Ribosomal RNA processing and an RNase R family member in chloroplasts of Arabidopsis |
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Authors: | Masahiro Kishine Atsushi Takabayashi Yuri Munekage Toshiharu Shikanai Tsuyoshi Endo Fumihiko Sato |
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Institution: | (1) Graduate School of Biostudies, Kyoto University, Japan;(2) Graduate School of Biological Sciences, Nara Institute of Science and Technology, Japan;(3) Graduate School of Agriculture, Kyushu University, Higashiku |
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Abstract: | An Arabidopsis mutant rnr1, which has a defect in the basic genetic system in chloroplasts, was isolated using the screening of the high chlorophyll fluorescence phenotype. Whereas chlorophyll fluorescence and immunoblot studies showed the mutant had reduced activities of photosystems I and II, molecular characterization of the mutant suggested that a T-DNA insertion impaired the expression of a gene encoding a RNase R family member with a targeting signal to chloroplasts. Since RNase R family members have a 3 –5 exoribonuclease activity, we examined the RNA profile in chloroplasts. In rnr1 the intercistronic cleavage between 23S and 4.5S rRNA was impaired, and a significant reduction in rRNA in chloroplasts was found, suggesting that RNR1 functions in the maturation of chloroplast rRNA. The present results suggest that defects in the genetic system in chloroplasts cause high chlorophyll fluorescence, pale green leaf, and marked reduction in the growth rate, whereas the levels of some chloroplast RNA were higher in rnr1 than in the wild-type. |
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Keywords: | chlorophyll fluorescence chloroplast RNA processing RNase R rRNA |
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