4JEN

Structure of Clostridium botulinum CMP N-glycosidase, BcmB


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3 Å
  • R-Value Free: 0.250 
  • R-Value Work: 0.234 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Reversal of the substrate specificity of CMP N-glycosidase to dCMP.

Sikowitz, M.D.Cooper, L.E.Begley, T.P.Kaminski, P.A.Ealick, S.E.

(2013) Biochemistry 52: 4037-4047

  • DOI: 10.1021/bi400316p
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • MilB is a CMP hydrolase involved in the early steps of biosynthesis of the antifungal compound mildiomycin. An enzyme from the bacimethrin biosynthetic pathway, BcmB, is closely related to MilB in both sequence and function. These two enzymes belong ...

    MilB is a CMP hydrolase involved in the early steps of biosynthesis of the antifungal compound mildiomycin. An enzyme from the bacimethrin biosynthetic pathway, BcmB, is closely related to MilB in both sequence and function. These two enzymes belong to the nucleoside 2'-deoxyribosyltransferase (NDT) superfamily. NDTs catalyze N-glycosidic bond cleavage of 2'-deoxynucleosides via a covalent 2-deoxyribosyl-enzyme intermediate. Conservation of key active site residues suggests that members of the NDT superfamily share a common mechanism; however, the enzymes differ in their substrate preferences. Substrates vary in the type of nucleobase, the presence or absence of a 2'-hydroxyl group, and the presence or absence of a 5'-phosphate group. We have determined the structures of MilB and BcmB and compared them to previously determined structures of NDT superfamily members. The comparisons reveal how these enzymes differentiate between ribosyl and deoxyribosyl nucleotides or nucleosides and among different nucleobases. The 1.6 Å structure of the MilB-CMP complex reveals an active site feature that is not obvious from comparisons of sequence alone. MilB and BcmB that prefer substrates containing 2'-ribosyl groups have a phenylalanine positioned in the active site, whereas NDT family members with a preference for 2'-deoxyribosyl groups have a tyrosine residue. Further studies show that the phenylalanine is critical for the specificity of MilB and BcmB toward CMP, and mutation of this phenylalanine residue to tyrosine results in a 1000-fold reversal of substrate specificity from CMP to dCMP.


    Organizational Affiliation

    Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
CMP N-GLYCOSIDASE
A, B, C
176N/AMutation(s): 0 
Protein Feature View is not available: No corresponding UniProt sequence found.
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
PO4
Query on PO4

Download SDF File 
Download CCD File 
A, B, C
PHOSPHATE ION
O4 P
NBIIXXVUZAFLBC-UHFFFAOYSA-K
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3 Å
  • R-Value Free: 0.250 
  • R-Value Work: 0.234 
  • Space Group: C 1 2 1
Unit Cell:
Length (Å)Angle (°)
a = 177.948α = 90.00
b = 104.006β = 97.98
c = 40.225γ = 90.00
Software Package:
Software NamePurpose
DENZOdata reduction
PHENIXrefinement
MOLREPphasing
PDB_EXTRACTdata extraction
SCALEPACKdata scaling
ADSCdata collection
HKL-2000data reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2013-09-11
    Type: Initial release
  • Version 1.1: 2017-11-15
    Type: Refinement description