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Isolation and characterization of Schizosaccharomyces pombe mutants phenotypically similar to ras1-
1Institute of Medical Science, University of Tokyo, Japan.
Abstract:
We isolated mutants of Schizosaccharomyces pombe which have deformed cell morphology, are deficient in conjugation and poor in sporulation. This phenotype is characteristic of the ras1 defective mutant previously identified. Tests of the mutants for allelism using cell fusion showed that they define five complementation groups, one of which is ras1 itself. The others are named ral1 through ral4 (ras like). Mutants in ral3 or ral4 conjugate at a very low frequency, while the others apparently do not conjugate at all. Plasmid clones complementing ral1, ral2 or ral3, which apparently carry the respective gene, were isolated from S. pombe genomic libraries. Multiple copies of either the ral2 or the ral3 gene could partially restore mating ability in ral1- strains. Multiple copies of the ras1 gene could partially restore mating ability in ral1- and ral2- strains. These results suggest that the ral1, ral2 and ras1 genes may function in a common pathway in that order. The ral3 gene may influence this pathway. Analysis of these gene products will aid identification of factors which interact with Ras proteins.
Insights
Researchers identified new genes (ral1-ral4) in yeast that are crucial for cell development and mating. These genes, along with ras1, appear to function in a shared pathway regulating these essential processes.
Area of Science:
- * Molecular and Cellular Biology
- * Yeast Genetics and Development
Background:
- * The ras1 gene in Schizosaccharomyces pombe is known to regulate cell morphology, conjugation, and sporulation.
- * Understanding the genetic pathways controlling these processes is vital for comprehending cell development.
Purpose of the Study:
- * To identify and characterize novel genes involved in Schizosaccharomyces pombe development and mating.
- * To elucidate the genetic interactions and pathway relationships between ras1 and newly discovered genes.
Main Methods:
- * Isolation and characterization of Schizosaccharomyces pombe mutants with defects in cell morphology, conjugation, and sporulation.
- * Complementation analysis (allelism tests) using cell fusion to group mutants.
- * Screening of genomic libraries to isolate complementing plasmids for identified genes.
- * Assessing mating ability restoration through gene copy number variations.
Main Results:
- * Five complementation groups were identified, including the known ras1 and four novel genes named ral1, ral2, ral3, and ral4.
- * Mutants in ral3 and ral4 showed reduced conjugation, while ral1 and ral2 mutants were severely impaired in mating.
- * Cloning and reintroduction of ral1, ral2, and ral3 genes partially restored mating ability in respective mutant strains.
- * Overexpression of ras1 partially rescued ral1 and ral2 mutant phenotypes, suggesting pathway involvement.
Conclusions:
- * The ral1, ral2, and ras1 genes likely function sequentially in a common pathway regulating yeast mating and development.
- * The ral3 gene may modulate this pathway, influencing conjugation efficiency.
- * Further analysis of these gene products will help identify novel Ras protein interaction factors.