1GK9

Crystal structures of penicillin acylase enzyme-substrate complexes: Structural insights into the catalytic mechanism


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.30 Å
  • R-Value Free: 0.169 
  • R-Value Work: 0.148 

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


Literature

Crystal Structures of Penicillin Acylase Enzyme-Substrate Complexes: Structural Insights Into the Catalytic Mechanism

Mcvey, C.E.Walsh, M.A.Dodson, G.G.S, K.Brannigan, J.A.

(2001) J Mol Biol 313: 139

  • DOI: https://doi.org/10.1006/jmbi.2001.5043
  • Primary Citation of Related Structures:  
    1GK9, 1GKF, 1GM7, 1GM8, 1GM9

  • PubMed Abstract: 

    The crystal structure of penicillin G acylase from Escherichia coli has been determined to a resolution of 1.3 A from a crystal form grown in the presence of ethylene glycol. To study aspects of the substrate specificity and catalytic mechanism of this key biotechnological enzyme, mutants were made to generate inactive protein useful for producing enzyme-substrate complexes. Owing to the intimate association of enzyme activity and precursor processing in this protein family (the Ntn hydrolases), most attempts to alter active-site residues lead to processing defects. Mutation of the invariant residue Arg B263 results in the accumulation of a protein precursor form. However, the mutation of Asn B241, a residue implicated in stabilisation of the tetrahedral intermediate during catalysis, inactivates the enzyme but does not prevent autocatalytic processing or the ability to bind substrates. The crystal structure of the Asn B241 Ala oxyanion hole mutant enzyme has been determined in its native form and in complex with penicillin G and penicillin G sulphoxide. We show that Asn B241 has an important role in maintaining the active site geometry and in productive substrate binding, hence the structure of the mutant protein is a poor model for the Michaelis complex. For this reason, we subsequently solved the structure of the wild-type protein in complex with the slowly processed substrate penicillin G sulphoxide. Analysis of this structure suggests that the reaction mechanism proceeds via direct nucleophilic attack of Ser B1 on the scissile amide and not as previously proposed via a tightly H-bonded water molecule acting as a "virtual" base.


  • Organizational Affiliation

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


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
PENICILLIN G ACYLASE ALPHA SUBUNIT260Escherichia coliMutation(s): 0 
Gene Names: PAC
EC: 3.5.1.11
UniProt
Find proteins for P06875 (Escherichia coli)
Explore P06875 
Go to UniProtKB:  P06875
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP06875
Sequence Annotations
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  • Reference Sequence
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
PENICILLIN G ACYLASE BETA SUBUNIT557Escherichia coliMutation(s): 0 
Gene Names: PAC
EC: 3.5.1.11
UniProt
Find proteins for P06875 (Escherichia coli)
Explore P06875 
Go to UniProtKB:  P06875
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP06875
Sequence Annotations
Expand
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
EDO
Query on EDO

Download Ideal Coordinates CCD File 
C [auth A]
D [auth A]
E [auth A]
F [auth B]
G [auth B]
C [auth A],
D [auth A],
E [auth A],
F [auth B],
G [auth B],
H [auth B],
I [auth B],
J [auth B],
K [auth B],
L [auth B],
M [auth B],
N [auth B],
O [auth B],
P [auth B],
Q [auth B],
R [auth B],
S [auth B],
T [auth B],
U [auth B],
V [auth B],
W [auth B],
X [auth B],
Y [auth B],
Z [auth B]
1,2-ETHANEDIOL
C2 H6 O2
LYCAIKOWRPUZTN-UHFFFAOYSA-N
CA
Query on CA

Download Ideal Coordinates CCD File 
AA [auth B]CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.30 Å
  • R-Value Free: 0.169 
  • R-Value Work: 0.148 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 51.3α = 90
b = 131.6β = 105.9
c = 63.9γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
DENZOdata reduction
SCALEPACKdata scaling
AMoREphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2002-01-04
    Type: Initial release
  • Version 1.1: 2011-05-08
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2023-12-13
    Changes: Data collection, Database references, Derived calculations, Other, Refinement description