A site-specific factor interacts directly with its cognate RNA editing site in chloroplast transcripts.
RNA editing involves a variety of genetic systems and occurs by different mechanisms. In higher plant chloroplasts, specific sites of some transcripts are subject to C-to-U conversion. We have previously shown that site-specific trans-acting factors for psbE and petB mRNA editing bind corresponding cis-elements, which are located 5 nucleotides upstream from the editing site. Here we report that, by using mRNAs labeled either at the center of the upstream cis-element or at the editing site, the site-specific factors can be cross-linked with nucleotides at both positions. Mutations of nucleotides in the proximal region of the editing site revealed a correlation between editing activity and cross-linking efficiency of factors with the editing site, even though cross-linking with the upstream cis-element was unaffected. These observations suggest that the site-specific factor binds stably to the upstream ciselement, whereas it interacts weakly with the editing site. This finding raises the intriguing possibility that the site-specific factor is involved in both site-determination and C-to-U conversion in chloroplast RNA editing.
Miyamoto
Tetsuya
T
Center for Gene Research, Nagoya University, Nagoya 464-8602, Japan.
Obokata
Junichi
J
Sugiura
Masahiro
M
D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002736:Chloroplasts / Q000235:genetics* / Q000378:metabolism*; D017343:Genes, Plant; D005816:Genetic Complementation Test; D008954:Models, Biological; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D017393:RNA Editing; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism
C104657:PetB protein, plant; D010940:Plant Proteins; D012333:RNA, Messenger; D018749:RNA, Plant