Journal Article

Transcriptional Activities of the Chloroplast-Nuclei and Proplastid-Nuclei Isolated from Tobacco Exhibit Different Sensitivities to Tagetitoxin: Implication of the Presence of Distinct RNA Polymerases

Atsushi Sakai, Chieko Saito, Noriko Inada and Tsuneyoshi Kuroiwa

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 39, issue 9, pages 928-934
Published in print September 1998 | ISSN: 0032-0781
Published online September 1998 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/oxfordjournals.pcp.a029456
Transcriptional Activities of the Chloroplast-Nuclei and Proplastid-Nuclei Isolated from Tobacco Exhibit Different Sensitivities to Tagetitoxin: Implication of the Presence of Distinct RNA Polymerases

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We examined the effects of tagetitoxin, a potent inhibitor of RNA polymerases from chloroplasts and Escherichia coli, on the transcriptional activities of chloroplast- and proplastid-nuclei (nucleoids) isolated from mature tobacco (Nicotiana tabacum L.) leaves and cultured tobacco cells (line BY-2), respectively. Transcription by the isolated chlo-roplast-nuclei was effectively inhibited by tagetitoxin (95–99% reduction at 10 μM tagetitoxin), but transcription by the isolated proplastid-nuclei was only partially inhibited (40–50% reduction) by this compound. Southern hybridization experiments revealed that the transcription of various plastid genes (psbA, atpA, rpoB, psaA/B, atpB, rbcL, petB, rpl16, and rrn23) was sensitive to tagetitoxin in the isolated chloroplast-nuclei, whereas the transcription of the same genes was relatively resistant to this compound in the isolated proplastid-nuclei. These results suggest that; (i) distinct RNA polymerase activities with different sensitivities to tagetitoxin are present in plastids, (ii) a tagetitoxin-sensitive RNA polymerase is the major RNA polymerase in chloroplasts whereas a tagetitoxin-insensitive enzyme is major in proplastids, and (iii) both RNA polymerases can transcribe various plastid genes.

Keywords: Chloroplast; Proplastid; RNA polymerase; Tagetitoxin; Transcription

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Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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