Light-induced gene expression during barley chloroplast development /
| Main Author: | |
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1989.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Abstract: | Several plastid genes (trnQ (UUG), psbK, psbl, trnS (GCU), psbD, psbC, psaA, and psaB) were localized on the barley chloroplast genome. In addition, two transcription units were identified. In etioplasts of dark-grown barley, the psaA-psaB transcription unit gives rise to two transcripts. A second transcription unit consists of psbK, psbl, psbD and psbC, followed by an open reading frame encoding 62 amino acids. Two trnS genes within the psbD-psbC transcription unit are transcribed from the opposite DNA strand. In barley etioplasts, the psbD-psbC transcription unit gives rise to at least ten transcripts (named RNAs 1a, 1b, 1c, 1d, 2a, 2b, 3a, 3b, 5a and 5b). Two of the ten transcripts (RNAs 1c and 1d) end encode psbK and/or psbl, ending upstream o f psbD - psbC. O f the remaining eight transcripts, six transcripts (R N As la, lb, 2a, 2b, 3a, and 3b) contain psbD and psbC, while two transcripts (RNAs 5a and 5b) contain psbC but not psbD. The ten transcripts share four 5' -ends (designated by numbers), two of which arise by transcription initiation (RNAs 1a -1d, RNAs 3a and 3b), and one of which may be generated by processing of longer psbD-psbC transcripts (transcripts 2a and 2b). The eight transcripts homologous to psbD and/or psbC also share two clusters of 3' -ends (designated by a or b). Illumination causes the gradual decline of all ten transcripts, and the accumulation of two unique mRNAs (RNAs 4a and 4b). The light-induced RNAs encode both psbD and psbG. Their accumulation does not correlate with the initial burst in psbD and psbC gene product synthesis, but rather appears to be involved in maintenance of psbD-psbC translation capability in mature chloroplasts. The two light-induced transcripts share a unique 5' -end, which spans a 23 nucleotide region. Capping and in vitro transcription/processing experiments indicated that this 5' -end arises by transcription initiation, and not by processing. Run-on transcription assays and RNA quantitation experiments showed that illumination causes a switch in promoter utilization, which, combined with a general increase in transcript stability, leads to the accumulation of the light-induced psbD-psbC transcripts. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Biochemistry." |
| Physical Description: | xi, 139 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |