FUNCTION OF PLASTID MESSENGER-RNA 3' INVERTED REPEATS - RNA STABILIZATION AND GENE-SPECIFIC PROTEIN-BINDING

  • 5 November 1989
    • journal article
    • research article
    • Vol. 264  (31) , 18742-18750
Abstract
Plastid protein coding regions in plants are generally flanked by 3'' inverted repeat (IR) sequences. In a previous work (Stern, D. B., and Gruissem, W. (1987) Cell 51, 1145-1157), we have shown that their role may be in RNA stabilization and as a processing signal that establishes the mature mRNA 3'' end. In this report we have investigated the stability and protein interaction of chloroplast mRNA 3'' IR-RNA sequences in more detail. Progressive deletions into the 3'' IR-RNA sequences for the chloroplast cytochrome b6/f subunit IV (petD) mRNA reduce the stability of the RNA, indicating that the potential to form a stem/loop is a minimum requirement for petD 3'' IR-RNA stability in vitro. Specific point mutants also destabilize the processed 3'' IR-RNA, suggesting an important role for the primary sequence. Gel mobility shift and UV-cross-linking analysis has shown that 3'' IR-RNAs of petD and two other chloroplast mRNAs (rbcL and psbA) interact with proteins in vitro. Comparison of the bound petD 3'' IR-RNA proteins with proteins that bind to rbcL and psbA reveals that binding of certain proteins is gene-specific. Also, precursor and processed petD 3'' IR-RNAs bind different sets of proteins. A single nucleotide transversion (T .fwdarw. A) near the base of the stem eliminates the binding of a 29-kDa protein to the petD 3'' IR-RNA precursor. We discuss the possible role of 3'' IR-RNA-protein interactions in plastid mRNA 3'' end maturation and differential mRNA stability.

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