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Cell cycle-regulated gene expression in transgenic plant cells.
T Kawata1, T Nakayama, N Ohtsubo
1Division of Developmental Biology, Faculty of Science, Hokkaido University, Sapporo, Japan.
Developmental Genetics
|January 1, 1990
Summary
Researchers identified key DNA sequences and proteins that regulate S-phase-specific transcription of wheat histone H3 genes. These findings shed light on gene regulation during the cell cycle and in plant promoters.
Area of Science:
- Molecular Biology
- Plant Genetics
- Gene Regulation
Background:
- Histone genes are crucial for DNA packaging and are primarily expressed during the S phase of the cell cycle.
- Understanding the regulation of histone gene expression is vital for comprehending cell cycle progression and genome stability.
- Previous studies indicated the existence of cis-acting elements controlling S-phase-specific gene transcription.
Purpose of the Study:
- To identify cis-acting control sequences responsible for the S-phase-specific transcription of wheat histone H3 genes.
- To identify nuclear DNA-binding proteins that interact with these regulatory sequences.
- To investigate the functional significance of identified motifs and proteins in gene regulation.
Main Methods:
- Utilized a gene expression system in transformed sunflower cells, introducing wheat histone H3 genes via Ti-plasmid gene transfer.
- Identified cis-acting control sequences (hexameric, octameric, and nonameric motifs) through functional analysis.
- Screened for nuclear DNA-binding proteins (HBP-1a, HBP-1b, HBP-2) interacting with identified motifs using electrophoretic mobility shift assays.
- Performed structural analysis of HBP-1a cDNA to determine protein domain characteristics.
Main Results:
- Three cis-acting control sequences (hexameric, octameric, and nonameric motifs) were identified as conferring S-phase-specific transcription of wheat histone H3 genes.
- Three nuclear DNA-binding proteins, HBP-1a, HBP-1b, and HBP-2, were identified as interacting with the hexameric and nonameric motifs.
- Structural analysis revealed HBP-1a possesses a leucine-zipper structure and a DNA-binding motif.
- The hexameric motif, also found in the cauliflower mosaic virus 35S (CaMV 35S) promoter, functions as a regulatory element, with wheat HBP-1b interacting with it.
Conclusions:
- The study successfully identified key cis-acting elements and DNA-binding proteins involved in the S-phase-specific regulation of wheat histone H3 genes.
- The identified hexameric motif and its interacting proteins (HBP-1a, HBP-1b) play significant roles in regulating both histone gene expression and the CaMV 35S promoter.
- These findings provide insights into the molecular mechanisms underlying cell cycle-dependent gene expression in plants.