PDBsum entry 2j6h

Transferase

PDB id: 2j6h

Contents

Protein chains

608 a.a. *

Ligands

ONL ×2

G6Q ×2

Waters ×385

* Residue conservation analysis

PDB id:

2j6h

Name:

Transferase

Title:

E. Coli glucosamine-6-p synthase in complex with glucose-6p and 5-oxo- l-norleucine

Structure:

Glucosamine-fructose-6-phosphate aminotransferase. Chain: a, b. Synonym: glucosamine-6-p synthase, hexosephosphate aminotransferase, d-fructose-6-phosphate amidotransferase, l-glutamine-d-fructose-6- phosphate amidotransferase, glucosamine-6-phosphate synthase, gfat. Engineered: yes

Source:

Escherichia coli. Organism_taxid: 562. Expressed in: escherichia coli. Expression_system_taxid: 562.

Biol. unit:

Dimer (from PDB file)

Resolution:

2.35Å R-factor: 0.187 R-free: 0.237

Authors:

S.Mouilleron,B.Golinelli-Pimpaneau

Key ref:

S.Mouilleron et al. (2006). Glutamine Binding Opens the Ammonia Channel and Activates Glucosamine-6P Synthase. J Biol Chem, 281, 4404-4412. PubMed id: 16339762 DOI: 10.1074/jbc.M511689200

Date:

28-Sep-06 Release date: 02-Oct-06

Supersedes:

2bpj

Protein chains

P17169  (GLMS_ECOLI) -  Glutamine--fructose-6-phosphate aminotransferase [isomerizing] from Escherichia coli (strain K12)

Seq: 609 a.a.

Struc: 608 a.a.

Enzyme reactions

• Enzyme class: E.C.2.6.1.16 - glutamine--fructose-6-phosphate transaminase (isomerizing).
• Pathway: UDP-N-acetylglucosamine Biosynthesis
• Reaction: D-fructose 6-phosphate + L-glutamine = D-glucosamine 6-phosphate + L-glutamate

D-fructose 6-phosphate (Bound ligand (Het Group name = G6Q) corresponds exactly) + L-glutamine (Bound ligand (Het Group name = ONL) matches with 81.82% similarity) = D-glucosamine 6-phosphate + L-glutamate

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

reference

DOI no: 10.1074/jbc.M511689200

J Biol Chem 281:4404-4412 (2006)

PubMed id: 16339762

Glutamine Binding Opens the Ammonia Channel and Activates Glucosamine-6P Synthase.

S.Mouilleron, M.A.Badet-Denisot, B.Golinelli-Pimpaneau.

ABSTRACT

Glucosamine-6P synthase catalyzes the synthesis of glucosamine-6P from fructose-6P and glutamine and uses a channel to transfer ammonia from its glutaminase to its synthase active site. X-ray structures of glucosamine-6P synthase have been determined at 2.05 A resolution in the presence of fructose-6P and at 2.35 A resolution in the presence of fructose-6P and 6-diazo-5-oxo-l-norleucine, a glutamine affinity analog that covalently modifies the N-terminal catalytic cysteine, therefore mimicking the gamma-glutamyl-thioester intermediate formed during hydrolysis of glutamine. The fixation of the glutamine analog activates the enzyme through several major structural changes: 1) the closure of a loop to shield the glutaminase site accompanied by significant domain hinging, 2) the activation of catalytic residues involved in glutamine hydrolysis, i.e. the alpha-amino group of Cys-1 and Asn-98 that is positioned to form the oxyanion hole, and 3) a 75 degrees rotation of the Trp-74 indole group that opens the ammonia channel.

Selected figure(s)

Figure 2.
FIGURE 2. Comparison of the synthase sites of the GlmS·Fru6P and GlmS·Glc6P·DON structures. In all the figures drawn with PYMOL (www.pymol.org), the protein in the GlmS·Fru6P structure is drawn in cyan and Fru6P in blue, whereas the protein in the GlmS·Glc6P·DON structure is drawn in orange, Glc6P in yellow, and DON in off-white. F[o] - F[c] electron density maps omitting the ligand and a 3.5 Å spherical region around it are contoured at the level of 2.5 . Hydrogen bonds <3.3 Å are indicated as dashed lines and water molecules as red spheres. A, GlmS·Fru6P structure. B, GlmS·Glc6P·DON structure. C, superposition of the synthase sites. The C s of the synthase domains (residues 300–600) were superimposed on each other (r.m.s.d., 0.48 Å). The C-tails (r.m.s.d., 1.2 Å over 9 C s) are indicated as coils. Only the water molecules and hydrogen bonds that explain the conformational changes occurring upon DON binding at the glutaminase site are indicated, respectively as blue spheres and green dashed lines for the GlmS·Fru6P structure and as orange spheres and gray dashed lines for the GlmS·Glc6P·DON structure. Together with the conformational changes of Arg-26 and Trp-74 from the glutaminase domain, the peptide bond of Lys-603 flips and the side-chains of Ser-604 and Lys-503^* adopt different conformations in the two structures. OH of Ser-401 is hydrogen bonded to O[2] of the sugar only in the GlmS·Fru6P structure.

Figure 5.
FIGURE 5. DON binding induces a rotation of the glutaminase domain relative to the synthase domain. The two monomers are drawn in orange and yellow for the GlmS·DON·Glc6P structure, and in cyan and green for the GlmS·Fru6P. The two glutaminase domains are at top and bottom, and the two synthase domains that form the dimeric interface in the middle. A, the superposition of the C s of the two synthase domains of the two structures results in a 21° rotation between the glutaminase domains. B, close-up view of the interacting zone between one glutaminase domain and the synthase domain of the neighboring monomer. The interaction between the Q-loop and the C-terminal region of the 524^*-539^* -helix and the ionic interaction between Asp-29 and Arg-539^* that is crucial for dimerization are conserved in the two structures.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2006, 281, 4404-4412) copyright 2006.

Figures were selected by an automated process.