Yeast RAS2 affects cell viability, mitotic division and transient gene expression in Nicotiana species
P Hilson1, J Dewulf, F Delporte
1Unité de Biologie Moléculaire et de Physiologie Animale, Faculté des Sciences Agronomiques de l'Etat, Gembloux, Belgium.
Abstract:
Overexpression of the budding yeast RAS2 gene in Nicotiana plumbaginifolia cells revealed that RAS2 acted as 'suicide' gene in freshly isolated protoplasts from leaves and blocked cell proliferation in cell suspension-derived protoplasts. Among a series of genes tested (such as npt II, CDC35, PDE2), RAS2 was the only one to block the expression of the cat gene, as measured in a transient gene expression assay. Another ras gene, v-Ha-ras, had similar effects. Furthermore, the RAS2 effect was species-specific and depended on the modulation of hormonal metabolism in the transfected cells, while no differences were noticed between the normal and the activated val19 gene. Transfected plant cells are shown to synthesize a RAS2 protein of the same electrophoretic mobility as the yeast RAS2 product. The results are discussed in the broader context of the evolutionarily conserved ras genes involved in vital cellular functions.
Insights
Budding yeast RAS2 gene overexpression in plant cells acts as a suicide gene, blocking cell proliferation and gene expression. This effect is species-specific and linked to hormonal metabolism changes.
Area of Science:
- Molecular Biology
- Plant Science
- Genetics
Background:
- Ras genes are evolutionarily conserved and play vital roles in cellular functions.
- Understanding the function of yeast RAS2 in plant cells can provide insights into conserved cellular pathways.
Purpose of the Study:
- To investigate the effects of overexpressing the budding yeast RAS2 gene in Nicotiana plumbaginifolia plant cells.
- To determine if RAS2 influences cell proliferation and gene expression in plants.
- To explore the species-specificity and underlying mechanisms of RAS2's effects in plant systems.
Main Methods:
- Overexpression of the budding yeast RAS2 gene in Nicotiana plumbaginifolia protoplasts.
- Transient gene expression assays to measure reporter gene (cat) expression.
- Comparison with other genes (npt II, CDC35, PDE2) and viral ras genes (v-Ha-ras).
- Analysis of hormonal metabolism modulation in transfected cells.
Main Results:
- RAS2 overexpression acted as a 'suicide' gene in leaf protoplasts and blocked cell proliferation in suspension-derived protoplasts.
- RAS2 uniquely inhibited cat gene expression among tested genes, unlike npt II, CDC35, or PDE2.
- The viral v-Ha-ras gene exhibited similar inhibitory effects.
- The observed effects were species-specific and dependent on hormonal metabolism.
- Transfected plant cells produced RAS2 protein with the same electrophoretic mobility as the yeast product.
Conclusions:
- The yeast RAS2 gene can disrupt essential cellular processes like proliferation and gene expression in plant cells.
- RAS2's function in plants is species-specific and involves modulation of hormonal pathways.
- These findings highlight the conserved nature of ras genes and their critical roles across different species.
