Chromosomal Replication, Plasmid Replication, and Cell Division

The study of chromosomal replication and cell division of bacteria has extended beyond , and important insights have emerged recently from studies in other species, especially and (55, 67). In contrast, there is still little information about cell division processes in . Analyses of the complete genome sequences of strains 26695 and J99 (2, 64) provide insights into the cell division mechanisms of this microorganism, a spiral-shaped gram-negative bacterium with a bundle of polar flagella. Many genes homologous to those involved in replication and cell division in are found in the genome, suggesting similar basic mechanisms for both bacteria. Orthologs of some genes have not been identified in the genome, suggesting differences in the cell proliferation machinery of both bacteria, which belong to different subdivisions of the . Cell division is coordinated with other cell cycle events such as genomic DNA synthesis that leads to chromosomal replication and partition, increase of cell mass, and cell expansion by cell wall synthesis. Thus, in this chapter the information about predicted genes related to chromosomal replication, plasmid replication, and cell division in is reviewed, and a plausible replication machinery of the bacterium is discussed in light of our current understanding of bacterial organization and function of replication and cell division. The focus of the section on chromosomal replication is on the replication origin and genes of the replication complex, while division site, filamenting, and other related genes are discussed in the section on cell division.