PDBsum entry 1kp3

Ligase

PDB id: 1kp3

Contents

Protein chain

439 a.a. *

Ligands

PO4

ATP

CIR ×2

GAI ×2

Waters ×186

* Residue conservation analysis

PDB id:

1kp3

Name:

Ligase

Title:

Crystal structure of e. Coli argininosuccinate synthetase in complex with atp and citrulline

Structure:

Argininosuccinate synthetase. Chain: a. Engineered: yes

Source:

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

Biol. unit:

Tetramer (from PDB file)

Resolution:

2.00Å R-factor: 0.192 R-free: 0.229

Authors:

C.T.Lemke,P.L.Howell

Key ref:

C.T.Lemke and P.L.Howell (2002). Substrate induced conformational changes in argininosuccinate synthetase. J Biol Chem, 277, 13074-13081. PubMed id: 11809762 DOI: 10.1074/jbc.M112436200

Date:

27-Dec-01 Release date: 17-Apr-02

Protein chain

P0A6E4  (ASSY_ECOLI) -  Argininosuccinate synthase from Escherichia coli (strain K12)

Seq: 447 a.a.

Struc: 439 a.a.

Enzyme reactions

• Enzyme class: E.C.6.3.4.5 - argininosuccinate synthase.
• Pathway: Urea Cycle and Arginine Biosynthesis
• Reaction: L-citrulline + L-aspartate + ATP = 2-(N(omega)-L-arginino)succinate + AMP + diphosphate + H⁺

L-citrulline (Bound ligand (Het Group name = ATP) corresponds exactly) + L-aspartate + ATP (Bound ligand (Het Group name = CIR) corresponds exactly) = 2-(N(omega)-L-arginino)succinate + AMP + diphosphate (Bound ligand (Het Group name = PO4) matches with 55.56% similarity) + H(+)

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

reference

DOI no: 10.1074/jbc.M112436200

J Biol Chem 277:13074-13081 (2002)

PubMed id: 11809762

Substrate induced conformational changes in argininosuccinate synthetase.

C.T.Lemke, P.L.Howell.

ABSTRACT

Argininosuccinate synthetase (AS) is the rate-limiting enzyme of both the urea and arginine-citrulline cycles. In mammals, deficiency of AS leads to citrullinemia, a debilitating and often fatal autosomal recessive urea cycle disorder, whereas its overexpression for sustained nitric oxide production via the arginine-citrulline cycle leads to the potentially fatal hypotension associated with septic and cytokine-induced circulatory shock. The crystal structures of Escherichia coli argininosuccinate synthetase (EAS) in complex with ATP and with ATP and citrulline have been determined at 2.0-A resolution. These are the first EAS structures to be solved in the presence of a nucleotide substrate and clearly identify the residues that interact with both ATP and citrulline. Two distinct conformations are revealed for ATP, both of which are believed to be catalytically relevant. In addition, comparisons of these EAS structures with those of the apoenzyme and EAS complexed with aspartate and citrulline (Lemke, C. T., and Howell, P. L. (2001) Structure (Lond.) 9, 1153-1164) provide structural evidence of ATP-induced conformational changes in the nucleotide binding domain. Combined, these structures also provide structural explanations of some of the observed kinetic properties of the enzyme and have enabled a detailed enzymatic mechanism of AS catalysis to be proposed.

Selected figure(s)

Figure 1.
Fig. 1. The argininosuccinate synthetase mechanism. Step 1, activated citrulline-adenylate is formed, releasing inorganic pyrophosphate. Step 2, nucleophilic attack by aspartate amino group forms argininosuccinate and releases AMP.

Figure 8.
Fig. 8. ATP conformations. The conformations of ATP observed in lysyl tRNA synthetase (a), EAS ( b), and NAD^+ synthetase (c) are shown. The dashed lines are drawn between the -phosphate of ATP and nucleophile.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2002, 277, 13074-13081) copyright 2002.

Figures were selected by an automated process.