4AXV

Biochemical and structural characterization of the MpaA amidase as part of a conserved scavenging pathway for peptidoglycan derived peptides in gamma-proteobacteria


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.17 Å
  • R-Value Free: 0.233 
  • R-Value Work: 0.196 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Mpaa is a Murein-Tripeptide-Specific Zinc Carboxypeptidase that Functions as Part of a Catabolic Pathway for Peptidoglycan Derived Peptides in Gamma-Proteobacteria.

Maqbool, A.Herve, M.Mengin-Lecreulx, D.Wilkinson, A.J.Thomas, G.H.

(2012) Biochem.J. 448: 329

  • DOI: 10.1042/BJ20121164

  • PubMed Abstract: 
  • The murein peptide amidase MpaA is a cytoplasmic enzyme that processes peptides derived from the turnover of murein. We have purified the enzyme from Escherichia coli and demonstrated that it efficiently hydrolyses the γ-D-glutamyl-diaminopimelic aci ...

    The murein peptide amidase MpaA is a cytoplasmic enzyme that processes peptides derived from the turnover of murein. We have purified the enzyme from Escherichia coli and demonstrated that it efficiently hydrolyses the γ-D-glutamyl-diaminopimelic acid bond in the murein tripeptide (L-Ala-γ-D-Glu-meso-Dap), with Km and kcat values of 0.41±0.05 mM and 38.3±10 s-1. However, it is unable to act on the murein tetrapeptide (L-Ala-γ-D-Glu-meso-Dap-D-Ala). E. coli MpaA is a homodimer containing one bound zinc ion per chain, as judged by mass spectrometric analysis and size-exclusion chromatography. To investigate the structure of MpaA we solved the crystal structure of the orthologous protein from Vibrio harveyi to 2.17 Å (1Å=0.1 nm). Vh_MpaA, which has identical enzymatic and biophysical properties to the E. coli enzyme, has high structural similarity to eukaryotic zinc carboxypeptidases. The structure confirms that MpaA is a dimeric zinc metalloprotein. Comparison of the structure of MpaA with those of other carboxypeptidases reveals additional structure that partially occludes the substrate-binding groove, perhaps explaining the narrower substrate specificity of the enzyme compared with other zinc carboxypeptidases. In γ-proteobacteria mpaA is often located adjacent to mppA which encodes a periplasmic transporter protein previously shown to bind murein tripeptide. We demonstrate that MppA can also bind murein tetrapeptide with high affinity. The genetic coupling of these genes and their related biochemical functions suggest that MpaA amidase and MppA transporter form part of a catabolic pathway for utilization of murein-derived peptides that operates in γ-proteobacteria in addition to the established murein recycling pathways.


    Organizational Affiliation

    Department of Biology (Area 10), Department of Chemistry, University of York, York YO10 5DD, UK.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
MPAA
A
243Vibrio campbellii (strain ATCC BAA-1116 / BB120)Mutation(s): 0 
Find proteins for A7N805 (Vibrio campbellii (strain ATCC BAA-1116 / BB120))
Go to UniProtKB:  A7N805
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ZN
Query on ZN

Download SDF File 
Download CCD File 
A
ZINC ION
Zn
PTFCDOFLOPIGGS-UHFFFAOYSA-N
 Ligand Interaction
EDO
Query on EDO

Download SDF File 
Download CCD File 
A
1,2-ETHANEDIOL
ETHYLENE GLYCOL
C2 H6 O2
LYCAIKOWRPUZTN-UHFFFAOYSA-N
 Ligand Interaction
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
MSE
Query on MSE
A
L-PEPTIDE LINKINGC5 H11 N O2 SeMET
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.17 Å
  • R-Value Free: 0.233 
  • R-Value Work: 0.196 
  • Space Group: P 65 2 2
Unit Cell:
Length (Å)Angle (°)
a = 73.600α = 90.00
b = 73.600β = 90.00
c = 208.710γ = 120.00
Software Package:
Software NamePurpose
REFMACrefinement
xia2data reduction
SHELXphasing
xia2data scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2012-09-26
    Type: Initial release
  • Version 1.1: 2012-12-05
    Type: Database references