Organ-specific transcription of the rrn operon in spinach plastids

Rabah Iratni, Ludger Diederich, Hassan Harrak, Muriel Bligny, Silva Lerbs-Mache

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)


The spinach rrn operon is used as a model system to study transcriptional regulation in higher plant photosynthetic and non- photosynthetic plastids. We performed capping experiments to determine whether P1, PC, or P2 promoters are employed for rrn transcription start sites in cotyledon and root tissues. By using a new method of analysis of capped RNA we demonstrate for the first time that 1) in both organs the rrn operon is expressed in a constitutive manner by cotranscription with the preceding tRNA(GAC)(Val) gene, and 2) the PC transcription start site is used only in cotyledons and leaves, i.e. we demonstrate the organ-specific usage of a plastid promoter. Both start sites, PC and that of the tRNA(GAC)(Val) cotranscript, lack Escherichia coli-like consensus sequences. The cotranscript is initiated 457 base pairs upstream of the tRNA(GAC)(Val) gene. The PC-specific DNA-binding factor, CDF2, is not detectable in root tissues confirming its regulatory role in PC-initiated rrn expression and the organ specificity of PC expression. Furthermore, our results show that rrn operon expression patterns differ in spinach and tobacco indicating species-specific transcriptional regulation of plant plastid gene expression.

Original languageEnglish
Pages (from-to)13676-13682
Number of pages7
JournalJournal of Biological Chemistry
Issue number21
Publication statusPublished - May 23 1997
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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