PROSITE documentation PDOC00536
Indole-3-glycerol phosphate synthase signature


Indole-3-glycerol phosphate synthase (EC (IGPS) catalyzes the fourth step in the biosynthesis of tryptophan: the ring closure of 1-(2-carboxy-phenylamino)-1-deoxyribulose into indol-3-glycerol-phosphate.

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 catalyzes 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 also contains a PRAI C-terminal domain and a glutamine amidotransferase N-terminal domain.

The N-terminal section of IGPS contains a highly conserved region which X-ray crystallography studies [1] have shown to be part of the active site cavity. We use this region as a signature pattern for IGPS.

Last update:

April 2006 / Pattern revised.


Technical section

PROSITE method (with tools and information) covered by this documentation:

IGPS, PS00614; Indole-3-glycerol phosphate synthase signature  (PATTERN)


1AuthorsWilmanns M. Priestle J.P. Niermann T. Jansonius J.N.
TitleThree-dimensional structure of the bifunctional enzyme phosphoribosylanthranilate isomerase: indoleglycerolphosphate synthase from Escherichia coli refined at 2.0 A resolution.
SourceJ. Mol. Biol. 223:477-507(1992).
PubMed ID1738159

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