Replication and recombination of 2-µm DNA in Schizosaccharomyces pombe

Area of Science:

• Molecular Biology
• Yeast Genetics
• Replication Mechanisms

Background:

• The 2-µm DNA is a high-copy-number plasmid in Saccharomyces cerevisiae.
• Understanding plasmid replication and stability in different yeast species is crucial for genetic engineering.
• Inverted repeat sequences within 2-µm DNA are known to play roles in its replication and stability.

Purpose of the Study:

• To investigate the replication capabilities of Saccharomyces cerevisiae 2-µm DNA elements in Schizosaccharomyces pombe.
• To analyze the stability and transformation pathways of plasmids containing complete 2-µm DNA in S. pombe.
• To determine the influence of 2-µm gene expression on plasmid behavior in S. pombe.

Main Methods:

• Construction of chimeric plasmids containing fragments or the complete 2-µm DNA from S. cerevisiae.
• Transformation of Schizosaccharomyces pombe with these chimeric plasmids.
• Analysis of plasmid stability, replication, and integration patterns in S. pombe.
• Assessment of 2-µm gene function expression in S. pombe.

Main Results:

• Individual inverted repeat sequences from S. cerevisiae 2-µm DNA can promote chimeric plasmid replication in S. pombe.
• Plasmids with complete 2-µm DNA exhibit instability and undergo systematic rearrangements in S. pombe.
• Two transformation pathways were observed: chromosomal integration and site-specific recombination leading to stable dimeric structures.
• The selection between these pathways appears to be regulated by the expression of 2-µm functions in S. pombe.

Conclusions:

• Specific elements of S. cerevisiae 2-µm DNA are functional in S. pombe replication.
• Complete 2-µm DNA introduces instability in S. pombe, mediated by recombination or integration.
• 2-µm gene expression is a key factor controlling plasmid fate in S. pombe, highlighting cross-species regulatory mechanisms.