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Structure of thermostable human MFSD2A in complex with thermostable human Sync2
Structural highlights
FunctionSYCY2_HUMAN This endogenous retroviral envelope protein has retained its original fusogenic properties and participates in trophoblast fusion and the formation of a syncytium during placenta morphogenesis. The interaction with MFSD2A is apparently important for this process (PubMed:18988732).[1] Endogenous envelope proteins may have kept, lost or modified their original function during evolution but this one can still make pseudotypes with MLV, HIV-1 or SIV-1 virions and confer infectivity. Retroviral envelope proteins mediate receptor recognition and membrane fusion during early infection. The surface protein mediates receptor recognition, while the transmembrane protein anchors the envelope heterodimer to the viral membrane through one transmembrane domain. The other hydrophobic domain, called fusion peptide, mediates fusion of the viral membrane with the target cell membrane (PubMed:14694139).[2] Publication Abstract from PubMedBrain development and function require uptake of essential omega-3 fatty acids in the form of lysophosphatidylcholine via major-facilitator superfamily transporter MFSD2A, a potential pharmaceutical target to modulate blood-brain barrier (BBB) permeability. MFSD2A is also the receptor of endogenous retroviral envelope syncytin-2 (SYNC2) in human placenta, where it mediates cell-cell fusion and formation of the maternal-fetal interface. Here, we report a cryo-electron microscopy structure of the human MFSD2A-SYNC2 complex that reveals a large hydrophobic cavity in the transporter C-terminal domain to occlude long aliphatic chains. The transporter architecture suggests an alternating-access transport mechanism for lipid substrates in mammalian MFS transporters. SYNC2 establishes an extensive binding interface with MFSD2A, and a SYNC2-soluble fragment acts as a long-sought-after inhibitor of MFSD2A transport. Our work uncovers molecular mechanisms important to brain and placenta development and function, and SYNC2-mediated inhibition of MFSD2A transport suggests strategies to aid delivery of therapeutic macromolecules across the BBB. Structural insights into the lysophospholipid brain uptake mechanism and its inhibition by syncytin-2.,Martinez-Molledo M, Nji E, Reyes N Nat Struct Mol Biol. 2022 Jun;29(6):604-612. doi: 10.1038/s41594-022-00786-8. , Epub 2022 Jun 16. PMID:35710838[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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