How might cohesin hold sister chromatids together?

Abstract

The sister chromatid cohesion essential for the bi-orientation of chromosomes on mitotic spindles depends on a multi-subunit complex called cohesin. This paper reviews the evidence that cohesin is directly responsible for holding sister DNAs together and considers how it might perform this function in the light of recent data on its structure.

Roles of the sister chromatid cohesion apparatus in gene expression, development, and human syndromes

“…The large ring-like structure of cohesin, and several other lines of evidence, including topological linkage of cohesin to circular DNA molecules (Ivanov and Nasmyth 2005) supports the attractive hypothesis that cohesin mediates cohesion by encircling both sister chromatids (Nasmyth 2005;Fig. 1b).…”

“…1b). Other models suggest that two cohesin rings bound via direct DNAprotein contacts to the two sisters interlock to establish cohesion (Huang et al 2005;Milutinovich and Koshland 2003;Nasmyth 2005). Another idea is that a cohesin ring encircling one sister can form protein-protein contacts with the other sister (Chang et al 2005).…”

“…In recent years, many of the proteins that mediate sister chromatid cohesion and its dissolution have been discovered and characterized. There are recent reviews that cover the structure and function of the sister chromatid cohesion apparatus in chromosome segregation (Nasmyth 2005;Nasmyth and Haering 2005;Yanagida 2005;Huang et al 2005;Hirano 2005), and on its potential roles in Cornelia de Lange syndrome (Dorsett 2004;Strachan 2005). In this paper, I review certain key components of the cohesion apparatus, discuss their roles in gene expression and development in model organisms, and then the implications of the model organism studies for Cornelia de Lange and Roberts-SC phocomelia human genetic syndromes.…”

The INO80 Chromatin Remodeling Complex Functions in Sister Chromatid Cohesion

“…Cohesin-associated regions occur at intervals of 8-13 kb along chromosome arms, and cohesin preferentially associates with AT-rich intergenic regions. 2 Importantly, the mechanisms of centromere and arm cohesion appear to be distinct. Cohesin establishes sister chromatid connections during replication at both centromeres and discrete sites along chromosome arms and appears to be enriched near centromeres.…”

“…Cohesin, which is loaded onto chromosomes before S phase, links newly duplicated sister chromatids during DNA replication. [1][2][3] In preparation for chromosome segregation, sister chromatid cohesion is dissolved by mechanisms involving proteolytic cleavage and phosphorylation of the cohesin subunit Scc1. In budding yeast, the cohesin complex is comprised of an evolutionarily conserved SMC (structural maintenance of chromosomes) heterodimer containing Smc1 and Smc3 and of the non-SMC proteins Scc1 and Scc3; the complex is believed to form a ring around sister chromatids.…”