title: Structures of the yeast dynamin-like GTPase Sey1p provide insight into homotypic ER fusion.
abstract: Homotypic membrane fusion of the endoplasmic reticulum is mediated by dynamin-like guanosine triphosphatases (GTPases), which include atlastin (ATL) in metazoans and Sey1p in yeast. In this paper, we determined the crystal structures of the cytosolic domain of Sey1p derived from Candida albicans. The structures reveal a stalk-like, helical bundle domain following the GTPase, which represents a previously unidentified configuration of the dynamin superfamily. This domain is significantly longer than that of ATL and critical for fusion. Sey1p forms a side-by-side dimer in complex with GMP-PNP or GDP/AlF4(-) but is monomeric with GDP. Surprisingly, Sey1p could mediate fusion without GTP hydrolysis, even though fusion was much more efficient with GTP. Sey1p was able to replace ATL in mammalian cells, and the punctate localization of Sey1p was dependent on its GTPase activity. Despite the common function of fusogenic GTPases, our results reveal unique features of Sey1p.
authors.affiliation: School of Medicine, Tsinghua University, Beijing, China 100084.
authors.forename: Liming
authors.initials: L
authors.lastname: Yan
authors.affiliation: Department of Genetics and Cell Biology, College of Life Sciences, Nankai University and Tianjin Key Laboratory of Protein Sciences, Tianjin, China 300071.
authors.forename: Sha
authors.initials: S
authors.lastname: Sun
authors.affiliation: School of Medicine, Tsinghua University, Beijing, China 100084 State Key Laboratory of Cotton Biology, Key Laboratory of Plant Stress Biology, Henan University, Kaifeng, China 475004.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Department of Genetics and Cell Biology, College of Life Sciences, Nankai University and Tianjin Key Laboratory of Protein Sciences, Tianjin, China 300071.
authors.forename: Juanming
authors.initials: J
authors.lastname: Shi
authors.affiliation: Department of Genetics and Cell Biology, College of Life Sciences, Nankai University and Tianjin Key Laboratory of Protein Sciences, Tianjin, China 300071.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Hu
authors.affiliation: State Key Laboratory of Cotton Biology, Key Laboratory of Plant Stress Biology, Henan University, Kaifeng, China 475004.
authors.forename: Shiyan
authors.initials: S
authors.lastname: Wang
authors.affiliation: Collaborative Innovation Center for Biotherapy, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, West China Medical School, Sichuan University, Chengdu, China 610041.
authors.forename: Dan
authors.initials: D
authors.lastname: Su
authors.affiliation: School of Medicine, Tsinghua University, Beijing, China 100084 National Laboratory of Macromolecules, Institute of Biophysics, Chinese Academy of Science, Beijing, China 100101 Collaborative Innovation Center for Biotherapy, West China Hospital, West China Medical School, Sichuan University, Chengdu, China 610041 huj@ibp.ac.cn louzy@mail.tsinghua.edu.cn.
authors.forename: Zihe
authors.initials: Z
authors.lastname: Rao
authors.affiliation: Department of Genetics and Cell Biology, College of Life Sciences, Nankai University and Tianjin Key Laboratory of Protein Sciences, Tianjin, China 300071 National Laboratory of Macromolecules, Institute of Biophysics, Chinese Academy of Science, Beijing, China 100101 huj@ibp.ac.cn louzy@mail.tsinghua.edu.cn.
authors.forename: Junjie
authors.initials: J
authors.lastname: Hu
authors.affiliation: School of Medicine, Tsinghua University, Beijing, China 100084 Collaborative Innovation Center for Biotherapy, West China Hospital, West China Medical School, Sichuan University, Chengdu, China 610041.
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Lou
mesh_terms: D000818:Animals; D051033:Apoptosis Inducing Factor / Q000737:chemistry / Q000378:metabolism; D019556:COS Cells; D002176:Candida albicans / Q000201:enzymology* / Q000235:genetics; D002522:Chlorocebus aethiops; D003460:Crystallization; D018360:Crystallography, X-Ray; D004721:Endoplasmic Reticulum / Q000201:enzymology*; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006153:Guanosine Diphosphate / Q000737:chemistry / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000737:chemistry / Q000378:metabolism; D006165:Guanylyl Imidodiphosphate / Q000737:chemistry / Q000378:metabolism; D006868:Hydrolysis; D008561:Membrane Fusion; D008958:Models, Molecular; D011485:Protein Binding; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism; D013329:Structure-Activity Relationship; D014162:Transfection; D033921:Vesicular Transport Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D051033:Apoptosis Inducing Factor; D005656:Fungal Proteins; C472231:SEY1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins; D006153:Guanosine Diphosphate; D006165:Guanylyl Imidodiphosphate; D006160:Guanosine Triphosphate; D020558:GTP Phosphohydrolases