Centromere interactions promote the maintenance of the multipartite genome in Agrobacterium tumefaciens

Many pathogens and symbionts contain multipartite genomes, but how they are stably maintained is poorly understood. The plant pathogen, Agrobacterium tumefaciens, contains four replicons. Recent work indicates that their replication origins cluster at cell poles in a manner that depends on their ParB-family centromeric proteins. Here, we provide evidence that centromeric clustering is mediated by interactions between these centromeric proteins. We further show that the disruption of centromere clustering results in the loss of replicons. Our data establish the role of centromeric clustering in multipartite genome maintenance. Hi-C and ChIP-seq experiments were performed on wild type and mutant cells of Agrobacterium tumefaciens C58 or 15955 growing in LB, ATGN and mutant cells of Bacillus subtilis PY79 growing in rich media.