Schizosaccharomyces Pombe - Comparison With Budding Yeast (Saccharomyces Cerevisiae)

Comparison With Budding Yeast (Saccharomyces Cerevisiae)

The yeast species S. pombe and S. cerevisiae are both extensively studied; these two species diverged approximately 300 to 600 million years before present, and are significant tools in molecular and cellular biology. Some of the technical discriminants between these two species are:

• S. cerevisiae has approximately 5,600 open reading frames; S. pombe has approximately 4,970 open reading frames.
• Despite similar gene numbers, S. cerevisiae has only about 250 introns, while S. pombe has nearly 5,000.
• S. cerevisiae has 16 chromosomes, S. pombe has 3.
• S. cerevisiae is often diploid while S. pombe is usually haploid.
• S. cerevisiae is in the G1 phase of the cell cycle for an extended period (consequently, G1-S transition is tightly controlled) while S. pombe remains in the G2 phase of the cell cycle for an extended period (consequently, G2-M transition is under tight control).
• Both species share genes with higher eukaryotes that they do not share with each other. S. pombe has RNAi machinery genes like those in vertebrates, while this is missing from S. cerevisiae. S. cerevisiae also has greatly simplified heterochromatin compared to S. pombe. Conversely, S. cerevisiae has well-developed peroxisomes, while S. pombe does not.
• S. cerevisiae has small point centromere of 125 bp, and sequence-defined replication origins of about the same size. Conversely, S. pombe has large, repetitive centromeres (40–100 kb) more similar to mammalian centromeres, and degenerate replication origins of at least 1kb.