title: Arabidopsis RABA1 GTPases are involved in transport between the trans-Golgi network and the plasma membrane, and are required for salinity stress tolerance.
abstract: RAB GTPases are key regulators of membrane traffic. Among them, RAB11, a widely conserved sub-group, has evolved in a unique way in plants; plant RAB11 members show notable diversity, whereas yeast and animals have only a few RAB11 members. Fifty-seven RAB GTPases are encoded in the Arabidopsis thaliana genome, 26 of which are classified in the RAB11 group (further divided into RABA1-RABA6 sub-groups). Although several plant RAB11 members have been shown to play pivotal roles in plant-unique developmental processes, including cytokinesis and tip growth, molecular and physiological functions of the majority of RAB11 members remain unknown. To reveal precise functions of plant RAB11, we investigated the subcellular localization and dynamics of the largest sub-group of Arabidopsis RAB11, RABA1, which has nine members. RABA1 members reside on mobile punctate structures adjacent to the trans-Golgi network and co-localized with VAMP721/722, R-SNARE proteins that operate in the secretory pathway. In addition, the constitutive-active mutant of RABA1b, RABA1b(Q72L) , was present on the plasma membrane. The RABA1b -containing membrane structures showed actin-dependent dynamic motion . Vesicles labeled by GFP-RABA1b moved dynamically, forming queues along actin filaments. Interestingly, Arabidopsis plants whose four major RABA1 members were knocked out, and those expressing the dominant-negative mutant of RABA1B, exhibited hypersensitivity to salinity stress. Altogether, these results indicate that RABA1 members mediate transport between the trans-Golgi network and the plasma membrane, and are required for salinity stress tolerance.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan.
authors.forename: Rin
authors.initials: R
authors.lastname: Asaoka
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Uemura
authors.affiliation: Molecular Membrane Biology Laboratory, RIKEN Advanced Science Institute, Wako, Saitama, 351-0198, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Ito
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan.
authors.forename: Masaru
authors.initials: M
authors.lastname: Fujimoto
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan.
authors.forename: Emi
authors.initials: E
authors.lastname: Ito
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan.|PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Ueda
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan.|Molecular Membrane Biology Laboratory, RIKEN Advanced Science Institute, Wako, Saitama, 351-0198, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Nakano
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D001692:Biological Transport; D002462:Cell Membrane / Q000502:physiology*; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D005810:Multigene Family; D054712:Salinity; D012965:Sodium Chloride / Q000633:toxicity; D013312:Stress, Physiological / Q000187:drug effects*; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D021601:trans-Golgi Network / Q000502:physiology*
chemical_list: D029681:Arabidopsis Proteins; D012965:Sodium Chloride; D020691:rab GTP-Binding Proteins