title: MODIFIED VACUOLE PHENOTYPE1 is an Arabidopsis myrosinase-associated protein involved in endomembrane protein trafficking.
abstract: We identified an Arabidopsis (Arabidopsis thaliana) ethyl methanesulfonate mutant, modified vacuole phenotype1-1 (mvp1-1), in a fluorescent confocal microscopy screen for plants with mislocalization of a green fluorescent protein-delta tonoplast intrinsic protein fusion. The mvp1-1 mutant displayed static perinuclear aggregates of the reporter protein. mvp1 mutants also exhibited a number of vacuole-related phenotypes, as demonstrated by defects in growth, utilization of stored carbon, gravitropic response, salt sensitivity, and specific susceptibility to the fungal necrotroph Alternaria brassicicola. Similarly, crosses with other endomembrane marker fusions identified mislocalization to aggregate structures, indicating a general defect in protein trafficking. Map-based cloning showed that the mvp1-1 mutation altered a gene encoding a putative myrosinase-associated protein, and glutathione S-transferase pull-down assays demonstrated that MVP1 interacted specifically with the Arabidopsis myrosinase protein, THIOGLUCOSIDE GLUCOHYDROLASE2 (TGG2), but not TGG1. Moreover, the mvp1-1 mutant showed increased nitrile production during glucosinolate hydrolysis, suggesting that MVP1 may play a role in modulation of myrosinase activity. We propose that MVP1 is a myrosinase-associated protein that functions, in part, to correctly localize the myrosinase TGG2 and prevent inappropriate glucosinolate hydrolysis that could generate cytotoxic molecules.
authors.affiliation: Center for Plant Cell Biology, University of California, Riverside, California 92521, USA.
authors.forename: April E
authors.initials: AE
authors.lastname: Agee
authors.forename: Marci
authors.initials: M
authors.lastname: Surpin
authors.forename: Eun Ju
authors.initials: EJ
authors.lastname: Sohn
authors.forename: Thomas
authors.initials: T
authors.lastname: Girke
authors.forename: Abel
authors.initials: A
authors.lastname: Rosado
authors.forename: Brian W
authors.initials: BW
authors.lastname: Kram
authors.forename: Clay
authors.initials: C
authors.lastname: Carter
authors.forename: Adam M
authors.initials: AM
authors.lastname: Wentzell
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Kliebenstein
authors.forename: Hak Chul
authors.initials: HC
authors.lastname: Jin
authors.forename: Ohkmae K
authors.initials: OK
authors.lastname: Park
authors.forename: Hailing
authors.initials: H
authors.lastname: Jin
authors.forename: Glenn R
authors.initials: GR
authors.lastname: Hicks
authors.forename: Natasha V
authors.initials: NV
authors.lastname: Raikhel
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D005961:Glucosinolates / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010802:Phylogeny; D021381:Protein Transport / Q000502:physiology*; D036226:Seedlings / Q000166:cytology / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D005961:Glucosinolates; D006026:Glycoside Hydrolases; C511863:TGG2 protein, Arabidopsis