PDBsum entry 1k9v

Transferase

PDB id: 1k9v

Contents

Protein chain

200 a.a. *

Ligands

ACY

Waters ×65

* Residue conservation analysis

PDB id:

1k9v

Name:

Transferase

Title:

Structural evidence for ammonia tunelling across the (beta-alpha)8- barrel of the imidazole glycerol phosphate synthase bienzyme complex

Structure:

Amidotransferase hish. Chain: f. Engineered: yes

Source:

Thermotoga maritima. Organism_taxid: 2336. Expressed in: escherichia coli. Expression_system_taxid: 562

Biol. unit:

Dimer (from PQS)

Resolution:

2.40Å R-factor: 0.224 R-free: 0.278

Authors:

A.Douangamath,M.Walker,S.Beismann-Driemeyer,M.C.Vega-Fernandez, R.Sterner,M.Wilmanns

Key ref:

A.Douangamath et al. (2002). Structural evidence for ammonia tunneling across the (beta alpha)(8) barrel of the imidazole glycerol phosphate synthase bienzyme complex. Structure, 10, 185-193. PubMed id: 11839304 DOI: 10.1016/S0969-2126(02)00702-5

Date:

31-Oct-01 Release date: 20-Feb-02

Protein chain

Q9X0C8  (HIS5_THEMA) -  Imidazole glycerol phosphate synthase subunit HisH from Thermotoga maritima (strain ATCC 43589 / DSM 3109 / JCM 10099 / NBRC 100826 / MSB8)

Seq: 201 a.a.

Struc: 200 a.a.

Enzyme reactions

• Enzyme class 2: E.C.3.5.1.2 - glutaminase.
• Reaction: L-glutamine + H2O = L-glutamate + NH4⁺

L-glutamine + H2O (Bound ligand (Het Group name = ACY) matches with 40.00% similarity) = L-glutamate + NH4(+)

• Enzyme class 3: E.C.4.3.2.10 - imidazole glycerol-phosphate synthase.
• Reaction: 5-[(5-phospho-1-deoxy-D-ribulos-1-ylimino)methylamino]-1-(5-phospho-beta- D-ribosyl)imidazole-4-carboxamide + L-glutamine = D-erythro-1-(imidazol- 4-yl)glycerol 3-phosphate + 5-amino-1-(5-phospho-beta-D- ribosyl)imidazole-4-carboxamide + L-glutamate + H⁺

5-[(5-phospho-1-deoxy-D-ribulos-1-ylimino)methylamino]-1-(5-phospho-beta- D-ribosyl)imidazole-4-carboxamide + L-glutamine (Bound ligand (Het Group name = ACY) matches with 40.00% similarity) = D-erythro-1-(imidazol- 4-yl)glycerol 3-phosphate + 5-amino-1-(5-phospho-beta-D- ribosyl)imidazole-4-carboxamide + L-glutamate + H(+)

Note, where more than one E.C. class is given (as above), each may correspond to a different protein domain or, in the case of polyprotein precursors, to a different mature protein.

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

DOI no: 10.1016/S0969-2126(02)00702-5

Structure 10:185-193 (2002)

PubMed id: 11839304

Structural evidence for ammonia tunneling across the (beta alpha)(8) barrel of the imidazole glycerol phosphate synthase bienzyme complex.

A.Douangamath, M.Walker, S.Beismann-Driemeyer, M.C.Vega-Fernandez, R.Sterner, M.Wilmanns.

ABSTRACT

Since reactive ammonia is not available under physiological conditions, glutamine is used as a source for the incorporation of nitrogen in a number of metabolic pathway intermediates. The heterodimeric ImGP synthase that links histidine and purine biosynthesis belongs to the family of glutamine amidotransferases in which the glutaminase activity is coupled with a subsequent synthase activity specific for each member of the enzyme family. Its X-ray structure from the hyperthermophile Thermotoga maritima shows that the glutaminase subunit is associated with the N-terminal face of the (beta alpha)(8) barrel cyclase subunit. The complex reveals a putative tunnel for the transfer of ammonia over a distance of 25 A. Although ammonia tunneling has been reported for glutamine amidotransferases, the ImGP synthase has evolved a novel mechanism, which extends the known functional properties of the versatile (beta alpha)(8) barrel fold.

Selected figure(s)

Figure 1.
Figure 1. Reactions Catalyzed by the Glutaminase Subunit HisH and the Cyclase Subunit HisF, which Constitute the ImGP SynthaseThe products ImGP and AICAR are further used in histidine and de novo purine biosynthesis, respectively.

The above figure is reprinted by permission from Cell Press: Structure (2002, 10, 185-193) copyright 2002.

Figure was selected by an automated process.