title: Structure of the WD40 domain of SCAP from fission yeast reveals the molecular basis for SREBP recognition.
abstract: The sterol regulatory element-binding protein (SREBP) and SREBP cleavage-activating protein (SCAP) are central players in the SREBP pathway, which control the cellular lipid homeostasis. SCAP binds to SREBP through their carboxyl (C) domains and escorts SREBP from the endoplasmic reticulum to the Golgi upon sterol depletion. A conserved pathway, with the homologues of SREBP and SCAP being Sre1 and Scp1, was identified in fission yeast Schizosaccharomyces pombe. Here we report the in vitro reconstitution of the complex between the C domains of Sre1 and Scp1 as well as the crystal structure of the WD40 domain of Scp1 at 2.1 Å resolution. The structure reveals an eight-bladed β-propeller that exhibits several distinctive features from a canonical WD40 repeat domain. Structural and biochemical characterization led to the identification of two Scp1 elements that are involved in Sre1 recognition, an Arg/Lys-enriched surface patch on the top face of the WD40 propeller and a 30-residue C-terminal tail. The structural and biochemical findings were corroborated by in vivo examinations. These studies serve as a framework for the mechanistic understanding and further functional characterization of the SREBP and SCAP proteins in fission yeast and higher organisms.
authors.affiliation: 1] State Key Laboratory of Bio-membrane and Membrane Biotechnology, Beijing 100084, China [2] Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Gong
authors.affiliation: 1] State Key Laboratory of Bio-membrane and Membrane Biotechnology, Beijing 100084, China [2] Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.
authors.forename: Jingxian
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Shao
authors.affiliation: 1] State Key Laboratory of Bio-membrane and Membrane Biotechnology, Beijing 100084, China [2] Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.
authors.forename: Jianping
authors.initials: J
authors.lastname: Wu
authors.affiliation: 1] State Key Laboratory of Bio-membrane and Membrane Biotechnology, Beijing 100084, China [2] Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.
authors.forename: Hongwu
authors.initials: H
authors.lastname: Qian
authors.affiliation: 1] State Key Laboratory of Bio-membrane and Membrane Biotechnology, Beijing 100084, China [2] Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.
authors.forename: Ruobing
authors.initials: R
authors.lastname: Ren
authors.affiliation: Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Espenshade
authors.affiliation: 1] State Key Laboratory of Bio-membrane and Membrane Biotechnology, Beijing 100084, China [2] Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.
authors.forename: Nieng
authors.initials: N
authors.lastname: Yan
mesh_terms: D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D018360:Crystallography, X-Ray; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006056:Golgi Apparatus / Q000737:chemistry / Q000378:metabolism; D008840:Microfilament Proteins / Q000737:chemistry* / Q000378:metabolism; D046912:Multiprotein Complexes / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D012568:Schizosaccharomyces / Q000737:chemistry*; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry* / Q000378:metabolism; D051779:Sterol Regulatory Element Binding Proteins; D013261:Sterols / Q000378:metabolism*
chemical_list: D008840:Microfilament Proteins; D046912:Multiprotein Complexes; D029702:Schizosaccharomyces pombe Proteins; C500469:Scp1 protein, S pombe; C500467:Sre1 protein, S pombe; D051779:Sterol Regulatory Element Binding Proteins; D013261:Sterols