title: Arabidopsis RHD3 mediates the generation of the tubular ER network and is required for Golgi distribution and motility in plant cells.
abstract: In plant cells, the endoplasmic reticulum (ER) and Golgi apparatus form a unique system in which single Golgi stacks are motile and in close association with the underlying ER tubules. Arabidopsis has three RHD3 (ROOT HAIR DEFECTIVE 3) isoforms that are analogous to the mammalian atlastin GTPases involved in shaping ER tubules. We used live-cell imaging, genetic complementation, split ubiquitin assays and western blot analyses in Arabidopsis and tobacco to show that RHD3 mediates the generation of the tubular ER network and is required for the distribution and motility of Golgi stacks in root and leaf epidermal cells. We established that RHD3 forms homotypic interactions at ER punctae. In addition, the activity of RHD3 on the tubular ER is specifically correlated with the cellular distribution and motility of Golgi stacks because ER to Golgi as well as Golgi to plasma membrane transport was not affected by RHD3 mutations in the conserved GDP/GTP motifs. We found a possible partial redundancy within the RHD3 isoforms in Arabidopsis. However, yeast Sey1p, a functional atlastin homologue, and RHD3 are not interchangeable in complementing the respective loss-of-function mutants, suggesting that the molecular mechanisms controlling ER tubular morphology might not be entirely conserved among eukaryotic lineages.
authors.affiliation: Developmental Biology Research Initiatives, Department of Biology, McGill University, 1205 Dr Penfield Avenue, Montreal, QC H3A1B1, Canada.
authors.forename: Jun
authors.initials: J
authors.lastname: Chen
authors.forename: Giovanni
authors.initials: G
authors.lastname: Stefano
authors.forename: Federica
authors.initials: F
authors.lastname: Brandizzi
authors.forename: Huanquan
authors.initials: H
authors.lastname: Zheng
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D002465:Cell Movement; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D019441:Plant Epidermis / Q000378:metabolism; D018515:Plant Leaves / Q000166:cytology; D018517:Plant Roots / Q000166:cytology; D016133:Polymerase Chain Reaction; D020033:Protein Isoforms / Q000378:metabolism; D014026:Nicotiana / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D020033:Protein Isoforms; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; C464507:RHD3 protein, Arabidopsis