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Molecular mechanism of thiamine pyrophosphate import into mitochondria: a molecular simulation study

F Van Liefferinge1, E-M Krammer1,2, J Waeytens1,3

  • 1Structure et Fonction des Membranes Biologiques, Université Libre de Bruxelles (ULB), Brussels, Belgium.

Journal of Computer-Aided Molecular Design
|August 18, 2021
PubMed

Insights

Thiamine pyrophosphate (TPP) crosses the mitochondrial outer membrane via the voltage-dependent anion channel and the inner membrane using a specific carrier with a single binding site. This transport mechanism is crucial for mitochondrial function.

Area of Science:

  • Mitochondrial biology
  • Molecular dynamics simulations
  • Biochemistry

Background:

  • Mitochondria import essential molecules like thiamine pyrophosphate (TPP) for cellular energy production.
  • Understanding the precise mechanisms of TPP transport across mitochondrial membranes is vital for comprehending cellular metabolism and potential therapeutic targets.

Purpose of the Study:

  • To elucidate the molecular mechanisms of thiamine pyrophosphate (TPP) import across both the mitochondrial outer and inner membranes.
  • To investigate the role of specific channels and carriers in TPP translocation.

Main Methods:

  • Utilized extensive (3-µs) molecular dynamics simulations.
  • Analyzed the interaction of TPP with mitochondrial membrane transport proteins.

Main Results:

  • Simulations suggest TPP traverses the outer mitochondrial membrane through the voltage-dependent anion channel, similar to ATP.
  • TPP transport across the inner mitochondrial membrane involves a dedicated carrier with an alternating access mechanism and a unique binding site.
  • The binding site's preference for TPP is determined by specific amino acid residues, differentiating it from the ATP/ADP carrier.
  • Energetics of TPP transport are influenced by salt bridge networks and ionic interactions, with a lower energy barrier observed on the cytosolic side.

Conclusions:

  • TPP import into mitochondria involves distinct pathways for the outer and inner membranes.
  • The identified TPP carrier mechanism provides insights into mitochondrial metabolite transport specificity.
  • Molecular dynamics simulations offer a powerful approach to study complex membrane transport processes.
Keywords:
Membrane TransportersMembrane channelsMetabolite transportMolecular dynamicsThiamine pyrophophate

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