4WKM

AmpR effector binding domain from Citrobacter freundii bound to UDP-MurNAc-pentapeptide


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.15 Å
  • R-Value Free: 0.254 
  • R-Value Work: 0.201 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

The beta-Lactamase Gene Regulator AmpR Is a Tetramer That Recognizes and Binds the d-Ala-d-Ala Motif of Its Repressor UDP-N-acetylmuramic Acid (MurNAc)-pentapeptide.

Vadlamani, G.Thomas, M.D.Patel, T.R.Donald, L.J.Reeve, T.M.Stetefeld, J.Standing, K.G.Vocadlo, D.J.Mark, B.L.

(2015) J.Biol.Chem. 290: 2630-2643

  • DOI: 10.1074/jbc.M114.618199

  • PubMed Abstract: 
  • Inducible expression of chromosomal AmpC β-lactamase is a major cause of β-lactam antibiotic resistance in the Gram-negative bacteria Pseudomonas aeruginosa and Enterobacteriaceae. AmpC expression is induced by the LysR-type transcriptional regulator ...

    Inducible expression of chromosomal AmpC β-lactamase is a major cause of β-lactam antibiotic resistance in the Gram-negative bacteria Pseudomonas aeruginosa and Enterobacteriaceae. AmpC expression is induced by the LysR-type transcriptional regulator (LTTR) AmpR, which activates ampC expression in response to changes in peptidoglycan (PG) metabolite levels that occur during exposure to β-lactams. Under normal conditions, AmpR represses ampC transcription by binding the PG precursor UDP-N-acetylmuramic acid (MurNAc)-pentapeptide. When exposed to β-lactams, however, PG catabolites (1,6-anhydroMurNAc-peptides) accumulate in the cytosol, which have been proposed to competitively displace UDP-MurNAc-pentapeptide from AmpR and convert it into an activator of ampC transcription. Here we describe the molecular interactions between AmpR (from Citrobacter freundii), its DNA operator, and repressor UDP-MurNAc-pentapeptide. Non-denaturing mass spectrometry revealed AmpR to be a homotetramer that is stabilized by DNA containing the T-N11-A LTTR binding motif and revealed that it can bind four repressor molecules in an apparently stepwise manner. A crystal structure of the AmpR effector-binding domain bound to UDP-MurNAc-pentapeptide revealed that the terminal D-Ala-D-Ala motif of the repressor forms the primary contacts with the protein. This observation suggests that 1,6-anhydroMurNAc-pentapeptide may convert AmpR into an activator of ampC transcription more effectively than 1,6-anhydroMurNAc-tripeptide (which lacks the D-Ala-D-Ala motif). Finally, small angle x-ray scattering demonstrates that the AmpR·DNA complex adopts a flat conformation similar to the LTTR protein AphB and undergoes only a slight conformational change when binding UDP-MurNAc-pentapeptide. Modeling the AmpR·DNA tetramer bound to UDP-MurNAc-pentapeptide predicts that the UDP-MurNAc moiety of the repressor participates in modulating AmpR function.


    Organizational Affiliation

    From the Departments of Microbiology.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
LysR family transcriptional regulator
A, B, C, D, E, F, G, H
219N/AMutation(s): 0 
Protein Feature View is not available: No corresponding UniProt sequence found.
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
ALA-FGA-API-DAL-DAL
I, J, K, L, M, N, O, P
5N/AMutation(s): 0 
Protein Feature View is not available: No corresponding UniProt sequence found.
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
GOL
Query on GOL

Download SDF File 
Download CCD File 
A, C, D, E, F, G, H
GLYCEROL
GLYCERIN; PROPANE-1,2,3-TRIOL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
 Ligand Interaction
MUB
Query on MUB

Download SDF File 
Download CCD File 
I, J, K, L, M, N, O, P
N-ACETYLMURAMIC ACID
C11 H19 N O8
MNLRQHMNZILYPY-MDMHTWEWSA-N
 Ligand Interaction
Modified Residues  3 Unique
IDChainsTypeFormula2D DiagramParent
API
Query on API
I, J, K, L, M, N, O, P
L-PEPTIDE LINKINGC7 H14 N2 O4LYS
FGA
Query on FGA
I, J, K, L, M, N, O, P
D-gamma-peptide, C-delta linkingC5 H9 N O4

--

DAL
Query on DAL
I, J, K, L, M, N, O, P
D-PEPTIDE LINKINGC3 H7 N O2

--

Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.15 Å
  • R-Value Free: 0.254 
  • R-Value Work: 0.201 
  • Space Group: P 21 21 2
Unit Cell:
Length (Å)Angle (°)
a = 62.700α = 90.00
b = 183.600β = 90.00
c = 197.810γ = 90.00
Software Package:
Software NamePurpose
PHENIXrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
Canadian Institutes of Health Research and Cystic Fibrosis CanadaCanada--

Revision History 

  • Version 1.0: 2014-12-17
    Type: Initial release
  • Version 1.1: 2015-02-11
    Type: Structure summary