4r6w

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

spinqualitylabelsall models 4r6w, resolution 1.59Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4r6w is a 2 chain structure. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: PC, SAH Related: 3uj6, 3uj7, 3uj8, 3uj9, 3uja, 3ujb, 4r6x Resources: FirstGlance, OCA, RCSB, PDBsum Publication Abstract from PubMed 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 (pCho) 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 Tyr19-His132 dyad, which indicated an energetically unfavorable mechanism. Instead, the QM/MM calculations suggested an alternate mechanism involving Asp128. The reaction coordinate involves the step-wise transfer of a proton to Asp128 via a bridging water molecule followed by a typical SN2-type methyl transfer from S-adenosylmethionine to pEA. Functional analysis of the D128A, D128N, D128Q, and D128N PfPMT mutants show 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 pCho reveal how mutation of Asp128 disrupts a hydrogen bond network in the active site. The combined QM/MM, biochemical, and structural studies identify a key role for Asp128 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. An Alternate Mechanism for the Methylation of Phosphoethanolamine Catalyzed by Plasmodium falciparum Phosphoethanolamine Methyltransferase.,Saen-Oon S, Lee SG, Jez JM, Guallar V J Biol Chem. 2014 Oct 6. pii: jbc.M114.611319. PMID:25288796 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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