glycerol phosphate synthase | |
| Pfam: | PF00218 |
| Pfam Clan: | CL0036 |
| Interpro: | IPR013798 |
| Prosite: | PDOC00536 |
| Scop: | 1pii |
The enzyme indole-3-glycerol-phosphate synthase (IGPS) catalyzes the chemical reaction
1-(2-carboxyphenylamino)-1-deoxy-D-ribulose 5-phosphate
\rightleftharpoons
This enzyme belongs to the family of lyases, to be specific, the carboxy-lyases, which cleave carbon-carbon bonds. The systematic name of this enzyme class is 1-(2-carboxyphenylamino)-1-deoxy-D-ribulose-5-phosphate carboxy-lyase [cyclizing 1-C-(indol-3-yl)glycerol-3-phosphate-forming]. Other names in common use include indoleglycerol phosphate synthetase, indoleglycerol phosphate synthase, indole-3-glycerophosphate synthase, 1-(2-carboxyphenylamino)-1-deoxy-D-ribulose-5-phosphate, and carboxy-lyase (cyclizing). This enzyme participates in phenylalanine, tyrosine and tryptophan biosynthesis and two-component system - general. It employs one cofactor, pyruvate.
In some bacteria, IGPS is a single chain enzyme. In others, such as Escherichia coli, it is the N-terminal domain of a bifunctional enzyme that also catalyses N-(5'-phosphoribosyl)anthranilate isomerase (PRAI) activity, the third step of tryptophan biosynthesis. In fungi, IGPS is the central domain of a trifunctional enzyme that contains a PRAI C-terminal domain and a glutamine amidotransferase (GATase) N-terminal domain.
A structure of the IGPS domain of the bifunctional enzyme from the mesophilic bacterium E. coli (eIGPS) has been compared with the monomeric indole-3-glycerol phosphate synthase from the hyperthermophilic archaeon Sulfolobus solfataricus (sIGPS). Both are single-domain (beta/alpha)8 barrel proteins, with one (eIGPS) or two (sIGPS) additional helices inserted before the first beta strand.[1]
As of late 2007, 11 structures have been solved for this class of enzymes, with PDB accession codes,,,,,,,,,, and .