A selfish DNA element engages a meiosis-specific motor and telomeres for germ-line propagation

Area of Science:

• * Molecular Biology
• * Genetics
• * Cell Biology

Background:

• * The yeast 2 micron plasmid exhibits chromosome-like mitotic stability, mediated by Rep1-Rep2 proteins and the STB locus.
• * This stability is thought to involve plasmid-chromosome association and segregation via hitchhiking.
• * Stable segregation during meiosis, however, remained less understood.

Purpose of the Study:

• * To investigate the mechanisms governing the stable segregation of the yeast 2 micron plasmid during meiosis.
• * To identify key proteins and cellular processes involved in plasmid segregation in meiotic cells.
• * To elucidate how the plasmid achieves germ-line transmission.

Main Methods:

• * Analysis of plasmid segregation in yeast mutants lacking key meiotic proteins (Ndj1, Csm4).
• * Microscopy techniques to track plasmid and telomere localization and movement during meiosis.
• * Examination of plasmid association with telomere-binding proteins like Rap1.

Main Results:

• * Stable plasmid segregation during meiosis requires the bouquet proteins Ndj1 and Csm4.
• * The plasmid relocalizes to the nuclear periphery near telomeres during prophase.
• * Plasmid movement during prophase is dependent on Ndj1 and Csm4, mirroring telomere dynamics.
• * Ndj1 is crucial for plasmid-telomere association, while Rap1 colocalization is unaffected.
• * Evidence suggests the plasmid utilizes a meiosis-specific motor for telomere-led segregation.

Conclusions:

• * The yeast 2 micron plasmid employs a novel mechanism for germ-line transmission during meiosis.
• * This mechanism involves association with the meiotic chromosome segregation machinery via telomeres.
• * The plasmid leverages bouquet proteins Ndj1 and Csm4 for its segregation, similar to chromosomes.