Characterization of a rice nuclear-encoded plastid RNA polymerase gene OsRpoTp.
We isolated and characterized two rice genes, OsRpoTp and OsRpoTm, that encode putative phage-type RNA polymerases. Predicted amino acid sequences showed high homology of these genes to known RpoT genes. A transient expression assay using green fluorescent protein indicated that the encoded proteins were localized to plastids and mitochondria, respectively. We demonstrated by reverse transcription-PCR experiments and immunoblot analysis that OsRpoTp expression occurred at an early stage of leaf development, prior to the transcript accumulation of the genes that were transcribed by the nuclear-encoded plastid RNA polymerase (NEP). Expression analyses of the chloroplast-deficient rice mutant, virescent-1, showed a discrepancy between OsRpoTp protein accumulation and the level of transcripts of NEP-transcribed genes. Our results suggest that NEP activation is regulated by a process after transcription, and is affected by the developmental state of chloroplast biogenesis.
Kusumi
Kensuke
K
Department of Biology, Faculty of Science, Kyushu University, Hakozaki, Higashi-ku, Fukuoka, 812-81 Japan. kkususcb@mbox.nc.kyushu-u.ac.jp
Yara
Asanori
A
Mitsui
Naoko
N
Tozawa
Yuzuru
Y
Iba
Koh
K
D001483:Base Sequence; D002467:Cell Nucleus / Q000201:enzymology*; D003001:Cloning, Molecular; D017931:DNA Primers; D012321:DNA-Directed RNA Polymerases / Q000235:genetics*; D008969:Molecular Sequence Data; D012275:Oryza / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D018515:Plant Leaves / Q000201:enzymology / Q000254:growth & development; D018087:Plastids / Q000235:genetics*; D011994:Recombinant Proteins / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
D017931:DNA Primers; D011994:Recombinant Proteins; D012321:DNA-Directed RNA Polymerases