Biological Assembly 1  

 3D View: Structure | Electron Density | Ligand Interaction

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Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A 

Biological assembly 1 assigned by authors.

Macromolecule Content

• Total Structure Weight: 71879.44 
• Atom Count: 4979 
• Residue Count: 631 
• Unique protein chains: 1

1SQC

SQUALENE-HOPENE-CYCLASE FROM ALICYCLOBACILLUS ACIDOCALDARIUS

• DOI: 10.2210/pdb1SQC/pdb

• Classification: ISOMERASE
• Organism(s): Alicyclobacillus acidocaldarius subsp. acidocaldarius (strain ATCC 27009 / DSM 446 / JCM 5260 / NBRC 15652 / NCIMB 11725 / NRRL B-14509 / 104-1A)
• Expression System: Escherichia coli K-12


• Deposited: 1997-09-01 Released: 1997-12-17 
• Deposition Author(s): Wendt, K.U., Schulz, G.E.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.85 Å
• R-Value Free: 0.243 
• R-Value Work: 0.167 

Literature

Structure and function of a squalene cyclase.

Wendt, K.U., Poralla, K., Schulz, G.E.

(1997) Science 277: 1811-1815

• PubMed: 9295270 
• Also Cited By: 1UMP, 1GSZ, 1O79, 1O6R, 1O6Q, 1O6H, 1H3C, 1H3B, 1H3A, 1H39, 1H37, 1H36, 1H35


• PubMed Abstract: 
  

The crystal structure of squalene-hopene cyclase from Alicyclobacillus acidocaldarius was determined at 2.9 angstrom resolution. The mechanism and sequence of this cyclase are closely related to those of 2,3-oxidosqualene cyclases that catalyze the cyclization step in cholesterol biosynthesis. The structure reveals a membrane protein with membrane-binding characteristics similar to those of prostaglandin-H2 synthase, the only other reported protein of this type. The active site of the enzyme is located in a large central cavity that is of suitable size to bind squalene in its required conformation and that is lined by aromatic residues. The structure supports a mechanism in which the acid starting the reaction by protonating a carbon-carbon double bond is an aspartate that is coupled to a histidine. Numerous surface alpha helices are connected by characteristic QW-motifs (Q is glutamine and W is tryptophan) that tighten the protein structure, possibly for absorbing the reaction energy without structural damage.

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Related Citations: 

• 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




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Organizational Affiliation: 

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

Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details
SQUALENE-HOPENE CYCLASE	A	631	Alicyclobacillus acidocaldarius subsp. acidocaldarius (strain ATCC 27009 / DSM 446 / JCM 5260 / NBRC 15652 / NCIMB 11725 / NRRL B-14509 / 104-1A)	Mutation(s): 0  Gene Names: shc EC: 4.2.1.129, 5.4.99.17
Find proteins for P33247 (Alicyclobacillus acidocaldarius subsp. acidocaldarius (strain ATCC 27009 / DSM 446 / JCM 5260 / NBRC 15652 / NCIMB 11725 / NRRL B-14509 / 104-1A)) Go to UniProtKB:  P33247

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram & Interactions
LDA	A	LAURYL DIMETHYLAMINE-N-OXIDE C14 H31 N O SYELZBGXAIXKHU-UHFFFAOYSA-N

External Ligand Annotations
ID	Binding Affinity (Sequence Identity %)
LDA	Ki: 140 nM PDBBIND

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.85 Å
• R-Value Free: 0.243 
• R-Value Work: 0.167 
• Space Group: P 3 2 1

Unit Cell:

Length (Å)	Angle (°)
a = 140.700	α = 90.00
b = 140.700	β = 90.00
c = 81.900	γ = 120.00

Software Package:

Software Name	Purpose
X-PLOR	model building
XSCALE	data scaling
X-PLOR	refinement
X-PLOR	phasing
XDS	data reduction
CCP4	data scaling

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 1997-09-01 
• Released Date: 1997-12-17 
• Deposition Author(s): Wendt, K.U., Schulz, G.E.

Revision History 

• Version 1.0: 1997-12-17
  Type: Initial release
• Version 1.1: 2008-03-24
  Type: Version format compliance
• Version 1.2: 2011-07-13
  Type: Version format compliance