6LPI

Crystal Structure of AHAS holo-enzyme


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.85 Å
  • R-Value Free: 0.243 
  • R-Value Work: 0.167 
  • R-Value Observed: 0.170 

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Literature

Molecular architecture of the acetohydroxyacid synthase holoenzyme.

Zhang, Y.Li, Y.Liu, X.Sun, J.Li, X.Lin, J.Yang, X.Xi, Z.Shen, Y.

(2020) Biochem J 477: 2439-2449

  • DOI: 10.1042/BCJ20200292
  • Primary Citation of Related Structures:  
    6LPI

  • PubMed Abstract: 
  • The acetohydroxyacid synthase (AHAS) holoenzyme catalyzes the first step of branch-chain amino acid biosynthesis and is essential for plants and bacteria. It consists of a regulatory subunit (RSU) and a catalytic subunit (CSU). The allosteric mechanism of the AHAS holoenzyme has remained elusive for decades ...

    The acetohydroxyacid synthase (AHAS) holoenzyme catalyzes the first step of branch-chain amino acid biosynthesis and is essential for plants and bacteria. It consists of a regulatory subunit (RSU) and a catalytic subunit (CSU). The allosteric mechanism of the AHAS holoenzyme has remained elusive for decades. Here, we determined the crystal structure of the AHAS holoenzyme, revealing the association between the RSU and CSU in an A2B2 mode. Structural analysis in combination with mutational studies demonstrated that the RSU dimer forms extensive interactions with the CSU dimer, in which a conserved salt bridge between R32 and D120 may act as a trigger to open the activation loop of the CSU, resulting in the activation of the CSU by the RSU. Our study reveals the activation mechanism of the AHAS holoenzyme.


    Organizational Affiliation

    Collaborative Innovation Center of Chemical Science and Engineering, Weijin 94, Tianjin 300071, China.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Acetolactate synthase isozyme 1 small subunitEFGH127Escherichia coli K-12Mutation(s): 0 
Gene Names: ilvNb3670JW3645
EC: 2.2.1.6
Find proteins for P0ADF8 (Escherichia coli (strain K12))
Explore P0ADF8 
Go to UniProtKB:  P0ADF8
Protein Feature View
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  • Reference Sequence
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
Acetolactate synthase isozyme 1 large subunitABCD562Escherichia coli K-12Mutation(s): 0 
Gene Names: ilvBb3671JW3646
EC: 2.2.1.6
Find proteins for P08142 (Escherichia coli (strain K12))
Explore P08142 
Go to UniProtKB:  P08142
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
FAD
Query on FAD

Download CCD File 
A, B, C, D
FLAVIN-ADENINE DINUCLEOTIDE
C27 H33 N9 O15 P2
VWWQXMAJTJZDQX-UYBVJOGSSA-N
 Ligand Interaction
TPP
Query on TPP

Download CCD File 
A, B, C, D
THIAMINE DIPHOSPHATE
C12 H19 N4 O7 P2 S
AYEKOFBPNLCAJY-UHFFFAOYSA-O
 Ligand Interaction
MG
Query on MG

Download CCD File 
A, B, C, D
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.85 Å
  • R-Value Free: 0.243 
  • R-Value Work: 0.167 
  • R-Value Observed: 0.170 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 111.173α = 90
b = 104.577β = 105.68
c = 118.535γ = 90
Software Package:
Software NamePurpose
PHENIXrefinement
PDB_EXTRACTdata extraction
HKL-2000data reduction
HKL-2000data scaling
PHASERphasing

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2020-11-18
    Type: Initial release