3RMJ

Crystal structure of truncated alpha-Isopropylmalate Synthase from Neisseria meningitidis


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.95 Å
  • R-Value Free: 0.191 
  • R-Value Work: 0.158 
  • R-Value Observed: 0.160 

wwPDB Validation   3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

Removal of the C-terminal regulatory domain of alpha-isopropylmalate synthase disrupts functional substrate binding

Huisman, F.H.A.Koon, N.Bulloch, E.M.M.Baker, H.M.Baker, E.N.Squire, C.J.Parker, E.J.

(2012) Biochemistry 51: 2289-2297

  • DOI: 10.1021/bi201717j
  • Primary Citation of Related Structures:  
    3HPX, 3U6W, 3RMJ

  • PubMed Abstract: 
  • α-Isopropylmalate synthase (α-IPMS) catalyzes the metal-dependent aldol reaction between α-ketoisovalerate (α-KIV) and acetyl-coenzyme A (AcCoA) to give α-isopropylmalate (α-IPM). This reaction is the first committed step in the biosynthesis of leucine in bacteria ...

    α-Isopropylmalate synthase (α-IPMS) catalyzes the metal-dependent aldol reaction between α-ketoisovalerate (α-KIV) and acetyl-coenzyme A (AcCoA) to give α-isopropylmalate (α-IPM). This reaction is the first committed step in the biosynthesis of leucine in bacteria. α-IPMS is homodimeric, with monomers consisting of (β/α)(8) barrel catalytic domains fused to a C-terminal regulatory domain, responsible for binding leucine and providing feedback regulation for leucine biosynthesis. In these studies, we demonstrate that removal of the regulatory domain from the α-IPMS enzymes of both Neisseria meningitidis (NmeIPMS) and Mycobacterium tuberculosis (MtuIPMS) results in enzymes that are unable to catalyze the formation of α-IPM, although truncated NmeIPMS was still able to slowly hydrolyze AcCoA. The lack of catalytic activity of these truncation variants was confirmed by complementation studies with Escherichia coli cells lacking the α-IPMS gene, where transformation with the plasmids encoding the truncated α-IPMS enzymes was not able to rescue α-IPMS activity. X-ray crystal structures of both truncation variants reveal that both proteins are dimeric and that the catalytic sites of the proteins are intact, although the divalent metal ion that is thought to be responsible for activating substrate α-KIV is displaced slightly relative to its position in the substrate-bound, wild-type structure. Isothermal titration calorimetry and WaterLOGSY nuclear magnetic resonance experiments demonstrate that although these truncation variants are not able to catalyze the reaction between α-KIV and AcCoA, they are still able to bind the substrate α-KIV. It is proposed that the regulatory domain is crucial for ensuring protein dynamics necessary for competent catalysis.


    Organizational Affiliation

    Biomolecular Interaction Centre and Department of Chemistry, University of Canterbury, Christchurch, New Zealand.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
2-isopropylmalate synthaseA, B370Neisseria meningitidis serogroup BMutation(s): 0 
Gene Names: leuANMB1070
EC: 2.3.3.13
Find proteins for Q9JZG1 (Neisseria meningitidis serogroup B (strain MC58))
Explore Q9JZG1 
Go to UniProtKB:  Q9JZG1
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.95 Å
  • R-Value Free: 0.191 
  • R-Value Work: 0.158 
  • R-Value Observed: 0.160 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 46.296α = 90
b = 103.581β = 90
c = 129.937γ = 90
Software Package:
Software NamePurpose
ADSCdata collection
BALBESphasing
REFMACrefinement
XDSdata reduction
SCALAdata scaling

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2012-03-14
    Type: Initial release
  • Version 1.1: 2014-03-12
    Changes: Database references