title: Polyhedral 3D structure of human plasma very low density lipoproteins by individual particle cryo-electron tomography1.
abstract: Human VLDLs assembled in the liver and secreted into the circulation supply energy to peripheral tissues. VLDL lipolysis yields atherogenic LDLs and VLDL remnants that strongly correlate with CVD. Although the composition of VLDL particles has been well-characterized, their 3D structure is elusive because of their variations in size, heterogeneity in composition, structural flexibility, and mobility in solution. Here, we employed cryo-electron microscopy and individual-particle electron tomography to study the 3D structure of individual VLDL particles (without averaging) at both below and above their lipid phase transition temperatures. The 3D reconstructions of VLDL and VLDL bound to antibodies revealed an unexpected polyhedral shape, in contrast to the generally accepted model of a spherical emulsion-like particle. The smaller curvature of surface lipids compared with HDL may also reduce surface hydrophobicity, resulting in lower binding affinity to the hydrophobic distal end of the N-terminal β-barrel domain of cholesteryl ester transfer protein (CETP) compared with HDL. The directional binding of CETP to HDL and VLDL may explain the function of CETP in transferring TGs and cholesteryl esters between these particles. This first visualization of the 3D structure of VLDL could improve our understanding of the role of VLDL in atherogenesis.
authors.affiliation: Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720.
authors.forename: Yadong
authors.initials: Y
authors.lastname: Yu
authors.affiliation: Atherosclerosis Research, Children's Hospital Oakland Research Institute, Oakland, CA 94609.
authors.forename: Yu-Lin
authors.initials: YL
authors.lastname: Kuang
authors.affiliation: Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720.
authors.forename: Dongsheng
authors.initials: D
authors.lastname: Lei
authors.affiliation: Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720.
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Zhai
authors.affiliation: Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720.
authors.forename: Meng
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Atherosclerosis Research, Children's Hospital Oakland Research Institute, Oakland, CA 94609.
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Krauss
authors.affiliation: Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720. Electronic address: gren@lbl.gov.
authors.forename: Gang
authors.initials: G
authors.lastname: Ren
mesh_terms: D020285:Cryoelectron Microscopy / Q000379:methods; D006801:Humans; D008079:Lipoproteins, VLDL / Q000737:chemistry*; D008958:Models, Molecular; D000072417:Protein Domains
chemical_list: D008079:Lipoproteins, VLDL
keywords: antibodies; apolipoprotein B; electron microscopy; three-dimensional