PDBsum entry 1ort

Transferase

PDB id: 1ort

Contents

Protein chains

(+ 6 more) 335 a.a. *

* Residue conservation analysis

PDB id:

1ort

Name:

Transferase

Title:

Ornithine transcarbamoylase from pseudomonas aeruginosa

Structure:

Ornithine transcarbamoylase. Chain: a, b, c, d, e, f, g, h, i, j, k, l. Synonym: ornithine carbamoyltransferase, otcase. Engineered: yes. Mutation: yes

Source:

Pseudomonas aeruginosa. Organism_taxid: 287

Biol. unit:

Dodecamer (from PQS)

Resolution:

3.00Å R-factor: 0.216

Authors:

V.Villeret,O.Dideberg

Key ref:

V.Villeret et al. (1995). Crystal structure of Pseudomonas aeruginosa catabolic ornithine transcarbamoylase at 3.0-A resolution: a different oligomeric organization in the transcarbamoylase family. Proc Natl Acad Sci U S A, 92, 10762-10766. PubMed id: 7479879 DOI: 10.1073/pnas.92.23.10762

Date:

24-Aug-95 Release date: 07-Dec-96

Protein chains

P08308  (OTCC_PSEAE) -  Ornithine carbamoyltransferase, catabolic from Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1)

Seq: 336 a.a.

Struc: 335 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: E.C.2.1.3.3 - ornithine carbamoyltransferase.
• Pathway: Urea Cycle and Arginine Biosynthesis
• Reaction: carbamoyl phosphate + L-ornithine = L-citrulline + phosphate + H⁺

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

reference

DOI no: 10.1073/pnas.92.23.10762

Proc Natl Acad Sci U S A 92:10762-10766 (1995)

PubMed id: 7479879

Crystal structure of Pseudomonas aeruginosa catabolic ornithine transcarbamoylase at 3.0-A resolution: a different oligomeric organization in the transcarbamoylase family.

V.Villeret, C.Tricot, V.Stalon, O.Dideberg.

ABSTRACT

The crystal structure of the Glu-105-->Gly mutant of catabolic ornithine transcarbamoylase (OTCase; carbamoyl phosphate + L-ornithine = orthophosphate + L-citrulline, EC 2.1.3.3) from Pseudomonas aeruginosa has been determined at 3.0-A resolution. This mutant is blocked in the active R (relaxed) state. The structure was solved by the molecular replacement method, starting from a crude molecular model built from a trimer of the catalytic subunit of another transcarbamoylase, the extensively studied aspartate transcarbamoylase (ATCase) from Escherichia coli. This model was used to generate initial low-resolution phases at 8-A resolution, which were extended to 3-A by noncrystallographic symmetry averaging. Four phase extensions were required to obtain an electron density map of very high quality from which the final model was built. The structure, including 4020 residues, has been refined to 3-A, and the current crystallographic R value is 0.216. No solvent molecules have been added to the model. The catabolic OTCase is a dodecamer composed of four trimers organized in a tetrahedral manner. Each monomer is composed of two domains. The carbamoyl phosphate binding domain shows a strong structural homology with the equivalent ATCase part. In contrast, the other domain, mainly implicated in the binding of the second substrate (ornithine for OTCase and aspartate for ATCase) is poorly conserved. The quaternary structures of these two allosteric transcarbamoylases are quite divergent: the E. coli ATCase has pseudo-32 point-group symmetry, with six catalytic and six regulatory chains; the catabolic OTCase has 23 point-group symmetry and only catalytic chains. However, both enzymes display homotropic and heterotropic cooperativity.