Biological Assembly 1  

 3D View: Structure | Electron Density

Global Symmetry: Dihedral - D2  (3D View)
Global Stoichiometry: Homo 4-mer - A4 

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

Macromolecule Content

• Total Structure Weight: 224.22 kDa 
• Atom Count: 15613 
• Residue Count: 1946 
• Unique protein chains: 1

1Q15

Carbapenam Synthetase

• DOI: 10.2210/pdb1Q15/pdb

• Classification: BIOSYNTHETIC PROTEIN
• Organism(s): Pectobacterium carotovorum
• Expression System: Escherichia coli BL21(DE3)
• Mutation(s): No 


• Deposited: 2003-07-18 Released: 2003-11-04 
• Deposition Author(s): Miller, M.T., Gerratana, B., Stapon, A., Townsend, C.A., Rosenzweig, A.C.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.30 Å
• R-Value Free: 0.249 
• R-Value Work: 0.203 
• R-Value Observed: 0.249 

Literature

Crystal Structure of Carbapenam Synthetase (CarA)

Miller, M.T., Gerratana, B., Stapon, A., Townsend, C.A., Rosenzweig, A.C.

(2003) J Biol Chem 278: 40996-41002

• PubMed: 12890666 
• DOI: 10.1074/jbc.M307901200
• Primary Citation of Related Structures:  
  1Q15, 1Q19


• PubMed Abstract: 
  

Carbapenam synthetase (CarA) is an ATP/Mg2+-dependent enzyme that catalyzes formation of the beta-lactam ring in (5R)-carbapenem-3-carboxylic acid biosynthesis. CarA is homologous to beta-lactam synthetase (beta-LS), which is involved in clavulanic acid biosynthesis. The catalytic cycles of CarA and beta-LS mediate substrate adenylation followed by beta-lactamization via a tetrahedral intermediate or transition state. Another member of this family of ATP/Mg2+-dependent enzymes, asparagine synthetase (AS-B), catalyzes intermolecular, rather than intramolecular, amide bond formation in asparagine biosynthesis. The crystal structures of apo-CarA and CarA complexed with the substrate (2S,5S)-5-carboxymethylproline (CMPr), ATP analog alpha,beta-methyleneadenosine 5'-triphosphate (AMP-CPP), and a single Mg2+ ion have been determined. CarA forms a tetramer. Each monomer resembles beta-LS and AS-B in overall fold, but key differences are observed. The N-terminal domain lacks the glutaminase active site found in AS-B, and an extended loop region not observed in beta-LS or AS-B is present. Comparison of the C-terminal synthetase active site to that in beta-LS reveals that the ATP binding site is highly conserved. By contrast, variations in the substrate binding pocket reflect the different substrates of the two enzymes. The Mg2+ coordination is also different. Several key residues in the active site are conserved between CarA and beta-LS, supporting proposed roles in beta-lactam formation. These data provide further insight into the structures of this class of enzymes and suggest that CarA might be a versatile target for protein engineering experiments aimed at developing improved production methods and new carbapenem antibiotics.

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Organizational Affiliation: 

Department of Biochemistry, Northwestern University, Evanston, Illinois 60208, USA.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
CarA	A, B, C, D	503	Pectobacterium carotovorum	Mutation(s): 0  EC: 6.3.3.6
Find proteins for Q9XB61 (Pectobacterium carotovorum subsp. carotovorum) Explore Q9XB61  Go to UniProtKB:  Q9XB61

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.30 Å
• R-Value Free: 0.249 
• R-Value Work: 0.203 
• R-Value Observed: 0.249 
• Space Group: P 1 2₁ 1

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 61.101	α = 90
b = 180.388	β = 97.46
c = 96.633	γ = 90

Software Package:

Software Name	Purpose
CNS	refinement
MOSFLM	data reduction
CCP4	data scaling
SOLVE	phasing

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2003-07-18 
• Released Date: 2003-11-04 
Deposition Author(s): Miller, M.T., Gerratana, B., Stapon, A., Townsend, C.A., Rosenzweig, A.C.

Revision History 

• Version 1.0: 2003-11-04
  Type: Initial release
  
• Version 1.1: 2008-04-29
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Version format compliance