1TOI

Hydrocinnamic acid-bound structure of Hexamutant + A293D mutant of E. coli aspartate aminotransferase


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.9 Å
  • R-Value Free: 0.197 
  • R-Value Work: 0.173 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Narrowing substrate specificity in a directly evolved enzyme: the A293D mutant of aspartate aminotransferase

Chow, M.A.McElroy, K.E.Corbett, K.D.Berger, J.M.Kirsch, J.F.

(2004) Biochemistry 43: 12780-12787

  • DOI: 10.1021/bi0487544
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Several mutant Escherichia coli aspartate aminotransferases (eAATases) have been characterized in the attempt to evolve or rationally redesign the substrate specificity of eAATase into that of E. coli tyrosine aminotransferase (eTATase). These includ ...

    Several mutant Escherichia coli aspartate aminotransferases (eAATases) have been characterized in the attempt to evolve or rationally redesign the substrate specificity of eAATase into that of E. coli tyrosine aminotransferase (eTATase). These include HEX (designed), HEX + A293D (design followed by directed evolution), and SRHEPT (directed evolution). The A293D mutation realized from directed evolution of HEX is here imported into the SRHEPT platform by site-directed mutagenesis, resulting in an enzyme (SRHEPT + A293D) with nearly the same ratio of k(cat)/K(m)(Phe) to k(cat)/K(m)(Asp) as that of wild-type eTATase. The A293D substitution is an important specificity determinant; it selectively disfavors interactions with dicarboxylic substrates and inhibitors compared to aromatic ones. Context dependence analysis is generalized to provide quantitative comparisons of a common substitution in two or more different protein scaffolds. High-resolution crystal structures of ligand complexes of HEX + A293D, SRHEPT, and SRHEPT + A293D were determined. We find that in both SRHEPT + A293D and HEX + A293D, the additional mutation holds the Arg 292 side chain away from the active site to allow increased specificity for phenylalanine over aspartate. The resulting movement of Arg 292 allows greater flexibility of the small domain in HEX + A293D. While HEX is always in the closed conformation, HEX + A293D is observed in both the closed and a novel open conformation, allowing for more rapid product release.


    Organizational Affiliation

    Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3206, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Aspartate aminotransferase
A
396Escherichia coli (strain K12)Mutation(s): 7 
Gene Names: aspC
EC: 2.6.1.1
Find proteins for P00509 (Escherichia coli (strain K12))
Go to UniProtKB:  P00509
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
HCI
Query on HCI

Download SDF File 
Download CCD File 
A
HYDROCINNAMIC ACID
3PP; 3-PHENYLPROPIONIC ACID
C9 H10 O2
XMIIGOLPHOKFCH-UHFFFAOYSA-N
 Ligand Interaction
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
LLP
Query on LLP
A
L-PEPTIDE LINKINGC14 H22 N3 O7 PLYS
External Ligand Annotations 
IDBinding Affinity (Sequence Identity %)
HCIKd: 90000 nM BINDINGMOAD
HCIKd: 90000 nM PDBBIND
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.9 Å
  • R-Value Free: 0.197 
  • R-Value Work: 0.173 
  • Space Group: C 2 2 21
Unit Cell:
Length (Å)Angle (°)
a = 83.789α = 90.00
b = 154.845β = 90.00
c = 77.915γ = 90.00
Software Package:
Software NamePurpose
REFMACrefinement
SCALEPACKdata scaling
HKL-2000data reduction
AMoREphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2004-10-05
    Type: Initial release
  • Version 1.1: 2008-04-30
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Advisory, Derived calculations, Version format compliance