, Volume 237, Issue 2, pp 441-449

First online:

Open Access This content is freely available online to anyone, anywhere at any time.

Complex RNA metabolism in the chloroplast: an update on the psbB operon

  • Rhea StoppelAffiliated withPlant Molecular Biology (Botany), Department Biology I, Ludwig Maximilians UniversityJoint BioEnergy Institute, Feedstocks Division, Lawrence Berkeley National Laboratory Email author 
  • , Jörg MeurerAffiliated withPlant Molecular Biology (Botany), Department Biology I, Ludwig Maximilians University


Expression of most plastid genes involves multiple post-transcriptional processing events, such as splicing, editing, and intercistronic processing. The latter involves the formation of mono-, di-, and multicistronic transcripts, which can further be regulated by differential stability and expression. The plastid pentacistronic psbB transcription unit has been well characterized in vascular plants. It encodes the subunits CP47 (psbB), T (psbT), and H (psbH) of photosystem II as well as cytochrome b 6 (petB) and subunit IV (petD) of the cytochrome b 6 f complex. Each of the petB and petD genes contains a group II intron, which is spliced during post-transcriptional modification. The small subunit of photosystem II, PsbN, is encoded in the intercistronic region between psbH and psbT but is transcribed in the opposite direction. Expression of the psbB gene cluster necessitates different processing events along with numerous newly evolved specificity factors conferring stability to many of the processed RNA transcripts, and thus exemplarily shows the complexity of RNA metabolism in the chloroplast.


Arabidopsis Editing Processing Splicing Stability