Membrane lipid as cofactor of cargo uptake and release by box-like lipid transfer proteins

ABSTRACT: Lipid transfer proteins (LTPs) shuttle their cargo lipids between cellular membranes. LTPs facilitate the costly extraction of a lipid from a donor membrane, and its delivery into the acceptor membrane, but the mechanisms remain poorly understood. We combined extensive molecular dynamics simulations and biochemical assays to investigate the box-like ceramide transfer protein STARD11 and other members of the STARD family. We show that a family-wide conserved arginine in the gate region is the keystone of a phospholipid binding site which, when occupied by a phosphate group, stabilizes an open gate that induces local disruption of the membrane packing, as evidenced by upward displacement of lipid acyl chains towards the membrane interface. Mutation of this residue slows down in vitro ceramide uptake by 20-fold, whereas other mutations in the gate region have little effect. UV-induced cross-linking experiments with liposomes containing a bifunctional phosphatidylcholine show close proximity of the lipid acyl chains and STARD11WT, but not the arginine mutant. Together our results demonstrate that a membrane-resident phospholipid acts as a cofactor for efficient lipid transfer by STARD11, STARD4 and STARD1. Simulations of STARD2, STARD10 and STARD13 support a conserved structural role for this arginine, which is present in 13 STARD family members with different cargo specificity.

INSTRUMENT(S): Direct infusion MS - positive, Direct infusion MS - negative

PROVIDER: MTBLS15933 | MetaboLights | 2026-10-06

REPOSITORIES: MetaboLights