title: GNOM-LIKE1/ERMO1 and SEC24a/ERMO2 are required for maintenance of endoplasmic reticulum morphology in Arabidopsis thaliana.
abstract: The endoplasmic reticulum (ER) is composed of tubules, sheets, and three-way junctions, resulting in a highly conserved polygonal network in all eukaryotes. The molecular mechanisms responsible for the organization of these structures are obscure. To identify novel factors responsible for ER morphology, we employed a forward genetic approach using a transgenic Arabidopsis thaliana plant (GFP-h) with fluorescently labeled ER. We isolated two mutants with defects in ER morphology and designated them endoplasmic reticulum morphology1 (ermo1) and ermo2. The cells of both mutants developed a number of ER-derived spherical bodies, approximately 1 microm in diameter, in addition to the typical polygonal network of ER. The spherical bodies were distributed throughout the ermo1 cells, while they formed a large aggregate in ermo2 cells. We identified the responsible gene for ermo1 to be GNOM-LIKE1 (GNL1) and the gene for ermo2 to be SEC24a. Homologs of both GNL1 and SEC24a are involved in membrane trafficking between the ER and Golgi in yeast and animal cells. Our findings, however, suggest that GNL1/ERMO1 and SEC24a/ERMO2 have a novel function in ER morphology in higher plants.
authors.affiliation: Department of Botany, Graduate School of Science, Kyoto University, Kyoto, Japan.
authors.forename: Ryohei Thomas
authors.initials: RT
authors.lastname: Nakano
authors.forename: Ryo
authors.initials: R
authors.lastname: Matsushima
authors.forename: Haruko
authors.initials: H
authors.lastname: Ueda
authors.forename: Kentaro
authors.initials: K
authors.lastname: Tamura
authors.forename: Tomoo
authors.initials: T
authors.lastname: Shimada
authors.forename: Lixin
authors.initials: L
authors.lastname: Li
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Hayashi
authors.forename: Maki
authors.initials: M
authors.lastname: Kondo
authors.forename: Mikio
authors.initials: M
authors.lastname: Nishimura
authors.forename: Ikuko
authors.initials: I
authors.lastname: Hara-Nishimura
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure*; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism / Q000648:ultrastructure; D010940:Plant Proteins / Q000096:biosynthesis / Q000235:genetics; D021381:Protein Transport / Q000502:physiology; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C522273:GNL1 protein, Arabidopsis; D020662:Guanine Nucleotide Exchange Factors; D010940:Plant Proteins; C547881:SEC24 protein, Arabidopsis; D033921:Vesicular Transport Proteins