2BHT

Crystal structure of O-acetylserine sulfhydrylase B

• PDB DOI: https://doi.org/10.2210/pdb2BHT/pdb

• Classification: TRANSFERASE
• Organism(s): Escherichia coli
• Expression System: Escherichia coli BL21(DE3)
• Mutation(s): Yes 


• Deposited: 2005-01-18 Released: 2005-06-22 
• Deposition Author(s): Claus, M.T., Zocher, G.E., Maier, T.H.P., Schulz, G.E.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.10 Å
• R-Value Free: 0.244 
• R-Value Observed: 0.225 

Starting Model: experimental

Literature

Structure of the O-Acetylserine Sulfhydrylase Isoenzyme Cysm from Escherichia Coli

Claus, M.T., Zocher, G.E., Maier, T.H.P., Schulz, G.E.

(2005) Biochemistry 44: 8620

• PubMed: 15952768 
• DOI: https://doi.org/10.1021/bi050485+
• Primary Citation of Related Structures:  
  2BHS, 2BHT


• PubMed Abstract: 
  

  The enzyme O-acetylserine sulfhydrylase participates in the biosynthesis of l-cysteine in bacteria and plants. The structure of isoenzyme B (CysM) from Escherichia coli was established in a hexagonal crystal form at 2.7 A resolution (wild-type) and in a merohedrally twinned tetragonal crystal form at 2.1 A resolution (surface mutant). Structural superpositions revealed the variations with respect to isoenzyme A (CysK) and explained the different substrate specificities. A geometric model of the reaction catalyzed by CysM is proposed. Both isoenzymes are used for the production of l-amino acid derivatives as building blocks for the synthesis of peptides and peptidomimetic drugs. Since the structure of CysM revealed a remarkable main chain variation at the active center, it constitutes a further starting point for engineering mutants with novel substrate specificities.

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Organizational Affiliation: 

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

Biological Assembly 1  

Global Symmetry: Cyclic - C2  (Explore in 3D)
Global Stoichiometry: Homo 2-mer - A2 

Biological assembly 1 assigned by authors and generated by PISA (software)

Biological Assembly 2  

Global Symmetry: Cyclic - C2  (Explore in 3D)
Global Stoichiometry: Homo 2-mer - A2 

Biological assembly 2 assigned by authors and generated by PISA (software)

Macromolecule Content

• Total Structure Weight: 131.65 kDa 
• Atom Count: 8,978 
• Modelled Residue Count: 1,152 
• Deposited Residue Count: 1,212 
• Unique protein chains: 1

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
CYSTEINE SYNTHASE B	A, B, C, D	303	Escherichia coli	Mutation(s): 3  EC: 2.5.1.47
UniProt
Find proteins for P16703 (Escherichia coli (strain K12)) Explore P16703  Go to UniProtKB:  P16703

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
PLP	E [auth A], F [auth B], G [auth C], H [auth D]	PYRIDOXAL-5'-PHOSPHATE C8 H10 N O6 P NGVDGCNFYWLIFO-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.10 Å
• R-Value Free: 0.244 
• R-Value Observed: 0.225 
• Space Group: I 4₁

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 149.94	α = 90
b = 149.94	β = 90
c = 194.01	γ = 90

Software Package:

Software Name	Purpose
SHELXL-97	refinement
XDS	data reduction
XSCALE	data scaling

Structure Validation

Entry History 

Deposition Data

• Released Date: 2005-06-22 
Deposition Author(s): Claus, M.T., Zocher, G.E., Maier, T.H.P., Schulz, G.E.

Revision History  

• Version 1.0: 2005-06-22
  Type: Initial release
  
• Version 1.1: 2015-11-11
  Changes: Atomic model, Database references, Derived calculations, Non-polymer description, Other, Refinement description, Structure summary, Version format compliance
• Version 1.2: 2023-12-13
  Changes: Data collection, Database references, Derived calculations, Other, Refinement description