Indole-3-glycerol-phosphate synthase

{{infobox enzyme

| Name = indole-3-glycerol-phosphate synthase

| EC_number = 4.1.1.48

| CAS_number = 9031-60-1

| GO_code = 0004425

| image = 3t55.jpg

| width = 270

| caption = Indole-3-glycerol-phosphate synthase monomer, Mycobacterium tuberculosis

}}

{{Infobox protein family

| Symbol = IGPS

| Name = Indole-3-glycerol phosphate synthase

| image = PDB 1pii EBI.jpg

| width =

| caption = three-dimensional structure of the bifunctional enzyme phosphoribosylanthranilate isomerase: indoleglycerolphosphate synthase from escherichia coli refined at 2.0 angstroms resolution

| Pfam = PF00218

| Pfam_clan = CL0036

| InterPro = IPR013798

| SMART =

| PROSITE = PDOC00536

| MEROPS =

| SCOP = 1pii

| TCDB =

| OPM family =

| OPM protein =

| CAZy =

| CDD =

}}

The enzyme indole-3-glycerol-phosphate synthase (IGPS) ({{EnzExplorer|4.1.1.48}}) catalyzes the chemical reaction

:1-(2-carboxyphenylamino)-1-deoxy-D-ribulose 5-phosphate $\rightleftharpoons$ 1-C-(indol-3-yl)-glycerol 3-phosphate + CO₂ + H₂O

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.

Structural studies

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 ({{EC number|5.3.1.24}}) (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 ({{EC number|2.4.2.-}}) (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.{{cite journal | author = Goldman A | title = How to make my blood boil | journal = Structure | volume = 3 | issue = 12 | pages = 1277–9 |date=December 1995 | pmid = 8747452 | doi = 10.1016/s0969-2126(01)00263-5| doi-access = free }}

As of late 2007, 11 structures have been solved for this class of enzymes, with PDB accession codes {{PDB link|1A53}}, {{PDB link|1I4N}}, {{PDB link|1J5T}}, {{PDB link|1JCM}}, {{PDB link|1JUK}}, {{PDB link|1JUL}}, {{PDB link|1LBF}}, {{PDB link|1LBL}}, {{PDB link|1PII}}, {{PDB link|1VC4}}, and {{PDB link|2C3Z}}.

Indole-3-glycerol-phosphate synthase

Structural studies

References

Further reading