PDBsum entry 1x2a

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Transferase PDB id
Protein chains
396 a.a. *
PDG ×2
Waters ×204
* Residue conservation analysis
PDB id:
Name: Transferase
Title: Crystal structure of e.Coli aspat complexed with n- phosphopyridoxyl-d-glutamic acid
Structure: Aspartate aminotransferase. Chain: a, b. Synonym: transaminase a, aspat. Engineered: yes
Source: Escherichia coli. Organism_taxid: 562. Expressed in: escherichia coli. Expression_system_taxid: 562.
Biol. unit: Dimer (from PQS)
2.20Å     R-factor:   0.193     R-free:   0.234
Authors: M.Goto
Key ref:
M.M.Islam et al. (2005). Binding of C5-dicarboxylic substrate to aspartate aminotransferase: implications for the conformational change at the transaldimination step. Biochemistry, 44, 8218-8229. PubMed id: 15938611 DOI: 10.1021/bi050071g
21-Apr-05     Release date:   14-Jun-05    
Go to PROCHECK summary

Protein chains
Pfam   ArchSchema ?
P00509  (AAT_ECOLI) -  Aspartate aminotransferase
396 a.a.
396 a.a.
Key:    PfamA domain  Secondary structure  CATH domain

 Enzyme reactions 
   Enzyme class: E.C.  - Aspartate transaminase.
[IntEnz]   [ExPASy]   [KEGG]   [BRENDA]
      Reaction: L-aspartate + 2-oxoglutarate = oxaloacetate + L-glutamate
+ 2-oxoglutarate
= oxaloacetate
+ L-glutamate
      Cofactor: Pyridoxal 5'-phosphate
Pyridoxal 5'-phosphate
Bound ligand (Het Group name = PDG) matches with 57.00% similarity
Molecule diagrams generated from .mol files obtained from the KEGG ftp site
 Gene Ontology (GO) functional annotation 
  GO annot!
  Cellular component     cytoplasm   2 terms 
  Biological process     biosynthetic process   4 terms 
  Biochemical function     catalytic activity     8 terms  


DOI no: 10.1021/bi050071g Biochemistry 44:8218-8229 (2005)
PubMed id: 15938611  
Binding of C5-dicarboxylic substrate to aspartate aminotransferase: implications for the conformational change at the transaldimination step.
M.M.Islam, M.Goto, I.Miyahara, H.Ikushiro, K.Hirotsu, H.Hayashi.
The mechanism for the reaction of aspartate aminotransferase with the C4 substrate, l-aspartate, has been well established. The binding of the C4 substrate induces conformational change in the enzyme from the open to the closed form, and the entire reaction proceeds in the closed form of the enzyme. On the contrary, little is known about the reaction with the C5 substrate, l-glutamate. In this study, we analyzed the pH-dependent binding of 2-methyl-l-glutamate to the enzyme and showed that the interaction between the amino group of 2-methyl-l-glutamate and the pyridoxal 5'-phosphate aldimine is weak compared to that between 2-methyl-l-aspartate and the aldimine. The structures of the Michaelis complexes of the enzyme with l-aspartate and l-glutamate were modeled on the basis of the maleate and glutarate complex structures of the enzyme. The result showed that l-glutamate binds to the open form of the enzyme in an extended conformation, and its alpha-amino group points in the opposite direction of the aldimine, while that of l-aspartate is close to the aldimine. These models explain the observations for 2-methyl-l-glutamate and 2-methyl-l-aspartate. The crystal structures of the complexes of aspartate aminotransferase with phosphopyridoxyl derivatives of l-glutamate, d-glutamate, and 2-methyl-l-glutamate were solved as the models for the external aldimine and ketimine complexes of l-glutamate. All the structures were in the closed form, and the two carboxylate groups and the arginine residues binding them are superimposable on the external aldimine complex with 2-methyl-l-aspartate. Taking these facts altogether, it was strongly suggested that the binding of l-glutamate to aspartate aminotransferase to form the Michaelis complex does not induce a conformational change in the enzyme, and that the conformational change to the closed form occurs during the transaldimination step. The hydrophobic residues of the entrance of the active site, including Tyr70, are considered to be important for promoting the transaldimination process and hence the recognition of the C5 substrate.

Literature references that cite this PDB file's key reference

  PubMed id Reference
18831049 T.Tomita, T.Miyagawa, T.Miyazaki, S.Fushinobu, T.Kuzuyama, and M.Nishiyama (2009).
Mechanism for multiple-substrates recognition of alpha-aminoadipate aminotransferase from Thermus thermophilus.
  Proteins, 75, 348-359.
PDB codes: 2zp7 3cbf
18366019 R.Z.Liao, W.J.Ding, J.G.Yu, W.H.Fang, and R.Z.Liu (2008).
Theoretical studies on pyridoxal 5'-phosphate-dependent transamination of alpha-amino acids.
  J Comput Chem, 29, 1919-1929.  
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