Crystal structures of Trypanosoma brucei and Staphylococcus aureus mevalonate diphosphate decarboxylase inform on the determinants of specificity and reactivity

Emma Byres, Magnus S. Alphey, Terry K Smith, William N. Hunter

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)

Abstract

Mevalonate diphosphate decarboxylase (MDD) catalyzes the ATP-dependent decarboxylation of mevalonate 5-diphosphate (MDP) to form isopentenyl pyrophosphate, a ubiquitous precursor for isoprenoid biosynthesis. MDD is a poorly understood component of this important metabolic pathway. Complementation of a temperature-sensitive yeast mutant by the putative mdd genes of Trypanosoma brucei and Staphylococcus aureus provides proof-of-function. Crystal structures of MDD from T. brucei (TbMDD, at 1.8 angstrom resolution) and S. aureus (SaMDD, in two distinct crystal forms, each diffracting to 2.3 angstrom resolution) have been determined. Gel-filtration chromatography and analytical ultracentrifugation experiments indicate that TbMDD is predominantly monomeric in solution while SaMDD is dimeric. The new crystal structures and comparison with that of the yeast Saccharomyces cerevisiae enzyme (ScMDD) reveal the structural basis for this variance in quaternary structure. The presence of an ordered sulfate in the structure of TbMDD reveals for the first time details of a ligand binding in the MDD active site and, in conjunction with well-ordered water molecules, comparisons with the related enzyme mevalonate kinase, structural and biochemical data derived on ScMDD and SaMDD, allows us to model a ternary complex with MDP and ATP. This model facilitates discussion of the molecular determinants of substrate recognition and contributions made by specific residues to the enzyme mechanism. (C) 2007 Elsevier Ltd. All rights reserved.

Original languageEnglish
Pages (from-to)540-553
Number of pages14
JournalJournal of Molecular Biology
Volume371
Issue number2
DOIs
Publication statusPublished - 10 Aug 2007

Keywords

  • enzyme
  • mechanism
  • isoprenoid
  • trypanosomatid parasites
  • GHMP KINASE SUPERFAMILY
  • PYROPHOSPHATE DECARBOXYLASE
  • METHANOCOCCUS-JANNASCHII
  • ISOPENTENYL DIPHOSPHATE
  • SUBSTRATE-SPECIFICITY
  • MOLECULAR REPLACEMENT
  • BIOSYNTHETIC-PATHWAY
  • PROTEIN PRENYLATION
  • CHICKEN LIVER
  • RESIDUES

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