title: OsPRA1 plays a significant role in targeting of OsRab7 into the tonoplast via the prevacuolar compartment during vacuolar trafficking in plant cells.
abstract: In yeast and mammals, the Yip/PRA1 family of proteins has been reported to facilitate the delivery of Rab GTPases to the membrane by dissociating the Rab-GDI complex during vesicle trafficking. Recently, we identified OsPRA1, a plant Yip/PRA1 homolog, as an OsRab7-interacting protein that localizes to the prevacuolar compartment, which suggests that it plays a role in vacuolar trafficking of plant cells. Here, we show that OsPRA1 is essential for vacuolar trafficking and that it has molecular properties that are typical of the Yip/PRA1 family of proteins. A trafficking assay using Arabidopsis protoplasts showed that the point mutant OsPRA1((Y94A)) strongly inhibits the vacuolar trafficking of cargo proteins, but has no inhibitory effect on the plasma membrane trafficking of H(+)-ATPase-GFP, suggesting its specific involvement in vacuolar trafficking. Moreover, OsPRA1 was shown to be an integral membrane protein, suggesting that its two hydrophobic domains may mediate membrane integration, and its cytoplasmic N- and C-terminal regions were found to be important for binding to OsRab7. OsPRA1 also interacted with OsVamp3, implying its involvement in vesicle fusion. Finally, we used a yeast expression system to show that OsPRA1 opposes OsGDI2 activity and facilitates the delivery of OsRab7 to the target membrane. Taken together, our results support strongly that OsPRA1 targets OsRab7 to the tonoplast during vacuolar trafficking.
authors.affiliation: Department of Biology, Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Jae Bok
authors.initials: JB
authors.lastname: Heo
authors.forename: Woo Young
authors.initials: WY
authors.lastname: Bang
authors.forename: Se Won
authors.initials: SW
authors.lastname: Kim
authors.forename: Sung Min
authors.initials: SM
authors.lastname: Hwang
authors.forename: Young Sim
authors.initials: YS
authors.lastname: Son
authors.forename: Chak Han
authors.initials: CH
authors.lastname: Im
authors.forename: Biswa R
authors.initials: BR
authors.lastname: Acharya
authors.forename: Chul Wook
authors.initials: CW
authors.lastname: Kim
authors.forename: Sam Woong
authors.initials: SW
authors.lastname: Kim
authors.forename: Byung Hyun
authors.initials: BH
authors.lastname: Lee
authors.forename: Jeong Dong
authors.initials: JD
authors.lastname: Bahk
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D001692:Biological Transport / Q000235:genetics / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D014617:Vacuoles / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D049452:Green Fluorescent Proteins; D006180:Proton-Translocating ATPases