title: Structure of the Sec13-Sec16 edge element, a template for assembly of the COPII vesicle coat.
abstract: Ancestral coatomer element 1 (ACE1) proteins assemble latticework coats for COPII vesicles and the nuclear pore complex. The ACE1 protein Sec31 and Sec13 make a 2:2 tetramer that forms the edge element of the COPII outer coat. In this study, we report that the COPII accessory protein Sec16 also contains an ACE1. The 165-kD crystal structure of the central domain of Sec16 in complex with Sec13 was solved at 2.7-A resolution. Sec16 and Sec13 also make a 2:2 tetramer, another edge element for the COPII system. Domain swapping at the ACE1-ACE1 interface is observed both in the prior structure of Sec13-Sec31 and in Sec13-Sec16. A Sec31 mutant in which domain swapping is prevented adopts an unprecedented laminated structure, solved at 2.8-A resolution. Our in vivo data suggest that the ACE1 element of Sec31 can functionally replace the ACE1 element of Sec16. Our data support Sec16 as a scaffold for the COPII system and a template for the Sec13-Sec31 coat.
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: James R R
authors.initials: JR
authors.lastname: Whittle
authors.forename: Thomas U
authors.initials: TU
authors.lastname: Schwartz
mesh_terms: D022181:COP-Coated Vesicles / Q000737:chemistry* / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000737:chemistry / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D009154:Mutation; D028861:Nuclear Pore Complex Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017433:Protein Structure, Secondary; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism
chemical_list: C060256:CUP2 protein, S cerevisiae; D004268:DNA-Binding Proteins; D008565:Membrane Proteins; D028861:Nuclear Pore Complex Proteins; C079620:SEC13 protein, S cerevisiae; C096367:SEC16 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors