Bacterial genome organisation by DNA topology remodelling machines (360G-Wellcome-227260_Z_23_Z)

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.