2SQC

SQUALENE-HOPENE CYCLASE FROM ALICYCLOBACILLUS ACIDOCALDARIUS


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.187 
  • R-Value Work: 0.153 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

The structure of the membrane protein squalene-hopene cyclase at 2.0 A resolution.

Wendt, K.U.Lenhart, A.Schulz, G.E.

(1999) J Mol Biol 286: 175-187

  • DOI: 10.1006/jmbi.1998.2470
  • Primary Citation of Related Structures:  
    2SQC, 3SQC

  • PubMed Abstract: 
  • Squalene cyclases catalyze a cationic cyclization cascade, which is homologous to a key step in cholesterol biosynthesis. The structure of the enzyme from Alicyclobacillus acidocaldarius has been determined in a new crystal form at 2.0 A resolution ( ...

    Squalene cyclases catalyze a cationic cyclization cascade, which is homologous to a key step in cholesterol biosynthesis. The structure of the enzyme from Alicyclobacillus acidocaldarius has been determined in a new crystal form at 2.0 A resolution (1 A=0.1 nm) and refined to an R-factor of 15.3 % (Rfree=18.7 %). The structure indicates how the initial protonation and the final deprotonation of squalene occur and how the transient carbocations are stabilized. The pathways of the flexible educt squalene from the membrane interior to the active center cavity and of the rigid fused-ring product hopene in the reverse direction are discussed. The enzyme contains eight so-called QW-sequence repeats that fortify the alpha/alpha-barrels by an intricate interaction network. They are unique to the known triterpene cyclases and are presumed to shield these enzymes against the released enthalpy of the highly exergonic catalyzed reaction. The enzyme is a monotopic membrane protein, the membrane-binding interactions of which are described and compared with those of two prostaglandin-H2 synthase isoenzymes, the only other structurally characterized proteins of this type. In the crystals the membrane-binding regions face each other, suggesting a micelle-type detergent structure between them.


    Related Citations: 
    • Structure and Function of a Squalene Cyclase
      Wendt, K.U., Poralla, K., Schulz, G.E.
      (1997) Science 277: 1811
    • Crystallization and Preliminary X-Ray Crystallographic Analysis of Squalene-Hopene Cyclase from Alicyclobacillus Acidocaldarius
      Wendt, K.U., Feil, C., Lenhart, A., Poralla, K., Schulz, G.E.
      (1997) Protein Sci 6: 722

    Organizational Affiliation

    Institut für Organische Chemie und Biochemie, Albertstr. 21, Freiburg im Breisgau, D-79104, Germany.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
SQUALENE-HOPENE CYCLASEAB631Alicyclobacillus acidocaldariusMutation(s): 2 
EC: 5.4.99 (PDB Primary Data), 4.2.1.129 (UniProt), 5.4.99.17 (UniProt)
Membrane protein
Mpstruc
Group: 
MONOTOPIC MEMBRANE PROTEINS
Sub Group: 
Squalene-Hopene Cyclases
Protein: 
Squalene-hopene cyclase
Find proteins for P33247 (Alicyclobacillus acidocaldarius subsp. acidocaldarius (strain ATCC 27009 / DSM 446 / JCM 5260 / NBRC 15652 / NCIMB 11725 / NRRL B-14509 / 104-1A))
Explore P33247 
Go to UniProtKB:  P33247
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
C8E
Query on C8E

Download CCD File 
A, B
(HYDROXYETHYLOXY)TRI(ETHYLOXY)OCTANE
C16 H34 O5
FEOZZFHAVXYAMB-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.187 
  • R-Value Work: 0.153 
  • Space Group: P 43 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 118.82α = 90
b = 118.82β = 90
c = 276.2γ = 90
Software Package:
Software NamePurpose
AMoREphasing
REFMACrefinement
XDSdata reduction
CCP4data scaling

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1999-04-27
    Type: Initial release
  • Version 1.1: 2008-03-03
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance