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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.cell.2009.02.035 Byline: Stephan Gruber (1), Jeff Errington (1) Keywords: CELLBIO; CELLCYCLE; MICROBIO Abstract: Proper segregation of DNA replication products is essential in all cells. In Bacillus subtilis, two protein complexes have been implicated in this process: the ParAB homologs, Soj and Spo0J, and the bacterial Smc/ScpAB complex, also called condensin. Here we demonstrate that Smc is highly enriched in the region around the origin of replication, specifically near parS sites to which Spo0J binds and at highly transcribed genes. Furthermore, we find that efficient recruitment of Smc to a large region around the origin of replication depends on the presence of Spo0J. We show that Spo0J performs two independent functions: regulation of initiation of DNA replication via Soj and promotion of chromosome segregation by Smc recruitment. Our results demonstrate a direct functional interaction between two widely conserved systems involved in chromosome replication and segregation. Author Affiliation: (1) Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle Upon Tyne, NE2 4HH, UK Article History: Received 1 October 2008; Revised 23 December 2008; Accepted 19 February 2009 Article Note: (miscellaneous) Published: May 14, 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.cell.2006.08.048 Byline: Stephan Gruber (1), Prakash Arumugam (1)(2), Yuki Katou (3), Daria Kuglitsch (1), Wolfgang Helmhart (1)(2), Katsuhiko Shirahige (3), Kim Nasmyth (1)(2) Abstract: Cohesin is a multisubunit complex that mediates sister-chromatid cohesion. Its Smc1 and Smc3 subunits possess ABC-like ATPases at one end of 50 nm long coiled coils. At the other ends are pseudosymmetrical hinge domains that interact to create V-shaped Smc1/Smc3 heterodimers. N- and C-terminal domains within cohesin's kleisin subunit Scc1 bind to Smc3 and Smc1 ATPase heads respectively, thereby creating a huge tripartite ring. It has been suggested that cohesin associates with chromosomes by trapping DNA within its ring. Opening of the ring due to cleavage of Scc1 by separase destroys sister-chromatid cohesion and triggers anaphase. We show that cohesin's hinges are not merely dimerization domains. They are essential for cohesin's association with chromosomes, which is blocked by artificially holding hinge domains together but not by preventing Scc1's dissociation from SMC ATPase heads. Our results suggest that entry of DNA into cohesin's ring requires transient dissociation of Smc1 and Smc3 hinge domains. Author Affiliation: (1) Institute of Molecular Pathology, Dr. Bohr-Gasse 7, 1030 Vienna, Austria (2) University of Oxford, Department of Biochemistry, South Parks Road, Oxford OX1 3QU, UK (3) Gene Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, 226-8501 Yokohama, Japan Article History: Received 10 January 2006; Revised 30 June 2006; Accepted 21 August 2006 Article Note: (miscellaneous) Published: November 2, 2006

Research points out that cohesin holds sister DNAs within a single ring and that all SMC protein complexes, like cohesin, allow passage of DNA inside two arms held together by Scc1-like bridges that open and close. This mechanism regulate the DNA packing within cells.