Invited Speaker
Valentin Rybenkov
DNA organization by bacterial condensin MukBEF
MukBEF is a bacterial prototype of eukaryotic condensins and cohesins and plays a key role in global organization of the Escherichia coli chromosome. The core of this complex, MukB, belongs to the ubiquitous, highly conserved family of SMC (structural maintenance of chromosome) proteins, which adopt the idiosyncratic, V-shaped structure in solution. Using a combination of biochemistry and DNA nanomanipulations, we show that MukBEF acts as an ATP modulated macromolecular assembly that can bring distant DNAs into a stable complex. MukBEF binds DNA in a highly cooperative, ATP-stimulated manner producing oligomeric protein clamps. The resulting clamps are highly resilient to applied force and can form a bridge with another DNA. Both linear and circular DNA can be efficiently bridged by MukBEF. We propose that MukBEF forms a network of loosely linked clamps that divides the chromosome into a set of giant loops.