PDBsum entry 1b4x

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protein ligands links
Transferase PDB id
Protein chain
396 a.a. *
Waters ×26
* Residue conservation analysis
PDB id:
Name: Transferase
Title: Aspartate aminotransferase from e. Coli, c191s mutation, wit maleate
Structure: Aspartate aminotransferase. Chain: a. Fragment: complete subunit. Engineered: yes. Mutation: yes. Other_details: pyridoxal phosphate cofactor covalently boun 258 via schiff base linkage
Source: Escherichia coli. Organism_taxid: 562. Cellular_location: cytoplasm. Expressed in: escherichia coli. Expression_system_taxid: 562.
Biol. unit: Dimer (from PDB file)
2.45Å     R-factor:   0.207    
Authors: C.J.Jeffery,L.M.Gloss,G.A.Petsko,D.Ringe
Key ref: C.J.Jeffery et al. (2000). The role of residues outside the active site: structural basis for function of C191 mutants of Escherichia coli aspartate aminotransferase. Protein Eng, 13, 105-112. PubMed id: 10708649
30-Dec-98     Release date:   27-Oct-00    
Go to PROCHECK summary

Protein chain
Pfam   ArchSchema ?
P00509  (AAT_ECOLI) -  Aspartate aminotransferase
396 a.a.
396 a.a.*
Key:    PfamA domain  Secondary structure  CATH domain
* PDB and UniProt seqs differ at 1 residue position (black cross)

 Enzyme reactions 
   Enzyme class: E.C.  - Aspartate transaminase.
[IntEnz]   [ExPASy]   [KEGG]   [BRENDA]
      Reaction: L-aspartate + 2-oxoglutarate = oxaloacetate + L-glutamate
Bound ligand (Het Group name = MAE)
matches with 88.89% similarity
+ 2-oxoglutarate
= oxaloacetate
+ L-glutamate
      Cofactor: Pyridoxal 5'-phosphate
Pyridoxal 5'-phosphate
Bound ligand (Het Group name = PLP) matches with 93.75% 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  


Protein Eng 13:105-112 (2000)
PubMed id: 10708649  
The role of residues outside the active site: structural basis for function of C191 mutants of Escherichia coli aspartate aminotransferase.
C.J.Jeffery, L.M.Gloss, G.A.Petsko, D.Ringe.
In previous kinetic studies of Escherichia coli aspartate aminotransferase, it was determined that some substitutions of conserved cysteine 191, which is located outside of the active site, altered the kinetic parameters of the enzyme (Gloss,L.M., Spencer,D. E. and Kirsch,J.F., 1996, Protein Struct. Funct. Genet., 24, 195-208). The mutations resulted in an alkaline shift of 0.6-0.8 pH units for the pK(a) of the internal aldimine between the PLP cofactor and Lys258. The change in the pK(a) affected the pH dependence of the k(cat)/K(m) (aspartate) values for the mutant enzymes. To help to understand these observations, crystal structures of five mutant forms of E.coli aspartate aminotransferase (the maleate complexes of C191S, C191F, C191Y and C191W, and C191S without maleate) were determined at about 2 A resolution in the presence of the pyridoxal phosphate cofactor. The overall three-dimensional fold of each mutant enzyme is the same as that of the wild-type protein, but there is a rotation of the mutated side chain around its C(alpha)-C(beta) bond. This side chain rotation results in a change in the pattern of hydrogen bonding connecting the mutant residue and the protonated Schiff base of the cofactor, which could account for the altered pK(a) of the Schiff base imine nitrogen that was reported previously. These results demonstrate how residues outside the active site can be important in helping determine the subtleties of the active site amino acid geometries and interactions and how mutations outside the active site can have effects on catalysis. In addition, these results help explain the surprising result previously reported that, for some mutant proteins, replacement of a buried cysteine with an aromatic side chain did not destabilize the protein fold. Instead, rotation around the C(alpha)-C(beta) bond allowed each large aromatic side chain to become buried in a nearby pocket without large changes in the enzyme's backbone geometry.

Literature references that cite this PDB file's key reference

  PubMed id Reference
  21332942 H.J.Wu, Y.Yang, S.Wang, J.Q.Qiao, Y.F.Xia, Y.Wang, W.D.Wang, S.F.Gao, J.Liu, P.Q.Xue, and X.W.Gao (2011).
Cloning, expression and characterization of a new aspartate aminotransferase from Bacillus subtilis B3.
  FEBS J, 278, 1345-1357.  
16741983 Z.Rozwadowski (2006).
Deuterium isotope effect on 13C chemical shifts of tetrabutylammonium salts of Schiff bases amino acids.
  Magn Reson Chem, 44, 881-886.  
15836621 J.Wei, and J.Y.Wu (2005).
Structural and functional analysis of cysteine residues in human glutamate decarboxylase 65 (GAD65) and GAD67.
  J Neurochem, 93, 624-633.  
11967363 E.Deu, K.A.Koch, and J.F.Kirsch (2002).
The role of the conserved Lys68*:Glu265 intersubunit salt bridge in aspartate aminotransferase kinetics: multiple forced covariant amino acid substitutions in natural variants.
  Protein Sci, 11, 1062-1073.  
12465031 S.K.Avrantinis, R.L.Stafford, X.Tian, and G.A.Weiss (2002).
Dissecting the streptavidin-biotin interaction by phage-displayed shotgun scanning.
  Chembiochem, 3, 1229-1234.  
The most recent references are shown first. Citation data come partly from CiteXplore and partly from an automated harvesting procedure. Note that this is likely to be only a partial list as not all journals are covered by either method. However, we are continually building up the citation data so more and more references will be included with time.