title: OsVPS9A functions cooperatively with OsRAB5A to regulate post-Golgi dense vesicle-mediated storage protein trafficking to the protein storage vacuole in rice endosperm cells.
abstract: In the rice endosperm cells, glutelins are synthesized on rough endoplasmic reticulum as proglutelins and are sorted to the protein storage vacuoles (PSVs) called protein body IIs (PBIIs), where they are converted to the mature forms. Dense vesicle (DV)-mediated trafficking of proglutelins in rice seeds has been proposed, but the post-Golgi control of this process is largely unknown. Whether DV can fuse directly with PSV is another matter of debate. In this study, we propose a regulatory mechanism underlying DV-mediated, post-Golgi proglutelin trafficking to PBII (PSV). gpa2, a loss-of-function mutant of OsVPS9A, which encodes a GEF of OsRAB5A, accumulated uncleaved proglutelins. Proglutelins were mis-targeted to the paramural bodies and to the apoplast along the cell wall in the form of DVs, which led to a concomitant reduction in PBII size. Previously reported gpa1, mutated in OsRab5a, has a similar phenotype, while gpa1gpa2 double mutant exacerbated the conditions. In addition, OsVPS9A interacted with OsRAB5A in vitro and in vivo. We concluded that OsVPS9A and OsRAB5A may work together and play a regulatory role in DV-mediated post-Golgi proglutelin trafficking to PBII (PSV). The evidence that DVs might fuse directly to PBII (PSV) to deliver cargos is also presented.
authors.affiliation: State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Liu
authors.forename: Yulong
authors.initials: Y
authors.lastname: Ren
authors.forename: Yihua
authors.initials: Y
authors.lastname: Wang
authors.forename: Cheng
authors.initials: C
authors.lastname: Peng
authors.forename: Kunneng
authors.initials: K
authors.lastname: Zhou
authors.forename: Jia
authors.initials: J
authors.lastname: Lv
authors.forename: Xiuping
authors.initials: X
authors.lastname: Guo
authors.forename: Xin
authors.initials: X
authors.lastname: Zhang
authors.forename: Mingsheng
authors.initials: M
authors.lastname: Zhong
authors.forename: Shaolu
authors.initials: S
authors.lastname: Zhao
authors.forename: Ling
authors.initials: L
authors.lastname: Jiang
authors.forename: Haiyang
authors.initials: H
authors.lastname: Wang
authors.forename: Yiqun
authors.initials: Y
authors.lastname: Bao
authors.forename: Jianmin
authors.initials: J
authors.lastname: Wan
mesh_terms: D056625:Endosperm / Q000166:cytology / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism*; D008969:Molecular Sequence Data; D012275:Oryza / Q000196:embryology / Q000378:metabolism*; D010940:Plant Proteins / Q000502:physiology*; D021381:Protein Transport; D012639:Seeds / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism*
chemical_list: D010940:Plant Proteins
keywords: 57H mutant; OsRAB5A.; OsVPS9A; PSV; dense vesicle