4ACI

Structure of the C. glutamicum AcnR Crystal Form II


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.65 Å
  • R-Value Free: 0.205 
  • R-Value Work: 0.142 
  • R-Value Observed: 0.145 

Starting Model: experimental
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This is version 1.3 of the entry. See complete history


Literature

Crystal and Solution Studies Reveal that the Transcriptional Regulator Acnr of Corynebacterium Glutamicum is Regulated by Citrate:Mg2+ Binding to a Non-Canonical Pocket.

Garcia-Nafria, J.Baumgart, M.Turkenburg, J.P.Wilkinson, A.J.Bott, M.Wilson, K.S.

(2013) J Biol Chem 288: 15800

  • DOI: https://doi.org/10.1074/jbc.M113.462440
  • Primary Citation of Related Structures:  
    4AC6, 4ACI, 4AF5

  • PubMed Abstract: 

    Corynebacterium glutamicum is an important industrial bacterium as well as a model organism for the order Corynebacteriales, whose citric acid cycle occupies a central position in energy and precursor supply. Expression of aconitase, which isomerizes citrate into isocitrate, is controlled by several transcriptional regulators, including the dimeric aconitase repressor AcnR, assigned by sequence identity to the TetR family. We report the structures of AcnR in two crystal forms together with ligand binding experiments and in vivo studies. First, there is a citrate-Mg(2+) moiety bound in both forms, not in the canonical TetR ligand binding site but rather in a second pocket more distant from the DNA binding domain. Second, the citrate-Mg(2+) binds with a KD of 6 mM, within the range of physiological significance. Third, citrate-Mg(2+) lowers the affinity of AcnR for its target DNA in vitro. Fourth, analyses of several AcnR point mutations provide evidence for the possible involvement of the corresponding residues in ligand binding, DNA binding, and signal transfer. AcnR derivatives defective in citrate-Mg(2+) binding severely inhibit growth of C. glutamicum on citrate. Finally, the structures do have a pocket corresponding to the canonical tetracycline site, and although we have not identified a ligand that binds there, comparison of the two crystal forms suggests differences in the region of the canonical pocket that may indicate a biological significance.


  • Organizational Affiliation

    York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, United Kingdom.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
HTH-TYPE TRANSCRIPTIONAL REPRESSOR ACNR
A, B
191Corynebacterium glutamicumMutation(s): 0 
UniProt
Find proteins for Q8NQ97 (Corynebacterium glutamicum (strain ATCC 13032 / DSM 20300 / JCM 1318 / BCRC 11384 / CCUG 27702 / LMG 3730 / NBRC 12168 / NCIMB 10025 / NRRL B-2784 / 534))
Explore Q8NQ97 
Go to UniProtKB:  Q8NQ97
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ8NQ97
Sequence Annotations
Expand
  • Reference Sequence
Small Molecules
Ligands 4 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
CIT
Query on CIT

Download Ideal Coordinates CCD File 
E [auth A],
H [auth B]
CITRIC ACID
C6 H8 O7
KRKNYBCHXYNGOX-UHFFFAOYSA-N
GOL
Query on GOL

Download Ideal Coordinates CCD File 
D [auth A],
I [auth B]
GLYCEROL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
MG
Query on MG

Download Ideal Coordinates CCD File 
C [auth A],
G [auth B]
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
NA
Query on NA

Download Ideal Coordinates CCD File 
F [auth B]SODIUM ION
Na
FKNQFGJONOIPTF-UHFFFAOYSA-N
Binding Affinity Annotations 
IDSourceBinding Affinity
CIT PDBBind:  4ACI Kd: 6.00e+6 (nM) from 1 assay(s)
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.65 Å
  • R-Value Free: 0.205 
  • R-Value Work: 0.142 
  • R-Value Observed: 0.145 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 34.21α = 90
b = 72.79β = 90
c = 145.57γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
MOSFLMdata reduction
SCALAdata scaling
PHASERphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2012-12-26
    Type: Initial release
  • Version 1.1: 2013-05-01
    Changes: Database references, Other, Structure summary
  • Version 1.2: 2013-06-19
    Changes: Database references
  • Version 1.3: 2023-12-20
    Changes: Data collection, Database references, Derived calculations, Other, Refinement description