Screening for telomeric recombination in wild-type Kluyveromyces lactis

Area of Science:

• Genetics
• Molecular Biology
• Yeast Biology

Background:

• Telomeres and subtelomeres are crucial for chromosome stability.
• Recombination at telomeres can be enhanced in mutants with short telomeres.
• Kluyveromyces lactis serves as a model organism for studying telomere dynamics.

Purpose of the Study:

• To investigate the frequency of telomeric repeat exchange in wild-type Kluyveromyces lactis.
• To determine the role of intertelomeric recombination in telomere maintenance.
• To assess telomeric repeat dynamics during mitotic and meiotic processes.

Main Methods:

• Utilized Kluyveromyces lactis cells with a single telomere containing mutant repeats.
• Monitored over 100 subclones during multiple passages of mitotic growth.
• Analyzed haploid cells derived from mating and sporulation for meiotic recombination events.

Main Results:

• Observed one instance of terminal duplication into subtelomeric sequence during mitotic growth; no intertelomeric recombination detected.
• Rare recombination events involved replacement of subtelomeric markers and telomeric repeat tracts, consistent with break-induced replication.
• No movement of subtelomeric or telomeric sequences between chromosome ends was observed during meiosis.

Conclusions:

• Intertelomeric recombination is not a significant contributor to telomere maintenance in normal Kluyveromyces lactis.
• Telomeric repeat exchange is infrequent during both mitotic and meiotic processes in wild-type K. lactis.
• Break-induced replication may play a role in rare recombination events at chromosome ends.