Model for the architecture of caveolae based on a flexible, net-like assembly of Cavin1 and Caveolin discs.
Caveolae are invaginated plasma membrane domains involved in mechanosensing, signaling, endocytosis, and membrane homeostasis. Oligomers of membrane-embedded caveolins and peripherally attached cavins form the caveolar coat whose structure has remained elusive. Here, purified Cavin1 60S complexes were analyzed structurally in solution and after liposome reconstitution by electron cryotomography. Cavin1 adopted a flexible, net-like protein mesh able to form polyhedral lattices on phosphatidylserine-containing vesicles. Mutating the two coiled-coil domains in Cavin1 revealed that they mediate distinct assembly steps during 60S complex formation. The organization of the cavin coat corresponded to a polyhedral nano-net held together by coiled-coil segments. Positive residues around the C-terminal coiled-coil domain were required for membrane binding. Purified caveolin 8S oligomers assumed disc-shaped arrangements of sizes that are consistent with the discs occupying the faces in the caveolar polyhedra. Polygonal caveolar membrane profiles were revealed in tomograms of native caveolae inside cells. We propose a model with a regular dodecahedron as structural basis for the caveolae architecture.
Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, United Kingdom.|Institute of Biochemistry, Swiss Federal Institute of Technology Zurich, 8093 Zurich, Switzerland.
Miriam
M
Stoeber
Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, United Kingdom.
Pascale
P
Schellenberger
Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, United Kingdom.
C Alistair
CA
Siebert
Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, United Kingdom.
Cedric
C
Leyrat
Institute of Biochemistry, Swiss Federal Institute of Technology Zurich, 8093 Zurich, Switzerland ari.helenius@bc.biol.ethz.ch kay@strubi.ox.ac.uk.
Ari
A
Helenius
Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, United Kingdom; ari.helenius@bc.biol.ethz.ch kay@strubi.ox.ac.uk.
Kay
0000-0002-4788-2691
K
Grünewald
D000818:Animals; D021941:Caveolae / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D051242:Caveolin 1 / Q000737:chemistry* / Q000378:metabolism*; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051379:Mice; D046529:Microscopy, Electron, Transmission; D008954:Models, Biological; D008958:Models, Molecular; D046912:Multiprotein Complexes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000072417:Protein Domains; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion
C495540:CAV1 protein, human; C497835:CAVIN1 protein, human; D051242:Caveolin 1; C112745:Cavin1 protein, mouse; D008565:Membrane Proteins; D046912:Multiprotein Complexes; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins
caveolae; coat assembly; coat proteins; electron cryomicroscopy; membrane organization