Bacterial genome organisation by DNA topology remodelling machines

Structural maintenance of chromosomes (SMC) complexes help to shape, segregate and guard the genome in prokaryotes and eukaryotes. How they execute these different functions at the molecular level remains unclear. I have pioneered the high-resolution electron cryo-microscopy (cryo-EM) analysis of the bacterial SMC complex MukBEF, which revealed a snapshot of its interaction with chromosomal DNA. I will now build upon my findings with a multi-disciplinary approach to ask: (i) how MukBEF extrudes DNA loops to compact and shape bacterial chromosomes; and (ii) how MukBEF cooperates with topoisomerase family proteins such as TopoIV to segregate replication origins and protect cells from plasmid infection. I will use in vitro reconstitution to study the genome organisation reaction by biochemistry and cryo-EM, aiming for a full structural understanding of its molecular mechanism. I will clarify the regulation by cellular housekeeping factors. I will determine the mechanism of MukBEF TopoIV supercomplex formation and establish how two fundamentally conserved chromosome segregation factors join forces. In addition, I will resolve how MukBEF homologues activate the topoisomerase-like MksG to sense and eliminate infective plasmids. This work will deliver unprecedented new insights into bacterial chromosome biology and inform related processes in eukaryotes.