Getting poster data...
Michael T. Hons, Pim J. Huis in ‘t Veld, Jan Kaesler, Franz Herzog, Alexander Schleiffer, Jan-Michael Peters & Holger Stark (MPI for Biophysical Chemistry, Am Faßberg 11, 37077 Göttingen)Cohesin is a protein complex which physically connects replicated DNA molecules until they are separated in anaphase. This cohesion is essential for bi-orientation of sister chromatids on the spindle and is thus required for proper chromosome segregation. The cohesin subunits Smc1, Smc3 and Scc1 form large tripartite rings which mediate sister chromatid cohesion and chromatin structure. These are thought to entrap DNA with the help of the associated proteins SA1/2 and Pds5A/B. Structural information of cohesin is limited by the internal flexibility related to the Smc1/3 coiled coils. An engineered more rigid “bonsai” cohesin with truncated Smc1/3 coiled coils could be analyzed by single particle electron microscopy. The HEAT-repeat protein Pds5B forms a curved structure around the nucleotide binding domains of Smc1 and Smc3 and bridges the Smc3-Scc1 and SA1-Scc1 interfaces. This indicates that Pds5B forms an integral part of the cohesin ring by contacting all other cohesin subunits, a property that may reflect the complex role of Pds5 proteins in controlling cohesin-DNA interactions.