The interplay between chromatin structure, PvAlf and ABA in the regulation of expression from the phaseolin promoter /
Phaseolin is the major seed protein of bean, Phaseolus film Inc. vulgaris. It is highly expressed and acculturated during embryogenesis, but is absent from vegetative tissues. To understand the molecular mechanisms conferring stringent developmental and spatial regulation of expression on phas prom...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1998.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=733050341&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Phaseolin is the major seed protein of bean, Phaseolus film Inc. vulgaris. It is highly expressed and acculturated during embryogenesis, but is absent from vegetative tissues. To understand the molecular mechanisms conferring stringent developmental and spatial regulation of expression on phas promoter, we conducted three major sets of experiments. The first set of experiments waste use footnoting in vivo to probate chromatin structure of both the active and the inactive phas promoter. Our results revealed that the lack of basal transcriptional activity in vegetative tissues is associated with the presence of a nucleosome that is rotationally positioned oversee phased TATA boxes present in phas promoter. During embryogenesis, this positioned nucleosome is disrupted, leading to an assembly of a transcriptionally competent nucleoprotein complex. The second set of experiments waste use DMS footprinting in vivo to determine phas cơs-element occupancy in transciptionally active and inactive tissues. In addiction, staged embryos were used to analyze changes in phas promoter occupancy during transciptional activation in ordered explore the temporal hierarchy of trans-acting factor binding to the phas promoter during embryogenesis. Our results revealed abundant factor binding to the actively/lay promoter. Although the involvement of multiple factors may be intrinsic to high level expression of the phas gene during the embryogenesis, histochemical analysis of [] expression patterns from various deletions of the 5' region of the promoter suggested that the complicated footprint profile maybe a summation of less complex footprints from differentiations of the embryo. Changes in the footprint profile during embryogenesis progressed from limited factor binding at early stages to abundant factor binding, at mid-maturation, then to reduced binding and, finally, to a footprinting profile similar to that of leaf tissue, which correspond nicely with the fact that phas is inactive in mature seeds. The third set of experiments was to evaluate the role of transcription factor PvAlf and abscisic acid (ABA) in phas gene regulation. By using tobacco plants transformed with both 35S/PvAlf and phas/uidA, it became apparent that the presence of PvAlf determines tissue specificity of sepias gene. lathe presence of PvAlf, phas becomes ABA-inducible vegetative tissue. This ABA inducibility is retained in in a construct containing only the -109 region of the phas promoter, indicating that both PvAlf and ABA-responsive elements represent in that region. Using an RNA protection assay (RPA) of PvAlf14 (a tobacco line transgenic for both -1470phas/uidA and 35S/PvAlf) treated under different ABA and cycloheximide treatments, we demonstrated that de novo protein synthesis is not required for the PvAlf-dependent ABA induction of expression from the phas promoter, suggesting modification (e.g. phosphorylation or dephosphorylation) of transcription factor(s) is involved in its transcriptional activation. |
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| Item Description: | Vita. "Major Subject: Biology". |
| Physical Description: | x, 115 leaves : illustrations ; 28 cm. |
| Bibliography: | Includes bibliographical references (leaves 92-113). |