Journal Article

An Arabidopsis Sigma Factor (SIG2)-Dependent Expression of Plastid-Encoded tRNAs in Chloroplasts

Kengo Kanamaru, Akitomo Nagashima, Makoto Fujiwara, Hiroshi Shimada, Yumiko Shirano, Kazumi Nakabayashi, Daisuke Shibata, Kan Tanaka and Hideo Takahashi

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 42, issue 10, pages 1034-1043
Published in print October 2001 | ISSN: 0032-0781
Published online October 2001 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pce155
An Arabidopsis Sigma Factor (SIG2)-Dependent Expression
of Plastid-Encoded tRNAs in
Chloroplasts

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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A eubacteria-type RNA polymerase (PEP) plays crucial roles for chloroplast development in higher plants. The core subunits are encoded on plastid DNA (rpo genes) while the regulatory sigma factors are encoded on the nuclear DNA (SIG genes). However, the definite gene specificity of each sigma factor is unknown. We recently identified an Arabidopsis recessive pale-green mutant abc1 in which T-DNA is inserted in SIG2 (sigB). In this mutant, almost normal etioplasts were developed under dark conditions while the small chloroplasts with poor thylakoid membranes and stacked lamellar were developed under light conditions. The sig2-1 mutant was deficient in accumulating enough photosynthetic and photosynthesis-related proteins as well as chlorophyll. However, mRNAs of their structural genes were not significantly reduced. Further analyses revealed that several plastid-encoded tRNAs including trnE-UUC that has dual function for protein and ALA biosyntheses were drastically reduced in the sig2-1 mutant. In contrast, nucleus-encoded T7 phage-type RNA polymerase (NEP)-dependent gene transcripts were steadily accumulated in the mutant. These results indicate that progress of chloroplast development requires SIG2-dependent expression of plastid genes, particularly some of the tRNA genes.

Keywords: Key words: Chloroplast — PEP — SIG2 — tRNA.

Journal Article.  6425 words.  Illustrated.

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

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