5'-UTR structural requirements for stability of rbcL transcripts in the chloroplast of Chlamydomonas reinhardtii

Abstract

The rbcL gene is constitutively expressed in the Chlamydomonas chloroplast. The gene encodes the large subunit of ribulose-l,S-bisphosphate carboxylase/oxygenase (Rubisco), the enzyme responsible for CO2 fixation in photosynthesis. The rbCL gene contains a 5’ untranslated region (5’ UTR) that harbours essential elements for regulation of gene expression. A basic promoter element located at position —10 relative to transcription start and several downstream regulatory elements Within the leader region have been recently characterized. Adding five extra nucleotides to the 5’ terminus of rbcL transcripts decreased transcript stability significantly. The results suggest that sequence and/or conformational features are important for RNA stability in chloroplasts.