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mRNA stability is regulated by a coding‐region element and the unique 5′ untranslated leader sequences of the three Synechococcus psbA transcripts
Author(s) -
Kulkarni Resham D.,
Golden Susan S.
Publication year - 1997
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.1997.4201768.x
Subject(s) - biology , minigene , untranslated region , au rich element , coding region , messenger rna , open reading frame , ribosome , rna , reporter gene , gene , three prime untranslated region , translation (biology) , ribosomal binding site , protein biosynthesis , gene expression , genetics , microbiology and biotechnology , rna splicing , peptide sequence
The psbAI and psbAIII transcripts in Synechococcus sp. strain PCC 7942 are subject to accelerated turnover when cells are exposed to high light intensities, but psbAII message stability is unaffected. We used a psbAI ‘minigene’ which has a part of the coding sequence removed as a reporter gene in order to identify the cis ‐acting elements of the transcript that determine stability. While engineering the minigene to optimally mimic the native gene, we identified a stabilizer element within the open reading frame, corresponding to the coding region for the first membrane span of the D1 protein, the presence of and translation through which was essential for normal psbA mRNA stability. We propose that this stabilizer is a site for ribosome pausing, and that accumulation of ribosomes on the transcript upstream of the pause site increases stability. To identify the elements that regulate the differential responses of the psbA transcripts to high‐light growth, sequences from psbAII and psbAIII were substituted in the psbAI minigene reporter. The chimeric reporter transcripts established that the psbAI and psbAIII untranslated leaders determine the faster turnover of these messages. The untranslated leader regions of the psbA transcripts may regulate mRNA stability by modulating translation and thereby stability, or by recruiting RNA‐binding proteins that affect mRNA turnover more directly.