Structural basis of omega-3 fatty acid transport across the blood-brain barrier

Nature. 2021 Jul;595(7866):315-319. doi: 10.1038/s41586-021-03650-9. Epub 2021 Jun 16.

Abstract

Docosahexaenoic acid is an omega-3 fatty acid that is essential for neurological development and function, and it is supplied to the brain and eyes predominantly from dietary sources1-6. This nutrient is transported across the blood-brain and blood-retina barriers in the form of lysophosphatidylcholine by major facilitator superfamily domain containing 2A (MFSD2A) in a Na+-dependent manner7,8. Here we present the structure of MFSD2A determined using single-particle cryo-electron microscopy, which reveals twelve transmembrane helices that are separated into two pseudosymmetric domains. The transporter is in an inward-facing conformation and features a large amphipathic cavity that contains the Na+-binding site and a bound lysolipid substrate, which we confirmed using native mass spectrometry. Together with our functional analyses and molecular dynamics simulations, this structure reveals details of how MFSD2A interacts with substrates and how Na+-dependent conformational changes allow for the release of these substrates into the membrane through a lateral gate. Our work provides insights into the molecular mechanism by which this atypical major facility superfamily transporter mediates the uptake of lysolipids into the brain, and has the potential to aid in the delivery of neurotherapeutic agents.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Binding Sites
  • Biological Transport*
  • Blood-Brain Barrier / metabolism*
  • Chickens
  • Cryoelectron Microscopy*
  • Fatty Acids, Omega-3 / chemistry
  • Fatty Acids, Omega-3 / metabolism*
  • Mass Spectrometry
  • Models, Molecular
  • Molecular Dynamics Simulation
  • Protein Domains
  • Sodium / metabolism
  • Symporters / chemistry*
  • Symporters / metabolism*
  • Symporters / ultrastructure

Substances

  • Fatty Acids, Omega-3
  • Symporters
  • Sodium