Transcription from heterologous rRNA operon promoters in chloroplasts reveals requirement for specific activating factors

Priya Sriraman, Daniel Silhavy, Pal Maliga

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The plastid rRNA (rrn) operon in chloroplasts of tobacco (Nicotiana tabacum), maize, and pea is transcribed by the plastid-encoded plastid RNA polymerase from a σ70-type promoter (P1). In contrast, the rrn operon in spinach (Spinacia oleracea) and mustard chloroplasts is transcribed from the distinct Pc promoter, probably also by the plastid-encoded plastid RNA polymerase. Primer-extension analysis reported here indicates that in Arabidopsis both promoters may be active. To understand promoter selection in the plastid rrn operon in the different species, we have tested transcription from the spinach rrn promoter in transplastomic tobacco and from the tobacco rrn promoter in transplastomic Arabidopsis. Our data suggest that transcription of the rrn operon depends on species-specific factors that facilitate transcription initiation by the general transcription machinery.

Original languageEnglish
Pages (from-to)1495-1499
Number of pages5
JournalPlant physiology
Issue number4
Publication statusPublished - Jan 1 1998


ASJC Scopus subject areas

  • Physiology
  • Genetics
  • Plant Science

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