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The downstream atpE cistron is efficiently translated via its own cis-element in partially overlapping atpB-atpE dicistronic mRNAs in chloroplasts.

Abstract

The chloroplast atpB and atpE genes encode subunits β and ε of the ATP synthase, respectively. They are co-transcribed as dicistronic mRNAs in flowering plants. An unusual feature is an overlap (AUGA) of the atpB stop codon (UGA) with the atpE start codon (AUG). Hence, atpE translation has been believed to depend on atpB translation (i.e. translational coupling). Using an in vitro translation system from tobacco chloroplasts, we showed that both atpB and atpE cistrons are translated from the tobacco dicistronic mRNA, and that the efficiency of atpB translation is higher than that of atpE translation. When the atpB 5'-UTR was replaced with lower efficiency 5'-UTRs, atpE translation was higher than atpB translation. Removal of the entire atpB 5'-UTR arrested atpB translation but atpE translation still proceeded. Introduction of a premature stop codon in the atpB cistron did not abolish atpE translation. These results indicate that atpE translation is independent of atpB translation. Mutation analysis showed that the atpE cistron possesses its own cis-element(s) for translation, located ~25 nt upstream from the start codon.

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  • Authors

    Suzuki H, Kuroda H, Yukawa Y, Sugiura M

    Institution

    Graduate School of Natural Sciences, Nagoya City University, Yamanohata, Mizuho, Nagoya 467-8501, Japan.

    Source

    Nucleic acids research 39:21 2011 Nov pg 9405-12

    MeSH

    5' Untranslated Regions
    Chloroplast Proton-Translocating ATPases
    Codon, Terminator
    Genes, Chloroplast
    Plant Proteins
    Protein Biosynthesis
    Protein Subunits
    RNA, Messenger
    Tobacco

    Pub Type(s)

    Journal Article
    Research Support, Non-U.S. Gov't

    Language

    eng

    PubMed ID

    21846772