Studies in groups in the Division are aimed at determining structures of large protein complexes using a combination of EM and X-ray crystallography. In the Wigley lab work is focused on several large multi-subunit protein complexes involved in the DNA double-strand break repair process. These include systems that remodel chromatin (Ino80), exchange histones (Ino80 & Swr1) and label them (Tip60 & NuA4). The broken DNA ends are processed by RecBCD/AddAB complexes in bacteria or by interaction s between the Blm/Dna2/RPA, Top3/Rmi1/Rmi2 and Mre11/Rad50/Nbs1 complexes in humans. The Barford lab is studying protein complexes involved in regulation of the cell cycle. A particular interest is the anaphase-promoting complex (APC/C) that functions as an E3 ubiquitin ligase to regulate defined cell cycle transition by targeting specific cell cycle regulatory proteins such as cyclins for degradation through the ubiquitin-proteasome system. The APC/C-co-activator complex comprises 14 differ ent proteins with a molecular mass of 1.2 MDa. The Vannini lab (starting March 2012) will be focussing on RNA polymerase III using a combination of cryo-EM and X-ray crystallography. The Guettler lab (starting October 2012) will be focussing on mechanisms of poly-ADP ribosylation.