Translation of psbC mRNAs starts from the downstream GUG, not the upstream AUG, and requires the extended Shine-Dalgarno sequence in tobacco chloroplasts.
The plastid gene psbC encodes the CP43 subunit of PSII. Most psbC mRNAs of many organisms possess two possible initiation codons, AUG and GUG, and their coding regions are generally annotated from the upstream AUG. Using a chloroplast in vitro translation system, we show here that translation of the tobacco plastid psbC mRNA initiates from the GUG. This mRNA possesses a long Shine-Dalgarno (SD)-like sequence, GAGGAGGU, nine nucleotides upstream of the GUG. Point mutations in this sequence abolished translation, suggesting that a strong interaction between this extended SD-like sequence and the 3' end of 16S rRNA facilitates translation initiation from the GUG.
Graduate School of Natural Sciences, Nagoya City University, Yamanohata, Mizuho, Nagoya, Japan.
Hiroshi
H
Kuroda
Haruka
H
Suzuki
Takahiro
T
Kusumegi
Tetsuro
T
Hirose
Yasushi
Y
Yukawa
Masahiro
M
Sugiura
D001483:Base Sequence; D002736:Chloroplasts / Q000235:genetics* / Q000378:metabolism; D018387:Codon, Initiator; D008969:Molecular Sequence Data; D045332:Photosystem II Protein Complex / Q000096:biosynthesis / Q000235:genetics*; D010940:Plant Proteins / Q000096:biosynthesis / Q000235:genetics; D014176:Protein Biosynthesis; D018747:RNA, Chloroplast / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics* / Q000378:metabolism
D018387:Codon, Initiator; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D018747:RNA, Chloroplast; D012333:RNA, Messenger