1PI4

Structure of N289A mutant of AmpC in complex with SM3, a phenylglyclboronic acid bearing the cephalothin R1 side chain


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.39 Å
  • R-Value Free: 0.173 
  • R-Value Work: 0.159 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Thermodynamic cycle analysis and inhibitor design against beta-lactamase.

Roth, T.A.Minasov, G.Morandi, S.Prati, F.Shoichet, B.K.

(2003) Biochemistry 42: 14483-14491

  • DOI: 10.1021/bi035054a
  • Primary Citation of Related Structures:  1PI5

  • PubMed Abstract: 
  • Beta-lactamases are the most widespread resistance mechanism to beta-lactam antibiotics, such as the penicillins and cephalosporins. Transition-state analogues that bind to the enzymes with nanomolar affinities have been introduced in an effort to re ...

    Beta-lactamases are the most widespread resistance mechanism to beta-lactam antibiotics, such as the penicillins and cephalosporins. Transition-state analogues that bind to the enzymes with nanomolar affinities have been introduced in an effort to reverse the resistance conferred by these enzymes. To understand the origins of this affinity, and to guide design of future inhibitors, double-mutant thermodynamic cycle experiments were undertaken. An unexpected hydrogen bond between the nonconserved Asn289 and a key inhibitor carboxylate was observed in the X-ray crystal structure of a 1 nM inhibitor (compound 1) in complex with AmpC beta-lactamase. To investigate the energy of this hydrogen bond, the mutant enzyme N289A was made, as was an analogue of 1 that lacked the carboxylate (compound 2). The differential affinity of the four different protein and analogue complexes indicates that the carboxylate-amide hydrogen bond contributes 1.7 kcal/mol to overall binding affinity. Synthesis of an analogue of 1 where the carboxylate was replaced with an aldehyde led to an inhibitor that lost all this hydrogen bond energy, consistent with the importance of the ionic nature of this hydrogen bond. To investigate the structural bases of these energies, X-ray crystal structures of N289A/1 and N289A/2 were determined to 1.49 and 1.39 A, respectively. These structures suggest that no significant rearrangement occurs in the mutant versus the wild-type complexes with both compounds. The mutant enzymes L119A and L293A were made to investigate the interaction between a phenyl ring in 1 and these residues. Whereas deletion of the phenyl itself diminishes affinity by 5-fold, the double-mutant cycles suggest that this energy does not come through interaction with the leucines, despite the close contact in the structure. The energies of these interactions provide key information for the design of improved inhibitors against beta-lactamases. The high magnitude of the ion-dipole interaction between Asn289 and the carboxylate of 1 is consistent with the idea that ionic interactions can provide significant net affinity in inhibitor complexes.


    Organizational Affiliation

    Department of Pharmaceutical Chemistry, University of California San Francisco, 600 16th Street, San Francisco, California 94143-2240, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Beta-lactamase
A, B
358Escherichia coli (strain K12)Gene Names: ampC (ampA)
EC: 3.5.2.6
Find proteins for P00811 (Escherichia coli (strain K12))
Go to UniProtKB:  P00811
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
K
Query on K

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Download CCD File 
A, B
POTASSIUM ION
K
NPYPAHLBTDXSSS-UHFFFAOYSA-N
 Ligand Interaction
PO4
Query on PO4

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Download CCD File 
A
PHOSPHATE ION
O4 P
NBIIXXVUZAFLBC-UHFFFAOYSA-K
 Ligand Interaction
SM3
Query on SM3

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Download CCD File 
A, B
(1R)-1-(2-THIENYLACETYLAMINO)-1-PHENYLMETHYLBORONIC ACID
C13 H14 B N O3 S
LGJCDEZMANATFA-ZDUSSCGKSA-N
 Ligand Interaction
External Ligand Annotations 
IDBinding Affinity (Sequence Identity %)
SM3Ki: 37 nM BINDINGMOAD
SM3Ki: 37 nM PDBBIND
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.39 Å
  • R-Value Free: 0.173 
  • R-Value Work: 0.159 
  • Space Group: C 1 2 1
Unit Cell:
Length (Å)Angle (°)
a = 118.628α = 90.00
b = 76.104β = 115.61
c = 97.836γ = 90.00
Software Package:
Software NamePurpose
AMoREphasing
DENZOdata reduction
SCALEPACKdata scaling
CNSrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2004-02-24
    Type: Initial release
  • Version 1.1: 2008-04-29
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance