Plasmodium falciparum phosphoethanolamine methyltransferase D128A mutant in complex with S-adenosylhomocysteine and phosphoethanolamine

Experimental Data Snapshot

  • Resolution: 2.55 Å
  • R-Value Free: 0.258 
  • R-Value Work: 0.203 
  • R-Value Observed: 0.205 

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An Alternative Mechanism for the Methylation of Phosphoethanolamine Catalyzed by Plasmodium falciparum Phosphoethanolamine Methyltransferase.

Saen-Oon, S.Lee, S.G.Jez, J.M.Guallar, V.

(2014) J Biol Chem 289: 33815-33825

  • DOI: https://doi.org/10.1074/jbc.M114.611319
  • Primary Citation of Related Structures:  
    4R6W, 4R6X

  • PubMed Abstract: 

    The phosphobase methylation pathway catalyzed by the phosphoethanolamine methyltransferase in Plasmodium falciparum (PfPMT), the malaria parasite, offers an attractive target for anti-parasitic drug development. PfPMT methylates phosphoethanolamine (pEA) to phosphocholine for use in membrane biogenesis. Quantum mechanics and molecular mechanics (QM/MM) calculations tested the proposed reaction mechanism for methylation of pEA involving the previously identified Tyr-19-His-132 dyad, which indicated an energetically unfavorable mechanism. Instead, the QM/MM calculations suggested an alternative mechanism involving Asp-128. The reaction coordinate involves the stepwise transfer of a proton to Asp-128 via a bridging water molecule followed by a typical Sn2-type methyl transfer from S-adenosylmethionine to pEA. Functional analysis of the D128A, D128E, D128Q, and D128N PfPMT mutants shows a loss of activity with pEA but not with the final substrate of the methylation pathway. X-ray crystal structures of the PfPMT-D128A mutant in complex with S-adenosylhomocysteine and either pEA or phosphocholine reveal how mutation of Asp-128 disrupts a hydrogen bond network in the active site. The combined QM/MM, biochemical, and structural studies identify a key role for Asp-128 in the initial step of the phosphobase methylation pathway in Plasmodium and provide molecular insight on the evolution of multiple activities in the active site of the PMT.

  • Organizational Affiliation

    From the Joint Barcelona Supercomputing Center-Centre for Genomic Regulation-Institute for Research in Biomedicine Research Program, Carrer de Jordi Girona 29, 08034 Barcelona, Spain.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Phosphoethanolamine N-methyltransferase
A, B
258Plasmodium falciparumMutation(s): 1 
Gene Names: PMT
Find proteins for Q8IDQ9 (Plasmodium falciparum (isolate 3D7))
Explore Q8IDQ9 
Go to UniProtKB:  Q8IDQ9
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ8IDQ9
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.55 Å
  • R-Value Free: 0.258 
  • R-Value Work: 0.203 
  • R-Value Observed: 0.205 
  • Space Group: P 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 76.826α = 90
b = 43.652β = 107.79
c = 88.053γ = 90
Software Package:
Software NamePurpose
HKL-3000data collection
HKL-3000data reduction
HKL-3000data 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: 2014-10-08
    Type: Initial release
  • Version 1.1: 2014-10-22
    Changes: Database references
  • Version 1.2: 2014-12-24
    Changes: Database references
  • Version 1.3: 2023-09-20
    Changes: Data collection, Database references, Derived calculations, Refinement description