2F1F

Crystal structure of the regulatory subunit of acetohydroxyacid synthase isozyme III from E. coli


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.75 Å
  • R-Value Free: 0.227 
  • R-Value Work: 0.171 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

Structure of the Regulatory Subunit of Acetohydroxyacid Synthase Isozyme III from Escherichia coli.

Kaplun, A.Vyazmensky, M.Zherdev, Y.Belenky, I.Slutzker, A.Mendel, S.Barak, Z.Chipman, D.M.Shaanan, B.

(2006) J.Mol.Biol. 357: 951-963

  • DOI: 10.1016/j.jmb.2005.12.077

  • PubMed Abstract: 
  • The enzyme acetohydroxyacid synthase (AHAS) catalyses the first common step in the biosynthesis of the three branched-chain amino acids. Enzymes in the AHAS family generally consist of regulatory and catalytic subunits. Here, we describe the first cr ...

    The enzyme acetohydroxyacid synthase (AHAS) catalyses the first common step in the biosynthesis of the three branched-chain amino acids. Enzymes in the AHAS family generally consist of regulatory and catalytic subunits. Here, we describe the first crystal structure of an AHAS regulatory subunit, the ilvH polypeptide, determined at a resolution of 1.75 A. IlvH is the regulatory subunit of one of three AHAS isozymes expressed in Escherichia coli, AHAS III. The protein is a dimer, with two beta alpha beta beta alpha beta ferredoxin domains in each monomer. The two N-terminal domains assemble to form an ACT domain structure remarkably close to the one predicted by us on the basis of the regulatory domain of 3-phosphoglycerate dehydrogenase (3PGDH). The two C-terminal domains combine so that their beta-sheets are roughly positioned back-to-back and perpendicular to the extended beta-sheet of the N-terminal ACT domain. On the basis of the properties of mutants and a comparison with 3PGDH, the effector (valine) binding sites can be located tentatively in two symmetrically related positions in the interface between a pair of N-terminal domains. The properties of mutants of the ilvH polypeptide outside the putative effector-binding site provide further insight into the functioning of the holoenzyme. The results of this study open avenues for further studies aimed at understanding the mechanism of regulation of AHAS by small-molecule effectors.


    Organizational Affiliation

    Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Acetolactate synthase isozyme III small subunit
A, B
164Escherichia coli (strain K12)Gene Names: ilvH (brnP)
EC: 2.2.1.6
Find proteins for P00894 (Escherichia coli (strain K12))
Go to UniProtKB:  P00894
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
P33
Query on P33

Download SDF File 
Download CCD File 
B
3,6,9,12,15,18-HEXAOXAICOSANE-1,20-DIOL
HEPTAETHYLENE GLYCOL, PEG330
C14 H30 O8
XPJRQAIZZQMSCM-UHFFFAOYSA-N
 Ligand Interaction
MG
Query on MG

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Download CCD File 
A, B
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
 Ligand Interaction
1PE
Query on 1PE

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Download CCD File 
A
PENTAETHYLENE GLYCOL
PEG400
C10 H22 O6
JLFNLZLINWHATN-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.75 Å
  • R-Value Free: 0.227 
  • R-Value Work: 0.171 
  • Space Group: I 4
Unit Cell:
Length (Å)Angle (°)
a = 98.600α = 90.00
b = 98.600β = 90.00
c = 80.000γ = 90.00
Software Package:
Software NamePurpose
REFMACrefinement
PDB_EXTRACTdata extraction
SHARPphasing
XSCALEdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2006-01-24
    Type: Initial release
  • Version 1.1: 2008-05-01
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2017-10-18
    Type: Refinement description