PDBsum entry: 1k92

Ligase

PDB id: 1k92

Contents

Protein chain

444 a.a. *

Ligands

SO4 ×5

GOL

Waters ×495

* Residue conservation analysis

PDB id:

1k92

Name:

Ligase

Title:

Crystal structure of uncomplexed e. Coli argininosuccinate s

Structure:

Argininosuccinate synthase. Chain: a. Fragment: residues 1 to 446. Synonym: citrulline--aspartate ligase. Argininosuccinate sy engineered: yes. Mutation: yes

Source:

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

Biol. unit:

Tetramer (from PDB file)

Resolution:

1.60Å R-factor: 0.163 R-free: 0.188

Authors:

C.T.Lemke,P.L.Howell

Key ref:

C.T.Lemke and P.L.Howell (2001). The 1.6 A crystal structure of E. coli argininosuccinate synthetase suggests a conformational change during catalysis. Structure, 9, 1153-1164. PubMed id: 11738042 DOI: 10.1016/S0969-2126(01)00683-9

Date:

26-Oct-01 Release date: 07-Dec-01

Protein chain

P0A6E4  (ASSY_ECOLI) -  Argininosuccinate synthase

Seq: 447 a.a.

Struc: 444 a.a.

Enzyme reactions

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

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

 Gene Ontology (GO) functional annotation 

• Cellular component: cytoplasm (1 term)
• Biological process: cellular amino acid biosynthetic process (2 terms)
• Biochemical function: nucleotide binding (5 terms)

reference

DOI no: 10.1016/S0969-2126(01)00683-9

Structure 9:1153-1164 (2001)

PubMed id: 11738042

The 1.6 A crystal structure of E. coli argininosuccinate synthetase suggests a conformational change during catalysis.

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

ABSTRACT

BACKGROUND: 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. RESULTS: The crystal structure of E. coli AS (EAS) has been determined by the use of selenomethionine incorporation and MAD phasing. The structure has been refined at 1.6 A resolution in the absence of its substrates and at 2.0 A in the presence of aspartate and citrulline (EAS*CIT+ASP). Each monomer of this tetrameric protein has two structural domains: a nucleotide binding domain similar to that of the "N-type" ATP pyrophosphatase class of enzymes, and a novel catalytic/multimerization domain. The EAS*CIT+ASP structure clearly describes the binding of citrulline at the cleft between the two domains and of aspartate to a loop of the nucleotide binding domain, whereas homology modeling with the N-type ATP pyrophosphatases has provided the location of ATP binding. CONCLUSIONS: The first three-dimensional structures of AS are reported. The fold of the nucleotide binding domain confirms AS as the fourth structurally defined member of the N-type ATP pyrophosphatases. The structures identify catalytically important residues and suggest the requirement for a conformational change during the catalytic cycle. Sequence similarity between the bacterial and human enzymes has been used for providing insight into the structural and functional effects of observed clinical mutations.

Selected figure(s)

Figure 2.
Figure 2. EAS Aspartate and Citrulline Binding Sitess[A]-weighted |F[o]| - |F[c]| omit map contoured at 3s shows the citrulline (a) and aspartate (c) binding sites. Schematic representation of the interactions between the protein and either citrulline (b) or aspartate (d). Dashed lines represent interactions between atoms, with distances given in Å.

The above figure is reprinted by permission from Cell Press: Structure (2001, 9, 1153-1164) copyright 2001.

Figure was selected by an automated process.