Membrane curvature induces cardiolipin sorting

7 pags., 3 figs.Cardiolipin is a cone-shaped lipid predominantly localized in curved membrane sites of bacteria and in the mitochondrial cristae. This specific localization has been argued to be geometry-driven, since the CL’s conical shape relaxes curvature frustration. Although previous evidence suggests a coupling between CL concentration and membrane shape in vivo, no precise experimental data are available for curvature-based CL sorting in vitro. Here, we test this hypothesis in experiments that isolate the effects of membrane curvature in lipid-bilayer nanotubes. CL sorting is observed with increasing tube curvature, reaching a maximum at optimal CL concentrations, a fact compatible with self-associative clustering. Observations are compatible with a model of membrane elasticity including van der Waals entropy, from which a negative intrinsic curvature of −1.1 nm is predicted for CL. The results contribute to understanding the physicochemical interplay between membrane curvature and composition, providing key insights into mitochondrial and bacterial membrane organization and dynamics.E.B.-H. acknowledges financial support from Ministerio de Educación, Cultura y Deporte (MECD, Spain) under FPU grant 13/02826. F.M. acknowledges financial support from Ministerio de Economía y Competitividad (MINECO, Spain) and European Regional Development Fund (ERDF) under grant FIS2015-70339-C2-1-R, and from Comunidad de Madrid (CAM, Spain) under grants S2013/MIT-2807, Y2018/BIO-5207 and S2018/NMT-4389. F.J.C. acknowledges financial support from MINECO and from ERDF under grant FIS2015-67745-R (MINECO/ FEDER). P.B.’s group belong to the CNRS consortium CellTiss, to the Labex CelTisPhyBio (ANR-11-LABX0038) and to Paris Sciences et Letters (ANR-10-IDEX-0001-02). F.-C.T. was funded by the EMBO Long-Term fellowship (ALTF 1527-2014) and Marie Curie actions (H2020-MSCA-IF-2014, project membrane ezrin-actin). F.M. is grateful to Fulbright Foundation and MECD to sponsor a sabbatical stay in UC Berkeley as a visiting scholar