To preserve the integrity of their genome, bacteria rely on several genome maintenance mechanisms that are co-ordinated with the cell cycle. All members of the family have a bipartite genome consisting of a primary chromosome (Chr1) homologous to the single chromosome of other bacteria such as and a secondary chromosome (Chr2) acquired by a common ancestor as a plasmid. In this review, we present our current understanding of genome maintenance in , which is the best-studied model for bacteria with multi-partite genomes. After a brief overview on the diversity of genomic architecture, we describe the specific, common, and co-ordinated mechanisms that control the replication and segregation of the two chromosomes of . Particular attention is given to the unique checkpoint mechanism that synchronizes Chr1 and Chr2 replication.