title: Arabidopsis Intracellular NHX-Type Sodium-Proton Antiporters are Required for Seed Storage Protein Processing.
abstract: The Arabidopsis intracellular sodium-proton exchanger (NHX) proteins AtNHX5 and AtNHX6 have a well-documented role in plant development, and have been used to improve salt tolerance in a variety of species. Despite evidence that intracellular NHX proteins are important in vacuolar trafficking, the mechanism of this role is poorly understood. Here we show that NHX5 and NHX6 are necessary for processing of the predominant seed storage proteins, and also influence the processing and activity of a vacuolar processing enzyme. Furthermore, we show by yeast two-hybrid and bimolecular fluorescence complementation (BiFC) technology that the C-terminal tail of NHX6 interacts with a component of Retromer, another component of the cell sorting machinery, and that this tail is critical for NHX6 activity. These findings demonstrate that NHX5 and NHX6 are important in processing and activity of vacuolar cargo, and suggest a mechanism by which NHX intracellular (IC)-II antiporters may be involved in subcellular trafficking.
authors.affiliation: Department of Animal, Plant and Soil Sciences, AgriBio, Centre for AgriBiosciences, 5 Ring Road, La Trobe University, Bundoora, VIC 3086, Australia.
authors.forename: Joanne R
authors.initials: JR
authors.lastname: Ashnest
authors.affiliation: Department of Animal, Plant and Soil Sciences, AgriBio, Centre for AgriBiosciences, 5 Ring Road, La Trobe University, Bundoora, VIC 3086, Australia.
authors.forename: Dung L
authors.initials: DL
authors.lastname: Huynh
authors.affiliation: Department of Animal, Plant and Soil Sciences, AgriBio, Centre for AgriBiosciences, 5 Ring Road, La Trobe University, Bundoora, VIC 3086, Australia.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Dragwidge
authors.affiliation: Department of Animal, Plant and Soil Sciences, AgriBio, Centre for AgriBiosciences, 5 Ring Road, La Trobe University, Bundoora, VIC 3086, Australia Present address: Commonwealth Scientific and Industrial Research Organization Agriculture Flagship, Clunies Ross Street, Acton, ACT 2601, Australia.
authors.forename: Brett A
authors.initials: BA
authors.lastname: Ford
authors.affiliation: Department of Animal, Plant and Soil Sciences, AgriBio, Centre for AgriBiosciences, 5 Ring Road, La Trobe University, Bundoora, VIC 3086, Australia t.gendall@latrobe.edu.au.
authors.forename: Anthony R
authors.initials: AR
authors.lastname: Gendall
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D012639:Seeds / Q000254:growth & development / Q000378:metabolism*; D058305:Sorting Nexins / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C000609621:NHX5 protein, Arabidopsis; C000609622:NHX6 protein, Arabidopsis; C584750:SNX1 protein, Arabidopsis; D058305:Sorting Nexins
keywords: Arabidopsis thaliana; Protein processing; Protein storage vacuole; Sorting nexin; Vacuolar processing enzyme