Mechanisms regulating psbD expression from a plastid blue light-responsive promoter : a glimpse of regulated plastid gene expression /
Mechanisms regulating light-induced psbD expression from the plastid psbD blue light-responsive promoter (psbD-LRP) were investigated. The structure of the 130 bp highly conserved psbD-LRP was analyzed in detail in vitro. The architecture of the psbD-LRP is unique in that along with prokaryotic li...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2000.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=728408771&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Mechanisms regulating light-induced psbD expression from the plastid psbD blue light-responsive promoter (psbD-LRP) were investigated. The structure of the 130 bp highly conserved psbD-LRP was analyzed in detail in vitro. The architecture of the psbD-LRP is unique in that along with prokaryotic like -10 and -35 sequences it also contains novel cis-elements, termed the AAG- and PGT-box. The minimal psbD-LRP sequence, sufficient for light-induced transcription was defined as a 53 bp DNA region, spanning -57 to -5 upstream of the psbD transcriptional initiation site. Further analysis revealed the putative prokaryotic -10 region was required for transcription, whereas the putative prokaryotic -35 region was not. Furthermore, spacing between the AAG-box, located -64 to -36, and the -10 region is important for psbD transcription from this promoter. An in vivo functional analysis of psbD-LRP promoter elements was carried out through the analysis of transplastomic tobacco lines containing various forms of the barley psbD-LRP. The barley psbD-LRP in tobacco was induced by blue and white light, but not by red light. The -10 region and AAG-box were shown to be required for psbD transcription, whereas the -35 region and PGT-box were not. Moreover, the barley psbD-LRP in tobacco maintained its responsiveness to circadian cycling. Therefore, the barley psbD-LRP in tobacco responded to light-modulated regulatory pathways in tobacco, emphasizing the conservation of this pathway between monocot and dicots. It was investigated whether psbD-LRP activity responds to plastid-derived redox signals. Interruption of normal photosynthetic electron flow abolished light-induced psbD-LRP transcription. Furthermore, binding of an activating complex to the AAG-box, required for psbD-LRP transcription, was regulated by vicinal dithiols. Therefore, plastid-derived redox signals may modulate psbD-LRP transcription by affecting binding activity of the activating complex to the AAG-box. Components of light signal transduction pathways modulating psbD-LRP transcription were identified using numerous photomorphogenic mutants. Blue-light activation of the psbD-LRP was mediated by cryptochrome 1 or cryptochrome 2 and was shown to be dependent on the phytochrome A high-irradiance signaling pathway through the genes, FHY1 and FHY3 (far-red elongated hypocotyl). Furthermore, blue light perceived and transduced through cryptochome 1 and cryptochrome 2 modulates overall plastid transcription. |
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| Item Description: | Vita. "Major Subject: Molecular and Environmental Plant Science". |
| Physical Description: | xiv, 190 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 153-189). |