GDP-perosamine synthase K186A mutant from Caulobacter crescentus with bound sugar ligand

Experimental Data Snapshot

  • Resolution: 1.60 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.166 

Starting Model: experimental
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Accommodation of GDP-linked sugars in the active site of GDP-perosamine synthase

Cook, P.D.Carney, A.E.Holden, H.M.

(2008) Biochemistry 47: 10685-10693

  • DOI: https://doi.org/10.1021/bi801309q
  • Primary Citation of Related Structures:  
    3DR4, 3DR7

  • PubMed Abstract: 

    Perosamine (4-amino-4,6-dideoxy- d-mannose), or its N-acetylated form, is one of several dideoxy sugars found in the O-antigens of such infamous Gram-negative bacteria as Vibrio cholerae O1 and Escherichia coli O157:H7. It is added to the bacterial O-antigen via a nucleotide-linked version, namely GDP-perosamine. Three enzymes are required for the biosynthesis of GDP-perosamine starting from mannose 1-phosphate. The focus of this investigation is GDP-perosamine synthase from Caulobacter crescentus, which catalyzes the final step in GDP-perosamine synthesis, the conversion of GDP-4-keto-6-deoxymannose to GDP-perosamine. The enzyme is PLP-dependent and belongs to the aspartate aminotransferase superfamily. It contains the typically conserved active site lysine residue, which forms a Schiff base with the PLP cofactor. Two crystal structures were determined for this investigation: a site-directed mutant protein (K186A) complexed with GDP-perosamine and the wild-type enzyme complexed with an unnatural ligand, GDP-3-deoxyperosamine. These structures, determined to 1.6 and 1.7 A resolution, respectively, revealed the manner in which products, and presumably substrates, are accommodated within the active site pocket of GDP-perosamine synthase. Additional kinetic analyses using both the natural and unnatural substrates revealed that the K m for the unnatural substrate was unperturbed relative to that of the natural substrate, but the k cat was lowered by a factor of approximately 200. Taken together, these studies shed light on why GDP-perosamine synthase functions as an aminotransferase whereas another very similar PLP-dependent enzyme, GDP-4-keto-6-deoxy- d-mannose 3-dehydratase or ColD, catalyzes a dehydration reaction using the same substrate.

  • Organizational Affiliation

    Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Putative perosamine synthetase
A, B, C, D
391Caulobacter vibrioidesMutation(s): 1 
Gene Names: per
Find proteins for Q9A9H3 (Caulobacter vibrioides (strain ATCC 19089 / CB15))
Explore Q9A9H3 
Go to UniProtKB:  Q9A9H3
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ9A9H3
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on G4M

Download Ideal Coordinates CCD File 
E [auth A],
F [auth B],
I [auth C],
J [auth D]
[(2R,3S,4R,5R)-5-(2-amino-6-oxo-1,6-dihydro-9H-purin-9-yl)-3,4-dihydroxytetrahydrofuran-2-yl]methyl (2R,3S,4S,5S,6R)-3,4-dihydroxy-5-[({3-hydroxy-2-methyl-5-[(phosphonooxy)methyl]pyridin-4-yl}methyl)amino]-6-methyltetrahydro-2H-pyran-2-yl dihydrogen diphosphate
C24 H36 N7 O19 P3
Query on EDO

Download Ideal Coordinates CCD File 
G [auth B],
H [auth B]
C2 H6 O2
Experimental Data & Validation

Experimental Data

  • Resolution: 1.60 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.166 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 50.099α = 90
b = 151.921β = 102.09
c = 105.747γ = 90
Software Package:
Software NamePurpose
HKL-2000data reduction
SCALEPACKdata scaling

Structure Validation

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Ligand Structure Quality Assessment 

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2008-10-14
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2021-07-28
    Changes: Database references, Derived calculations, Refinement description, Source and taxonomy
  • Version 1.3: 2021-10-20
    Changes: Database references
  • Version 1.4: 2023-08-30
    Changes: Data collection, Refinement description