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-d 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.

The KEEP ON GOING Protein of Arabidopsis Regulates Intracellular Protein Trafficking and Is Degraded during Fungal Infection

“…GOLD36 is a member of the myrosinase superfamily that resides in the vacuole but is synthesized in the ER and is subsequently transported to the vacuole via an unknown route (Agee et al, 2010;Marti et al, 2010). In contrast with ARA6-sYFP and BRI1-sYFP, steady state accumulation of GOLD36/MVP1-mCherry was not affected by the keg-1 mutation in transgenic plants grown in the dark ( Figures 5M and 5N).…”

Engineering Glucosinolates in Plants: Current Knowledge and Potential Uses

“…Moreover, in Arabidopsis ESM1, locus was found to epistatically interact with the ESP locus, but the resulting outcome of GSL breakdown product depends on the functional allele in ESP or ESM1 locus, which causes the production of nitrile or ITCs, respectively [196]. Agee et al [187] reported that an increased conversion of allyl GSL to simple nitrile was observed in the MVP1 mutant, and in vitro studies provided the evidence that MVP1 interacts with TGG2 alone. Interestingly, myrosinasemediated hydrolysis of IGSL results in the production of I3AN, which, in turn, serves as a substrate for the IAA synthesis catalyzed through nitrilases [197][198][199].…”

“…Recently, another myrosinase-associated protein called modified vacuolar phenotype (MVP1) was identified, and it was reported to interact specifically with TGG2. Further, it was suggested that this interaction might regulate GSL breakdown in intact tissues by a direct effect on TGG2 activity, or by changing the location of TGG2 relative to the GSLs [187].…”

PROTEIN S-ACYL TRANSFERASE10 Is Critical for Development and Salt Tolerance in Arabidopsis

“…Plant vacuoles are acidic organelles essential for nutrient remobilization, maintenance of turgor pressure, sequestration of toxic compounds, ions and secondary metabolites, and accumulation of storage proteins (Maeshima, 2001;Mimura et al, 2003;Hamaji et al, 2009;Agee et al, 2010;Krebs et al, 2010;Barragán et al, 2012). Vacuoles occupy ;80 to 90% of the total cell volume and provide cells with the ability to withstand salt and osmotic stresses (Mimura et al, 2003;Hamaji et al, 2009;Barragán et al, 2012).…”