title: SNAREs support atlastin-mediated homotypic ER fusion in Saccharomyces cerevisiae.
abstract: Dynamin-like GTPases of the atlastin family are thought to mediate homotypic endoplasmic reticulum (ER) membrane fusion; however, the underlying mechanism remains largely unclear. Here, we developed a simple and quantitative in vitro assay using isolated yeast microsomes for measuring yeast atlastin Sey1p-dependent ER fusion. Using this assay, we found that the ER SNAREs Sec22p and Sec20p were required for Sey1p-mediated ER fusion. Consistently, ER fusion was significantly reduced by inhibition of Sec18p and Sec17p, which regulate SNARE-mediated membrane fusion. The involvement of SNAREs in Sey1p-dependent ER fusion was further supported by the physical interaction of Sey1p with Sec22p and Ufe1p, another ER SNARE. Furthermore, our estimation of the concentration of Sey1p on isolated microsomes, together with the lack of fusion between Sey1p proteoliposomes even with a 25-fold excess of the physiological concentration of Sey1p, suggests that Sey1p requires additional factors to support ER fusion in vivo. Collectively, our data strongly suggest that SNARE-mediated membrane fusion is involved in atlastin-initiated homotypic ER fusion.
authors.affiliation: School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Integrative Aging Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Cell Dynamics Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea.
authors.forename: Miriam
authors.initials: M
authors.lastname: Lee
authors.affiliation: School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Integrative Aging Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Cell Dynamics Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea.
authors.forename: Young-Joon
authors.initials: YJ
authors.lastname: Ko
authors.affiliation: School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Integrative Aging Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea.
authors.forename: Yeojin
authors.initials: Y
authors.lastname: Moon
authors.affiliation: School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Integrative Aging Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea.
authors.forename: Minsoo
authors.initials: M
authors.lastname: Han
authors.affiliation: College of Life Sciences, Sejong University, Seoul 143-747, Korea.
authors.forename: Hyung-Wook
authors.initials: HW
authors.lastname: Kim
authors.affiliation: Department of Cellular and Molecular Medicine, Chosun University School of Medicine, Gwangju 501-759, Korea.
authors.forename: Sung Haeng
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Department of Anatomy and Cell Biology, School of Medicine, Sungkyunkwan University, Suwon 440-746, Korea.
authors.forename: KyeongJin
authors.initials: K
authors.lastname: Kang
authors.affiliation: School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Integrative Aging Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Cell Dynamics Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea junys@gist.ac.kr.
authors.forename: Youngsoo
authors.initials: Y
authors.lastname: Jun
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D008561:Membrane Fusion / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000378:metabolism; D008861:Microsomes / Q000378:metabolism; D011510:Proteolipids / Q000378:metabolism; D050765:Qa-SNARE Proteins / Q000378:metabolism; D050766:Qb-SNARE Proteins / Q000378:metabolism; D050683:R-SNARE Proteins / Q000378:metabolism; D050600:SNARE Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins / Q000037:antagonists & inhibitors; D033921:Vesicular Transport Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D008562:Membrane Glycoproteins; D011510:Proteolipids; D050765:Qa-SNARE Proteins; D050766:Qb-SNARE Proteins; D050683:R-SNARE Proteins; C505725:Rtn1 protein, S cerevisiae; C075137:SEC17 protein, S cerevisiae; C073173:SEC20 protein, S cerevisiae; C472231:SEY1 protein, S cerevisiae; D050600:SNARE Proteins; D029701:Saccharomyces cerevisiae Proteins; C106909:Sec22 protein, S cerevisiae; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins; C103868:UFE1 protein, S cerevisiae; D033921:Vesicular Transport Proteins; C020485:proteoliposomes; D000251:Adenosine Triphosphatases; D020558:GTP Phosphohydrolases; C064404:SEC18 protein, S cerevisiae