This study employed both bioinformatics and molecular methods to predict and biologically characterize the replication origins on CI and CII of R. sphaeroides. Z-curve and GC skew analyses indicated that CI and CII have three and five putative replication origins regions, respectively. They were named as OriCI1, OriCI2, OriCI3, OriCII1, OriCII2, OriCII3, OriCII4, and OriCII5. Analyses of gene conservation and gene density ratios distribution further imply that OriCI3 and OriCII4 are the formidable candidates of the true origins of CI and CII of R. sphaeroides. Thus, the current study concludes the identification of a single origin of replication of CI and CII in R. sphaeroides.
The continuity of bacterial species requires replication of their chromosomes, partitioning of the chromosomes into two haploid nucleoids, and formation of the septum, which together assure each of the newly divided cells with a full set of genetic information. The bacterial cell cycle consists of three stages, B period, C period, and D period, which correspond broadly to G1, S, and G2/M phases of eukaryotic cell cycle, respectively. These three stages are sequentially coordinated and genetically regulated. The bacterial cell cycle begins with a newly divided cell, and when it reaches to an optimal size, the chromosomal replication initiates and continues till the genome gets fully replicated.