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Localization and nucleotide specificity of Blastocystis succinyl-CoA synthetase

  • Robin Maytum
    ,
  • Karleigh Hamblin
    ,
  • Daron M. Standley
    ,
  • Matthew B. Rogers
    ,
  • Alexandra Stechmann
    ,
  • Andrew J. Roger
  • University of Exeter
    ,
  • Queen Mary University of London
    ,
  • Osaka University
    ,
  • Japan Science and Technology Agency
    ,
  • Dalhousie University
Research Output: Contribution to journal Article Peer-review

Abstract

The anaerobic lifestyle of the intestinal parasite Blastocystis raises questions about the biochemistry and function of its mitochondria-like organelles. We have characterized the Blastocystis succinyl-CoA synthetase (SCS), a tricarboxylic acid cycle enzyme that conserves energy by substrate-level phosphorylation. We show that SCS localizes to the enigmatic Blastocystis organelles, indicating that these organelles might play a similar role in energy metabolism as classic mitochondria. Although analysis of residues inside the nucleotide-binding site suggests that Blastocystis SCS is GTP-specific, we demonstrate that it is ATP-specific. Homology modelling, followed by flexible docking and molecular dynamics simulations, indicates that while both ATP and GTP fit into the Blastocystis SCS active site, GTP is destabilized by electrostatic dipole interactions with Lys 42 and Lys 110, the side-chains of which lie outside the nucleotide-binding cavity. It has been proposed that residues in direct contact with the substrate determine nucleotide specificity in SCS. However, our results indicate that, in Blastocystis, an electrostatic gatekeeper controls which ligands can enter the binding site.

Publication Information

Output type

Research Output: Contribution to journal Article Peer-review

Original language

English

Pages from-to (Number of pages)

Pages 1395-1405

Journal (Volume, Issue Number)

Molecular Microbiology (Volume 68, Issue 6)

Publication milestones

  • Published - 01/06/2008

Publication status

Published - 01/06/2008

ISSN

0950-382X

External Publication IDs

  • handle.net: 10547/228938
  • Scopus: 44249108135

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