The cytoplasmic-localized, cytoskeletal-associated RNA binding protein OsTudor-SN: evidence for an essential role in storage protein RNA transport and localization.
Previous studies have demonstrated that the major storage protein RNAs found in the rice endosperm are transported as particles via actomyosin to specific subdomains of the cortical endoplasmic reticulum. In this study, we examined the potential role of OsTudor-SN, a major cytoskeletal-associated RNA binding protein, in RNA transport and localization. OsTudor-SN molecules occur as high-molecular-weight forms, the integrity of which are sensitive to RNase. Immunoprecipitation followed by RT-PCR showed that OsTudor-SN binds prolamine and glutelin RNAs. Immunofluorescence studies using affinity-purified antibodies show that OsTudor-SNs exists as particles in the cytoplasm, and are distributed to both the protein body endoplasmic reticulum (ER) and cisternal ER. Examination of OsTudor-SN particles in transgenic rice plants expressing GFP-tagged prolamine RNA transport particles showed co-localization of OsTudor-SN and GFP, suggesting a role in RNA transport. Consistent with this view, GFP-tagged OsTudor-SN is observed in living endosperm sections as moving particles, a property inhibited by microfilament inhibitors. Downregulation of OsTudor-SN by antisense and RNAi resulted in a decrease in steady state prolamine RNA and protein levels, and a reduction in the number of prolamine protein bodies. Collectively, these results show that OsTudor-SN is a component of the RNA transport particle, and may control storage protein biosynthesis by regulating one or more processes leading to the transport, localization and anchoring of their RNAs to the cortical ER.
Wang
Changlin
C
Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, USA.
Washida
Haruhiko
H
Crofts
Andrew J
AJ
Hamada
Shigeki
S
Katsube-Tanaka
Tomoyuki
T
Kim
Dongwook
D
Choi
Sang-Bong
SB
Modi
Mahendra
M
Singh
Salvinder
S
Okita
Thomas W
TW
D003593:Cytoplasm / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D049452:Green Fluorescent Proteins / Q000032:analysis; D008868:Microtubule Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000502:physiology*; D012275:Oryza / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D010940:Plant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D055315:Prolamins; D034622:RNA Interference; D034443:RNA Transport; D018749:RNA, Plant / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000032:analysis; D012639:Seeds / Q000235:genetics / Q000254:growth & development / Q000378:metabolism
D008868:Microtubule Proteins; D010940:Plant Proteins; D055315:Prolamins; D018749:RNA, Plant; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins