1V7L

Structure of 3-isopropylmalate isomerase small subunit from Pyrococcus horikoshii

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.98 Å
  • R-Value Free: 0.247 
  • R-Value Work: 0.206 

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This is version 1.2 of the entry. See complete history. 


Literature

Crystal Structure of the Pyrococcus horikoshii Isopropylmalate Isomerase Small Subunit Provides Insight into the Dual Substrate Specificity of the Enzyme

Yasutake, Y., Yao, M., Sakai, N., Kirita, T., Tanaka, I.

(2004) J Mol Biol 344: 325-333

  • DOI: 10.1016/j.jmb.2004.09.035
  • Primary Citation of Related Structures:  
    1V7L

  • PubMed Abstract: 

    • Recent studies have implied that the isopropylmalate isomerase small subunit of the hyperthermophilic archaea Pyrococcus horikoshii (PhIPMI-s) functions as isopropylmalate isomerase in the leucine biosynthesis pathway, and as homoaconitase (HACN) in the lysine biosynthesis pathway via alpha-aminoadipic acid ...

    Recent studies have implied that the isopropylmalate isomerase small subunit of the hyperthermophilic archaea Pyrococcus horikoshii (PhIPMI-s) functions as isopropylmalate isomerase in the leucine biosynthesis pathway, and as homoaconitase (HACN) in the lysine biosynthesis pathway via alpha-aminoadipic acid. PhIPMI is thus considered a key to understanding the fundamental metabolism of the earliest organisms. We describe for the first time the crystal structure of PhIPMI-s, which displays dual substrate specificity. The crystal structure unexpectedly shows that four molecules create an interlocked assembly with intermolecular disulfide linkages having a skewed 222 point-group symmetry. Although the overall fold of the PhIPMI-s monomer is related closely to domain 4 of the aconitase (ACN), one alpha-helix in the ACN structure is replaced by a short loop with relatively high temperature factor values. Because this region is essential for discriminating the structurally similar substrate based on interactions with its diversified gamma-moiety, the loop structure in the PhIPMI-s must be dependent on the presence of a substrate. The flexibility of the loop region might be a structural basis for recognizing both hydrophobic and hydrophilic gamma-moieties of two distinct substrates, isopropylmalate and homocitrate.

    Organizational Affiliation: 

    Division of Biological Sciences, Graduate School of Science, Hokkaido University, Kita-10, Nishi-8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan.



Macromolecules
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(by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
3-isopropylmalate dehydratase small subunitA, B163Pyrococcus horikoshii OT3Mutation(s): 0 
Gene Names: PH1724, leuD
EC: 4.2.1.33
UniProt
Find proteins for O59393 (Pyrococcus horikoshii (strain ATCC 700860 / DSM 12428 / JCM 9974 / NBRC 100139 / OT-3))
Explore O59393 
Go to UniProtKB:  O59393
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupO59393
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.98 Å
  • R-Value Free: 0.247 
  • R-Value Work: 0.206 
  • Space Group: P 62 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 95.208α = 90
b = 95.208β = 90
c = 152.258γ = 120
Software Package:
Software NamePurpose
MOSFLMdata reduction
SCALAdata scaling
SOLVEphasing
SHARPphasing
CNSrefinement
CCP4data scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2004-11-16
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Source and taxonomy, Version format compliance