PDBsum entry 1kjx

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protein ligands links
Ligase PDB id
Protein chain
431 a.a. *
Waters ×312
* Residue conservation analysis
PDB id:
Name: Ligase
Title: Imp complex of e. Coli adenylosuccinate synthetase
Structure: Adenylosuccinate synthetase. Chain: a. Engineered: yes
Source: Escherichia coli k12. Organism_taxid: 83333. Strain: k-12. Expressed in: escherichia coli. Expression_system_taxid: 562.
Biol. unit: Dimer (from PDB file)
2.60Å     R-factor:   0.196     R-free:   0.283
Authors: Z.Hou,W.Wang,H.J.Fromm,R.B.Honzatko
Key ref:
Z.Hou et al. (2002). IMP Alone Organizes the Active Site of Adenylosuccinate Synthetase from Escherichia coli. J Biol Chem, 277, 5970-5976. PubMed id: 11741996 DOI: 10.1074/jbc.M109561200
05-Dec-01     Release date:   20-Mar-02    
Go to PROCHECK summary

Protein chain
Pfam   ArchSchema ?
P0A7D4  (PURA_ECOLI) -  Adenylosuccinate synthetase
432 a.a.
431 a.a.
Key:    PfamA domain  Secondary structure  CATH domain

 Enzyme reactions 
   Enzyme class: E.C.  - Adenylosuccinate synthase.
[IntEnz]   [ExPASy]   [KEGG]   [BRENDA]

AMP and GMP Biosynthesis
      Reaction: GTP + IMP + L-aspartate = GDP + phosphate + N6-(1,2-dicarboxyethyl)- AMP
Bound ligand (Het Group name = IMP)
corresponds exactly
+ L-aspartate
+ phosphate
+ N(6)-(1,2-dicarboxyethyl)- AMP
Molecule diagrams generated from .mol files obtained from the KEGG ftp site
 Gene Ontology (GO) functional annotation 
  GO annot!
  Cellular component     membrane   3 terms 
  Biological process     'de novo' AMP biosynthetic process   6 terms 
  Biochemical function     nucleotide binding     6 terms  


DOI no: 10.1074/jbc.M109561200 J Biol Chem 277:5970-5976 (2002)
PubMed id: 11741996  
IMP Alone Organizes the Active Site of Adenylosuccinate Synthetase from Escherichia coli.
Z.Hou, W.Wang, H.J.Fromm, R.B.Honzatko.
A complete set of substrate/substrate analogs of adenylosuccinate synthetase from Escherichia coli induces dimer formation and a transition from a disordered to an ordered active site. The most striking of the ligand-induced effects is the movement of loop 40-53 by up to 9 A. Crystal structures of the partially ligated synthetase, which either combine IMP and hadacidin or IMP, hadacidin, and Mg(2+)-pyrophosphate, have ordered active sites, comparable with the fully ligated enzyme. More significantly, a crystal structure of the synthetase with IMP alone exhibits a largely ordered active site, which includes the 9 A movement of loop 40-53 but does not include conformational adjustments to backbone carbonyl 40 (Mg(2+) interaction element) and loop 298-304 (L-aspartate binding element). Interactions involving the 5'-phosphoryl group of IMP evidently trigger the formation of salt links some 30 A away. The above provides a structural basis for ligand binding synergism, effects on k(cat) due to mutations far from the site of catalysis, and the complete loss of substrate efficacy due to minor alterations of the 5'-phosphoryl group of IMP.
  Selected figure(s)  
Figure 2.
Fig. 2. Stereoview of ligand interactions in the pyrophosphate complex. Dashed lines are donor-acceptor interactions between pyrophosphate-Mg2+ and the active site.
Figure 5.
Fig. 5. Stereoview of the IMP-ligated active site. Dashed lines represent donor-acceptor interactions.
  The above figures are reprinted by permission from the ASBMB: J Biol Chem (2002, 277, 5970-5976) copyright 2002.  
  Figures were selected by an automated process.