Fission yeast mating-type switching: programmed damage and repair.

Area of Science:

• Molecular biology
• Genetics
• Cell biology

Background:

• Mating-type switching in yeast species shares functional similarities but differs mechanistically.
• Budding yeast requires double-strand break repair for survival, while fission yeast utilizes single-strand damage.
• Replication fork stalling is implicated in generating site-specific nicks during mating-type switching.

Purpose of the Study:

• To investigate the molecular safeguards protecting replication forks from DNA damage.
• To understand the mechanism of single-strand nick generation and repair in fission yeast mating-type switching.
• To explore a conditional system for controlling mating-type switching.

Main Methods:

• Utilizing fission yeast (Schizosaccharomyces pombe) as a model organism.
• Investigating replication fork dynamics and DNA repair pathways.
• Employing a newly developed conditional system for genetic manipulation.

Main Results:

• A single-strand nick, rather than a double-strand break, initiates mating-type switching in fission yeast.
• This nick is protected and interferes with replication in the subsequent S-phase.
• A conditional system allows for regulated repression and derepression of mating-type switching.

Conclusions:

• Fission yeast mating-type switching provides a model for studying replication fork protection mechanisms.
• Gap repair in situ seals the nick, potentially imprinting for mating-type switching.
• The conditional system enhances the experimental versatility for studying these processes.