Faithful segregation of the multicopy yeast plasmid through cohesin-mediated recognition of sisters.
The 2-microm yeast plasmid, a benign high-copy nuclear parasite, propagates itself with nearly the same fidelity as the chromosomes of its host. Equal plasmid segregation is absolutely dependent on the cohesin complex assembled at the plasmid partitioning locus STB. However, the mechanism of cohesin action in the context of multiple plasmid copies, resident within two separate clusters after DNA replication, is unknown. By using "single-copy" derivatives of the 2-microm plasmid, we demonstrate that recruitment of cohesin at STB during S phase indeed translates into cohesion between plasmid molecules. Through binary fluorescence tagging, we reveal that segregation of replicated plasmids occurs in a sister-to-sister fashion. Thus, cohesin serves the same fundamental purpose in plasmid and chromosome segregation.
Section of Molecular Genetics and Microbiology, University of Texas, Austin, TX 78712, USA.
Santanu K
SK
Ghosh
Sujata
S
Hajra
Makkuni
M
Jayaram
D018797:Cell Cycle Proteins / Q000502:physiology*; D002868:Chromosomal Proteins, Non-Histone / Q000502:physiology*; D020090:Chromosome Segregation; D009687:Nuclear Proteins / Q000502:physiology*; D010957:Plasmids; D008941:Spindle Apparatus / Q000502:physiology; D015003:Yeasts / Q000235:genetics*; D000097722:Cohesins
D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D009687:Nuclear Proteins; D000097722:Cohesins