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An evolutionarily conserved protein binding sequence upstream of a plant light-regulated gene
G Giuliano1, E Pichersky, V S Malik
1Department of Biology, University of Pennsylvania, Philadelphia 19104.
Summary
A novel protein factor, the G box binding factor (GBF), specifically binds to regulatory sequences in plant genes. This discovery sheds light on the molecular mechanisms controlling gene expression in response to light.
Area of Science:
- Plant Molecular Biology
- Gene Regulation
- Biochemistry
Background:
- The small subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase (RBCS) is encoded by a plant light-regulated gene family.
- Understanding the regulatory elements controlling RBCS gene expression is crucial for plant science.
Purpose of the Study:
- To identify and characterize protein factors that bind to upstream regulatory sequences of plant RBCS genes.
- To elucidate the specific DNA sequences involved in this binding interaction.
Main Methods:
- Nuclear extracts from tomato and Arabidopsis seedlings were used.
- Electrophoretic mobility shift assays (EMSAs) were employed to detect DNA-protein interactions.
- Sequence analysis identified conserved motifs within RBCS promoters.
Main Results:
- A protein factor, termed G box binding factor (GBF), was identified that binds to upstream sequences of RBCS genes from tomato, pea, and Arabidopsis.
- The binding site was mapped to a conserved G box sequence (5'-TCTTACACGTGGCAYY-3'), distinct from previously identified GT motifs.
- GBF was found in leaf extracts but significantly reduced in root extracts, suggesting tissue-specific regulation.
Conclusions:
- GBF is a key transcription factor involved in the light-regulated expression of RBCS genes in plants.
- The G box is an essential regulatory element recognized by GBF for controlling RBCS gene transcription.
- The presence and activity of GBF may vary depending on plant tissue and light conditions.