Identification of cis-localization elements of the maize 10-kDa delta-zein and their use in targeting RNAs to specific cortical endoplasmic reticulum subdomains.
The RNAs for the storage proteins of rice (Oryza sativa), prolamines and glutelins, which are stored as inclusions in the lumen of the endoplasmic reticulum (ER) and storage vacuoles, respectively, are targeted by specific cis-localization elements to distinct subdomains of the cortical ER. Glutelin RNA has one or more cis-localization elements (zip codes) at the 3' end of the RNA, whereas prolamine has two cis-elements; one located in the 5' end of the coding sequence and a second residing in the 3'-untranslated region (UTR). We had earlier demonstrated that the RNAs for the maize zeins ('prolamine' class) are localized to the spherical protein body ER (PB-ER) in developing maize endosperm. As the PB-ER localization of the 10-kDa delta-zein RNA is maintained in developing rice seeds, we determined the number and proximate location of their cis-localization elements by expressing GFP fusions containing various zein RNA sequences in transgenic rice and analyzing their spatial distribution on the cortical ER by in situ RT-PCR and confocal microscopy. Four putative cis-localization elements were identified; three in the coding sequences and one in the 3'-UTR. Two of these zip codes are required for restricted localization to the PB-ER. Using RNA targeting determinants we show, by mis-targeting the storage protein RNAs from their normal destination on the cortical ER, that the coded proteins are redirected from their normal site of deposition. Targeting of RNA to distinct cortical ER subdomains may be the underlying basis for the variable use of the ER lumen or storage vacuole as the final storage deposition site of storage proteins among flowering plant species.
Washida
Haruhiko
H
Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, USA.
Sugino
Aya
A
Kaneko
Sachiyo
S
Crofts
Naoko
N
Sakulsingharoj
Chotipa
C
Kim
Dongwook
D
Choi
Sang-Bong
SB
Hamada
Shigeki
S
Ogawa
Masahiro
M
Wang
Changlin
C
Esen
Asim
A
Higgins
Thomas J V
TJ
Okita
Thomas W
TW
D020413:3' Untranslated Regions; D001483:Base Sequence; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D034443:RNA Transport; D018749:RNA, Plant / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017423:Sequence Analysis, RNA; D003313:Zea mays / Q000235:genetics* / Q000378:metabolism; D015028:Zein / Q000235:genetics* / Q000378:metabolism
D020413:3' Untranslated Regions; D018749:RNA, Plant; D015028:Zein