BACKGROUND: Cohesion between sister chromatids is promoted by the chromosomal cohesin complex that forms a proteinaceous ring, large enough in principle to embrace two sister strands. The mechanism by which cohesin binds to DNA, and how sister chromatid cohesion is established, is unknown. RESULTS: Biochemical studies of cohesin have largely been limited to protein isolated from soluble cellular fractions. Here, we characterize cohesin purified from budding @entity375 chromatin, suggesting that chromosomal cohesin is sufficiently described by its known distinctive ring structure. We present evidence that the two Smc subunits of cohesin by themselves form a ring, closed at interacting ATPase head domains. A motif in the @entity32218 subunit implicated in @entity855 hydrolysis is essential for loading cohesin onto DNA. In addition to functional ATPase heads, an intact cohesin ring structure is indispensable for DNA binding, suggesting that @entity855 hydrolysis may be coupled to DNA transport into the cohesin ring. DNA is released in anaphase when @entity23524 cleaves cohesin's @entity32217 subunit. We show that a cleavage fragment of @entity32217 disrupts the interaction between the two Smc heads, thereby opening the ring. CONCLUSIONS: We present a model for cohesin binding to chromatin by @entity855 hydrolysis-dependent transport of DNA into the cohesin ring. After DNA replication, two DNA strands may be trapped to promote sister chromatid cohesion. In anaphase, @entity32217 cleavage opens the ring to release sister chromatids.

A model for XXXX hydrolysis-dependent binding of cohesin to DNA.

@entity23524 :: ('852990(Tax:4932)', 'Gene') :: ['separase'] @entity375 :: ('4932', 'Species') :: ['yeast'] @entity32217 :: ('851561(Tax:4932)', 'Gene') :: ['Scc1'] @entity32218 :: ('850540(Tax:4932)', 'Gene') :: ['Smc1'] @entity855 :: ('MESH:D000255', 'Chemical') :: ['ATP']
@entity855 :: (MESH:D000255,Chemical) :: ['ATP']
