Mutations in a Partitioning Protein and Altered Chromatin Structure at the Partitioning Locus Prevent Cohesin Recruitment by the Saccharomyces cerevisiae Plasmid and Cause Plasmid Missegregation

摘要: The 2μm circle is a highly persistent “selfish” DNA element resident in the Saccharomyces cerevisiae nucleus whose stability approaches that of chromosomes. plasmid partitioning system, consisting two plasmid-encoded proteins, Rep1p and Rep2p, cis-acting locus, STB, apparently feeds into chromosome segregation pathway. Rep proteins assist recruitment yeast cohesin complex to STB during S phase, presumably apportion replicated molecules equally daughter cells. DNA-protein protein-protein interactions as well chromatin organization at are important for recruitment. variants incompetent binding or both fail assembly nonfunctional maintenance. Preventing cohesin-STB association without impeding Rep1p-Rep2p-STB also causes missegregation. During cell cycle, Rep2p expelled from short interval between late G1 early phases. This dissociation reassociation event ensures loading replication dependent coordinated with chromosomal In an rsc2Δ strain lacking specific remodeling exhibiting high degree loss, neither nor can be recruited STB. phenotypes mutations mutant consistent role being analogous partitioning.