3PTY

Crystal structure of the C-terminal extracellular domain of Mycobacterium tuberculosis EmbC


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å
  • R-Value Free: 0.207 
  • R-Value Work: 0.187 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

The C-Terminal Domain of the Arabinosyltransferase Mycobacterium tuberculosis EmbC Is a Lectin-Like Carbohydrate Binding Module.

Alderwick, L.J.Lloyd, G.S.Ghadbane, H.May, J.W.Bhatt, A.Eggeling, L.Futterer, K.Besra, G.S.

(2011) Plos Pathog. 7: e1001299-e1001299

  • DOI: 10.1371/journal.ppat.1001299

  • PubMed Abstract: 
  • The D-arabinan-containing polymers arabinogalactan (AG) and lipoarabinomannan (LAM) are essential components of the unique cell envelope of the pathogen Mycobacterium tuberculosis. Biosynthesis of AG and LAM involves a series of membrane-embedded ara ...

    The D-arabinan-containing polymers arabinogalactan (AG) and lipoarabinomannan (LAM) are essential components of the unique cell envelope of the pathogen Mycobacterium tuberculosis. Biosynthesis of AG and LAM involves a series of membrane-embedded arabinofuranosyl (Araf) transferases whose structures are largely uncharacterised, despite the fact that several of them are pharmacological targets of ethambutol, a frontline drug in tuberculosis therapy. Herein, we present the crystal structure of the C-terminal hydrophilic domain of the ethambutol-sensitive Araf transferase M. tuberculosis EmbC, which is essential for LAM synthesis. The structure of the C-terminal domain of EmbC (EmbC(CT)) encompasses two sub-domains of different folds, of which subdomain II shows distinct similarity to lectin-like carbohydrate-binding modules (CBM). Co-crystallisation with a cell wall-derived di-arabinoside acceptor analogue and structural comparison with ligand-bound CBMs suggest that EmbC(CT) contains two separate carbohydrate binding sites, associated with subdomains I and II, respectively. Single-residue substitution of conserved tryptophan residues (Trp868, Trp985) at these respective sites inhibited EmbC-catalysed extension of LAM. The same substitutions differentially abrogated binding of di- and penta-arabinofuranoside acceptor analogues to EmbC(CT), linking the loss of activity to compromised acceptor substrate binding, indicating the presence of two separate carbohydrate binding sites, and demonstrating that subdomain II indeed functions as a carbohydrate-binding module. This work provides the first step towards unravelling the structure and function of a GT-C-type glycosyltransferase that is essential in M. tuberculosis.


    Organizational Affiliation

    School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Arabinosyltransferase C
A
406Mycobacterium tuberculosis (strain ATCC 25618 / H37Rv)Mutation(s): 0 
Gene Names: embC
EC: 2.4.2.-
Find proteins for P9WNL5 (Mycobacterium tuberculosis (strain ATCC 25618 / H37Rv))
Go to UniProtKB:  P9WNL5
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
PO4
Query on PO4

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

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Download CCD File 
A
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
AFO
Query on AFO

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Download CCD File 
A
octyl alpha-D-arabinofuranoside
C13 H26 O5
DULPXMOVQIYGDB-NDBYEHHHSA-N
 Ligand Interaction
External Ligand Annotations 
IDBinding Affinity (Sequence Identity %)
AFOKd: 3650 nM PDBBIND
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å
  • R-Value Free: 0.207 
  • R-Value Work: 0.187 
  • Space Group: P 65 2 2
Unit Cell:
Length (Å)Angle (°)
a = 129.130α = 90.00
b = 129.130β = 90.00
c = 136.730γ = 120.00
Software Package:
Software NamePurpose
ADSCdata collection
XDSdata reduction
SHELXDEphasing
XDSdata scaling
PHENIXrefinement

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2010-12-15
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance