Solution NMR studies of the dimeric regulatory subunit IlvN of the E.coli Acetohydroxyacid synthase I (AHAS I)

Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 100 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the lowest energy 

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The coil-to-helix transition in IlvN regulates the allosteric control of Escherichia coli acetohydroxyacid synthase I

Karanth, N.M.Sarma, S.P.

(2013) Biochemistry 52: 70-83

  • DOI: https://doi.org/10.1021/bi301415m
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    The solution structure of IlvN, the regulatory subunit of Escherichia coli acetohydroxyacid synthase I, in the valine-bound form has been determined using high-resolution multidimensional, multinuclear nuclear magnetic resonance (NMR) methods. IlvN in the presence or absence of the effector molecule is present as a 22.5 kDa dimeric molecule. The ensemble of 20 low-energy structures shows a backbone root-mean-square deviation of 0.73 ± 0.13 Å and a root-mean-square deviation of 1.16 ± 0.13 Å for all heavy atoms. Furthermore, more than 98% of the backbone φ and ψ dihedral angles occupy the allowed and additionally allowed regions of the Ramachandran map, which is indicative of the fact that the structures are of high stereochemical quality. Each protomer exhibits a βαββαβα topology that is a characteristic feature of the ACT domain seen in metabolic enzymes. In the valine-bound form, IlvN exists apparently as a single conformer. In the free form, IlvN exists as a mixture of conformational states that are in intermediate exchange on the NMR time scale. Thus, a large shift in the conformational equilibrium is observed upon going from the free form to the bound form. The structure of the valine-bound form of IlvN was found to be similar to that of the ACT domain of the unliganded form of IlvH. Comparisons of the structures of the unliganded forms of these proteins suggest significant differences. The structural and conformational properties of IlvN determined here have allowed a better understanding of the mechanism of regulation of branched chain amino acid biosynthesis.

  • Organizational Affiliation

    Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, Karnataka, India.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Acetolactate synthase isozyme 1 small subunit
A, B
98Escherichia coli K-12Mutation(s): 0 
Gene Names: b3670ilvNJW3645
Find proteins for P0ADF8 (Escherichia coli (strain K12))
Explore P0ADF8 
Go to UniProtKB:  P0ADF8
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP0ADF8
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 100 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the lowest energy 

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2013-05-29
    Type: Initial release
  • Version 1.1: 2024-05-01
    Changes: Data collection, Database references