4WCJ

Structure of IcaB from Ammonifex degensii


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.7 Å
  • R-Value Free: 0.231 
  • R-Value Work: 0.204 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Structural Basis for the De-N-acetylation of Poly-beta-1,6-N-acetyl-d-glucosamine in Gram-positive Bacteria.

Little, D.J.Bamford, N.C.Pokrovskaya, V.Robinson, H.Nitz, M.Howell, P.L.

(2014) J.Biol.Chem. 289: 35907-35917

  • DOI: 10.1074/jbc.M114.611400

  • PubMed Abstract: 
  • Exopolysaccharides are required for the development and integrity of biofilms produced by a wide variety of bacteria. In staphylococci, partial de-N-acetylation of the exopolysaccharide poly-β-1,6-N-acetyl-d-glucosamine (PNAG) by the extracellular pr ...

    Exopolysaccharides are required for the development and integrity of biofilms produced by a wide variety of bacteria. In staphylococci, partial de-N-acetylation of the exopolysaccharide poly-β-1,6-N-acetyl-d-glucosamine (PNAG) by the extracellular protein IcaB is required for biofilm formation. To understand the molecular basis for PNAG de-N-acetylation, the structure of IcaB from Ammonifex degensii (IcaBAd) has been determined to 1.7 Å resolution. The structure of IcaBAd reveals a (β/α)7 barrel common to the family four carbohydrate esterases (CE4s) with the canonical motifs circularly permuted. The metal dependence of IcaBAd is similar to most CE4s showing the maximum rates of de-N-acetylation with Ni(2+), Co(2+), and Zn(2+). From docking studies with β-1,6-GlcNAc oligomers and structural comparison to PgaB from Escherichia coli, the Gram-negative homologue of IcaB, we identify Arg-45, Tyr-67, and Trp-180 as key residues for PNAG binding during catalysis. The absence of these residues in PgaB provides a rationale for the requirement of a C-terminal domain for efficient deacetylation of PNAG in Gram-negative species. Mutational analysis of conserved active site residues suggests that IcaB uses an altered catalytic mechanism in comparison to other characterized CE4 members. Furthermore, we identified a conserved surface-exposed hydrophobic loop found only in Gram-positive homologues of IcaB. Our data suggest that this loop is required for membrane association and likely anchors IcaB to the membrane during polysaccharide biosynthesis. The work presented herein will help guide the design of IcaB inhibitors to combat biofilm formation by staphylococci.


    Organizational Affiliation

    From the Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada, Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada.,Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada, and mnitz@chem.utoronto.ca.,From the Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada, Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada, howell@sickkids.ca.,Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada, and.,Photon Sciences Division, Brookhaven National Laboratory, Upton, New York 11973-5000.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Polysaccharide deacetylase
A
264Ammonifex degensii (strain DSM 10501 / KC4)Mutation(s): 0 
Find proteins for C9RCK9 (Ammonifex degensii (strain DSM 10501 / KC4))
Go to UniProtKB:  C9RCK9
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
CL
Query on CL

Download SDF File 
Download CCD File 
A
CHLORIDE ION
Cl
VEXZGXHMUGYJMC-UHFFFAOYSA-M
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.7 Å
  • R-Value Free: 0.231 
  • R-Value Work: 0.204 
  • Space Group: I 4
Unit Cell:
Length (Å)Angle (°)
a = 84.686α = 90.00
b = 84.686β = 90.00
c = 71.940γ = 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 ResearchCanada43998

Revision History 

  • Version 1.0: 2014-11-12
    Type: Initial release
  • Version 1.1: 2015-01-07
    Type: Database references