Reference "Transcripts of the ndhH-D operon of barley plastids: possible role of unedited site III in splicing of the ndhA intron"

Reference ID

8711

Title

Transcripts of the ndhH-D operon of barley plastids: possible role of unedited site III in splicing of the ndhA intron

Source

Nucleic acids research, 2000, vol. 28, pp. 1092-1098

Authors (2)

Sabater-B

Martin-M

Abstract

The plastid ndhH-D operon produces several transcripts containing ndhA sequence
with and without its group II intron. After sequencing an 8125 bp fragment of
barley plastid DNA including the ndhH-D operon, we investigated the editing-
splicing status of transcripts in the range 1.0-7.8 kb. Reverse transcription
and sequencing of RNA bands separated by electrophoresis were used to determine
C-->U editing sites. Sites I, II and IV of ndhA and site V of ndhD were edited
in all transcripts analysed and, probably, were edited before any splicing had
taken place. In contrast, site III of ndhA (13 bp from the 5'-end base of the
second exon) was not edited in transcripts containing the intron (including the
1.7 kb intermediary transcript consisting of the intron and the second exon) but
was edited in all transcripts lacking the ndhA intron. Comparison of the
secondary structures of the ndhA intron and intron-second exon intermediate
suggests that G pairing prevents editing of site III in transcripts containing
the intron and maintains the secondary structure required for splicing. Splicing
of the ndhA intron releases the site III C from pairing and, probably, brings it
close to cis-acting elements for editing upstream in the first exon.