Processing of the psbA 5' untranslated region in Chlamydomonas reinhardtii depends upon factors mediating ribosome association

Richard K. Bruick, Stephen P. Mayfield

Research output: Contribution to journalArticle

46 Scopus citations

Abstract

The 5' untranslated region of the chloroplast psbA mRNA, encoding the D1 protein, is processed in Chlamydomonas reinhardtii. Processing occurs just upstream of a consensus Shine-Dalgarno sequence and results in the removal of 54 nucleotides from the 5' terminus, including a stem-loop element identified previously as an important structure for D1 expression. Examination of this processing event in C. reinhardtii strains containing mutations within the chloroplast or nuclear genomes that block psbA translation reveals a correlation between processing and ribosome association. Mutations within the 5' untranslated region of the psbA mRNA that disrupt the Shine-Dalgarno sequence, acting as a ribosome binding site, preclude translation and prevent mRNA processing. Similarly, nuclear mutations that specifically affect synthesis of the D1 protein specifically affect processing of the psbA mRNA. In vitro, loss of the stem-loop element does not prohibit the binding of a message-specific protein complex required for translational activation of psbA upon illumination. These results are consistent with a hierarchical maturation pathway for chloroplast messages, mediated by nuclear-encoded factors, that integrates mRNA processing, message stability, ribosome association, and translation.

Original languageEnglish (US)
Pages (from-to)1145-1153
Number of pages9
JournalJournal of Cell Biology
Volume143
Issue number5
DOIs
StatePublished - Nov 30 1998

Keywords

  • Chloroplast
  • Ribosome binding sequence
  • Translation
  • mRNA processing
  • psbA

ASJC Scopus subject areas

  • Cell Biology

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