PDBsum entry: 1uu1

Transferase

PDB id: 1uu1

Contents

Protein chains

330 a.a. *

Ligands

PMP-HSA ×4

Waters ×369

* Residue conservation analysis

PDB id:

1uu1

Name:

Transferase

Title:

Complex of histidinol-phosphate aminotransferase (hisc) from thermotoga maritima (apo-form)

Structure:

Histidinol-phosphate aminotransferase. Chain: a, b, c, d. Synonym: imidazole acetol-phosphate tranaminase, hisc. Engineered: yes. Other_details: phosphate anion attached per chain

Source:

Thermotoga maritima. Organism_taxid: 2336. Expressed in: escherichia coli. Expression_system_taxid: 469008.

Biol. unit:

Dimer (from PDB file)

Resolution:

2.38Å R-factor: 0.206 R-free: 0.268

Authors:

M.C.Vega,F.J.Fernandez,F.Lehman,M.Wilmanns

Key ref:

F.J.Fernandez et al. (2004). Structural studies of the catalytic reaction pathway of a hyperthermophilic histidinol-phosphate aminotransferase. J Biol Chem, 279, 21478-21488. PubMed id: 15007066 DOI: 10.1074/jbc.M400291200

Date:

12-Dec-03 Release date: 18-Mar-04

Protein chains

Q9X0D0  (HIS8_THEMA) -  Histidinol-phosphate aminotransferase

Seq: 335 a.a.

Struc: 330 a.a.

Enzyme reactions

• Enzyme class: E.C.2.6.1.9 - Histidinol-phosphate transaminase.
• Pathway: Histidine Biosynthesis (late stages)
• Reaction: L-histidinol phosphate + 2-oxoglutarate = 3-(imidazol-4-yl)-2-oxopropyl phosphate + L-glutamate

L-histidinol phosphate (Bound ligand (Het Group name = HSA) matches with 92.00% similarity) + 2-oxoglutarate = 3-(imidazol-4-yl)-2-oxopropyl phosphate + L-glutamate

• Cofactor: Pyridoxal 5'-phosphate

Pyridoxal 5'-phosphate (Bound ligand (Het Group name = PMP) matches with 88.00% similarity)

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

 Gene Ontology (GO) functional annotation 

• Biological process: metabolic process (4 terms)
• Biochemical function: catalytic activity (7 terms)

reference

DOI no: 10.1074/jbc.M400291200

J Biol Chem 279:21478-21488 (2004)

PubMed id: 15007066

Structural studies of the catalytic reaction pathway of a hyperthermophilic histidinol-phosphate aminotransferase.

F.J.Fernandez, M.C.Vega, F.Lehmann, E.Sandmeier, H.Gehring, P.Christen, M.Wilmanns.

ABSTRACT

In histidine biosynthesis, histidinol-phosphate aminotransferase catalyzes the transfer of the amino group from glutamate to imidazole acetol-phosphate producing 2-oxoglutarate and histidinol phosphate. In some organisms such as the hyperthermophile Thermotoga maritima, specific tyrosine and aromatic amino acid transaminases have not been identified to date, suggesting an additional role for histidinol-phosphate aminotransferase in other transamination reactions generating aromatic amino acids. To gain insight into the specific function of this transaminase, we have determined its crystal structure in the absence of any ligand except phosphate, in the presence of covalently bound pyridoxal 5'-phosphate, of the coenzyme histidinol phosphate adduct, and of pyridoxamine 5'-phosphate. The enzyme accepts histidinol phosphate, tyrosine, tryptophan, and phenylalanine, but not histidine, as substrates. The structures provide a model of how these different substrates could be accommodated by histidinol-phosphate aminotransferase. Some of the structural features of the enzyme are more preserved between the T. maritima enzyme and a related threonine-phosphate decarboxylase from S. typhimurium than with histidinol-phosphate aminotransferases from different organisms.

Selected figure(s)

Figure 1.
FIG. 1. Scheme of the proposed mechanism for the transamination reaction catalyzed by tmHspAT. Crystal structures of tmHspAT have been determined in the absence of any ligand except phosphate (tmHspAT), in the presence of PLP or internal aldimine 1a (tmHspAT·PLP), in the presence PLP and Hsp forming the Hsp-PLP adduct 5 (tmHspAT·Hsp-PLP), and in the presence of PMP 6a (tmHspAT·PMP). L-Histidinol phosphate 1b must be deprotonated to form the Michaelis-Menten complex with tmHspAT·PLP. The reversible scheme is shown opposite to the reaction catalyzed in histidine biosynthesis in accordance with conventions in recent reviews (2, 3). The absorption maximum for each of the intermediates is shown in parentheses, with the exception of the proposed gem-diamino intermediate 2, which does not have a pronounced absorption maximum between 300 and 600 nm (45).

Figure 3.
FIG. 3. Structure of active site ligands bound to tmHspAT. A, tmHspAT in the apo form, displaying an inorganic phosphate ion in the active site; B, tmHspAT·PLP, showing the internal aldimine PLP in the active site; C, tmHspAT· Hsp-PLP, displaying the Hsp-PLP adduct in the ketimine form; D, the tmHspAT· PMP complex. Each panel shows the ligand and specific hydrogen bonds or salt bridges. The atom type colors are the same as those in Fig. 2. In each panel, the final [A]-weighted electron density map contoured at 1.0 is also shown. The bond lengths quoted in A-C are averaged from four copies per asymmetric unit, and the bond lengths in D are from two copies per asymmetric unit. The average r.m.s deviations in protein-ligand bond lengths are as follows: A, tmHspAT, 0.27 Å (7 bonds); tmHspAT·PLP, 0.14 Å (13 bonds), tmHspAT·Hsp-PLP, 0.14 Å (16 bonds). Tyr-53' originates from the other tmH-spAT subunit. tmHspAT main chain interactions are labeled by an asterisk. The figure has been produced with DINO (www.dino3d.org).

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2004, 279, 21478-21488) copyright 2004.

Figures were selected by an automated process.